Mandibular overdentures supported by two Brånemark, IMZ or ITI implants: a ten-year prospective randomized study

Surface Topography Has Less Influence on Peri-Implantitis than Patient Factors: A Comparative Clinical Study of Two Dental Implant Systems

OBJECTIVES

This study aims to assess the risk of peri-implantitis (PI) onset among different implant systems and evaluate the severity of the disease from a population of patients treated in a university clinic. Furthermore, this study intends to thoroughly examine the surface properties of the implant systems that have been identified and investigated.

MATERIAL AND METHODS

Data from a total of six hundred and 14 patients were extracted from the Institute of Clinical Dentistry, Dental Faculty, University of Oslo. Subject- and implant-based variables were collected, including the type of implant, date of implant installation, medical records, recall appointments up to 2022, periodontal measurements, information on diabetes, smoking status, sex, and age. The outcome of interest was the diagnosis of PI, defined as the occurrence of bleeding on probing (BoP), peri-implant probing depth (PD) ≥ 5 mm, and bone loss (BL). Data were analyzed using multivariate linear and logistic regression. Scanning electron microscopy, light laser profilometer, and X-ray photoelectron spectroscopy were utilized for surface and chemical analyses.

RESULTS

Among the patients evaluated, 6.8% were diagnosed with PI. A comparison was made between two different implant systems: Dentsply Sirona, OsseospeedTM and Straumann SLActive, with mean follow-up times of 3.84 years (SE: 0.15) and 3.34 years (SE: 0.15), respectively. The surfaces have different topographies and surface chemistry. However, no significant association was found between PI and implant surface/system, including no difference in the onset or severity of the disease. Nonetheless, plaque control was associated with an increased risk of developing PI, along with the gender of the patient. Furthermore, patients suffering from PI exhibited increased BL in the anterior region.

CONCLUSION

No differences were observed among the evaluated implant systems, although the surfaces have different topography and chemistry. Factors that affected the risk of developing PI were plaque index and male gender. The severity of BL in patients with PI was more pronounced in the anterior region. Consequently, our findings show that success in implantology is less contingent on selecting implant systems and more on a better understanding of patient-specific risk factors, as well as on implementing biomaterials that can more effectively debride dental implants.

Single lateral implant for mandibular overdentures as a fallback solution or a viable treatment alternative: Four case reports

This report of four clinical cases aims to illustrate the use of a lateral implant as a solution for implant overdentures in the mandible in different clinical situations. The first two cases describe the clinical situations of patients wearing two-implant mandibular overdentures until the failure of one of the implants, one due to implant loss and the other due to a fracture of an abutment screw, and how the conditions were managed. The third case illustrates the placement of a single implant to retain an overdenture, where a midline implant, as originally planned, was not feasible due to anatomic reasons. The final case describes the use of a lateral implant to support and retain a single-implant mandibular overdenture. The four cases demonstrate that a single lateral implant can be utilized as sole retention in cases of a failing contra-lateral implant and as an alternative to a single implant in the midline.

Prosthetic complications with mandibular bar-retained implant overdentures having distal attachments and metal frameworks: A 2- to 12-year retrospective analysis

STATEMENT OF PROBLEM

Long-term reports on 2-implant-retained overdentures having metal frameworks and bars containing distal attachments are scarce.

PURPOSE

The purpose of this retrospective study was to evaluate prosthetic complications with 2-implant-retained mandibular overdentures with metal frameworks having either screw- or cement-retained cantilevered bars with distal attachments.

MATERIAL AND METHODS

Seventy-three edentulous study participants who had been treated with mandibular overdentures with 2 implants were included. The parameters assessed were acrylic resin fractures (base fracture, fracture at midline), debonding of teeth, opposing prosthesis fracture, need for relining or rebasing, abutment and bar screw loosening and fracture, ball or bar attachment or clip wear, fracture or detachment, bar fracture, and implant loss. Statistical analysis was performed by using the Mann-Whitney U test as the data were not normally distributed. The categorical variables between the groups were analyzed by using the Fisher exact test (α=.05).

RESULTS

Twenty-seven prostheses had a cement-retained bar, and 46 bars were screw-retained. Of 73 overdentures, 68 were metal-reinforced. The mean observation time was 5.9 years with a range between 2 and 12 years. The most common complication was wear of the Rhein 83 polymer attachment followed by bar screw loosening. The cumulative survival rate for overdentures was 91.9% at 6.8 years. The service life of cement-retained prostheses was significantly longer (P<.05). Bar, resin base, and mid-line fractures were only seen with cement-retained prostheses. The number of times an attachment change was required did not differ between cement- and screw-retained bars. Of 191 implants, 3 were lost, and the cumulative survival rate was 93.5% at 7.5 years. No significant difference was found between retention types in terms of implant loss (P>.05).

CONCLUSIONS

Based on the participant population observed, the survival rates of 2-implant-retained mandibular overdentures and their implants in the medium term were high. Wear of the polymer attachment was commonly seen. Overdentures with cement-retained bars had bar or acrylic resin fractures. Mandibular 2-implant-retained overdentures with a screw-retained bar containing bilateral distal attachments had fewer prosthetic complications and high implant survival in the medium term.

