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In fixed partial denture
Content• Introduction
• Concepts of crown contour
• Photographic analysis of emergence profile
• Emergence Margin in Periodontally Involved Teeth
• Recording soft tissue emergence profile.
• Emergence profile in ovate pontic.
• Summary
• Conclusion
• References
The term “emergence profile” was first used in 1977 by Stein and Kuwata to describe tooth and crown contours as they traversed soft tissue and rose toward the contact area interproximally and height of contour facially and lingually.
In 1989, Croll B M it was explained as the portion of axial tooth contour extending from the base of the gingival sulcus past the free gingival margin into the oral environment.
Croll BM. Emergence profiles in natural tooth contour. Part I: Photographic observations. J Prosthet Dent 1989;62:4–10.
1989 Fugazzotto explained •emergence profile as the angle at which the tooth comes out of the supporting osseous structure.
He suggested that a tooth should emerge in a perpendicular manner from the osseous structure to obtain good periodontal health.
Preparation of the Periodontium for Restorative Dentistry.Tokyo: Ishiyaku Euro America, 1989:17.
Glossary of Prosthodontic Terms
•defined it as the contour of a tooth or restoration, such as a crown on a natural tooth or dental implant abutment, as it relates to the adjacent tissues.
The Glossary of Prosthodontic Terms, ed 7. J Prosthet Dent 1999;81:48
The location and emergence of the prosthetic margin are crucial to the :
• gingival health and maintenance of oral hygiene.
• esthetic objectives
A proper emergence profile will help avoid swelling and inflammation of soft tissue
and conversely will prevent the unsightly dark spaces in the area near the gums and between the teeth.
Croll BM. Emergence profiles in natural tooth contour. Part II: Clinical considerations. J Prosthet Dent 1990;63:374–379
Emergence profiles are the most crucial link between tooth form and gingival health.
The microorganisms that cause periodontitis and gingival inflammation can colonize on these surface areas.
Careful attention to developing the proper emergence profile in the definitive restoration will reduce not only plaque retentive areas but also iatrogenic inflammation
Restorative margin placement and periodontal health. J Prosthet Dent 1991;66: 733–736.
• Clinical longevity of any prosthesis is directly related in achieving proper coronal contours.
• This involves close attention to detail between periodontal and prosthodontic principles during the fabrication of the prosthesis.
• TEN RULES FOR DEVELOPING CROWN CONTOURS IN RESTORATIONS
• Burch, J.G. Ten rules for developing crown contours in restorations. DCNA 1971;15:611-618. 1)Faciolingual crown dimensions- no more than 1mm larger than the faciolingual width at the CEJ. Possible exception: mandibular molars and second premolars.
• 2)Facial contours- all facial contour crests are in the gingival third, and should not bulge more than one-half mm beyond
CEJ.
• 3)Lingual contours- greatest convexity at gingival 1/3 except mandibular molars and sometimes mandibular second premolar, where greatest convexity is found in the middle 1/3 of
crown.
4)Proximal contact points- in the occlusal 1/3 of crown.
5)Proximal surfacesProximal surface is flat or slightly concave buccolingually as
well as occlusocervically.
• 6)Axial transitional line angles-
• straight between the proximal contact point and the CEJ,
• with the exception of the lingual line angles of maxillary molars, where there may be a slight convexity.
• 7)Marginal ridges- should be the same height for adjacent teeth. The facial ½ of
any tooth is wider than the lingual. Lingual embrasures are always larger than buccal embrasures when viewed occlusally
• 8)Crown margin- should be supragingivally except due to esthetics, crown length to
gain adequate retention, root caries, root sensitivity, existing restorations.
9)Thickness of restoration:
•The subgingival contour has considerable effect upon the free marginal gingiva and the gingival crevice.
•subgingivally- inadequate contour may not provide for adequate support for the gingival unit.
•Subgingival contour should support the gingiva, so that the free marginal gingiva does not tend to form a roll around the tooth.
10)Crown margin/Bone• relationship- do not encroach on the biologic width.
• Contour of the crown should not be bulky as it might tear circumferential fibres and undue stress might be exerted on gingiva beyond their physiologic limits of tolerance.
DESIGINING CROWN CONTOUR IN FIXED PROSTHODONTICS:A NEGLECTED ARENA Annals and Essences of (DentistryVol III Issue 1 jan- Mar 2011
Some common clinical problems
•improper axial, facial or lingual contour of crown.
•Contour of artificial crown are not generally made self protective.
•Overcontouring leads to food trap and hence complicating the periodontal status.
•Interdental papilla is often neglected due to improper design of interdental space.
•These shortcomings can be fulfilled by following the general principles of crown designing.
current controversies in axial contour design: JPD 1980 vol 44 pg 536
• Traditional concepts of crown contour:
1)Food deflection theory (Wheeler) 1961.
He advocated that artificial crowns should have convexities in their cervical third which will help in deflecting food away from the free gingiva.
• Herlands et al questioned the rationale of the
food deflecting contour concept. He noted that• When prepared tooth is left uncovered for an extended
period of time, complete lack of contour is usually seen but the surrounding gingiva is usually healthy.
current controversies in axial contour design: JPD 1980 vol 44 pg 536
Later found
Crowns made with Wheeler’s concept
Overcontoured
Food impaction
gingival inflammation
current controversies in axial contour design: JPD 1980 vol 44 pg 536
• current controversies in axial contour design: JPD 1980 vol 44 pg 536
2)Muscle action theory (1962)(Herlands et al and Morris).
• They emphasized on muscle moulding and cleansing, rather than food impaction.
• This theory upholds the principle of constant cleansing and molding action by the muscles of the cheeks, lips and tongue.
• Muscle action can be impaired when the necessary intimate contact is prevented by an over contoured crown or bone.
Mortan L. Perel (1971) studied the relationship between axial tooth contour and marginal
periodontium on dogs.
• Procedures producing undercontours and overcontours on buccal and lingual crown surfaces on surrounding marginal gingiva. were performed.
• Clinical and microscopic evaluations were made in respect to the condition of the marginal periodontium and the crevicular areas, He concluded that:
1. Undercontouring of axial surfaces did not produce any significant changes in healthy gingivae.
2. Overcontouring of axial surfaces, on the other hand, produced inflammatory and hyperplastic changes in the marginal gingivae. Such changes were seen both clinically as well as histologically, after 4 weeks.
