A controlled clinical trial of implant-retained mandibular overdentures: 10 years' results of clinical aspects and aftercare of IMZ implants and Branemark implants

Screw-Type Collar vs. Non-Screw-Type Collar Implants—Comparison of Initial Stability, Soft Tissue Adaptation, and Early Marginal Bone Loss—A Preclinical Study in the Dog

Simple Summary

Implant neck characteristics may affect initial implant stability, soft tissue healing, and early marginal bone loss (EMBL) at second-stage surgery. Screw-type rough-surface collar implants had statistically significant poorer soft tissue healing and increased marginal bone loss compared to non-screw type implants at the time of 2nd-stage surgery. The significance of the novel implant design results in preventing EMBL awaits further research.

Abstract

Background: Implant neck characteristics may affect initial implant stability, soft tissue healing, and early marginal bone loss (EMBL) at second-stage surgery. The null hypothesis was that, following two-stage implant insertion, rough surface, non-screw-type collar implants will present lower EMBL at 2nd-stage surgery than rough-surface, screw-type collar implants. Methods: The study comprised seven male beagle dogs (mean weight 10.57 ± 2.8 kg; range 9–17 kg). A novel implant design was developed, composed of 2 parts: an apical part resembling a regular threaded implant, and a coronal non-screw-type collar, 4.2 mm long, served as the study group, whereas standard threaded implants served as control. Twenty-eight implants were placed: two on each side of the mandible. All implants were sand-blasted/acid-etched and of similar dimensions. Each dog received four implants. To assess location (anterior vs. posterior) impact on the outcomes, implants were placed as follows: group I—posterior mandible right—non-screw-type collar implants; group II—anterior mandible right—similar non-screw-type collar implants. To assess the collar-design effect on the outcomes, implants were placed as follows—Group III—anterior mandible left—control group, screw-type collar implants; Group IV—study group, posterior mandible left—non-screw-type collar implants. The following parameters were measured and recorded: insertion torque, soft tissue healing, early implant failure, and EMBL at 2nd-stage surgery. Results: No statistically significant differences were noted between groups I and II regarding all outcome parameters. At the same time, although insertion torque (55 N/cm) and early implant failure (0) were similar between groups III and IV, group III presented significantly poorer soft tissue healing (1.43 vs. 0.14) and increased marginal bone loss (0.86 vs. 0 mm). Conclusions: When a two-stage implant protocol was used, rough-surface non-screw-type collar implants led to superior outcomes at 2nd-stage surgery. Implant location did not affect the results. The significance of this result in preventing EMBL awaits further research.

A Novel Design to Optimize Biomechanical Properties of Dental Implant

Objective: The main objective of this study is to evaluate a novel design to optimize dental implant biomechanics. According to this objective, evaluations of the resilient implant design which aimed to mimic biomechanical behaviors of natural tooth have been made and outcomes were compared with natural tooth and standard dental implants with using 3D hyper-elastic finite element analysis. Methods: Models used in the study corresponding to conventional dental implant, natural tooth and resilient dental implant design. Hyperelastic model analysis were performed for close presentment of mechanical behaviors of resilient materials like periodontal ligament and medical silicone. Top values of maximum principal stress, minimum principal stress of surrounding bone and displacement of each model were evaluated under axial and non-axial loading conditions with magnitude of 30N, 80N and 100N. Results: Outcomes of finite element study showed reduction on maximum principal stress and minimum principal stress levels with the use of resilient dental implant comparing to the standard implant model. Standard implant model had been observed notably rigid in all loading conditions compared to the other models. Resilient implant model showed similar biomechanical characteristics with natural tooth model within the limitations of this study. Conclusion: According to finite element analysis results; resilient implant design was able to resolve some biomechanical discrepancies and seem to have adequate biomechanical similarity with natural tooth under both axial and non-axial loading conditions.

Maintenance requirements and marginal bone loss associated with implant-retained overdentures: a retrospective cohort study

OBJECTIVES

To evaluate the maintenance requirements and the presence of prosthetic complications associated with marginal bone loss in the implant-retained bar and locator prostheses.

