GINGIVAL RETRACTION IN FIXED DENTAL PROSTHESIS

INTRODUCTION :

GINGIVAL DISPLACEMENT : Change in the form or position of tissues as a result of pressure

Definition: The deflection of the marginal gingiva away from a tooth [GPT 8]

Synonyms : Gingival retraction

Tissue dilation

GINGIVAL RETRACTION

HISTORY:-

1951-Thomson M.J. emphasised that before making impression for crown & bridge procedure the need of gingival retraction 1961- James D. Harison suggested that 8% epinephrine&100%alum may be used safely for 5-10 minutes for gingival retraction and zinc chloride should not be used 1978-Roger B. did a study to compare the effect of epinephrine impregnated [4-8%] cords on cardiovascular system and unimpregnated cord and found that pulse rate of patients was more 1983-R. Azzi compared the different methods used for gingival retraction like cords, electro- surgery, rotary curettage - more damage was found with rotary gingival curettage

AIMS & OBJECTIVES Reflect gingiva and produce enlargement or dilation of gingival sulcus To obtain 0.2 - 0.4 mm of horizontal displacement of marginal gingiva To achieve 0.5 mm of vertical exposure of unprepared portion of tooth To expose the prepared finish line To control the GCF To evaluate the depth and uniformity of finish line Allow refinement of finish line without laceration of soft tissues Provide access for the impression materials to record accurately the finished margins and a part of the unprepared tooth beyond the finish lines. Helps to obtain accurate marginal fit which will reduce the marginal leakage and subsequent deterioration of the tooth

METHODS FOR GINGIVAL DISPLACEMENT Mechanical Methods Mechanical chemicalChemicalSurgical

Mechanical methods: Rubber dam Copper band Retraction cords Plain Temporary acrylic resin coping Cotton thread Magic foam [RECENT] Aluminium shell

RUBBER DAM

INDICATIONS:1. Used when limited number of teeth in one quadrant 2. Preparation not extending sub-gingivallyPRECAUTIONS:

Block out the clamp impression may tear

Do not use addition silicone rubber interferes with the setting

RETRACTION CORDS - PLAINAdvantages (Plain cord) Tissue recovery is excellent Provide pressure hemostasis Ease of manipulation Commonly used

Disadvantages Poor in its ability to displace gingiva Trauma and recession from packing pressure

ALUMINIUM SHELL TECHNIQUE

Aluminium shell of correct size is selected, trimmed to confirm to the gingival contour and occlusion and margins are smoothened

Fill it with compound or guttapercha and place it over the prepared tooth under occlusal pressure it is forced into the predetermined position

The excess material from gingival end will displace the tissues

Aluminium shell is removed and excess material is trimmed to a point where it will not cause the blanching (excess pressure)of tissues.

Try it on the tooth & mould the gutta percha compound in the gingival crevice with a warm instrument.

Cement it with temporary cement for 24 hrs

COPPER BAND Carries the impression material

Displaces gingiva

Impression compound and elastomeric material used

Advantages To retrieve the localized impression defect in multiple preparation

Disadvantages Incisional injury Inaccuracy Minimal retraction

COTTON THREADS Retraction achieved is purely mechanical, minimal and transient

No hemostasis

MAGIC FOAM Recent development

Consists of : Comprecap hollow cotton- Magic foam cord polyvinyl siloxane material

PROCEDURE MAGIC FOAMSelect a desired size of comprecap

Inject magic foamcord around preparation and inside comprecap

Place over prepared tooth

Ask patient to gently bite for 3-4 minutes and then remove it

Disadvantage:1. Less retraction than cord2. Should establish hemostasis prior to retraction

Advantages1. Easy to use2. Less trauma

A study was conducted to evaluate a new gingival retraction system relative to clinical success for fixed dental restorations under various clinical conditions.

The result was that in cases of epigingival and subgingival (< 2 mm) preparation margins, MFC was a less traumatic alternative method of gingival retraction. However, when there were deep subgingival margins and a beveled preparation, the material was less effective than the single cord retraction technique.[Quality of impressions after use of the Magic FoamCord gingival retraction system--a clinical study of 269 abutment teeth. Beier US,Kranewitter R,Dumfahrt H. Int J Prosthodont.2009 Mar-Apr;22(2):143-7]

Preloaded dental cap and retraction material for gingival tissue retraction William B. Dragan,John J. Discko Patented 2013 OCT 17TH

A method and a device for effecting the cordless retraction of the gingival sulcus tissue that includes a cap or dam to be fitted onto a tooth.