3) Plaque retention theory• According to this theory
Crown contours should be such that it should not provide any niche for plaque retention and should promote self-cleaning.
• Design of axial contour should be based on muscle-action theory
…4) Anatomic/ Biologic theory • It was proposed by Kraus et al. in 1969.
According to this theory:• A biologic contour is a self protective contour to the
supporting tissues and defended the gingival unit, attachment apparatus, and protected bone from trauma and irritation.
• Improper contour often induced early breakdown of the supporting structures and tooth tissue, resulting in premature loss of teeth.
5) Theory of access for oral hygiene
• Based on the concept that plaque is the prime etiologic factor in caries and gingivitis.
• Crown contour should facilitate and not hinder plaque removal.
4 guidelines contouring crowns to access for oral hygiene are:
1)Flat (and not fat) buccal contours.2)Open embrasures.3)Location of contact areas.
4)Fluted or barreled out furcations.
…1)Buccal and lingual contours - flat, not
fat The normal buccal-lingual width of a non-restored natural tooth is
approximately 1 mm wider at the maximum buccal-lingual dimension (height of contours) than the buccal-lingual width at the CEJ.
.
Therefore there is a minimum infrabulge so that muscle action cleansing that might be present can be operable
• Buccal bulge on a normal tooth is no more than 0.5 mm prominent from the CEJ
• There is also a gradual sloping, giving a flat appearance.
Sharp angles or abrupt convexities or concavities should be avoided to maintain tone of musculature of lips, cheek and tongue.
The facial and lingual surface contours should have gradual curvatures in all directions to facilitate the rubbing and cleaning function of the lips, cheeks, and tongue
• Plaque retention on the buccal and lingual surfaces occurs primarily at the infrabulge of the tooth.
• Reduction or elimination of the infrabulge would reduce plaque retention.
2. Open embrasures: To allow easy access to the interproximal area for
plaque control.
• The faciolingual width of the contact area is generally in harmony with faciolingual width of the interproximal papilla.
• lnterdental papillae should not be impinged by interproximal surface.
• An overcontoured embrasure will reduce the space intended for the gingival papilla.
• The result is a broadening of the col area, causing pressure and irritation on the papilla.
• This also inhibits effective oral hygiene
If the faciolingual width of the contact area is wider than the papillla, an overhang is created which will permit plaque accumulation.
• . Spaces between interproximal areas which are created due to gingival recession should be closed toward the papilla without impinging them.
:3. Location of contact areas Contacts should be high ( incisal third ) and buccal to
the central fossa ( except between the first and second molars).
This creates a large lingual embrasure for optimum
health of the lingual papilla.
• A rationale for comparison of plaque retaining properties in crown systems. J Prosthet Dent. 1989,62:264-9.
Hazen and Osborne have warned of the consequences of an ‘‘oversized’’ col resulting from broad (buccolingual) contacts.
• The col is a nonkeratinized area which is thought to be more susceptible to plaque.
• The broad contact produces a larger col, thereby leading to increased chance of inflammation.
Ramfjord S. Periodontal aspects of restorative dentistry. J Oral Rehabil 1974;1:107
• Ramfjord recommends placement of contact areas as far occlusally as possible to facilitate access for interproximal plaque control.
4. Furcations should be “fluted” or “barreled out”.
• The final restoration should not follow the anatomy of the original clinical crown, but should be an extension of the contours of the periodontally exposed roots.
Triangular region created by the roots and the cervical
bulge is eliminated
• The concept of fluting into molar furcations is based on the desire to eliminate ‘‘plaque traps’’ and facilitate plaque control
This triangular region is the most difficult area to maintain in a plaque-free condition with conventional brushing techniques.
• In 1989, a photographic analysis of natural teeth by Croll confirmed that most emergence profiles are relatively straight as opposed to convex or concave. If a restoration introduced a convexity or concavity where it didn’t belong, the unnatural contour might trap plaque or otherwise disrupt the gingiva.
Croll BM. Emergence profiles in natural tooth contour. Part I: Photographic observations. J Prosthetic Dent 1989;62(1):4-10.
• Several hundred extracted teeth were photorgaphed for this study.
• Photographs were made with a 105 mm macro lens to minimize parallax.
• Anatomic observation were also recorded from
1)Intraoral photographs of natural teeth.
2)Photographs of mounted diagnostic casts in cross section.
3)Radiographs of teeth made by using a parallel cone technique in vivo.
• A straight edge placed on the photogragh provides a gauge to evaluate relative straightness, convexity, and concavity of the tooth structure.
• Observation were made to establish the anatomic norm for emergence profiles at specific sites through out the dentition for developing a basis of accurate reproduction in clinical dental restorations.
Convexities were discovered palatally in the maxillary incisors and lingually on mandibular
incisors viewed mesiodistally.
Maxillary incisor Mandibular incisor
Maxillary canine, anatomic crown.
Maxillary canine, sectioned diagnostic casts.
Maxillary canine, gingival overlay.
41
2
A comparison of figures A, B and C indicates that most of the buccal surface emergence profile of the anatomic crown may be submerged below the free marginal gingiva, extending only 1 mm into the oral cavity.
Palatal convexity in maxillary canine
the convexity on the lingual surface may also be submerged below the free marginal gingiva palatally.
The emergence profile often extends buccally and lingually to the height of contour of the crown of a tooth.
Interproximally, the emergence profile extends from the base of the gingival sulcus at the cement enamel junction (CEJ) to the contact area.
Emergence profile of maxillary first premolar, buccal view
The buccal and palatal surfaces of maxillary posterior teeth present straight emergence profiles in the gingival third of the anatomic crown.
Restorations made with convexities in the gingival third should be considered overcontoured.
Over contoured buccal and lingual surfaces.
Concavities were regularly observed on the: distal surfaces of canines
mesial surfaces of maxillary first premolars
Interproximal view b/n maxillary canine n 1st premolar.
The concave emergence profile of each tooth present a mirror image of the other.
Croll BM. Emergence profiles in natural tooth contour. Part I: Photographic observations. J Prosthetic Dent 1989;62(1):4-10.
The lingual surfaces of mandibular posterior teeth have straight emergence profiles from the CEJ to
points one half to two thirds of the distance to the occlusal surface.
Mandibular second premolar, anatomic crown.
Mandibular second premolar, sectioned diagnostic cast.
