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THE OUTCOME OF ORAL IMPLANTSPLACED IN BONE WITH LIMITED

BUCCO-ORAL DIMENSIONS: A 3-YEARFOLLOW-UP STUDY

Temmerman A et al.J Clin Periodontol 2015

Shilpa Shivanand

II MDS

Introduction• The clinical success of an implant partially depends on several

external factors primary implant stability, bone quality, time of loading, infection control, surgical technique and height and width of the alveolar bone.

• Primary implant stability is determined by the properties of the bone that contribute to its strength.

• Implant micro-movements within a range of 50–150 μm seem to be acceptable for optimal bone healing

Szmukler-Moncler et al 1998

4

Parts Of A Dental Implant

IMPLANT BODY

COLLAR

ABUTMENT SCREW

FIXATION SCREW

LAB ANALOGUE

Inter Implant Distance • Atleast 1mm of bone on all the 4 sides.

1mm 1.0-1.5 mm

1mm

1mm

1mm

1mm

• Inter-arch space:

For fixed implant-supported

prosthesis:

7 mm - in the posterior region

8-10 mm - in the anterior areas.

An implant-retained removable

prosthesis requires at least 12

mm.

8-10mm

12 mm

7mm

Adjacent teeth:

• At least 7 mm between two

adjacent teeth.

• Adjacent teeth must be

infection free:

all restorative, periodontal,

and endodontic procedures

should be completed prior to

implant planning.

7 mm

7 mm

• The defining factors for bone quality are trabecular thickness, mineral density and micro-architecture

Ribeiro-Rotta et al 2007• In relation to time of loading, a recent review showed no

differences in marginal bone level changes between different loading protocols

Suarez et al 2013• However, the length of the implant seems of interest for the

survival rate of most implant systems.

• Since implant survival decreases when the implant is shorter than 7 mm

Pommer et al 2011• To determine the health of the peri-implant tissues a

radiological assessment of the marginal bone level around the shoulder of an implant is a reliable option

Grusovin et al 2008

• To consider an implant as successful, it has to meet criteria with respect to tissue physiology (osseointegration), function (mastication), absence of pain and user satisfaction

Tonetti & Palmer 2012

• In 1986, Albrektsson et al stated that a mean marginal bone loss of 1.5 mm after the first year of loading is acceptable.

• More recent studies show a mean marginal bone loss of 1.0 mm after the first year of loading and in the following years an annual 0.1 mm additional bone loss

Cecchinato et al 2008• Some papers indicate that the bone thickness around an

implant should be at least 1 or 2 mm to assure long-term success and bone coverage

Esposito et al 2007, Grunder et al 2005

Aim• This prospective follow-up study aims to evaluate the

radiological interproximal bone changes of oral implants placed in sites with ≤ 4.5 mm of bucco-oral bone width.

Material and Methods• This prospective, single-centre study was carried out at the

Department of Periodontology of the University Hospitals Leuven.

• All oral implants (Astra Tech, Dentsply Implants, M€olndal, Sweden) were placed in the period between 2009 and 2010.

Inclusion criteria• Implant sites with ≤4.5 mm bone in bucco-oral dimensions, as

measured on CBCT cross-sectional images (2-mm subcrestally)• Only those patients, with a very limited bucco-oral dimension

over the crest were included.• Patients expectations were pure functional, without any

severe aesthetical demand.

• All implant sites were analysed on a multi-slice CT (Somatom Plus S, Siemens, Erlangen, Germany) or cone-beam CT (Scanora 3D, Soredex, Tuusula, Finland).

• The implants were placed according to the surgical protocol provided by the implant company (Instruction manual, Astra Tech, DentsplyImplants, M€olndal, Sweden).

• However, in most cases, the surgical protocol was changed accordingly to the situation.

• The amount of buccal bone on the implant was <1 mm at each implant site.

• Whenever a fenestration or dehiscence occurred, a GBR procedure was performed.

• A thin layer of “deproteinized bovine bone matrix” (Bio- OssTM, Geistlich, Switzerland) was used and covered with a resorbable collagen membrane (Bio-GideTM, Geistlich, Switzerland).

• The digital intra-oral radiographs (follow-up) were obtained

Marginal bone level changes• The intra-oral, long-cone radiographs were taken at: implant

placement, functional loading, 1, 2 and 3-years follow-up.• The distances, in millimetres, between the shoulder of the

implant and the first clear bone-to-implant contact were recorded both mesially and distally.

• The thread pitch distance and the full length of the implant were also recorded.

• These measurements (accuracy of 0.01 mm) were performed with a software program (IMAGE J, NIH, Bethesda, Maryland, USA).

• The measurements were initially made in a pixel format.• Linear distance measurement (mm) could be retrieved after

calibration of the images according to the respective thread pitch distance, provided by the manufacturer.

• The full length of the implant was used for the conversion.

Width of the alveolar process• The width of the alveolar process on the future implant

osteotomy sites was measured, pre-operatively, on cross-sectional images of the conebeam

• CT or multi-slice CT, using the software tool to the nearest 0.1 mm (PACS lightbox, IMPAX pacs, Agfa).

• Measurements were made at the top of the crest and at every 2 mm (2, 4, 6, 8, 10 and 12 mm below the first measurement).

Clinical case with intra-oral radiographs showing the bone level after 3 years of loading.

Results- Patient and implant data• A total of 28 patients (three males and 25 females) were

included. • A total of 100 implants were placed (13 in males, 87 in

females). Two in one patient with diabetes and seven in two patients with a history of radiotherapy outside the head and neck region.

