Two-stage IMZ implants and ITI implants inserted in a single-stage procedure. A prospective comparative study

Metagenomic analysis of healthy and diseased peri-implant microbiome under different periodontal conditions: a cross-sectional study

BACKGROUND

Peri-implantitis is a polybacterial infection that can lead to the failure of dental implant rehabilitation. This study aimed to profile the microbiome of the peri-implant plaque and estimate the effect of periodontitis on it among 40 Chinese participants with dental implant prostheses and presenting with varying peri-implant and periodontal health states.

METHODS

Submucosal plaque samples were collected from four distinct clinical categories based on both their implant and periodontal health status at sampling point. Clinical examinations of dental implant and remaining teeth were carried out. Metagenomic analysis was then performed.

RESULTS

The microbiome of the peri-implantitis sites differed from that of healthy implant sites, both taxonomically and functionally. Moreover, the predominant species in peri-implantitis sites were slightly affected by the presence of periodontitis. T. forsythia, P. gingivalis, T. denticola, and P. endodontalis were consistently associated with peri-implantitis and inflammatory clinical parameters regardless of the presence of periodontitis. Prevotella spp. and P. endodontalis showed significant differences in the peri-implantitis cohorts under different periodontal conditions. The most distinguishing function between diseased and healthy implants is related to flagellar assembly, which plays an important role in epithelial cell invasion.

CONCLUSIONS

The composition of the peri-implant microbiome varied in the diseased and healthy states of implants and is affected by individual periodontal conditions. Based on their correlations with clinical parameters, certain species are associated with disease and healthy implants. Flagellar assembly may play a vital role in the process of peri-implantitis.

WITHDRAWN: Interventions for replacing missing teeth: different types of dental implants

BACKGROUND

Dental implants are available in different materials, shapes and with different surface characteristics. In particular, numerous implant designs and surface modifications have been developed for improving clinical outcome. This is an update of a Cochrane review first published in 2002, and previously updated in 2003, 2005 and 2007.

OBJECTIVES

Primary: to compare the clinical effects of different root-formed osseointegrated dental implant types for replacing missing teeth for the following specific comparisons: implants with different surface preparations, but having similar shape and material; implants with different shapes, but having similar surface preparation and material; implants made of different materials, but having similar surface preparation and shape; different implant types differing in surface preparation, shape, material or a combination of these.Secondary: to compare turned and roughened dental implants for occurrence of early implant failure (before prosthetic loading) and occurrence of peri-implantitis.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 17 January 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 12), MEDLINE via OVID (1946 to 17 January 2014) and EMBASE via OVID (1980 to 17 January 2014). We placed no restrictions on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included any randomised controlled trial (RCT) comparing osseointegrated dental implants of different materials, shapes and surface properties having a follow-up in function of at least one year. Outcome measures were success of the implants, radiographic peri-implant marginal bone levels changes and incidence of peri-implantitis.

DATA COLLECTION AND ANALYSIS

At least two review authors independently conducted screening, risk of bias assessment and data extraction of eligible trials in duplicate. We expressed results using fixed-effect models (if up to three studies were present in a meta-analysis) or random-effects models (when there were more than three studies) using mean differences (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CI). We reported the following endpoints: one, three, five and 10 years after functional loading.

MAIN RESULTS

We identified 81 different RCTs. We included 27 of these RCTs, reporting results from 1512 participants and 3230 implants in the review. We compared 38 different implant types with a follow-up ranging from one to 10 years. All implants were made of commercially pure titanium or its alloys, and had different shapes and surface preparations. We judged two trials to be at low risk of bias, 10 to be at unclear risk of bias and 15 to be at high risk of bias. On a 'per participant' rather than 'per implant' basis, we found no significant differences between various implant types for implant failures. The only observed statistically significant difference for the primary objective regarded more peri-implant bone loss at Nobel Speedy Groovy implants when compared with NobelActive implants (MD -0.59 mm; 95% CI -0.74 to -0.44, different implant shapes). The only observed statistically significant difference for the secondary objective was that implants with turned (smoother) surfaces had a 20% reduction in risk to be affected by peri-implantitis than implants with rough surfaces three years after loading (RR 0.80; 95% CI 0.67 to 0.96). There was a tendency for implants with turned surfaces to fail early more often than implants with roughened surfaces.