Interproximally, the mesial surface emergence profile of maxillary first molars is concave below the
contact area.
Maxillary first molar, buccal view, concave emergence profile below mesial contact on right.
The emergence profile on the buccal surface of the mandibular posterior teeth is one of three straight lines comprising the entire facial profile. Restorations made with these facial contours are natural in appearance.
Intra oral view showing straight emergence profiles in the buccal vestibule of mandibular posterior metal ceramic restorations following patterns on contours in natural teeth.
Radiographs are useful to visualize the interproximal emergence profiles of one tooth as it relates to adjacent teeth and the emergence profile of completed restorations.
In Interproximal black triangles can be identified radiographically, with the base formed by the bone and the other sides formed by the adjacent teeth.
A radiograph of a completed restoration having retainers with straight interproximal emergence profiles creates black triangular spaces and adequate embrasure spaces that duplicate the morphology of natural teeth.
A comparison of the two demonstrates the relationship of interproximal emergence profiles of maxillary incisor teeth
seen clinically with a radiograph.
..
Radiograph of same maxillary incisors demonstrating straight emergence profiles below long contact areas extending to CEJ.
Metal ceramic crowns were inserted with long contact areas
and straight interproximal emergence profiles for natural
looking restorations, while closing the interproximal gap.
4 maxillary inicisors after periodontal surgery prepared for metal ceramic crowns
without interproximal papillas.
When the contact areas are long occlusogingivally, the normal emergence profile on the palatal surface provides a wide open gingival embrasure to support the tissue in its proper relationship to the restoration and to facilitate hygiene procedures.
Concluded that with a few exceptions, teeth have straight emergence profiles in the gingival third.
Burney M. Croll
Emergence profiles in natural tooth contour. Part I: Photographic observations: Burney M. Croll; JPD vol 62 1989
• Emergence profiles in natural tooth contour. Part II: Clinical considerations: Burney M. Croll; JPD vol 63 1990
• confirmed the straight emergence profile as the norm in naturally occurring axiogingival tooth contour.
• Observations supporting a straight emergence profile as the normally occurring tooth morphology approximating the gingival sulcus, based on photographic measurment ,are a departure from traditional concepts by wheeler and other authors.
• The curved transition of axial tooth contour at the height of contour is not always located at the gingival one third.
• Interpreting emergence profiles as geometric shapes can provide guidelines for oral hygiene, restoration design, and tooth preparation.
A straight line and a curve meet only at one point, the tangent.
•Conversely, a straight line and a flat emergence profile can be adapted to one another.
• The emergence profile affects the convenience and effectiveness of oral hygiene procedures.
• Toothbrush bristles and tooth picks used in conjunction with handles such as Perio-aid device are straight in profile.
• Restorations designed and placed with straight emergence profiles in the gingival one-third provide the patients with a shape that is accessible and facilitates oral hygiene.
• This same rationale is applicable in the convex tissue-facing surface of the modified ridge lap, recommended by Stein, with optimal contact of the dental floss, improving oral hygiene.
Emergence profiles in natural tooth contour. Part II: Clinical considerati
The Journal of Prosthetic Dentistry 63, Issue 4, April 1990, Pages 374–379
• A straight emergence profile will enable effective reaching to the depth of the sulcus in close contact with the surface of the restoration.
• This is especially desirable on the surface of the tooth beyond the cavosurface margin, to facilitate removal of the accumulated microbial plaque.
• If the emergence profile of the restoration is convex in the gingival one-third, it is possible, but inconvenient, to remove the bacterial plaque on the tooth surface contacting the gingival sulcus below the point of tangency.
The lingual surfaces of mandibular incisors provide an example where a convex emergence profile in the
gingival third is common.
Lingual convexity below the gingival tissue.
Convexity above the gingival tissue with the tooth extruded and gingival recession
creating a niche, difficult to keep clean.
The calculus and bacterial plaque accumulated on the surface below the lingually convex
emergence profile are evident because it is inconvenient for the patient to maintain.
• A modification of the natural tooth can create a surface that is more easily maintained by the patient.
• Specifically, the lingual surface of mandibular incisors may be restored with a straight emergence profile.
Straight emergence profile selected for lingual surface of mandibular anterior restoration to facilitate oral hygiene.
• If the dentist chooses to extend the contact area between anterior teeth from the incisal embrasure to a level of the gingival papilla for esthetics, the lingual embrasure must be wide enough for access to the gingival tissue under the contact area from the lingual surface.
When viewed from the facial surface, the mandibular incisors have straight interproximal
emergence profiles that begin at the end of a long contact area and extend to the CEJ
Relationship of natural anterior teeth-contact areas and gingival tissue.
Sectioned diagnostic casts reveal a flat facial emergence profile of mandibular anterior teeth extending to a point midway on the facial surface when viewed from the inter proximal aspect.
If restorations follow this pattern, they can be esthetic and allow convenient interproximal
threading of dental floss.
Mandibular anterior teeth with long contact area and straight emergence profile.
Mandibular anterior teeth with long contact area and straight emergence profile on pontic of
mandibular lateral incisor.
Similar to the maxillary canine, the mandibular canine has a concavity below the contact area on
its distal surface.
• Tooth preparations must be designed to accommodate dimensional requirements of restorative materials within the limits of the emergence profile.
• Depth cut” controlled shoulder preparations with a hollow-ground bevel are an approach that meets these requirements.
• Hollow Ground (Concave) Bevel: Allows more space for the cast material bulk Used to improve retention and resistance to stresses
“The emergence angle made by the emergence profile and the long axis of the tooth is +15 degrees.
On the basis of mathematical axioms, Kuwata concluded that if the path of insertion was parallel to the long axis of the tooth, all metal ceramic restorations with cavosurface bevel angles less than 35 degrees with the path of insertion should have metal collars to prevent over contouring and opaque exposure.
If adequate space has been created for
the restorative materials during tooth preparation, retainers of fixed partial dentures can be made with suitable emergence profiles.
Selection of the straight emergence profile in designing artificial crowns for teeth has shown to improve the effectiveness of oral hygiene near the gingival sulcus.
The axial profile of teeth can be viewed as a series of straight lines with curved transitions. Reproduction of these geometric patterns facilitates fabrication of restorations that appear natural.
LABORATORY APPLICATION
Several waxing instruments have a flat surface to create a flat profile in the marginal area of the
wax pattern.