Long-term outcome of the IMZ implant system: a retrospective clinical study with a follow-up between 23 and 34 years

PURPOSE

To evaluate the radiographic and peri-implant outcomes of intramobile cylinder implants (IMZs) and the feasibility of long-term follow-up studies after nearly 30 years.

METHODS

Of the 94 patients treated with IMZ implants between 1981 and 1995, 39 patients were successfully contacted (contact group, CG), of which 15 patients with a total of 32 implants agreed to participate in the present follow-up study (clinical evaluation group, CEG). The overall implant survival rate was calculated. Information on implant status and oral and general health data was collected. Marginal bone level was evaluated and then compared to the patients' baseline data. Possible risk factors for peri-implantitis were also identified.

RESULTS

In total, 16 implants in seven patients were lost, amounting to an overall survival rate of 79.5% after 30 years with a mean follow-up time of 24 ± 10 years (CG). Eight patients were treated with bar-retained mandibular overdentures and seven patients had fixed partial dentures. After a mean observation time of 29 ± 3 years, the surviving implants showed a peri-implantitis rate of 9.4% with a mean marginal bone loss of 2.5 ± 1.8 mm (CEG). No significant correlation between peri-implantitis and possible risk factors could be found.

CONCLUSIONS

Long-term follow-up studies with acceptable response rates after nearly 30 years are not feasible. Contact was only possible with 41% of the patients. This contact group showed a high implant survival rate. Due to the retrospective study design, additional risk factors could not be considered in a conclusive analysis.

Biomechanical Stress Analysis of Platform Switch Implants of Varying Diameters on Different Densities of Bone

Purpose

The purpose of this study was to evaluate and compare the strain developed in D2 and D3 types of bones on vertical loading by platform switch implants of different diameters.

Materials and Methods

Implants of diameters 3.25 mm, 4.2 mm, and 5.0 mm and of length 11.5 mm were taken and placed each on D2 and D3 bone models. Strain gauges were attached on the buccal and the lingual sides on each of these samples, and a vertical load of 190N was placed on the samples. The strain was recorded using a data logger. The data obtained was analysed using one-way ANOVA and post hoc Tukey test.

Results

In D2 and D3 bone models, 3.25 mm significantly showed greater bone strain values. The buccal side strain was higher irrespective of the implant diameter and density of bone.

Conclusion

Within the limitations of the study, it may be concluded that the narrow diameter implant produces greater strain than 4.2 and 5.0 mm diameter implants, respectively. The buccal side consistently produced higher bone strain values.

What is the influence of implant surface characteristics and/or implant material on the incidence and progression of peri-implantitis? A systematic literature review

OBJECTIVES

To answer the focused question, 'In animals or patients with dental implants, does implant surface characteristics and/or implant material have an effect on incidence and progression of peri-implantitis?'

MATERIAL AND METHODS

Pre-clinical in vivo experiments on experimental peri-implantitis and clinical trials with any aim and design, and ≥5 years follow-up, where the effect of ≥2 different type of implant material and/or surface characteristics on peri-implantitis incidence or severity, and/or progression, implant survival or losses due to peri-implantitis, and/or marginal bone levels/loss was assessed.

RESULTS

Meta-analyses based on data of pre-clinical experiments, using the ligature induced peri-implantitis model in the dog, indicated that after the spontaneous progression phase implants with a modified surface showed significantly greater radiographic bone loss (effect size 0.44 mm; 95%CI 0.10-0.79; p = .012; 8 publications) and area of infiltrated connective tissue (effect size 0.75 mm² ; 95%CI 0.15-1.34; p = .014; 5 publications) compared to non-modified surfaces. However, in 9 out of the 18 included experiments, reported in 25 publications, no significant differences were shown among the different implant surface types assessed. Clinical and/or radiographic data from 7605 patients with 26,188 implants, reported in 31 publications (20 RCTs, 3 CTs, 4 prospective cohort, and 4 retrospective studies; 12 with follow-up ≥10 years), overall did not show significant differences in the incidence of peri-implantitis, when this was reported or could be inferred, among the various implant surfaces. In general, high survival rates (90-100%) up to 30 years and no clinically relevant differences in marginal bone loss/levels, merely compatible with crestal remodelling, were presented for the various implant types.

CONCLUSION

Pre-clinical in vivo experiments indicate that surface characteristics of modified implants may have a significant negative impact on peri-implantitis progression, while clinical studies do not support the notion that there is a difference in peri-implantitis incidence among the various types of implant surfaces. No assumptions can be made regarding the possible impact of implant material on incidence and/or peri-implantitis progression due to limited information.

Implant-supported mandibular overdentures: a retrospective case series study in a daily dental practice

Background

Evaluation of dental implant treatment is mostly based on studies with well-controlled study groups treated within a university-based setting. There are no long-term observational practice-based studies known on implant-supported overdentures. The present retrospective study deals with implant survival, peri-implant hard and soft tissue health, surgical and prosthetic aftercare, and satisfaction of patients treated with an implant-supported mandibular overdenture in a daily dental practice.