The well of the cap is pre-filled with a predetermined amount of a flowable non-setting kaolin based retraction material having a heavy viscosity or putty consistency.

The preloaded cap is fitted to a prepared tooth so that when pressure is applied onto the cap, the retraction material is displaced under pressure and forced to flow into the sulcus, causing the gingival tissue to retract away from the tooth to enlarge the gingival sulcus.

An internal ridge aids in retaining the retraction material within the cap.

Mechanical-chemical methodChemical action + pressure pack- enlargement of gingival sulcus

Materials used- retraction cord & medicaments

Mechanical action: separate the tissue from the prepared marginChemical action: astringent / hemostasis

Chemicals used are,(any of them)1.epinephrine 1:10002.zinc chloride 8%3.alum 40%4.tanic acid 20%5. Negatan6.aluminium chloride7.pottassium alum 9%8.phenyl ephrine Hcl 0.05%The technique involves packing the gingival crevice of the prepared tooth with a cord impregnated with chemicals .

Classification Surface texture -Wet or Dry Configuration :Twisted, knitted or braidedKnitted: made up of compressible interlocking chains transport greater amount of chemical agentBraided: do not separate easily and do not unravel on insertion

Surface finish: Waxed or unwaxed

Thickness (colour coded)Black 000 (extra small)Yellow 00 (small)Purple 0Blue 1Green 2Red 3 (extra large)

Chemical treatment-Plain or impregnated[Cords can be dipped in specific agents before packing cause transient ischaemia and tissue shrinkage which controls gingival fluid and provide haemostasis]Common chemicals are: ferric sulphate 20-25% and aluminium chloride 15-29% and racemic epinephrine 8%Studies indicated that fluid absorbancy increased in linear proportion to the increase in thickness of the retraction cord.Number of strands-Single or Double string[Comparative evaluation of fluid absorbancy of retraction cords of different thickness after various medicament immersions - Shushant K Garg,Sandeep Garg,Sanjeev Mittal,Sangeeta Goyal JOURNAL OF INTERDISCIPLINARY DENTISTRY - Year: 2012 |Volume: 2 |Issue: 1 |Page: 30-34]

IDEAL REQUIREMENTS Safe locally , and systemically Effective for its intended use Effects should be spontaneously reversible Absorbent Provide hemostasis No Physical & chemical injury to gingival tissues Dark colour and never red Strong enough to resist placement and should not snap Should be available in various diameters for varying morphology of the gingival sulcus

Criteria

Effectiveness of gingival displacement and hemostasis Absence of irreversible damage to gingiva Paucity of untoward systemic effectsTechniques

Single string technique Deknatel technique / double string technique Selective double string

Packing Instruments Fischers cord packer1.Should be thin enough to be placed in sulcus without damaging the tissues2. Tip serrated to enhance grip of instrument on cord3. Angle of instrument should allow packing of cord all around tooth

SINGLE CORD TECHNIQUEIndication: to make impression of 1-3 prepared teeth with healthy gingivaSimple and efficient techniqueOperating field must be dry, isolated with cotton rolls and fluid removed with saliva ejector

TECHNIQUE: Cut of 2 inch of cord Twist the cord and make it as tight as possible A[u] is formed & loop of the cord around the tooth and hold it with the thumb and forefinger. Cut end towards the lingual side Start placement of retraction cord by pushing it into the sulcus on the mesial surface of the tooth. It should also be tucked tightly into the distal surface, to hold it in place As cord is placed subgingivaly, the instrument must be pushed slightly toward the area already tucked into place If the force of the instrument is directed away from the area, already packed cord will be pulled out. Instrument must be angled slightly towards the root to facilitate the subgingival placement of the cord. If the instrument is kept parallel to long axis of the tooth,the retraction cord will be pushed against the wall of the gingival crevice and it will be rebased Cut the excess in the mesial interproximal areas Finish the placement of the distal end ,until it overlaps the mesial. The cord is allowed to remain in sulcus for 5-10 minutes. After 10 minutes moisten the cord with saline or sterile water and remove the cord slowly If bleeding persists- apply ferric sulphate

DOUBLE CORD TECHNIQUEIndication: Impressions of multiple teeth Tissue health compromised with more than normal bleeding

RETRACTION CORD V/S PASTEThe gingival retraction paste has better effect on gingival health, tooth preparation and clarity of the impression and plaster model, while the aptness of the prosthesis is as good as the cord and can be considered as a good candidate of the gingival retraction cord, but more randomized controlled trials are needed

[Gingival retraction paste versus gingival retraction cord for fixed prosthodontics: a systematic review. Hong LG,Guo LP,Xue LL. Shanghai Journal of Stomatology[2013, 22(4):456-461]

CHEMICAL METHODS

Chemicals can be broadly classified as a) Vasoconstrictors. b) Drugs with styptic action. c) Astringents.