The convex side of the waxing instruments can develop concave contours in the wax pattern such
as the distal surfaces of maxillary canines and mesial surfaces of the premolars.
• Mounted grinding wheels and sandpaper disks have flat cutting profiles that can machine straight emergence profiles and finish restorations during fabrication.
• Clinically, the facial and lingual surfaces of the restorations can be easily evaluated for straight emergence profile with a periodontal probe.
Interproximally, radiographs provide the best picture to establish that the desired emergence profile and
adaptation between the restoration and root have been accomplished.
• Reproduction of these geometric patterns creates restorations that appear natural.
The Emergence Margin in Periodontally Involved Teeth
• International journal of periodontics n restorative DentistryVolume 13, Number 4, 1993
The Emergence Margin in Periodontally Involved Teeth
• Following periodontol treatment, Periodontally involved teeth often exhibit elongated clinical crowns that create esthetic problems.
• Prosthetic design may be difficult because changes in root morphology and angulation increase the technical demands of creating parallelism for a common path of insertion,also the design of the crown margin and the placement of the preparation's finish line in relation to the gingival margin could be difficult, because of esthetic, prosthetic, and biologic factors.
• The precision of the marginal fit and the emergence profile of the root should be key concepts in prosthetic construction of periodontolly treated patients.
Two features of importance in preparing finish lines and prosthetic margins:
• Marginal fit of the crown must be precise
• Restoration margin must follow the direction of the emergence profile of the root.
Feather-edge margin traditionally has been the preparation of choice, because it allows the achievement of abutment parallelism with minimal removal of tooth structure at the marginal areas.
•This type of preparation margin has some limitations for metal-ceramic restorations.
• 1)the preparation margins are not always clear and distinct therefore, the dental technician does not always have a clear landmark for the position of the finish line in relation to the gingiva.
• 2)Space is limited for the porcelain in the cervical area, thus the crown emergence profile could have some degree of overcontour.
• Shillingburg etal indicated that margins of metalceramic restorations fit on featheredge finish lines offer poor resistance to the distortion that results when the ceramic is baked onto metal.
• International journal of periodontics n restorative DentistryVolume 13, Number 4, 1993
• Busto Garolfo
a new preparation margin, the emergence margin in prosthetic reconstruction of periodontolly involved teeth.
Because this type of preparation may help in maintaining a biologic relation between restoration and periodontium.
• it is conducive to periodontal health while it satisfies the patient's esthetic demands.
Finish line preparation • The 50-degree finish line was selected for Periodontally
involved teeth.
• Emergence profile of root
A line drawn tangentally to the cementoenamel junction frequently continues as a coronal extension of the root
• This line continues apically in the root portion of the finish line and draws the ideal margin of the emergence profile of the cervical portion of the prosthetic crown.
In this manner, vertical or horizontal overcontours and undercontours gingival margin are avoided.
This emergence profile will have different angulations, depending on different root anatomy and the position of the preparation margin along the root surface.
• relatively easy to prepare
• always results in a clear margin
• prevents great tooth loss
• achieves a precise marginal fit without a visible metal collar
• and can be prepared around all surfaces of the tooth.
• Allows enough space for the metal-ceramic restoration in the buccal surface, and enough clearance at the interproximal surfaces of mandibular anterior teeth for the metal collar fit, without damaging the biologic sulcular space.
Placement of the restoration margin 1 mm subgingivally is recommended to avoid root sensitivity and root caries and to satisfy the patient's esthetic demands.
• When the technician is to be given anatomic indications of the emergence profile, the impression material should extend more apically than the finish line preparation to record the direction and contour of the root emergence profile.
Laboratory procedures
•To obtain an optimal orientation of the prosthetic profile, and to reach absolute precision of the marginal fit, every step in the laboratory procedures performed under the stereo micros cope at 10 xmagnification.
After the final impressions and stone pours are evaluated, the laboratory work continues with the exposure of the preparation margins
and the visualization of the root emergence profile.
carving of the wax margin seen under the stereomicroscope
The metal cast must be finished in the traditional way except at the margin.
metal must be polished until there is enough thickness for the ceramic layer. The metal finish margin must be entirely covered by the ceramic layer, but without overcontour.
To avoid the possibility of metal distortion around the preparation margin, a contra chamfer is made around the metal margin finish line, the angle of which increases the metal thickness in the critical region, preserving the ceramic layer.
• Opaque is applied to the metal margin, again using stereomicroscope visualisation.
show the final results of the emergence margin
Case
•A patient presented with extensive caries and tooth loss in the maxillary and mandibular arches.
• After periodontal and occlusal treatment were completed, final prosthetic restoration was initiated.
• After the final impressions were taken, stone casts were mounted in a fully adjustable articulator, maintaining the same occlusal relationships as in the provisional restorations..
• Then, a centric relation record was taken with the metal frames and transferred to the articulator.
• After the bisque try-in, position impressions were taken to remount the casts in articulator before the prosthesis was finalized..
• The intracrevicular margination was precise.
• The standard of precision was maintained also for the fitting surfaces in which the metal was covered by ceramic layer.
• One year later, the periodontal condition was stable.
• This patient had severe periodontal and prosthetic involvement. During the course of following periodontal treatment, provisional prostheses were used to allow periodontal healing.
• Precision of the margins in the provisional prosthesis was very important to promote adequate plaque control and healing of periodontal tissues
Provisional restoration finished under the stereomicroscope to check for prosthetic contour as well as root profile .This will prevent undercontouring or overcontouring, either of which would be harmful to the gingival tissues during the healing phase..
Recording the gingival emergence profile after tooth preparations for fixed partial dentures.
Gingival contour and occlusion of restorations are 2 important factors that influence periodontal health.
•Overcontoured restorations result in food and plaque retention in the interproximal, facial, and lingual cervical areas. This can lead to caries, gingival inflammation and gingival hyperplasia.
•Undercontoured restorations may create excessive interproximal spaces and problems with phonetics and esthetics.
•In clinical practices, dies are trimmed to expose margins of preparations.
•The soft tissue emergence profile that surrounds the prepared tooth is destroyed in the process.
• Modified soft tissue cast for fixed partial denture: a technique
J Adv Prosthodont. 2011 March; 3(1): 33–36. ]
The soft tissue casts have become a popular aid in fabrication of the cervical contours of the implant crowns, but their use in a conventional fixed partial denture also play an important role.