Materials and methods

Within the years 2006 till 2015, 295 patients were treated with two, three, or four implants for mandibular overdenture treatment in a daily dental practice in Zaandam, The Netherlands. Outcome parameters were scored at a routine yearly inspection including implant loss, plaque index, gingival index, bleeding index, presence of calculus, probing depth, and satisfaction with implant-supported overdenture. Radiographic analysis was performed to assess peri-implant bone changes. Surgical and prosthetic aftercare was obtained from the medical record.

Results

A total of 133 patients were seen for an evaluation visit (mean follow-up 51.2 months). Cumulative implant survival rate in the 2-implant group, 3-implant group, and 4-implant group was 100%, 99.1%, and 97.8% respectively, with a mean peri-implant bone loss of 0.53 mm, 0.61 mm, and 0.40 mm. Patients’ satisfaction was high in all groups.

Conclusion

It was demonstrated, within the limitations of this study, that patients, who were treated with an implant-supported mandibular overdenture in a daily dental practice, experienced a high cumulative implant survival rate and a good peri-implant health, and were very satisfied.

Trial registration

Netherlands Trial Register, NL8867. Registered 15 September 2020—retrospectively registered.

Masticatory function and oral health-related quality of life of patients with atrophic and non-atrophic mandibles using implant-retained mandibular overdentures: 3-year results of a prospective clinical study

BACKGROUND

Long-term changes in masticatory function, oral health-related quality of life (OHRQoL) and prosthetic complications in implant-retained mandibular overdenture (IMO) wearers as a function of bone atrophy require detailed investigations.

OBJECTIVE

Investigating the evolution of masticatory function, OHRQoL and prosthetic occurrences of IMO wearers according to mandibular bone atrophy over 3 years of usage.

METHODS

This study evaluated 26 IMO wearers after 2 and 3 years of IMO loading categorised according to mandibular resorption degree into atrophic mandible (AM) and a non-atrophic mandible (NAM) group. Masticatory function was assessed by the Masticatory Performance (MP) and Swallowing Threshold (ST) tests; OHRQoL and satisfaction via the Dental Impact on Daily Living (DIDL) questionnaire; and the prosthetic maintenance requirements and complications were monitored.

RESULTS

After the second year, the AM Group performed 32% more cycles (P = .047) than the NAM Group during the ST test. The DIDL questionnaire showed no significant difference for all domains, except for a moderate effect size in the General Performance domain after the third year. AM Group had more prosthetic occurrences (n = 109) than NAM Group (n = 60) in the first year, mainly due to Equator attachment dislodgment. During the third year, NAM Group presented a greater number of events (n = 45) than AM Group (n = 21) due to the greater number of O-ring exchanges.

CONCLUSION

Masticatory function and OHRQoL are not related to mandibular bone atrophy until 3 years after IMO rehabilitation. The prosthetic complications profile differs between groups, mainly in the first year.

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.

Does the implant-abutment interface interfere on marginal bone loss? A systematic review and meta-analysis

The objective of this systematic review was to compare the conical internal connection (IC) with the external hexagonal connection (EH) on the occurrence of marginal bone loss (ΔMBL). Different databases were used to carry out the selection of the elected studies. The studies were judged according to the risk of bias as "high", "low" and "unclear" risk. For the meta-analysis we included only studies that could extract the data of ΔMBL, survival rate (SR) and probing depth (PD). No statistically significant differences were found for ΔMBL data at one, three- and five-year survival rates between implant connections (p <0.05), however statistically significant differences were found for PD between EH and IC implants (1-year follow-up) -0.53 [95%CI -0.82 to -0.24, p = 0.0004]. This present systematic review demonstrated that there are no significant differences between IC and EH implants for both ΔMBL and SR at 1, 3 e 5 years after functional loading, although better PD values were observed for implants pertaining to the IC connections. Considering the high heterogeneity, more well-delineated, randomized clinical trials should be conducted.

Surface Roughness and Necessity of Manual Refinishing Requirements of CAD/CAM-Manufactured Titanium and Cobalt-Chrome Bars – A Pilot Study

Background:

Due to their increased precision, CAD/CAM generated bars (Computer-Aided Design/ Computer-Aided Manufacturing) are increasingly utilized in implant prosthodontics. For optimal clinical results, surface morphology should promote the integration of soft tissue while minimizing plaque and bacterial retention.

Objective:

Despite their clinical use, only limited information on the biological and clinical surface quality of CAD/CAM milled bars is available. The aim of the study was therefore to characterize the surface topography of bars of different manufacturers based on the profilometric analysis and the need for manual post-processing in the laboratory.

Methods:

A custom mandibular edentulous cast with four anterior implants was used as a reference cast and reproduced eight times. On each reproduction cast, corresponding scan flags were positioned and digitized. Acrylic 3D printed bar frameworks were produced and sent to the respective production center along with the digital files of the CAD bars for milling. In the course of profilometric analysis, all bars were examined in three critical Regions of Interest (ROI): Transmucosal, labial, basal. Sa and Ra values of each construction were determined. To evaluate the necessary refinishing time eight dental technicians macroscopically evaluated the bars by performing a subjective visual inspection. Kruskal-Wallis H-tests and Tukey and Kramer's post hoc tests were applied to detect differences between the samples.