Vasoconstrictors act by a)transitory gingival shrinkage. b)transient ischemia. c)controlling seepage of gingival fluids.

Most commonly used vasoconstrictor is epinephrine and is contraindicated in condition likea) hypertensive patientb) patient having CVS disordersc) patient on pacemaker.d) hyper-thyroidism.e) patient on drugs like 1) Rawolfia compound. 2) Ganglionic blockers. 3) Epinephrine potentiating drugs.

Studies done by Felex F. Woycheshin 1964 and John B. 1970 suggest that these chemicals are not significantly absorbed in the circulation unless the epithelium is lacerated

Maximum dose is 0.2 mg in healthy adult,0.04mg in cardiac patients.

1 inch of cord contains 1mg of racemic epinephrine ie, 2 times the maximum dose for healthy patient and 12 times the maximum dose for cardiac patients.

Hence gingival retraction cord is a potential source of overdose.

ABSORPTION POTENTIAL64-94 % of available epinephrine in the retraction cord is absorbed when it is kept in gingival sulcus for 10 minutes

REBOUND POTENTIAL:It is estimated that the crevice returns to 0.02 in just 30 seconds

EPINEPHRINE 0.1 & 8%Recommended time & Mechanism of action5-10 min . Pronounced vasoconstriction AdvantagesGood displacement & hemostasis Tissue RecoveryFair DisadvantagesSystemic reactions

Contraindications Cardiovascular disease, hyperthroidism, hypersensitivity to epinephrine

Epinephrine syndrome Increased heart rate, respiratory rate and BP.

ALUM (100%)POTASSIUM ALUMINIUM SULPHATE Recommended time & Mechanism of action10 20 min. Precipitation of protein and inhibiting transcapillary movement of plasma protein AdvantagesMinimal tissue loss Extended working time

Tissue RecoveryGood Disadvantages Less displacement and haemostasis

ALUMINIUM CHLORIDE 5%-25%ALUMINIUM SULPHATE 25%

Recommended time & Mechanism of action10 mins. Weak Vasoconstrictor Advantages

Minimal tissue lossGood haemostasis

Tissue recovery Good Disadvantages Local tissue destruction > 10% concentration

FERRIC SULPHATE 13.3%

Recommended time & Mechanism of action1 3 minutes Advantages Good tissue response Compatible with Aluminium Chloride

Tissue recovery Good Disadvantages Not compatible with epinephrine Transient tissue discoloration

FERRIC SUB SULPHATE (MONSELS SOLUTION)

Recommended time & Mechanism of action1) 3 mins AdvantagesGood displacement

Tissue recovery Good Disadvantages Highly acidic and messy to work

ZINC CHLORIDE 8% & 40% AdvantagesGood displacement

Tissue recovery 8% - Fair40% - Fair DisadvantagesTissue necrosis and permanent tissue injury

SURGICAL METHODS ROTARY CURETTAGE ELECTRO-SURGERY SOFT TISSUE LASERS

RotaryCurettage[GINGETTAGE]HISTORY:1954 Amsterdam described the conceptHansing described the technique and later modified by Ingraham

PRINCIPLE: The removal of sulcular epithelium by rotary curettage & producing a finish line on the tooth It is a troughing technique Material used: reversible hydrocolloid impression material.

INDICATIONS:Healthy gingiva - Absence of bleeding on probingSulcus depth less than 3mmPresence of adequate keratinized gingiva

TECHNIQUE:Shoulder finish line is prepared at the level of the gingival crest or supra-gingivallyTorpedo diamond is used to extend finish line apically & do gingival curettage chamfer finish line is producedGenerous water spray used.Aluminum chloride or alum impregnated cord is packed to control hemorrhage.After 4-8 minutes remove the cord, irrigate sulcus with water and impression is made.

ADVANTAGES: It is easy to perform It does not require any special equipment.

DISADVANTAGES : Poor tactile sensation Can produce deepening of sulcus Can produce potential damage to the periodontium.