AUTHORS' CONCLUSIONS

Based on the results of the included RCTs, we found no evidence showing that any particular type of dental implant had superior long-term success. There was limited evidence showing that implants with relatively smooth (turned) surfaces were less prone to lose bone due to chronic infection (peri-implantitis) than implants with much rougher surfaces (titanium-plasma-sprayed). These findings were based on several RCTs, often at high risk of bias, with few participants and relatively short follow-up periods.

Mandibular implant-supported overdentures in (frail) elderly: A prospective study with 20-year follow-up

Purpose

To prospectively assess long‐term (20 year) clinical, radiographic, and patient‐reported outcomes of an elderly population provided with mandibular implant‐supported overdentures.

Materials and Methods

A total of 53 elderly (aged ≥60 years at the time of treatment) were provided with two endosseous implants supporting a mandibular overdenture and a conventional maxillary denture. Outcome parameters—including implant loss, plaque index, gingival index, bleeding index, presence of calculus, probing depth, and satisfaction with implant‐supported overdenture—were scored 1, 5, 10, and 20 years after prosthetic treatment. Radiographic analysis was performed to assess peri‐implant bone changes. At the 20‐year evaluation, frailty (Groningen Frailty Index) and quality of life (EuroQol 5D) were additionally assessed.

Results

A total of 15 patients completed the 20‐year follow‐up. The 20‐year implant survival rate was 92.5%. Plaque index, bleeding index, and probing depth increased slightly over time, while gingival index and presence of calculus remained unchanged. Radiographic analysis revealed minor marginal bone loss during the first 10 years and no further loss thereafter. Participants were very satisfied with their prosthesis and reported a good quality of life. At the 20‐year evaluation, 64.3% of the patients were classified as frail.

Conclusions

The long‐term survival of implants supporting a mandibular overdenture is high. Although most elderly in the study became frail over time, peri‐implant health and marginal bone level remained at a satisfactory level.

Small-Diameter Implants: A 7-Year Retrospective Study

Oral implantology has become a major discipline within the field of dentistry. Small or mini dental implants have demonstrated success in the retention of removable and fixed prostheses. Small-diameter implants (SDI) and mini-diameter implants (MDI) describe a group of implants that demonstrate a diameter less than 3 mm. This retrospective study reports on 335 SDI placed during a 7-year period. All implants were placed in healed sites (>6 months) and loaded immediately or after waiting 3 months. A total of 321 implants were restored and functional within the study's time interval. A total of 14 implants failed, resulting in a 96.1% implant success rate. Treatment plan considerations should include prosthetic design, specific arch, and immediate load. Overall, SDI can be utilized as an alternative implant treatment option for patients with atrophic bone, compromised medical histories and financial constraints.

Osseointegrated implants placed at supracrestal level may harbour higher counts of A. gerencseriae and S. constellatus - a randomized, controlled pilot study

Purpose

This study aimed at evaluating the bacterial colonization in dental implants inserted in the crestal or supracrestal position and correlated it to radiographic bone measurements.

Methods

Thirty-five implants with regular platform in nine patients (mean age 62.4±11.2 years) were inserted either at the bone crest level (control group) or at a suprecrestal level (test group). Radiographic examination was performed at baseline (implant installation) and after 6 months. Clinical and microbiological data were collected after 6 months. Digital radiography was used to assess bone remodeling (marginal bone loss and optical alveolar density). Bacterial profile was analyzed by checkerboard DNA–DNA hybridization, including a panel of 40 bacterial species.

Results

After 6 months, there were significantly higher counts of Actinomyces gerencseriae (p=0.009) and Streptococcus constellatus (p=0.05) in the test group. No significant differences between test and control groups were observed for marginal bone loss (p=0.725) and optical alveolar density (p=0.975). Probing depth was similar in both groups.

Conclusion

Significantly higher counts of A. gerencseriae and S. constellatus were found in implants placed at the supracrestal level compared to the ones placed at the bone level. No relation was found between the installation level of dental implants and peri-implant bone remodeling.

Periodontal and peri-implant microbiota in patients with healthy and inflamed periodontal and peri-implant tissues

OBJECTIVE

To compare the prevalence and levels of six bacterial pathogens within the subgingival/submucosal microbiota at teeth versus implants with various clinical conditions.