Results:

After profilometric examination, three specimens (Dentsply Sirona: ZDC; Straumann: ZST; CAMLOG: ZCC) demonstrated surface roughness values in the biological acceptable range (Sa 0.2-0.4 μm) in the transmucosal region and provided optimal conditions for a reliable soft tissue adaptation. The Ra measurements revealed values beyond the acceptable threshold in the transmucosal region for three bars (Straumann: ZST; Dentsply Sirona: ZDC; Amann Girrbach: LAC). Four bars (LAC: Amann Girrbach; ZBC: BEGO; Datron: LDC & LDT; Zirkonzahn: ZZC) needed undesirable extensive manual rework. The evaluation of quality and time for manual post-processing by dental technicians confirmed the measurement-based ranking of the bars.

Conclusion:

It is desirable to define a clear roughness threshold for the clinical acceptance of transmucosal CAD/CAM generated surfaces. Clinical studies with profilometric data could help to further improve the surface quality of CAD/CAM milled bars and reduce the need for manual reworking time and effort.

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.

[Oral hygiene maintenance of locator attachments implant overdentures in edentulous population: A longitudinal study]

OBJECTIVE

To investigate the oral hygiene status of edentulous patients with locator attachments implant overdentures (IOD) and to analyze the relationship among daily hygiene behavior, oral hygiene status and peri-implant diseases.

METHODS

Edentulous patients who received IOD treatment with locator attachments from January 2012 to May 2016 were recruited. Clinical and radiographic examinations were conducted to assess the peri-implant tissue status. Modified plaque index (mPLI), sulcus bleeding index (SBI), gingival index (GI), and probing depth (PD) were recorded and peri-implant marginal bone loss (MBL) was measured using paralleling projection technique. Patients' peri-implant oral hygiene maintainence habits were investigated. The correlation between peri-implant diseases and oral hygiene status and behaviors was analyzed.

RESULTS

Fifty patients (125 implants) with an average follow-up time of 22 months (6-54 months) were enrolled. The mean values of mPLI, SBI, and GI were 1.4±1.2, 0.8±0.7, and 0.7± 0.6, respectively. Average PD was (2.2±0.7) mm. Mesial and distal maginal bone resorptions were (1.1±1.1) mm and (0.9±0.9) mm, respectively. The prevalance of mucositis and peri-implantitis of the implants were 49.6% and 0. The prevelance of mucositis in the patients with poor oral hygiene (mPLI≥2) was 11.9 times as much as that of those with adequate oral hygiene (mPLI<1). The patients who performed oral hygiene procedure on attachments at least twice a day achieved much lower mPLI scores than those who cleaned less than twice a day.

CONCLUSION

Oral hygiene condition in the group of patients with implant overdentures was poor, and it contributed to increased risk of peri-implant mucositis. The prevelance of musositis of the paitients with poor oral hygiene was 11.9 times as much as that of those with proper oral hygiene. Patients wearing IOD should pay more attention to the hygiene of the attachments.

Maxillary implant-supported overdentures opposed by (partial) natural dentitions: a 5-year prospective case series study

The aim of this study was to assess the 5-year treatment outcome of maxillary implant-retained overdentures opposed by natural antagonistic teeth. Fifty consecutive patients received maxillary overdentures supported by six dental implants. Implants were placed in the anterior region, if enough bone was present (n = 25 patients) Implant were placed in the posterior region if implant placement in the anterior region was not possible (n = 25 patients). Variables assessed included survival of implants, condition of hard and soft peri-implant tissues and patients' satisfaction. The five-year implant survival rate was 97·0% and 99·3%, and mean radiographic bone loss was 0·23 and 0·69 mm in the anterior and posterior group, respectively. Median scores for plaque, calculus, gingiva, bleeding and mean scores for pocket probing depth were low and stayed low. Patients' satisfaction after treatment was high in both groups. Within the limits of this 5-year study, it is concluded that six dental implants (placed in the anterior or posterior region) connected with a bar and opposed to natural antagonistic teeth result in acceptable results for clinical parameters and good outcomes for marginal bone level changes and patient satisfaction.

A pilot randomised controlled trial evaluating mini and conventional implant retained dentures on the function and quality of life of patients with an edentulous mandible

BACKGROUND

Total tooth loss (edentulism) can be a debilitating condition, impacting on ability to chew, speak and interact with others. The most common treatment is with complete removable dentures, which may be successful, but in the lower jaw, bone resorption that worsens over time makes denture-wearing difficult. Two dental implants in the mandible to retain the lower denture has been advocated as the gold standard of treatment, but has not been universally provided due largely to financial constraints and also patient fear. Mini implants (MI) are cheaper and less invasive than conventional implants (CI), but may not have equivalent longevity. Therefore, it is unknown whether they represent a cost-effective treatment modality over time. The aim of this pilot randomised controlled trial was to assess the feasibility of carrying out a trial on this cohort of patients, and to inform the study design of a large multicentre trial.