These models have gingival masks which duplicate the gingival architecture of the involved abutments.
• Modified soft tissue cast for fixed partial denture: a technique
J Adv Prosthodont. 2011 March; 3(1): 33–36. ]
Uses:
1) allow the lab technician to see the existing gingival architecture surrounding the involved abutments and make corrections in the metal substructure to allow for proper emergence profile and contour.
2) provide the key to proper ceramic application.
• TECHNIQUE• Abutment teeth were prepared to receive a fixed partial
denture. The impression was made with a polyvinyl-siloxane material.
• The impression was disinfected and poured. After retrieval of the master cast, impression was washed thoroughly to prepare it for second pour to fabricate a modified soft tissue cast
• A polymethylmethacrylate based resilient liner carefully mixed and applied onto the facial and proximal aspects of the impression surface around the prepared and edentulous spaces with a small painting brush.
• Multiple undercuts in the form of irregular surfaces prepared to achieve mechanical interlocking in the gypsum material.
• The resilient liner was polymerized by immersing the liner-applied portion of the impression in the hot water (60 for 2-4 minutes) as per the manufacturer's ℃instructions.
• The water temperature should not be increased more than 70 to prevent any dimensional change in the ℃impression.
• After complete polymerization of the resilient liner, remaining portion of the impression was poured in type III gypsum material .The cast was retrieved from the impression after setting of the gypsum material.
• This soft tissue cast was used along with master cast to develop and evaluate ideal axial contours of the fixed partial denture.
Fixed partial denture in place with correct gingival emergence profile.
• Soft Tissue Transfer Models: The Patient-Dentist-Laboratory Connection (Canadian Dental Association)
Bulky metal substructure for anterior maxillary porcelain fused to metal bridge
• This is due to the loss of reference gingival architecture during die trimming and separation procedures.
• The framework can still be related to the gingival architecture with the use of soft tissue transfer models.
Recording Technique • The metal substructure is seated intraorally and a
transfer impression made using:- dual wash (light/medium body) technique: - light body impression material (injected around the
seated framework medium body impression material within a stock tray
.
Transfer impression incorporating porcelain fused to metal substructure.
After the impression has been made, the inside of each abutment retainer is slightly lubricated with a thin layer of Vaseline.
Pattern Resin is painted inside each retainer.
• Pattern Resin is used to register the location of the abutments within the soft tissue model. The dimensional stability of this resin upon setting, allows for a very accurate representation of the position of the abutments.
• The gingival mask is then made by mixing Coe-Soft reline material into a disposable syringe and injecting it around the bridge, and the model is poured with die stone.
Properly contoured porcelain of anterior maxillary bridgework:
on the soft tissue transfer model respecting the clinical gingival contour.
intraoral view, respecting the clinical gingival contour.
• Accurate procedure for simultaneous registration of gingival emergence profile and maximal intercuspal position for metal ceramic restorations. (J Prosthet Dent 2000;83:681-5.)
This article describes a simple and accurate procedure that can be used to simultaneously register the gingival emergence profile and maximal intercuspal position.
• After adjusting and seating of the copings, dry the entire surface of the copings.
• Wetting the sable brush (size 0) with monomer and picking up the polymer (this is commonly referred to as the Nealon technique )and applying the mixture in small increments.
• Apply autopolymerizing hard acrylic onto the occlusal facial surfaces of the copings and onto the facial free gingival margin
• Avoid painting the acrylic resin into undercut areas. The undercut area is usually the gingival embrasure area of the adjacent teeth. When the undercut areas are large, a small amount of soft wax may be used to block them out.
The free gingival margin distance from interdental papilla to interdental papilla should be covered with
Duralay acrylic resin.
• After the record is clinically verified, remove the copings from the patient’s mouth ensuring that the acrylic resin remains attached to the copings.
If the acrylic resin does not adhere to the copings, the procedure should be repeated, making certain that the surfaces are roughened and dried before application of resin.
• Remove any excess acrylic resin that interferes with the seating of copings on the dies and with seating the dies back onto the working cast.
Articulate and mount the mandibular cast using the acrylic resin interocclusal record that was made in the maximal intercuspal position.
• Inject low-viscosity polyvinyl siloxane impression material into the space between the seated dies and copings and the acrylic resin. The impression material may be extended onto any part of the working cast for indexing purposes.
• Remove the acrylic resin from the copings and from the polyvinyl siloxane impression material. If the resin cannot be easily removed from the copings, it can be softened by heat in an oven or with a torch, and then removed. The resin does not adhere to the polyvinyl siloxane material.
• Complete the porcelain addition and finish the metal ceramic restorations
Tissue sculpturing: An alternative method for improving emergence profile of anterior
fixed prosthodontics J Prosthet Dent 1999;81:630-3.
• This article described a method for improvement of emergence profile and soft tissue health by exerting pressure on tissue with provisional restorations.
• A gradual, controlled hyperpressure can transform an unfavorable tissue configuration to favorable.
• This allowed a more natural, functional FPD. There is also a possibility of closing undesirable “black holes” through papilla “formation” by pressuring tissue.
• Specific tissue dilation can also be accomplished with eletrosurgery when removing soft tissue to create pontic sites.
• Nonsurgical, • Minimally invasive and safe procedure• Patient is not exposed to complications of surgery. • There is no tissue removal.• Interdental papilla was enhanced or sculptured by
the lateral displacement of the tissue over a residual ridge
Similar hyperpressure procedures have been used for tissue conditioning before implant placement.
• Fabricate a provisional FPD with slight pontic contact beneath the residual ridge.
• Apply gradual, gentle compression over the soft tissue by adding acrylic resin over the pontic surface toward the ridge.
• The amount of acrylic resin added should not exceed 1 mm to avoid excessive pressure. The provisional restoration should be inserted only after final curing of acrylic resin to evaluate hyperpressure.
• The pressure should be capable of producing a tissue ischemia without interfering with the fit of the provisional restoration
• Develop a convex shape for the pontic both buccolingually and mesiodistally.
• This shape allowed easy, accessible flossing, which is critical for longterm treatment outcomes.
• Highly polish all surfaces, especially the surface contacting the ridge.
• Cement the provisional restoration.
• Recall the patient in 1 week to evaluate accommodation of the tissue beneath the pontic.