MATERIALS AND METHODS

The study was executed between the years 2013 and 2018 on 114 patients who had undergone 283 dental implants. Patients were examined at follow-up recall sessions at 12 and 24 months after the placement of the dentures. The clinical examination also included intraoral and extraoral examinations of the patients; compatibility of the prostheses placed to about occlusion; an adaptation of the prosthesis to the tissues, health, and continuity of the soft tissues; complaints of the patients; implant success rates; and marginal bone loss, and prosthetic complications were evaluated at follow-up sessions, and statistical analysis was performed.

RESULTS

Locator attachment was placed in 94 patients with separated mandibles and maxillae, and a removable prosthesis with a bar attachment was placed in 20 patients. When evaluating the level of marginal bone loss regardless of the presence of complications, the area where the implant was set, the number of days after loading, and the type of retainer, it was found to be significant at the end of the 12th the 24th months. The results showed a significant relationship between the prosthesis type and the presence of complications at month 24 (p < 0.05). There was no significant relationship between the position of the denture and the presence of complications at month 12 (p > 0.05). There was no significant relationship between the location of the denture and the presence of complications at month 24 (p > 0.05).

CONCLUSION

Complications do not affect marginal bone loss, but the resulting marginal bone loss is the result of the patient not paying enough attention to oral hygiene. Routine inspections of the prosthesis after the completion of treatment seem to be important. If the requirements resulting from these checks are met, complications that may occur in the future will be prevented.

CLINICAL RELEVANCE

The maintenance requirements and the presence of prosthetic complications associated with marginal bone loss in the implant-retained bar and locator prostheses were evaluated. Complications occurred more frequently with the bar-supported removable implant prostheses.

Immediate vs conventional loading of mandibular overdentures: A comprehensive systematic review and meta-analysis of randomized controlled trials

Clinicians treating overdenture patients need to know if immediate loading and conventional loading results in similar outcomes. This study aimed to perform a systematic literature search of studies comparing immediate and conventional loading of mandibular overdentures irrespective of the number of implants and conduct a meta-analysis of implant failure and marginal bone loss (MBL). A literature search of PubMed, ScienceDirect, Ovoid, Springer, and Google Scholar databases was performed for randomized controlled trials (RCTs) comparing immediate vs conventional loading of mandibular overdentures. The primary outcome was implant failure and the secondary outcome was marginal bine loss (MBL). A descriptive analysis was performed for other outcomes. Thirteen trials were included. Only one trial compared the immediate and delayed loading of single implant-supported overdenture. Seven trials used two implants, one trial used three implants while four trials used four implants. Meta-analysis indicated no statistically significant difference in implant failure and MBL between immediate and conventional loading of two-implant and four-implant supported overdentures. Descriptive analysis indicated no difference in peri-implant tissue indices, implant stability, and quality of life outcomes between the two loading protocols.There may be no difference in implant failure and MBL with immediate loading or conventional loading of two and four-implant supported mandibular overdentures. Literature review indicates that there may be no difference in peri-implant tissue indices, implant stability, and QoL outcomes between the two loading protocols. The overall quality of evidence is moderate. Further, adequately powered RCTs are required to strengthen the evidence.

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.

Titanium dental implants with different collar design and surface modifications: A systematic review on survival rates and marginal bone levels

AIM

The aim of this study was to compare clinical and radiographic outcomes of dental implants with different neck characteristics.

METHODS

A protocol-oriented search aimed at the question: "In patients subjected to tooth replacement with screw-type dental implants does the modification of the implant neck macro- or microgeometry contribute to the improvement of survival rates and maintenance of the peri-implant marginal bone levels?" Primary outcomes were survival and marginal bone level (MBL) changes evaluated on randomized controlled trials with >10 participants and follow-up >1 year. Risk of bias was evaluated using the Cochrane Collaboration's tool. The review follows the PRISMA statement.