METHODS

Forty-six patients were randomly allocated to receive either two mini implants or two conventional implants in the mandible to retain their lower dentures. Quality of life (QoL) questionnaires, pain and anxiety scores, and an objective "gummy jelly" chewing test were carried out at multiple timepoints, along with detailed health economics information. Implants were placed one-stage, and an early loading protocol was utilised. Patients were reviewed 8 weeks post-placement, and finally at 6 months. Implant failure, recruitment and retention rates were recorded and analysed.

RESULTS

The pilot study demonstrated that it is possible to recruit, randomise and retain edentulous (mainly elderly) patients for an implant trial. We recruited to target and retention rates were acceptable. The large number of questionnaires was onerous for participants to complete, but the distribution of scores and feedback from participants helped inform the choice of primary and secondary outcomes in a full trial. The chewing test was time-consuming and inconsistent. Implant failure rate was low (1/46). The data on indirect costs gathered at every visit was viewed as repetitive and unnecessary, as there was little or no change between visits.

CONCLUSIONS

The pilot study has shown that acceptable recruitment and retention rates are achievable in this population of patients for this intervention. The results provide valuable information for selection of outcome variables and sample size calculations for future trials.

TRIAL REGISTRATION

(ISRCTN): 87342238 Trial registration date: 05/07/2013.

Is dental implantation indicated in patients with oral mucosal diseases

Background/Aim: Dental implants are a reliable treatment choice for rehabilitation of healthy patients as well as subjects with several systemic conditions. Patients with oral mucosal diseases often exhibit oral mucosal fragility and dryness, erosions, blisters, ulcers or microstomia that complicate the use of removable dentures and emphasize the need for dental implants. The aim of the current study is to review the pertinent literature regarding the dental implantation prospects for patients with oral mucosal diseases. Material and Method: The English literature was searched through PubMed and Google Scholar electronic databases with key words: dental implants, oral mucosal diseases, oral lichen planus (OLP), epidermolysis bullosa (EB), Sjögren’s syndrome (SS), cicatricial pemphigoid, bullous pemphigoid, pemphigus vulgaris, scleroderma/systemic sclerosis, lupus erythematosus, leukoplakia, oral potentially malignant disorders, oral premalignant lesions, oral cancer and oral squamous cell carcinoma (SCC). Results: Literature review revealed dental implantation in patients with OLP (14 articles), EB (11 articles), pemphigus vulgaris (1 article), SS (14 articles), systemic sclerosis (11 articles), systemic lupus erythematosus (3 articles) and oral SCC development associated with leukoplakia (5 articles). No articles regarding dental implants in patients with pemphigoid or leukoplakia without SCC development were identified. Most articles were case-reports, while only a few retrospective, prospective or observational studies were identified. Conclusions: Dental implants represent an acceptable treatment option with a high success rate in patients with chronic mucocutaneous and autoimmune diseases with oral manifestations, such as OLP, SS, EB and systemic sclerosis. Patients with oral possibly malignant disorders should be closely monitored to rule out the development of periimplant malignancy. Further studies with long follow-up, clinical and radiographic dental data are required to predict with accuracy the outcome of dental implants in patients with oral mucosal diseases.

Histomorphometric evaluation of a dual acid-etched vs. a chemically modified hydrophilic dual acid-etched implant surface. An experimental study in dogs

OBJECTIVE

The aim of this preclinical in vivo study was to compare histologically and histomorphometrically osseointegration of dual acid-etched vs. hydrophilic implants.

MATERIAL AND METHODS

Two pairs of implants (Neodent, Curitiba, Brazil), with same macrogeometry but different surface technology (i) dual acid-etched surface (SAE) treatment with hydrochloric and sulfuric acid followed by microwave treatment and insertion in isotonic saline solution to increase hydrophilicity (SAE-HD) (test, n = 12); (ii) dual SAE (control, n = 12) were installed bilaterally in the proximal tibia of six beagle dogs. Histologic and histomorphometric evaluation was performed after 2 and 4 weeks in vivo, on non-decalcified sections. Percentages of bone-to-implant contact (BIC) and bone density (BD) were estimated and tested for significant differences with the Wilcoxon signed-rank test for paired samples (P < 0.05).

RESULTS

In general, new bone formation along and in contact with the implant surface could be observed irrespective of the experimental group and observation period. Most of the bone was woven but small quantities of lamellar bone, mainly in close proximity to the cortex could also be observed. BIC at 2 weeks was 19.57 ± 13.57 and 20.33 ± 7.99 (P = 0.75), and at 4 weeks was 42.80 ± 14.48 and 40.25 ± 9.45 (P = 0.65) for SAE-HD and SAE implants respectively. BD at 2 weeks was 24.85 ± 16.31 and 25.66 ± 8.59 (P = 0.35) and at 4 weeks 44.13 ± 6.46 and 40.13 ± 6.46 (P = 0.25) for SAE-HD and SAE implants respectively.

CONCLUSION

Bone-to-implant contact and BD increased with time in both SAE-HD and SAE implants. No significant differences were observed between the two different implant surfaces for any of the evaluated parameters and at any observation time-point.