• Remove the provisional restoration during this visit and add a new layer of acrylic resin to continue the tissue conditioning.
• The amount of resin to be added is judged through an analysis of the shape of tissue and esthetics .
• After adding the acrylic resin, polish and recement the provisional restoration.
• Repeat this procedure every week until final esthetic conditioning.
• An improvement in emergence profile of the pontic and the appearance of an extruded pontic from the gingival tissue can be achieved at this time .
• The dentist must be aware of the limit of tissue resilience, which should be closely monitored. Strength and direction of pressure are determined by esthetics.
• Make a standard impression after completion of conditioning to provide a master cast with a removable artificial gingiva.
• Transfer the tissue shape to the cast. This will allow the dental technician to fabricate a pontic with identical final characteristics.
Disadvantage
residual ridge deformities types I, II, and III, according to Seibert. Soft tissue grafts are indicated for these patients, before conditioning tissue
Dent Update 2012; 39: 407–415
Ovate pontic : A natural look•The emergence profile of the pontic is especially important if the bridge is planned in the anterior maxilla and the patient has a high smile line.•This pontic design has been proposed to address the issue of emergence profile aesthetics.
•An ovate pontic design can be defined as one which has an increased amount of mucosal contact and applies light pressure to the underlying mucosa in an attempt to improve aesthetics.
Dent Update 2012; 39: 407–415
• The ovate pontic has been suggested as a more accurate duplication of emergence profile for natural teeth to provide an esthetic.
• The goal of an ovate pontic is the illusion that the tooth is emerging from the gingiva with a cuff of tissue surrounding it on the facial.
• The ovate pontic :• Excellent aesthetics, especially emergence profile.• Helps to create or maintain the presence of interdental
papilla.• Reduce the presence of black triangles;• Avoid alveolar collapse.
Ridge Evaluation of Ovate Pontics J esthet restor dent 2013,273-78
•for the ovate pontic to be successful, there must be sufficient height and width of alveolar ridge
•There are three things we look at in order to decide whether the ridge is adequate, or if it would need augmentation to accommodate the pontic.
1)Interproximal height
2)Free gingival margin
3)Facial prominence
• The interproximal tissue should be preserved after the removal of a tooth.
• It is important to preserve the socket size, shape, and the space of the gingival tissue in order to preserve the tissue height.
• extracted socket must be preserved in the same shape and location.
• recession of the interproximal papilla and the collapse of the buccal bone
Tooth is extracted,
Loss of support to the papilla
slumping of the papillary tissues immediatelyWithin 30-60 minutes that papilla will have slumped to the point of no return.
•The worst thing that can happen, when patient bite on the gauze immediately after extraction, forcing the papilla down into the socket site.
• Meticulous care should be given during surgery on interproximal crestal bone.
• Damage the buccal or lingual plate of bone or the soft tissue is crucial to the formation of a natural looking ovate pontic site.
• To preserve the papilla during the extraction procedure fill the extraction site with the provisional pontic as soon as possible.
By creating a preoperative temporary bridge for the socket area with an ovate pontic design, the papillae will be supported during the healing phase postoperatively.
• Tooth is missing for some time, generally there will be a loss of ridge support creating a deficiency or depression in the ridge overlying the missing root.
There is no way to regenerate a papilla, however by building up the ridge with soft tissue, and then sinking a round diamond into the soft tissue buildup, a simulated papilla can be created.
A small round depression in the gingival tissue along the ridge is created, allowing the pontic to be embedded within the "crater" so as to appear to be emerging from the ridge as would be seen in a natural emergence profile.
Preparation of ovate pontic site will create illusion of papillae interproximally
• Once the ridge augmentation and ovate pontic site has been developed and supported during healing with a temporary bridge, the final bridge can be fabricated.
Ovate pontic appears to be naturally emerging from ridge.
• In clinical situations where there is a black hole, carefully measure the crestal bone to contact height.
• Leave the case in provisional restorations for 3-8 months and allow the papilla to grow back before finishing the case.
• Completing the case prematurely will not allow enough time for the papilla to regrow and overbuilding will be required to eliminate the black hole
Robert, A. Lowe. Ovate Pontic design: Maximizing aesthetics function of fixed
partial bridges. Aesthetic dentistry 2012
A 30-year-old healthy female complained about the cross-bite relationship of tooth 12.
The patient did not want to go through orthodontic treatment and refused implants. She was looking for a quick way to correct the appearance of her tooth.
• Alginate impressions were made to fabricate study models.
• The study models were sent to the laboratory for fabrication of the temporary bridge.
• A diagnostic wax-up was made. Pictures were taken. Teeth 13 and 11 were prepared for bridge abutments and Periapical radiographs taken.
A critical factor is a delicate/ atraumatic extraction of the tooth for bone preservation. (do not break the labial plate of bone).
Atraumatic extraction of tooth 12.
Socket site is intact
The hard and soft tissues heights were in acceptable levels. Bone grafting and connective tissue build-up was unnecessary.
Temporary bridge resin was added to the underside of the pontic, and reseated so that the resin flows into the socket.
• The provisional pontic was constructed so that the “egg” portion is submerged into the extraction site about 2 to 3 mm .
The temporary bridge cemented in place after extraction
and site preparation.
• The patient was instructed to return in 48 hours for removal of the temporary and evaluation of the extraction socket for proper healing.
• After evaluation the temporary was re-cemented.
• After two weeks the socket was revaluated and the gingival contour was sculpted with electrosurgery.
• A series of temporary bridges was necessary to manipulate the soft tissues to recreate ovate pontic receptor sites and natural-looking interdental papillae.
• After six weeks a slight inflammatory reaction was observed in the soft tissues.
With each new temporary bridge, the aesthetics was improved and the soft tissues compressed to help form the papillae.
The tissue has adapted to the temporary ovate pontic.
Maturation of the pontic site
• Approximately four months after extraction and four provisional bridges later the soft tissues had neared maturation.
• A further increase in the buccal contraction was seen, giving a significant increase in the tooth length while the papillae closed the interproximal spaces almost completely.
Once the final work is in place, the gingival architecture was seen to be preserved and harmony was satisfactory
Final impression and cementation
• The final impression may be taken three to four months after extraction, due to the variability in the healing process for each patient.
• In this case the final impression for the final restoration was taken four months after the extraction.