MATERIAL AND METHODS

Twenty-two Chinese were included. Four subgingival/submucosal sites were selected for microbiological sampling within each subject, that is, (1) healthy peri-implant tissues; (2) peri-implantitis [PPD ≥ 5 mm, presence of bleeding on probing (BOP) and confirmed radiographic bone loss]; (3) healthy gingiva; and (4) periodontitis (PPD ≥4 mm). Subgingival/submucosal plaque was sampled using paper points. Quantitative real-time polymerase chain reaction (q-PCR) was used to quantify six pathogens, including Porphyromonas gingivalis (P.g.), Treponema denticola (T.d.), Aggregatibacter actinomycetemcomitans (A.a.), Fusobacterium nucleatum (F.n.), Prevotella intermedia (P.i.), and Staphylococcus aureus (S.a.). Counts were log10-transformed.

RESULTS

The most commonly detected species were S. a. and F. n., while A. a. and. P. i. had the lowest detection frequency. The detection frequencies of diseased tooth or implant sites for each of the six target species were either equal to or higher than the respective frequencies at the corresponding healthy sites. There were no statistically significant differences for any of the species or clinical sites (P > 0.05, Cochran's Q test). No statistically significant differences in the bacterial loads were found among the four clinical sites; with the exception of F. nucleatum. This was more abundant in periodontitis sites (P = 0.023, Friedman's 2-way anova). Both periodontal and peri-implant sites, irrespective of their health status, were revealed to harbor S. aureus cells. The log10-transformed loads of S. aureus were approximately 3.5 within each of the clinical sites (P = 0.232). This was the highest of the six species analyzed.

CONCLUSIONS

Within the same subjects, putative periodontal pathogens were common to both periodontal and peri-implant sites irrespective of health status. The prevalence and levels of P. gingivalis and F. nucleatum were significantly associated with periodontitis, but not with peri-implantitis. A. actinomycetemcomitans was associated with both disease conditions, periodontitis and peri-implantitis, but not with either gingival or mucosal health.

Interventions for replacing missing teeth: different types of dental implants

BACKGROUND

Dental implants are available in different materials, shapes and with different surface characteristics. In particular, numerous implant designs and surface modifications have been developed for improving clinical outcome. This is an update of a Cochrane review first published in 2002, and previously updated in 2003, 2005 and 2007.

OBJECTIVES

Primary: to compare the clinical effects of different root-formed osseointegrated dental implant types for replacing missing teeth for the following specific comparisons: implants with different surface preparations, but having similar shape and material; implants with different shapes, but having similar surface preparation and material; implants made of different materials, but having similar surface preparation and shape; different implant types differing in surface preparation, shape, material or a combination of these.Secondary: to compare turned and roughened dental implants for occurrence of early implant failure (before prosthetic loading) and occurrence of peri-implantitis.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 17 January 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 12), MEDLINE via OVID (1946 to 17 January 2014) and EMBASE via OVID (1980 to 17 January 2014). We placed no restrictions on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included any randomised controlled trial (RCT) comparing osseointegrated dental implants of different materials, shapes and surface properties having a follow-up in function of at least one year. Outcome measures were success of the implants, radiographic peri-implant marginal bone levels changes and incidence of peri-implantitis.

DATA COLLECTION AND ANALYSIS

At least two review authors independently conducted screening, risk of bias assessment and data extraction of eligible trials in duplicate. We expressed results using fixed-effect models (if up to three studies were present in a meta-analysis) or random-effects models (when there were more than three studies) using mean differences (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CI). We reported the following endpoints: one, three, five and 10 years after functional loading.

MAIN RESULTS

We identified 81 different RCTs. We included 27 of these RCTs, reporting results from 1512 participants and 3230 implants in the review. We compared 38 different implant types with a follow-up ranging from one to 10 years. All implants were made of commercially pure titanium or its alloys, and had different shapes and surface preparations. We judged two trials to be at low risk of bias, 10 to be at unclear risk of bias and 15 to be at high risk of bias. On a 'per participant' rather than 'per implant' basis, we found no significant differences between various implant types for implant failures. The only observed statistically significant difference for the primary objective regarded more peri-implant bone loss at Nobel Speedy Groovy implants when compared with NobelActive implants (MD -0.59 mm; 95% CI -0.74 to -0.44, different implant shapes). The only observed statistically significant difference for the secondary objective was that implants with turned (smoother) surfaces had a 20% reduction in risk to be affected by peri-implantitis than implants with rough surfaces three years after loading (RR 0.80; 95% CI 0.67 to 0.96). There was a tendency for implants with turned surfaces to fail early more often than implants with roughened surfaces.