RESULTS

Forty-three studies compared: (a) One- versus two-piece implants (N = 7); (b) Two-piece implants with different neck characteristics (machined and rough collars, microthreads, LASER microtexturing) (N = 21); (c) Two-piece implants with macrogeometry modifications (tapering, back-tapering, and scalloping) (N = 6). One- and two-piece implants showed similar survival (RR = 0.45, 95% CI: [0.12, 1.66], p = 0.23) and MBL changes (WMD = 0.09 mm, 95% CI: [-0.27, 0.45], p = 0.64) at 1-year post-loading. Machined collar implants have higher risk of early failure than rough collar implants (RR = 3.96, 95% CI: [1.12, 13.93], p = 0.03) and 0.43 mm higher bone resorption (95% CI: [0.0, 0.86], p = 0.05). Microthreads (WMD = 0.07 mm, 95% CI: [-0.01, 0.15], p = 0.10) and LASER microtexturing (WMD = 0.15 mm, 95% CI: [-0.35, 0.65], p = 0.56) do not reduce bone resorption. Scalloped implants have 1.26 mm higher resorption (95% CI: [0.72, 2.00], p < 0.001).

CONCLUSIONS

One- and two-piece implants have similar survival and MBL changes. Rough collar implants have lower MBL changes than machined collar implants. Additional modifications to rough collars are irrelevant.

High Level of Disagreement Exists Concerning the Prosthetic Maintenance of Different Mandibular Implant Overdentures

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Prosthetic maintenance of different mandibular implant overdentures: A systematic review. Assaf A, Daas M, Boittin A, Eid N, Postaire M. J Prosthet Dent 2017; 118(2):144-52.

SOURCE OF FUNDING

Information not available TYPE OF STUDY/DESIGN: Systematic review.

Prosthetic maintenance of different mandibular implant overdentures: A systematic review

STATEMENT OF PROBLEM

Different factors can affect prosthetic maintenance requirements for mandibular implant overdentures (IODs). However, the literature shows a high level of disagreement concerning the effect of each factor on maintenance needs.

PURPOSE

The purpose of this systematic review was to address the focus question: "In the clinical studies published since 2004 of adult patients with totally edentulous mandibles treated by IODs with a variable number of implants and different designs, what were the maintenance types, frequencies, and complications?"

MATERIAL AND METHODS

A search of MEDLINE and PubMed databases was performed targeting papers in English on prosthetic maintenance of mandibular IODs published between 2004 and June 2015, aiming at recognizing the needs for adjustment, repair, and renewal. The recorded data were divided into 6 categories, and a percentage value was attributed to each.

RESULTS

From a total of 130 articles, 33 studies met the specified inclusion criteria for the review (14 randomized controlled trials, 8 prospective clinical trials, 3 retrospective studies, and 4 systematic reviews). These articles provided evidence that a mean complication rate was impossible to determine because of the multiplicity of contributing factors. No clear identification of the causes of mechanical complications was found, nor was there any clear evidence of superiority of one implant and/or attachment design over another.

CONCLUSIONS

Prosthetic complications with IODs are unavoidable. However, they can be reduced to an expected level if a close follow-up protocol is implemented aiming at anticipating risks of unexpected complications. Further clinical studies are needed to achieve a constructive meta-analysis that accounts for different parameters such as opposite arch, attachment functional variety, connection method, and prosthesis quality.

Retrospective Analysis of Implant Overdenture Treatment in the Advanced Prosthodontic Clinic at the University of Illinois at Chicago

The aim of the present retrospective study was to evaluate the clinical outcomes of implant-supported overdenture treatment provided by prosthodontic specialty residents. Twenty-three patients with 25 implant-supported overdentures (IODs) participated in the study. Seventy-four implants were placed by periodontic, prosthodontics, or oral and maxillofacial surgery students. All prostheses were fabricated in the advanced prosthodontics clinic at University of Illinois at Chicago. The condition of the peri-implant soft tissue, implants, and prostheses were evaluated. Complications and any maintenance were documented. Patients completed an oral health impact profile-14 and semantic differential scale questionnaires. Statistical analyses were performed using SPSS statistical software. Twenty mandibular and 5 maxillary IODs were evaluated. Ninety-seven percent of the attachments were locators (Zest Anchors) and 3% ball attachments. None of the implants had lost osseointegration, but 14 implants (19%) had developed marginal bone loss in one-third of the implant length or more. Fourteen (19%) implants had developed dehiscence, which ranged from 1 to 4 mm. A variation in the width of the keratinized tissue, gingival, plaque, and calculus index was observed. There was a statistically significant relationship between the presence of plaque and the bleeding on probing on the buccal aspect of implants (P = .012). The incidence of dehiscence was significantly higher on the midfacial when the keratinized tissue was less than 2 mm (P &lt; .0001). The majority of the complications were prosthetic in nature, such as broken denture teeth (74%) and worn or loose matrices (35%). Debris was observed in 19% of the locator abutments, and 36% of the overdentures were not stable in application of anterior force. Patients were compliant with oral hygiene protocols and their chewing ability was high (mean = 8.0). The overall experience was pleasant (mean = 7.5); the treatment provided good esthetics (mean = 8.3) and great satisfaction (mean = 8.5). From an educational and clinical perspective, IOD therapy has been documented to be a predictable and successful treatment option. Patients should be informed of the required maintenance and the possible complications related to IOD therapy.