The all-ceramic restorations are shown bounded in place. The gingival architecture, although more apical in position, appeared to be preserved and demonstrated satisfactory harmony.
• The patient was instructed to clean this specific area with super floss, to prevent any possible inflammatory reaction.
• Also, the use of a waterpik system using low pressure, aiming the water stream at the teeth at a 90-degree angle, not at the gum tissue, was advocated.
• The convex shape of the pontic allows proper cleansing of the edentulous area.
Pre-treatment.
Post-treatment.
REVIEW OF LITERATURE
Artificial crown contours and gingival healthJ Prosthet Dent 12:1146, 1962.
This article presents a rationale for not producing overcontoured crowns because it causes and does not prevent gingival inflammation..
Conclusions: The rationale of muscular molding and cleansing rather than that of food impaction, more adequately explains clinical phenomena and is a more accurate guide for the construction of gingivally tolerated crowns.
• Burch, J.G Ten rules for developing crown contours in restorations.
DCNA 1971;15:611-618
• Purpose: To discuss the relationship between crown contours, and the occlusal surface and cervical portion of individual teeth. The ten rules for developing contours are:
• 1)Faciolingual crown dimensions- no more than 1mm larger than the faciolingual width at the CEJ. Possible exception: mandibular molars and second premolars.
• 2)Facial contours- all facial contour crests are in the gingival third, and should not bulge more than one-half mm beyond CEJ
• 3)Lingual contours- greatest convexity at gingival 1/3 except mandibular molars and sometimes mandibular second premolar, where greatest convexity is found in the middle 1/3 of crown.
• 4)Proximal contact points- in the occlusal 1/3 of crown. Maxillary molars may be at the level of the junction of occlusal and middle thirds. Proximal contact points are buccal to the central fossa line, except for maxillary molars which are in the middle 1/3.
• 5)Proximal surfaces- between the marginal ridge and the CEJ, the proximal surface is flat or slightly concave buccolingually as well as occlusocervically.
• 6)Axial transitional line angles- straight between the proximal contact point and the CEJ, with the exception of the lingual line angles of maxillary molars, where there may be a slight convexity.
• 7)Marginal ridges- should be the same height for adjacent teeth. The facial ½ of any tooth is wider than the lingual. Lingual embrasures are always larger than buccal embrasures when viewed occlusally.
• 8)Crown margin- should be supragingivally except due to esthetics, crown length to gain adequate retention, root caries, root sensitivity, existing restorations.
• 9)Thickness of restoration subgingivally- inadequate contour may not provide for adequate support for the gingival unit.
• 10)Crown margin/Bone relationship- do not encroach on the biologic width.
• Physiologic design criteria for fixed dental restorations. DCNA Vol 15, 3:543-568, 1971.
• Purpose: To explore the contours of axial tooth surfaces in relationship to their environment so that they may function physiologically.
As it is the function of the occlusal form to generate the least amount of stress in the supporting tissues, it is the function of the axial form of teeth to afford protection and stimulation to the investing tissues or, more specifically, the marginal periodontium.
Axial crown contours. J Prosthet Dent 25:642, 1971.• The relationship between axial tooth contours and the surrounding
marginal gingiva was studied on six dogs and observed over 9 weeks.
• Procedures producing undercontours and overcontours, on buccal and lingual crown surfaces, were performed. Clinical and microscopic observations were made with respect to the marginal gingiva and the crevicular areas: Undercontouring of axial surfaces did not produce any significant changes in gingival health. Overcontouring produced inflammatory and hyperplastic changes in the marginal gingiva. These changes were seen clinically and microscopically at 4 weeks.
Facial and lingual contours of artificial complete crown restorations and their effect on the gingiva. J Prosthet Dent 29:61, 1973.
• Purpose: to evaluate the purpose of the cervical bulge found in teeth and its effect on protecting the gingiva from the traumatic effects of mastication.
• authors opinion, this cervical bulge overprotects the microbial plaque, and this can be clinically demonstrated by utilizing disclosing solution.
• He states that to promote accessability of oral hygiene, final fixed restorations should not follow the original anatomic crown but should recreate the normal contours of the root portion.
• By flattening the facial and lingual contours, this would reduce unnecessary bulges, and facilitate cleansability to the gingival third of fluted and furcation areas of teeth.
• This is especially true in teeth that have undergone periodontal therapy.
The interproximal embrasure. DCNA 15:641, 1971. • Purpose: Identify problems related to the interproximal embrasure and
space during treatment procedures.
• Adequate tooth reduction and a proper provisional is the most predictable way to establish a healthy embrasure zone. An over- contoured restoration due to inadequate reduction will create an inflammatory response of the periodontium and the resultant change in the quality of the embrasure tissues.
• The interdental space must be kept free of bacterial plaque and restorative materials to create an environment that will retain a state of periodontal health
Excessive crown contours facilitate endemic plaque niches. J Prosthet Dent 35:424, 1976.
• Purpose: To study the facial – lingual width and the plaque indices of crowned teeth and to compare the data to that for unrestored contralateral teeth.
• Materials and Methods: 25 cast metal crowns and PFM’s were evaluated.
• Measurements of the facial – lingual width at the height of contour were made on the sample teeth as well as the contralateral tooth. Assessments of soft deposits were made according to the plaque index system proposed by Silness and Loe.
• Results: A significant difference in the plaque accumulation was found in the samples. More plaque was found on the teeth with restorations than with out. The restorations were wider than the contralateral control teeth.
Conclusion: The creation of restorations with facial – lingual width greater than natural tooth convexities must be considered another parameter to promote plaque.
The role of coronal contour in gingival health. J Prosthet Dent 37:280, 1977• Purpose: To evaluate the role of coronal contour in gingival health.
• Conclusion: Total clinical crown contour is related to gingival health.
• Undercontour is better than overcontour where clinical judgement is vague.
• The facial and lingual surface contours should have gradual curvatures in all directions to facilitate the rubbing and cleaning function of the lips, cheeks, and tongue.
• The interproximal contour of the adjacent teeth, contact areas, and the teeth in relation to the papilla must provide easy access for the patient to perform oral hygiene.
• The subgingival convexity of a tooth or a restoration should extend facially or lingually no more than ½ of the thickness of the gingiva. This protects the gingival crevice and promotes knifelike free gingival margin, important in plaque control.