Electro Surgery HISTORY: 1891- dArsonval & Telsa- concept1924 -William Clark- He is also known as the Father of American electro surgery - technique1924 - Wyeth introduced endothermic knife.

PrincipleIt produces controlled tissue destruction to achieve a surgical result

MECHANISMHigh density current flows from a small cutting electrode that produces a rapid temperature rise at its point of contact with tissue leading to tissue destruction. Unmodulated AC recommended for gingival displacement

The circuit is completed by contact between the patient and ground electrode that will not generate heat in the tissues because its large surface area produces a low current density even though the same amount of current passes through it.:TYPES OF CURRENT:UNRECTIFIED DAMPED CURRENT:

characterised by recurring peaks of power that rapidly diminish current is produced by the spark gap generator. it causes dehydration, necrosis and coagulation. healing is slow and painful.

PARTIALLY RECTIFIED DAMPED CURRENT:( Half wave modulated)

produces a wave form with a damping in the second half of each cycle. There is a lateral penetration of heat with slower healing occurring in deeper tissues damping effect produces good coagulation and hemostasis but tissue destruction is greater and healing is slow.

FULLY RECTIFIED CURRENT:-

produces a continous flow of energy and better current for enlargement of gingival sulcus. good cutting characteristics with some hemostasis

FULLY RECTIFIED FILTERED CURRENT:-

Continous wave, which produces excellent cutting. superior healing of wound. continous wave produces less injury to tissues than wave modulated.

INDICATIONS: Finish line exposure - GINGIVECTOMY Before insertion of permanent prosthesis. Removal of edentulous cuff. Crown lengthening purposes. Areas of inflammation and granulation tissues Finish line close to epithelial attachment.

CONTRAINDICATIONS: Patients with cardiac pace-makers In the presence of flammable agents such as ether, ethyl chloride & oxygen Do not use with metal instruments produce shock Not used in thin attached gingiva Patients with delayed healing - radiotherapy od debilitating diseases

TECHNIQUE Profound anesthesia. Pleasant aromatic oil is applied at the vermillion border of the lip (to mask the unpleasant odor). Small, straight or J-shaped electrode is selected Connections are checked, cutting electrode should be completely seated in the hand piece. Plastic evacuator tip should be placed close to the cutting electrode to remove the odor. Electrode tip is kept parallel to the long axis of the tooth. Very light pressure and quick and deft strokes. Electrode should move at a speed of 7mm/sec Tooth should be encompassed in four separate motions (facial, mesial, lingual, distal).8 to10 seconds before proceeding to the next area. Clean the electrode tip after each stroke. Sulcular debris are removed using cotton pellet dipped in hydrogen peroxide.

Disadvantages Production of offensive odor . Improper use leads to excessive elimination of tissues. Permanent marginal tissue recession by faulty positioning of electrode. Retarded healing if not used carefully . Should be used with great care in the thin labial gingiva of upper anterior (canines).

Three important points1. Proper power setting 2. Quick passes with the electrode3. Adequate time interval between strokes .

SOFT TISSUE LASERSUse of lasers assists the operator to achieve proper retraction with good clinical resultsA study was conducted to assess the amount of lateral gingival retraction achieved quantitatively by using diode lasers which could conclude that gingival retraction achieved was closer to the thickness of sulcular epithelium and greater than the minimum required retraction of 200um.

Laser Gingival Retraction: A Quantitative Assessment Vamsi Krishna Ch,Nidhi Gupta,K. Mahendranadh Reddy,N. Chandra Sekhar,Venkata AdityaandG.V.K. Mohan Reddy . J Clin Diagn Res.2013 August;7(8): 17871788.

Tissue Friendly Retraction material - ExpasylExpasyl a unique paste system specifically designed for gingival retraction that ensures separation of the gingival margin and drying of the sulcus.Injectable retraction method to detach the marginal gingiva without injuring the epithelial attachment with additional quality of haemostasis.System consists of injectable material that contains a haemostatic agent, a specially designed gun, and tips prepackaged in a carpule. Components -- a highly viscous organic binder, kaolin, essentially a clay (responsible for the rigidity) which is mixed with a small amount of Aluminium chloride to act as a haemostatic agent, also to keep the working field dry. PROCEDURE:

The viscous paste is dispensed into the sulcus with the special syringe or cotton pellet or microbrush.