Does a large dehiscent implant surface at placement affect the 5-year treatment outcome? An assessment of implants placed to support a maxillary overdenture

The aim of this study was to assess the 5-year clinical and radiographic outcome of implants with a dehiscent surface at implant placement. A total of 26 consecutive patients (mean age 61.6 years; SD 8.0 years) with at least one implant with a dehiscent implant surface of ≥ two thirds of the implant length on the labial side were included. All implants were placed to support a maxillary overdenture. The implants were placed with adequate primary stability and the dehiscent surface was covered with autologous bone, inorganic bovine bone and a resorbable membrane. Outcome measures were soft tissue conditions, change of radiographic marginal bone level and implant survival. Baseline data (at loading, T0) were compared with 1-year (T1) and 5-year (T5) post loading data. Of the 116 implants, 40 implants had no dehiscence, 16 had a buccal dehiscence < two thirds of the implant length, and 60 implants had a dehiscence ≥ two thirds. The peri-implant tissues were healthy and 5-year marginal bone changes were well within normal limits (-0.4 mm; range: -0.8 to -0.1). One implant was lost during the osseointegration period. Even when implants are placed with a dehiscence ≥ two thirds of the buccal implant surface, favorable 5-year peri-implant health can be achieved provided these dehiscences are covered with autologous bone, inorganic bone and a resorbable membrane, and there is good initial stability of the implants.

Prevention of distal extension cantilever fracture in mandibular overdentures

OBJECTIVES

Fractures of distal bar extensions, supporting a mandibular overdenture, do occur with significant functional and economic consequences for the patient. This study therefore aims to evaluate the effect of different bar cross-sectional shapes and surfaces, bar extension lengths and the placement of a support rib under the distal bar extension on fracture resistance.

MATERIALS AND METHODS

The 2nd moment area and static strength were calculated for 11 frequently used bar designs using finite element analysis (FEA). For two specific designs (Ackermann round Ø 1.8mm and Dolder-Y macro, the former with and without a support rib) additional physical static and fatigue strength tests were included.

RESULTS

The FEA static strength data corresponded well to the 2nd moment area (a similar ranking when maximum allowed force was considered). The application of a rib support (Ackermann Ø 1.8mm) and limitations of the bar extension length (6mm for the Ackermann Ø 1.8mm, 8mm for the Dolder-Y macro) allowed the bars to exceed 5 × 10(6) cycles of 120 and 250N, respectively, before fracture. The region of highest stresses in FEA corresponded well with the locations of the fractures observed in static- and fatigue-testing.

CONCLUSIONS

With some simple guidelines/modifications, the number of bar extension fractures can be reduced significantly.

CLINICAL SIGNIFICANCE

This study focusses on distal bar extensions which improve the positioning of an implant supported overdenture. By combining laboratory testing and finite element simulations we aim to: (1) explain why fractures occur (dependent on physical characteristics of the bar), and (2) give clinical guidelines on how to prevent such fractures.

A systematic review and meta-analysis of removable and fixed implant-supported prostheses in edentulous jaws: post-loading implant loss

Objectives

The aim of this systematic review was to analyze post‐loading implant loss for implant‐supported prostheses in edentulous jaws, regarding a potential impact of implant location (maxilla vs. mandible), implant number per patient, type of prosthesis (removable vs. fixed), and type of attachment system (screw‐retained, ball vs. bar vs. telescopic crown).

Material and methods

A systematic literature search for randomized‐controlled trials (RCTs) or prospective studies was conducted within PubMed, Cochrane Library, and Embase. Quality assessment of the included studies was carried out, and the review was structured according to PRISMA. Implant loss and corresponding 3‐ and 5‐year survival rates were estimated by means of a Poisson regression model with total exposure time as offset.

Results

After title, abstract, and full‐text screening, 54 studies were included for qualitative analyses. Estimated 5‐year survival rates of implants were 97.9% [95% CI 97.4; 98.4] in the maxilla and 98.9% [95% CI 98.7; 99.1] in the mandible. Corresponding implant loss rates per 100 implant years were significantly higher in the maxilla (0.42 [95% CI 0.33; 0.53] vs. 0.22 [95% CI 0.17; 0.27]; P = 0.0001). Implant loss rates for fixed restorations were significantly lower compared to removable restorations (0.23 [95% CI 0.18; 0.29] vs. 0.35 [95% CI 0.28; 0.44]; P = 0.0148). Four implants and a fixed restoration in the mandible resulted in significantly higher implant loss rates compared to five or more implants with a fixed restoration. The analysis of one implant and a mandibular overdenture also revealed higher implant loss rates than an overdenture on two implants. The same (lower implant number = higher implant loss rate) applied when comparing 2 vs. 4 implants and a mandibular overdenture. Implant loss rates for maxillary overdentures on <4 implants were significantly higher than for four implants (7.22 [95% CI 5.41; 9.64] vs. 2.31 [1.56; 3.42]; P < 0.0001).

Conclusions

Implant location, type of restoration, and implant number do have an influence on the estimated implant loss rate. Consistent reporting of clinical studies is necessary and high‐quality studies are needed to confirm the present results.