The Interdental Space. DCNA 24: 169, 1980• The interdental area is the primary site of dental disease, both periodontal
disease and caries. Both diseases are microbial in origin and result from growth and accumulation in the interdental area.
• Interproximal contours should minimize plaque retention areas optimize ease in cleansing.
• A common error is to make the contact area too wide which leads to lack of space for an occlusal embrasure and adequate marginal ridge.
• Current controversies in axial contour design. J Prosthet Dent 44:536, 1980.
Purpose: A review of theories of axial contour design.
• Food Deflection Theory:
• WHEELER- Proposed that convexities should be created in the cervical third of artificial crowns and these convexities were deflect food away from the free gingiva.
• MORRIS- Noted that the position of the gingival margin in part is determined by the lingual or buccal tooth surface prominence. He placed an emphasis on accessibility and oral hygiene measurement.
• HERLANDS et al- Questioned the rationale of the food deflecting contour concept. He found that these crowns were overcontoured causing gingival inflammation as well as the following:
• Papillae Impaction mechanism requires certain physical conditions, substances being impacted must be fairly firm, there must be a propelling force directing it towards an easily accessible area.
• Maximum bulge in a natural crown contour is 0.5 mm, this is considered as inadequate protection against food impaction.
• Complete lack of contour is often observed when a tooth prepared for full coverage is left uncovered for an extended period of time, but the surrounding gingiva is usually healthy.
• MUSCLE ACTION THEORY
• HERLANDS et al and MORRIS- Introduced the theory. they used the rationale of muscle molding and cleansing, rather than food impaction, to explain the observable clinical phenomena found around natural and artificial crowns. the theory promotes constant cleansing and molding action by the muscles of the cheeks, lips and tongue.
• PEREL- Studies revealed:
• Undercontouring of axial surfaces did not produce any significant changes in healthy gingiva.
• Overcontouring of axial surfaces produced inflammation and hyperplastic changes in the marginal gingiva.
• YUODELIS et al- Questioned the food defection theory. They stated that microbial plaque is the primary etiological factor in both caries and periodontal disease.
• There is little in our modern diets that could injure the free gingival margin.
• Propreceptive response usually provides adequate protection for the free gingiva during mastication.
• The potential impact of food as the crushed bolus passes over the axial contoue of the teeth is usually dissipated by the time the food reaches the gingiva, since it tis directed by the cheeks, lips and tongue into a position of deglutition.
• Most human dentition have little clinical bulge and show no deleterious effect on mastication.
• PLAQUE RETENTION THEORY
• Axial conour design is based on the muscle-action theory.
• Crown contour should not harbor any plaque traps and promote self-cleaning.
• ANATOMIC THEORY
• Anatomic or biologic concept of tooth contour, a contour which simulated natural, healthy and self prtecting teeth.
• the facial and lingual convexities form the height of contour of tooth crowns, which are located at the gingival third of each tooth and are approximately 0.5 mm wider than the adjoining CEJ. (Exception- lingual of mandibular molars and second premolars.)
• MARGIN PLACEMENT
• WAGMAN- Subgingival contour should be made convex facially and lingually. Proper contour to maintain "knife-like" shape of the free gingival margin. The degree of these convexities should not exceed 1/2 of the thickness of the gingiva at the height of the attachment.
• ROSS- If the subgingival contour is made flat and does not sopport the gingiva, the free marginal gingiva will tend to form a "roll" around the tooth. A margin placed coronal to the CEJ, the subgingival contour should be made convex. Below the CEJ, should be made flat
• SPUROW AND LYTLE- Interproximal embrasure as a yardstick of periodontal health in a patient with virgin teeth. Emphasized the importance of creating proper embrasure space for the health of the interdental
Faciolingual width before and after tooth restoration: A comparative study. J Prosthet Dent 46:153, 1981.
• Purpose: To compare the data between the facial-lingual width of restored teeth and the same unrestored teeth..
• study suggests that increases in the buccolingual dimension of approximately 0.7 to 1.0 mm may be accepted clinically by the surrounding tissues.
The results of this study indicate that measurements of the natural teeth, dies, and provisional restorations can provide the dentist and the laboratory a method to control the buccolingual width of the final restoration
Crown contours and gingival response. J Prosthet Dent 47:620-624, 1982. • Purpose: Review of the current methods of evaluating gingival
response to restorative procedures and material, the design theories of crown contours, and the guidelines for gingival margin placement.
• Methods of evaluationg gingival response:
• -Subjective indices: color, texture, and bleeding on probing. (prone to the dentists perception)
• Renggli and Regolati: compared plaque scores, those with subgingival margins found to have more inflammation.
• Greatest increase in gingivitis, pocket depth, and loss of attachment occurs with subgingival margins.
• Margins placed at the level of the free gingival margin result in an insignificant increase in gingivitis.
• Closer a subgingival crown margin is placed to the base of the gingival sulcus, the more severe the gingival inflammation.
Restoration of the interdental space. Int J Perio and Rest Dent 3:30-45, 1983. • Purpose: To understand the anatomy and biology of the
interdental area and how it influences the restorative considerations in treatment.
Conclusions: By thoroughly planning the design of a restoration, not only function and esthetics are restored but the health of the interdental area is preserved.
Gingival esthetics. J Prosthet Dent 64:1-12,1990
to achieve gingival health and esthetics in fixed prosthodontics. Gingival contact should be avoided whenever possible through the use of partial veneer crowns, supragingival margins, or with colorless metal ceramic restorations with margins located at the gingival crest.
•When subgingival margins are required, attention must be paid to:
Achieving optimal preprosthetic gingival health.
Minimizing gingival trauma from rotary instruments during tooth preparation.
•Careful use of gingival retraction cord.
• Sulcus inspection following impression making to remove any residual impression material.
• Well fitting , properly contoured, and smooth provisional and definitive restorations.
• Postplacement follow up and reinforcement of adequate oral hygiene
Combined therapy for teeth with furcation involvement used as abutments for fixed restorations. Int J Prosthodont 3:470-476,1990.
• Purpose: To describe the preprosthodontic and prosthodontic procedures for preparing molars with degree 3 furcation for use as abutments for a fixed prosthesis.
followed 58 patients for 10-18 years, 67 teeth received root resection or root separation, 6 failed from recurrent caries and 4 from periodontal disease.
• showed 93% success rate restored with metal ceramic fixed restorations.