AUTHORS' CONCLUSIONS

Based on the results of the included RCTs, we found no evidence showing that any particular type of dental implant had superior long-term success. There was limited evidence showing that implants with relatively smooth (turned) surfaces were less prone to lose bone due to chronic infection (peri-implantitis) than implants with much rougher surfaces (titanium-plasma-sprayed). These findings were based on several RCTs, often at high risk of bias, with few participants and relatively short follow-up periods.

Reasons for failures of oral implants

This study reviews the literature regarding the factors contributing to failures of dental implants. An electronic search was undertaken including papers from 2004 onwards. The titles and abstracts from these results were read to identify studies within the selection criteria. All reference lists of the selected studies were then hand-searched, this time without time restrictions. A narrative review discussed some findings from the first two parts where separate data from non-comparative studies may have indicated conclusions different from those possible to draw in the systematic analysis. It may be suggested that the following situations are correlated to increase the implant failure rate: a low insertion torque of implants that are planned to be immediately or early loaded, inexperienced surgeons inserting the implants, implant insertion in the maxilla, implant insertion in the posterior region of the jaws, implants in heavy smokers, implant insertion in bone qualities type III and IV, implant insertion in places with small bone volumes, use of shorter length implants, greater number of implants placed per patient, lack of initial implant stability, use of cylindrical (non-threaded) implants and prosthetic rehabilitation with implant-supported overdentures. Moreover, it may be suggested that the following situations may be correlated with an increase in the implant failure rate: use of the non-submerged technique, immediate loading, implant insertion in fresh extraction sockets, smaller diameter implants. Some recently published studies suggest that modern, moderately rough implants may present with similar results irrespective if placed in maxillas, in smoking patients or using only short implants.

Comparative evaluation of bone in mandibular implant retained overdentures using delayed and immediate loading protocol: an in-vivo study

The aim of the present study was to evaluate the changes in periimplant bone quality, crestal bone level and the implant stability (periotest) for mandibular implant retained overdentures with ball attachments using delayed and immediate loading protocols. Ten completely edentulous patients had two alpha bio dental implants placed in the anterior part of the mandible. The loading protocols for the patients was chosen randomly by drawing lots. Five patients were loaded under immediate loading protocols and other five following delayed. Crestal bone loss and bone quality were assessed around each implant. Periotest values were recorded for each implant at 3, 6 and 12 months after loading. Two implants were lost and were excluded from the study. However mean crestal bone loss around implants was 0.81 mm from the time of prosthetic loading to 12 months after prosthetic loading was seen and no significant result was found between the two groups for the crestal bone loss and the periotest values. Though the periotest value decreased (indicates increased stability) over the time period. The bone density changes were significant for both the groups at coronal level at all time intervals but at middle level significant only after 12 months of prosthetic loading, although individual variation was high. This study concluded that the changes in crestal bone level and periotest values were insignificant for the two groups. But the implant stability increased over the time and the crestal bone loss was evident with decreased rate over the period of time. There was wide individual variation for the bone density changes but overall increase in the density was seen.

In Vivo Evaluation of Two-Piece Implants Placed Following One-Stage and Two-Stage Surgical Protocol in Posterior Mandibular Region. Assessment of Alterations in Crestal Bone Level

BACKGROUND

Endosseous implants can be placed following either two-stage technique requiring second-stage surgery or one-stage technique, which does not involve a second surgical intervention.

PURPOSE

The present study was undertaken to evaluate and compare the changes in crestal bone level when two-piece implants were placed in posterior mandibular region following one-stage and two-stage surgical protocol.

MATERIALS AND METHODS

A parallel group randomized prospective study was designed in which 20 two-piece implants were placed in the posterior mandibular region of 16 partially edentulous healthy patients following either one-stage (Group I) or a two-stage surgical protocol (Group II). Alterations in crestal bone level were assessed with the help of DentaScan at baseline, that is, at the time of implant placement, third month and sixth month.

RESULTS

Nonsignificant differences were seen in both groups in terms of changes in crestal bone level at the final evaluation.

CONCLUSIONS

Hence, it could be concluded that two-piece implants can be placed following one-stage surgical protocol as predictably as when two-stage surgical technique is followed.

Small Diameter Implants: Specific Indications and Considerations for the Posterior Mandible: A Case Report

The field of implant dentistry continues to grow globally as clinicians embrace the evolution of various endosseous implant technologies and the array of enhanced surgical and prosthetic products. The utilization of small diameter implants in limited osseous regions increases patients' ability to choose implants as a viable restorative option. Although small diameter implants have been indicated in the incisor region for the maxilla and mandible primarily, their usage should be considered in select posterior regions. These 2 case reports demonstrate the incorporation of small diameter implants to replace missing mandibular posterior teeth.