Improving masticatory performance, bite force, nutritional state and patient's satisfaction with implant overdentures: a systematic review of the literature

Oral function with removable dentures is improved when dental implants are used for support. A variety of methods is used to measure change in masticatory performance, bite force, patient's satisfaction and nutritional state. A systematic review describing the outcome of the various methods to assess patients' appreciation has not been reported. The objective is to systematically review the literature on the possible methods to measure change in masticatory performance, bite force, patient's satisfaction and nutritional state of patients with removable dentures and to describe the outcome of these. Medline, Embase and The Cochrane Central Register of Controlled Trials were searched (last search July 1, 2014). The search was completed by hand to identify eligible studies. Two reviewers independently assessed the articles. Articles should be written in English. Study design should be prospective. The outcome should be any assessment of function/satisfaction before and at least 1 year after treatment. Study population should consist of fully edentulous subjects. Treatment should be placement of any kind of root-form implant(s) to support a mandibular and/or maxillary overdenture. Fifty-three of 920 found articles fulfilled the inclusion criteria. A variety of methods was used to measure oral function; mostly follow-up was 1 year. Most studies included mandibular overdentures, three studies included maxillary overdentures. Implant-supported dentures were accompanied by high patient's satisfaction with regard to denture comfort, but this high satisfaction was not always accompanied by improvement in general quality of life (QoL) and/or health-related QoL. Bite force improved, masseter thickness increased and muscle activity in rest decreased. Patients could chew better and eat more tough foods. No changes were seen in dietary intake, BMI and blood markers. Improvements reported after 1 year apparently decreased slightly with time, at least on the long run. Treating complete denture wearers with implants to support their denture improves their chewing efficiency, increases maximum bite force and clearly improves satisfaction. The effect on QoL is uncertain, and there is no effect on nutritional state.

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.

Attitudes of general dental practitioners to the maintenance of Locator retained implant overdentures

INTRODUCTION

Locator retained implant overdentures are associated with a high incidence of prosthodontic complications. This study investigated whether general dental practitioners (GDPs) were willing to maintain these prostheses in primary dental care.

METHOD

A questionnaire was distributed to all GDPs referring patients for an implant assessment to the Charles Clifford Dental Hospital, Sheffield between 1 January 2012 and 30 June 2012.

RESULTS

Ninety-four out of one hundred and forty-six questionnaires were returned (response rate: 64%). Thirteen GDPs (14%) were able to identify the Locator attachment system from clinical photographs. Eighty-two GDPs (87%) would adjust the fit surface of a Locator retained implant overdenture. Twenty-three GDPs (25%) would replace a retentive insert, 18 GDPs (19%) would tighten a loose abutment, 68 GDPs (72%) would debride abutments and 25 GDPs (27%) would remake a Locator-retained implant overdenture. Forty-seven GDPs (50%) felt that the maintenance of these prostheses was not their responsibility. The main barriers identified to maintenance by GDPs were a lack of training, knowledge and equipment. Seventy GDPs (74%) would like further training in this area.

CONCLUSIONS

GDPs are not familiar with the Locator attachment system and are reluctant to maintain implant retained overdentures. GDPs would like further training in this area.

Effect of Implant Height Differences on Different Attachment Types and Peri-Implant Bone in Mandibular Two-Implant Overdentures: 3D Finite Element Study

Implant-supported overdentures with self-aligning attachment systems are preferred to improve the stability and retention of complete dentures. The positioning of the implant attachments is a very important aspect of two-implant overdentures in obtaining better stress distribution. Therefore, the objective of this study was to compare two different attachment systems in a two-implant overdenture by evaluating the stress distributions in peri-implant bone and stresses on the attachments with positioning at different height levels using the 3D FEA method. Six models with ball attachments and 6 models with locator attachments-totaling 12 models (including 2 controls)-with the left implant positioned unilaterally at different height levels were subjected to 3 loading conditions (anterior, right posterior, and left posterior). Data for Von Misses stresses were produced numerically, color coded, and compared among the models for attachments and peri-implant cortical bone. The configurations in which implants presented 3 mm height differences in the bone level showed the most successful results in the peri-implant bone. When stresses on the attachments were compared, greater stress values were obtained from the ball attachments. As a conclusion, the configurations with a considerable (3 mm) height difference between quadrants of the mandible in the anterior segment showed the most successful results in the peri-implant bone. On the contrary, peak stress values around the implant observed from the models with less (1 mm) bone height difference may require leveling of the bone during surgery. However, these findings should be corroborated with clinical studies.

Implant-supported mandibular overdentures and cortical bone formation: clinical and radiographic results

PURPOSE

The aim of this study was to evaluate the hard and soft tissue parameters around implants supporting overdentures and the possible influence of increased periimplant bone density (IPBD) on implant success.

MATERIALS AND METHODS

A total of 44 dental implants placed in the mandible of 12 patients were included in the study. Implants were divided in 2 groups in relation to the optically detected IPBD. Periimplant clinical and radiographic variables were collected over the period of 5 years.