• Eighty-eight per cent of the implants were placed in the upper jaw and 12% in the lower jaw, primarily in the region between the 2nd incisor and 2nd premolar.

• All implants had a diameter of 3.5 mm and their length ranged from 8 mm to 15 mm.

• The majority of the implants had a length of 13 mm (45%) or 11 mm (33%). The mean width of the future osteotomy at the top of the crest was 2.8 mm (SD: 0.8;range [1.1; 4.4]).

• None of the implants were placed in extraction sockets. • The mean submerged healing period was 3.6±0.9 months.

Marginal bone level changes• The implants were primarily placed subcrestally (mesially:

0.94 mm±0.87, and distally: 0.68 mm±0.97 below bone level).• At abutment connection the marginal bone was located 0.65

±0.6 mm apically of the implant shoulder (mesially 0.63 ±0.7 mm, distally 0.67 ±0.6).

• One, 2 and 3 years after final abutment connection, this “bone level” was slightly more apically (0.80, 0.84 and 0.79 mm apically to the implant shoulder, respectively).

Marginal bone level changes

Discussion• The results of this prospective clinical follow-up study

demonstrated that the interproximal bone changes for implants placed in sites with ≤ 4.5 mm of bucco-oral bone width were stable during the 3 years of functional loading.

• Furthermore, the implant survival rate was 100%.• The marginal bone changes around implants are most

common, between abutment connection and the first year of functional loading.

• The present study showed a mean marginal bone loss of 0.17 mm ±0.40 in the first year of functional loading.

• After the first year the marginal bone loss varied a bit with after 2 years a marginal bone loss increase with another 0.05 mm ±0.37 and after 3 years a marginal bone loss decrease with 0.06 mm ±0.14.

• The bucco-oral bone width is considered to be crucial for osseointegration and even more important for an aesthetic outcome.

• In the literature there are some guidelines available which suggested a zone of 1.5–2 mm of bone around the implant

Esposito et al 2007, Grunder et al 2005

• Small-diameter implants have become a popular treatment option to avoid bone augmentation procedures and more complex surgery.

• In some studies, implants with a width of 3.5 mm are considered small diameter implants

Sohrabi et al 2012• Other studies consider small diameter implants as those with

a width ≤3.3 mm Ortega-Oller et al 2014

• A recent (systematic/narrative) reviews concluded that the survival rates small-diameter implants are similar to those reported for standard width implants

Hasan et al 2014, Sohrabi et al 2012• The present study indicates that bone grafting procedures can

be avoided when sites with ≤4.5 mm of bucco-oral bone width are available.

• All patients included in the study, were following a very strict maintenance protocol and as a result had a high level of oral hygiene.

• This might not be the best reflection of an average patient in the daily practice.

Conclusion • Within the limits of this study, it can be concluded that

implants placed in sites with limited dimensions (≤4.5 mm vestibule-oral) can be successful for a period of 3 years, comparable to implants placed in wider alveolar crests.

• This effect could be explained by the microthreads in the conical and marginal part of the implant system used as well as by the special drilling sequence avoiding bone compression.

• These results showed that if patients are not ready for bone grafting procedures this treatment option could be a good alternative.

CROSS REFERENCE

I. Survival rates of short (6 mm) micro-rough surface implants: a review of literature and meta-analysisSrinivasan M et al , Clin Oral Implants Res 2014OBJECTIVE:• The aim of this review was to test the hypothesis that 6 mm

micro-rough short Straumann implants provide predictable survival rates and verify that most failures occurring are early failures.

MATERIALS AND METHODS:• A PubMed and hand search was performed to identify studies

involving micro-rough 6-mm-short implants published between January 1987 and August 2011. Studies were included that (i) involve Straumann(®) 6 mm implants placed in the human jaws, (ii) provide data on the survival rate, (iii) mention the time of failure, and (iv) report a minimum follow-up period of 12 months following placement.

RESULTS:• From a total of 842 publications that were screened, 12

methodologically sound articles qualified to be included for the statistical evaluation based on our inclusion criteria.

CONCLUSION:• This meta-analysis provides robust evidence that micro-rough

6-mm-short dental implants are a predictable treatment option, providing favorable survival rates. The failures encountered with 6-mm-short implants were predominantly early and their survival in the mandible was slightly superior.

II. Failure rates of short (≤ 10 mm) dental implants and factors influencing their failure: a systematic reviewSun HL , Int J Oral Maxillofac Implants.2011PURPOSE:• The aim of this study was to evaluate the long-term failure

rates of short dental implants (≤ 10 mm) and to analyze the influence of various factors on implant failure.

MATERIALS AND METHODS:• The PubMed and Cochrane Library databases were consulted

for follow-up studies published between the years 1980 and 2009. For those studies that met the inclusion and exclusion criteria, data concerning the number of implants (≤ 10 mm) placed and lost and any related risk factors were gathered in tables and subjected to analysis. Univariate and multivariate analyses were performed.

RESULTS:• The heterogeneity and low quality of the included studies made

meta-analysis impossible. A total of 35 human studies fulfilled the criteria. There was a tendency toward higher failure rates for the maxilla and for dental implants with a machined surface compared with the mandible.

CONCLUSIONS:• Among the risk factors examined, most failures of short implants

can be attributed to poor bone quality in the maxilla and a machined surface. Although short implants in atrophied jaws can achieve similar long-term prognoses as standard dental implants with a reasonable prosthetic design according to this review, stronger evidence is essential to confirm this finding.