USING SYRINGEUSING COTTON PELLETUSING MICROBRUSHCare to be taken to place the tip of the syringe parallel to the long axis of the tooth to achieve successful apical and lateral deflection of the gingiva.The paste to introduced into the sulcus very slowly at a rate of app. 2mm/sec.When dispensing, the sulcus should be filled with paste and the tissue should blanch which ensures adequate filling of the sulcus.The material holds its body after it is injected into the sulcus.It is left in place for app. 1 to 2 minutes depending on the tonicity or fragility of the gingival margin.Normal time is upto 2 minutes. Thin and friable tissue should be treated only for 1 minute.

Also if used along with epithelial detachment via rotary curettage or with an electro surgical unit, required time is only 30 secs.Material is thoroughly rinsed with air and water.

PRECAUTIONS:Material is water soluble and begin to lose its body and effectiveness to retract the gingiva if wetted by saliva or water.Tip of the syringe to be parallel to the long axis of the tooth and not to be placed subgingivally.Ideally, the material should be used with any polyvinyl siloxane impression material.When using hydrocolloid impression or polyether materials, the material should be thoroughly rinsed to avoid any potential reaction between the aluminium chloride and the material.Advantages:

The overall positive effects are: Minimal trauma to the periodontium delivery of the material is gentle, hence the risk of damage to the epithelial attachment, gingival recession and bone resorption is greatly reduced Excellent haemostasis and good sulcular moisture control to provide a dry field ready for impression or cementation. Can be with the single-cord technique to access the margin. Reduced chair time and more convenient quick and easy procedure. Painless procedure and hence anesthesia not required. No chemical reaction or material expansion. Yield stress of Expasyl- higher than the force exerted on the tooth by the gingiva helping it to keep the sulcus open- Reduces when it becomes wet. Force exerted 20 times less than a single cord and 50 times less than double-cord technique.

A study is carried out to evaluate the effect of different retraction materials, such as, Expasyl, Magic Foam Cord, and impregnated retraction cord on the gingival sulcular epithelium which concluded that there is a significant association between retraction materials and gingival sulcular epithelium

[Effect of retraction materials on gingival health: A histopathological study.Phatale S,Marawar PP,Byakod G,Lagdive SB,Kalburge JV. J Indian Soc Periodontol.2010 Jan;14(1):35-9. doi: 10.4103/0972-124X.65436]

It can be stated that impregnated retraction cord, may be used commonly but it needs proper tissue manipulation and is technique sensitive. Newly advanced material in the form of retraction paste like Expasyl or Magic Foam Cord was found to be better than cord as assessed histologically, it respects periodontium

GINGIVAL RETRACTION IN IMPLANTSThe use of cordless retraction paste material in implant dentistry is a relatively novel application.

However, few studies have been conducted on the use of retraction pastes and their possible interaction with implant surfaces.

Recent literature has described remnants on titanium implant surfaces and expressed the need for an assessment of the biocompatibility of the exposed surface (Changet al.).

A study evaluated the effect of a cordless gingival retraction paste on sterile titanium disks. Surface chemistry was determined using energy-dispersive X-ray spectroscopy (EDS), and further investigated using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).

After exposure to retraction paste, surface chemistry alterations were identified.

A fibroblast cell line (L929) was exposed to the disks and the live/dead viability/cytotoxicity assay was used to determine any effects on the proliferation and health of cells.

The disks exposed to the retraction paste showed fewer dead cells compared to the unexposed disks. This was statistically significant.

A review and comparison for gingival retraction techniques used for implants and teeth was conducted

The authors found insufficient evidence relating to gingival displacement techniques for impression making for implant dentistry. Gingival retraction techniques and materials are designed primarily for peridental applications; the authors considered their relevance to peri-implant applications and determined that further research and new product development are needed

The use of injectable materials that form an expanding matrix to provide gingival retraction offers effective exposure of preparation finish lines and is suitable for conventional impression-making methods or computer-aided design/computer-aided manufacturing digital impressions in many situations. There are, however, limitations with any retraction technique, including injectable matrices, for situations in which clinicians place deep implants.

Gingival retraction techniques for implants versus teeth: current status.Bennani V,Schwass D,Chandler N. J Am Dent Assoc.2008 Oct;139(10):1354-63

CONCLUSION Gingival displacement is an important procedure for fabricating indirect restoration especially when subgingival finish lines are used. Gingival displacement is relatively simple and effective when dealing with healthy gingival tissue and when margins are properly placed. Most common technique retraction cord with hemostatic medicament.