RESULTS

Periimplant clinical and radiographic parameters for all implants did not change significantly throughout the observation period (P > 0.05). Significant differences were observed between implants with and without IPBD for periimplant soft tissue parameters and Periotest values (P < 0.05). Implants with and without IPBD at 5-year control showed mean bone loss of 0.04 ± 0.48 mm and 0.55 ± 0.96 mm, respectively (P = 0.026). All density values decreased throughout the observation period, except maximal values for implants with IPBD that overcome the initial values at the 5-year control.

CONCLUSIONS

Implants supporting overdentures were clinically successful over the period of follow-up. IPBD may be related to the maintenance of the periimplant bone level.

A comparison between 4 and 6 implants in the maxillary posterior region to support an overdenture; 1-year results from a randomized controlled trial

OBJECTIVE

To compare the treatment outcome of 4 vs. 6 bar-connected implants in the posterior region of the maxilla to support an overdenture during a 1-year follow-up period.

MATERIALS AND METHODS

Sixty-six edentulous patients with an insufficient amount of bone volume in the maxilla to place implants were asked to participate in this study. Randomization assigned patients to either 4 or 6 implants. In all patients, a maxillary sinus floor elevation procedure with bone from the iliac crest was performed, and after a 3-month healing period, 4 or 6 dental implants were inserted in the maxillary posterior region in a one-stage procedure. After 3 months of osseointegration, a bar-supported overdenture was constructed. Implant survival, overdenture survival, clinical scores, peri-implant bone height changes and patients' satisfaction were assessed. Study analysis was performed according a non-inferiority design.

RESULTS

All patients completed the one-year follow-up. After a functional period of 1-year, implant survival was 100% in the 4 implants group and 99.5% in the 6 implants group. Overdenture survival was 100% in both groups. Mean clinical scores were very low and did not significantly differ between groups. Mean marginal bone resorption was 0.35 ± 0.31 mm and 0.46 ± 0.34 mm in the 4 and 6 implants group, respectively. Patients' satisfaction improved significantly in both groups, but did not differ between groups.

CONCLUSION

A bar-supported overdenture on 4 implants in the posterior maxillary region is not inferior to an overdenture supported by 6 bar-connected dental implants.

Maxillary overdentures supported by four or six implants in the anterior region; 1-year results from a randomized controlled trial

OBJECTIVE

Comparing treatment outcome of four and six bar-connected implants in the anterior maxillary region to support an overdenture during a 1-year follow-up period.

MATERIAL AND METHODS

Fifty edentulous patients with lack of retention and stability of the upper denture, but with sufficient bone volume to place implants in the anterior maxillary region, were selected. Randomization assigned patients to either four or six implants. Implant survival, overdenture survival, clinical scores, radiographic bone height changes, and patients' satisfaction were assessed.

RESULTS

Forty-nine patients (one drop out) completed the 1-year follow-up. After 1 year, implant survival was 100% in the four implants group and 99.3% in the six implants group (one implant lost). Overdenture survival was 100% in both groups. Mean clinical scores were low and did not differ between groups (independent Student's t-test). Mean marginal bone resorption was 0.24 ± 0.32 mm in the four implants group and 0.25 ± 0.29 mm in the six implants group. Patients' satisfaction had improved in both groups (paired Student's t-test).

CONCLUSION

Bar-supported overdentures on four implants in the anterior maxillary region are not inferior to overdentures supported by six bar-connected implants. Implant survival was high, peri-implant conditions were healthy and patients' satisfaction had increased significantly in both groups.

Clinical and radiographic outcome of dental implants supporting fixed prostheses: the relevance of cortical bone formation

PURPOSE

To evaluate the hard and the soft tissue parameters around implants supporting fixed prostheses over a period of 5 years and the possible association to the increase in periimplant bone density (IPBD).

MATERIAL AND METHODS

A total of 39 dental implants placed in 29 patients were included in the study. Periimplant clinical (gingival index, probing depth, keratinized mucosa, sulcus fluid flow rate) and radiographic variables (bone loss, bone density) were collected, and the data analysis performed.

RESULTS

Periimplant hard and soft tissue parameters remained stable throughout the follow-up period. Of the 39 implants, 20 demonstrated IPBD. The mean distance between first bone-to-implant contact and the microgap for implants with and without IPBD was significantly different at 1-year, 2-year, and 5-year follow-up. The evidence of IPBD demonstrated no influence on the periimplant soft tissue parameters. All mean values of bone density for implants with IPBD were higher than those for implants without IPBD throughout the whole observation period.

CONCLUSION

All implants were clinically successful over the period of follow-up. IPBD might be more indicative of a stable periimplant bone level.

Implant-retained overdentures: a review

Implant-retained overdentures represent a treatment option for many patients unable to tolerate conventional dentures. They may be specifically indicated in patients with altered anatomy, neuromuscular disorders, a pronounced gag reflex or severe residual ridge resorption. This article discusses the different ways in which implant overdentures can be retained, outlines some of the clinical stages involved in planning and providing these prostheses, and highlights long-term maintenance requirements associated with implant-retained overdentures.

CLINICAL RELEVANCE

Patients with implant-retained overdentures are likely to present in general dental practice. Practitioners should be aware of issues associated with the design, treatment planning and maintenance of these prostheses.