A finite element method approach for the mechanobiological modeling of the osseointegration of a dental implant

The aim of this paper is to introduce a new mathematical model using a mechanobiological approach describing the process of osseointegration at the bone-dental implant interface in terms of biological and mechanical factors and the implant surface. The model has been computationally implemented by using the finite element method. The results show the spatial-temporal patterns distribution at the bone-dental implant interface and demonstrate the ability of the model to reproduce features of the wound healing process such as blood clotting, osteogenic cell migration, granulation tissue formation, collagen-like matrix displacements and new osteoid formation. The model might be used as a methodological basis for designing a dental tool useful to predict the degree of osseointegration of dental implants and subsequent formulation of mathematical models associated with different types of bone injuries and different types of implantable devices.

Titanium oral implants: surface characteristics, interface biology and clinical outcome

Bone-anchored titanium implants have revolutionized oral healthcare. Surface properties of oral titanium implants play decisive roles for molecular interactions, cellular response and bone regeneration. Nevertheless, the role of specific surface properties, such as chemical and phase composition and nanoscale features, for the biological in vivo performance remains to be established. Partly, this is due to limited transfer of state-of-the-art preparation techniques to complex three-dimensional geometries, analytical tools and access to minute, intact interfacial layers. As judged by the available results of a few randomized clinical trials, there is no evidence that any particular type of oral implant has superior long-term success. Important insights into the recruitment of mesenchymal stem cells, cell-cell communication at the interface and high-resolution imaging of the interface between the surface oxide and the biological host are prerequisites for the understanding of the mechanisms of osseointegration. Strategies for development of the next generation of material surface modifications for compromised tissue are likely to include time and functionally programmed properties, pharmacological modulation and incorporation of cellular components.

Interventions for replacing missing teeth: different types of dental implants

BACKGROUND

Dental implants are available in different materials, shapes and with different surface characteristics. In particular, numerous implant surface modifications have been developed for enhancing clinical performance.

OBJECTIVES

To test the null hypothesis of no difference in clinical performance between various root-formed osseointegrated dental implant types.

SEARCH STRATEGY

We searched the Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. Handsearching included several dental journals. We checked the bibliographies of relevant clinical trials and review articles for studies outside the handsearched journals. We wrote to authors of the identified randomised controlled trials (RCTs), to more than 55 oral implant manufacturers; we used personal contacts and we asked on an internet discussion group in an attempt to identify unpublished or ongoing RCTs. No language restriction was applied. The last electronic search was conducted on 13 June 2007.

SELECTION CRITERIA

All RCTs of oral implants comparing osseointegrated implants with different materials, shapes and surface properties having a follow up of at least 1 year.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two review authors. Results were expressed as random-effects models using mean differences for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CI).

MAIN RESULTS

Forty different RCTs were identified. Sixteen of these RCTs, reporting results from a total of 771 patients, were suitable for inclusion in the review. Eighteen different implant types were compared with a follow up ranging from 1 to 5 years. All implants were made in commercially pure titanium and had different shapes and surface preparations. On a 'per patient' rather than 'per implant' basis no significant differences were observed between various implant types for implant failures. There were statistically significant differences for perimplant bone level changes on intraoral radiographs in three comparisons in two trials. In one trial there was more bone loss only at 1 year for IMZ implants compared to Brånemark (mean difference 0.60 mm; 95% CI 0.01 to 1.10) and to ITI implants (mean difference 0.50 mm; 95% CI 0.01 to 0.99). In the other trial Southern implants displayed more bone loss at 5 years than Steri-Oss implants (mean difference -0.35 mm; 95% CI -0.70 to -0.01). However this difference disappeared in the meta-analysis. More implants with rough surfaces were affected by perimplantitis (RR 0.80; 95% CI 0.67 to 0.96) meaning that turned implant surfaces had a 20% reduction in risk of being affected by perimplantitis over a 3-year period.

AUTHORS' CONCLUSIONS

Based on the available results of RCTs, there is limited evidence showing that implants with relatively smooth (turned) surfaces are less prone to lose bone due to chronic infection (perimplantitis) than implants with rougher surfaces. On the other hand, there is no evidence showing that any particular type of dental implant has superior long-term success. These findings are based on a few RCTs, often at high risk of bias, with few participants and relatively short follow-up periods. More RCTs should be conducted, with follow up of at least 5 years including a sufficient number of patients to detect a true difference. Such trials should be reported according to the CONSORT recommendations (http://www.consort-statement.org/).

Clinical and radiographic evaluation of implant-retained mandibular overdentures with immediate loading

PURPOSE

The aim of this study was to evaluate and compare immediate-loaded implant-retained mandibular overdentures and delayed-loaded implant-retained mandibular overdentures.

MATERIALS

Ten completely edentulous male patients received 40 dental implants. Patients were randomly divided into 2 equal groups, 5 patients each. Patients of both groups received conventional maxillary complete denture and had stage 1 surgery for placing 4 dental implant fixtures, 2 on each side anterior to the mental foramina. Group A: One-stage surgical procedure and immediate loading. Patients in this group received mandibular bar-retained overdenture supported by 4 endosseous implants loaded immediately after implant placement. Group B: The original 2-stage concept and delayed loading. Patients in this group received mandibular bar-retained overdenture supported by 4 endosseous implants that remained submerged for a period of 4 months before loading. The patients were evaluated clinically and radiographically immediately after overdenture delivery and after 6 months, 12 months, 18 months, and 24 months.

RESULTS

The results of clinical evaluation showed no statistical significant difference between the 2 groups regarding the effect of treatment. The radiographic assessment showed no statistical significant difference in mesial and distal alveolar bone loss at the different intervals of the follow-up period, except at the 12-month period, where immediately loaded implants showed a decrease in the amount of alveolar bone loss mesially and distally compared to delayed loaded implants.

CONCLUSIONS

The results suggest that immediate-loaded implants provide promising results compared to delayed-loaded implants and can be a possible alternative procedure in implant dentistry.

Immediate and early implant loading protocols: a literature review of clinical studies

The purpose of this literature review is to present the outcomes of clinical studies on immediate and early loading protocols, identify shortcomings, and suggest a number of questions that still require exploration. English language clinical studies, limited to peer-reviewed journals between 1975 and 2004, were reviewed to identify treatment outcomes with these loading protocols. The data were tabulated from studies reporting on patients treated with fixed and overdenture prostheses. The former included partially edentulous patients treated with single or multi-unit prostheses. Within the limitations of this review, it can be concluded that these treatment protocols are predictable in the anterior mandible, irrespective of implant type, surface topography, and prosthesis design (success rates 90%-100%). Limited evidence for the edentulous maxilla (success rates 90%-100%) and the partially edentulous patient (success rates 93%-100%) are available, underscoring the need for further research. Studies suggest that to achieve predictable results in extraction sites, implant placement should be restricted to sites without a history of periodontal involvement (success rates 61%-100%). A number of questions require further exploration. There is a need to thoroughly investigate clinical outcomes to measure the economic benefit of these protocols and the impact of treatment on a patient's quality of life. Furthermore, more accurate long-term studies reporting on treatment protocols for separate clinical situations are required to allow meaningful comparisons.

Interventions for replacing missing teeth: different types of dental implants

BACKGROUND

Dental implants are available in different materials, shapes and with different surface characteristics. In particular, numerous implant surface modifications have been developed for enhancing clinical performances.

OBJECTIVES

To test the null hypothesis of no difference in clinical performance between various root-formed osseointegrated dental implant types.

SEARCH STRATEGY

We searched the Cochrane Oral Health Group's Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. Handsearching included several dental journals. We checked the bibliographies of relevant clinical trials and review articles for studies outside the handsearched journals. We wrote to authors of the identified randomised controlled trials (RCTs), to more than 55 oral implant manufacturers; we used personal contacts and we asked on an internet discussion group in an attempt to identify unpublished or ongoing RCTs. No language restriction was applied. The last electronic search was conducted on 28 June 2004.

SELECTION CRITERIA

All RCTs of oral implants comparing osseointegrated implants with different materials, shapes and surface properties having a follow up of at least 1 year.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two reviewers. Results were expressed as random effects models using weighted mean differences for continuous outcomes and relative risk for dichotomous outcomes with 95% confidence intervals.

MAIN RESULTS

Thirty-one different RCTs were identified. Twelve of these RCTs, reporting results from a total of 512 patients, were suitable for inclusion in the review. Twelve different implant types were compared with a follow up ranging from 1 to 5 years. All implants were made in commercially pure titanium and had different shapes and surface preparations. On a 'per patient ' rather than 'per implant' basis no significant differences were observed between various implant types for implant failures. There were statistically significant differences for peri-implant bone level changes on intraoral radiographs in three comparisons in two trials. In one trial there was more bone loss only at 1 year for IMZ implants compared to Branemark (mean difference 0.60 mm; 95% CI 0.01 to 1.10) and to ITI implants (mean difference 0.50 mm; 95% CI 0.01 to 0.99). In the other trial Southern implants displayed more bone loss at 5 years than Steri-Oss implants (mean difference -0.35 mm; 95% CI -0.70 to -0.01). However this difference disappeared in the meta-analysis. More implants with rough surfaces were affected by perimplantitis (RR 0.80; 95% CI 0.67 to 0.96) meaning that turned implant surfaces had a 20% reduction in risk of being affected by perimplantitis over a 3-year period.

AUTHORS' CONCLUSIONS

Based on the available results of RCTs, there is limited evidence showing that implants with relatively smooth (turned) surfaces are less prone to loose bone due to chronic infection (perimplantitis) than implants with rougher surfaces. On the other hand, there is no evidence showing that any particular type of dental implant has superior long-term success. These findings are based on a few RCTs, often at high risk of bias, with few participants and relatively short follow-up periods. More RCTs should be conducted, with follow up of at least 5 years including a sufficient number of patients to detect a true difference if any exists. Such trials should be reported according to the CONSORT recommendations (http://www.consort-statement.org/).

Mandibular overdentures supported by two or four endosseous implants

OBJECTIVE

The aim of this 5-year prospective comparative study was to evaluate treatment outcome (survival rate, condition of hard and soft peri-implant tissues, patient satisfaction, prosthetic and surgical aftercare) of mandibular overdentures supported by two or four implants.

MATERIAL AND METHODS

Sixty edentulous patients with a mandibular height between 12 and 18 mm participated. Thirty patients were treated with an overdenture supported by two IMZ implants (group A) and 30 patients were treated with an overdenture supported by four IMZ implants (group B). Standardised clinical and radiographic parameters were evaluated 6 weeks after completion of the prosthetic treatment and after 1, 2, 3, 4 and 5 years of functional loading. Prosthetic and surgical aftercare was scored during the evaluation period.

RESULTS

One implant was lost (group A) during the healing period. There were no significant differences with regard to any of the studied clinical or radiographic parameters of the peri-implant tissues between the groups. None of the patients reported sensory disturbances in the lip or chin region. No differences in satisfaction were observed between the groups. With regard to aftercare, there was a tendency of a greater need of prosthetic interventions in group A, while correction of soft-tissue problems was restricted to patients of group B.

CONCLUSION

There is no difference in clinical and radiographical state of patients treated with an overdenture on two or four implants during a 5-year evaluation period. Patients of both groups were as satisfied with their overdentures.

Force transmission of one- and two-piece morse-taper oral implants: a nonlinear finite element analysis

PURPOSE

To compare force transmission behaviors of one-piece (1-P) and two-piece (2-P) morse-taper oral implants.

MATERIAL AND METHODS

A three-dimensional finite element model of a morse-taper oral implant and a solid abutment was constructed separately. The implant-abutment complex was embedded in a phi 1.5 cm x 1.5 cm acrylic resin cylinder. Vertical and oblique forces of 50 N and 100 N were applied on the abutment and solved by two different analyses. First, contact analysis was performed in the implant-abutment complex to evaluate a 2-P implant. Then, the components were bonded with a separation force of 10(20) N to analyze a 1-P implant.

RESULTS

Von Mises stresses in the implant, principal stresses, and displacements in the resin were the same for both designs under vertical loading. Under oblique loading, principal stresses and displacement values in the resin were the same, but the magnitudes of Von Mises stresses were higher in the 2-P implant. The principal stress distributions around both implants in the acrylic bone were similar under both loading conditions.

CONCLUSION

2-P implants experience higher mechanical stress under oblique loading. Nevertheless, the 1-P- or 2-P morse-taper nature of an implant is not a decisive factor for the magnitude and distribution of stresses, and displacements in supporting tissues.

A prospective evaluation of Frialoc®implants with ball-abutments in the edentulous mandible: 1-year results

Several surgical and prosthetic concepts for the treatment of patients with mandibular atrophy and related lower denture problems are proposed and described in the literature. The present study discusses and evaluates the use of a new single-stage implant and overdenture with ball-attachment for this purpose. This study evaluates the clinical performance of the implants and abutments and addresses surgical and prosthetic complications that were encountered. Eighteen fully edentulous patients received two, single-stage Frialoc implants (Friadent, Mannheim, Germany). The implants were left to osseointegrate for 3 months and were subsequently provided with ball-abutments and loaded through a mandibular overdenture. After 1-year of clinical service, two implants were lost, which accumulated to a 1-year survival rate of 93.9% (SE 4.2%). Patient satisfaction was high, and prosthetic complications and postinsertion maintenance were minimal. Three abutments loosened, one of which subsequently broke after 5 months of loading. Retightening of the attachment (gold matrix) was performed on seven occasions in four patients. Soft tissue response was excellent. Although minor hypertrophy of the peri-implant mucosa was observed, hardly any marginal bone loss between baseline and 1-year observations occurred. Short-term results indicate that mandibular implant overdenture treatment by means of two ball-abutments, using Frialoc implants and prosthetic components, leads to good clinical results, both from an objective and a subjective perspective.

Quality of dental implants

BACKGROUND

Clinicians need quality research data to decide which dental implant should be selected for patient treatment. AIM(S)/OBJECTIVE(S): To present the scientific evidence for claims of relationship between characteristics of dental implants and clinical performance.

STUDY DESIGN

Systematic search of promotional material and Internet sites to find claims of implant superiority related to specific characteristics of the implant, and of the dental research literature to find scientific support for the claims.

MAIN OUTCOME MEASURES

Critical appraisal of the research documentation to establish the scientific external and internal validity as a basis for the likelihood of reported treatment outcomes as a function of implant characteristics.

RESULTS

More than 220 implant brands have been identified, produced by about 80 manufacturers. The implants are made from different materials, undergo different surface treatments and come in different shapes, lengths, widths and forms. The dentist can in theory choose among more than 2,000 implants in a given patient treatment situation. Implants made from titanium and titanium alloys appear to perform well clinically in properly surgically prepared bone, regardless of small variations of shapes and forms. Various surface treatments are currently being developed to improve the capacity of a more rapid anchorage of the implant into bone. A substantial number of claims made by different manufacturers on alleged superiority due to design characteristics are not based on sound and long-term clinical scientific research. Implants are, in some parts of the world, manufactured and sold with no demonstration of adherence to any international standards.

CONCLUSIONS

The scientific literature does not provide any clear directives to claims of alleged benefits of specific morphological characteristics of dental implants.

Early Functional Loading of Unsplinted Roughened Surface Implants with Mandibular Overdentures 2 Weeks after Surgery

BACKGROUND

Before early functional loading of unsplinted implants with mandibular overdentures can become widespread, more clinical studies are needed to investigate the success of the approach.

PURPOSE

To evaluate the success rates of two types of roughened titanium surface implants with early 2-week functional loading of paired mandibular interforaminal implants with overdentures.

MATERIALS AND METHODS

Random allocation divided 24 strictly selected edentulous participants into two groups, with each group to receive a different implant system (ITI Dental Implant System, Straumann AG, Waldenburg, Switzerland; or Southern Implant System, Southern Implants, Irene, South Africa). Two implants were placed in the anterior mandible of all participants using one-stage standardized surgical procedures. Previously constructed conventional mandibular dentures (opposing maxillary complete dentures) were temporarily relined and worn by the participants for the first 2 weeks; participants used a soft diet. Two weeks after implant surgery and following some mucosal healing, the mandibular dentures had the tissue conditioner removed and the appropriate matrices included for an unsplinted prosthodontic design.

RESULTS

No implant from either group was lost. Resonance frequency analysis (RFA) indicated higher primary stability at surgery for the Southern group than for the ITI group, with a statistically significant difference between the groups throughout the study period. The drop in RF values between surgery and 6 weeks was significant and was greater for the Southern group. RFA also indicated stabilized osseointegration between 6 to 12 and 12 to 52 weeks, with no participant showing any decrease in those values over time. Participants with type 3 bone showed a significant improvement in RF values between 12 and 52 weeks, eventually matching those of participants with type 2 bone. There were no significant differences in marginal bone loss, periimplant parameters, or prosthodontic maintenance between the groups over the study period.

CONCLUSIONS

Using only strict patient selection criteria, 1-year follow-up data indicate that early functional loading of ITI and Southern implants with mandibular two-implant overdentures is possible as early as 2 weeks after implant surgery.