Implant-retained prostheses: ball vs. conus attachments - A randomized controlled clinical trial

OBJECTIVE

To evaluate implant survival, peri-implant tissue conditions, prosthodontic maintenance requirements and patient satisfaction of two differently retained implant-supported mandibular overdentures (IOD) after the 3 years of observation.

MATERIALS AND METHODS

Twenty-five patients with edentulous mandibles received two implants each. Twelve patients were randomly selected to receive ball attachments, whereas 13 patients received prefabricated coni. Implant survival, peri-implant parameters (modified Plaque Index, Bleeding on Probing, modified Gingival Index, probing depth and marginal bone loss) and patient satisfaction were assessed. Additionally, prosthodontic maintenance was monitored. Clinical and radiographic follow-ups were performed 1, 2 and 3 years after prosthetic delivery. The Kaplan-Meier method was used to calculate complication rates.

RESULTS

After a mean observation period of 29.6 months, an implant survival rate of 100% could be observed. There were no significant differences in the peri-implant parameters. During the observation period, six patients with conus attachment refused to further participate in follow-ups due to dissatisfaction with their treatment and had to be regarded as dropouts. Based on the Kaplan-Meier method, inacceptable retention was calculated for 80% and 75% of the patients in the ball and the conus groups, respectively. Patient satisfaction was 64% for the ball- and 100% for the conus-retained IODs, the latter only respecting five of initially 13 patients.

CONCLUSION

The evaluated treatment method revealed high implant survival rates, but the prosthetic reconstruction required intensive maintenance. Therefore, a trend toward the reduced patient satisfaction was observed, and the promoted economy of the evaluated attachment systems should be questioned. For the conical attachment, the recommendation of the manufacturer is to use four interforaminal implants to support a removable prostheses.

Biomaterial aspects: A key factor in the longevity of implant overdenture attachment systems

Background:

New attachment systems are released for mandibular two-implant overdentures often without evidence-based support. Biomaterial aspects are now the parameters considered when choosing the appropriate attachment. Studies regarding their properties remain scarce.

Purpose:

The purpose of this review was to help the clinician in selrcting the most adapted stud attachments according evidence-based dentistry.

Materials and Methods:

An electronic search was conducted using specific databases (PubMed, Medline, and Elsevier libraries). Peer-reviewed articles published in English up to July 2014 were identified. Emphasis was given on the biomaterial aspects and technical complications. No hand search was added.

Results:

The electronic search generated 115 full-text papers, of which 84 papers were included in the review. The majority were clinical and in vitro studies. Some review articles were also considered. Papers reported survival and failures of overdenture connection systems. Emphasis was laid on attachment deformation.

Conclusion:

Implant overdentures long-term follow-up studies may provide useful guidelines for the clinician in selecting the type of attachment system and overdenture design. Locator attachments are more and more used, with lesser complications reported.

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.

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.

Stud attachments for the mandibular implant-retained overdentures: Prosthetic complications. A literature review

A plethora of attachment systems for mandibular two-implant overdentures is currently available often without evidence-based support. Technical aspects are now parameters considered when choosing the appropriate attachment. Despite the increasing use of the Locator attachments, studies regarding their properties remain scarce. Peer reviewed articles published in English up to 2011, were identified through a MEDLINE search (Pubmed and Elsevier) and a hand search of relevant textbooks and annual publications. Emphasis was made on the technical complications as well as the loss of retention related to the attachments in implant-retained overdentures, primarily the Locator attachment. The evaluation of the long-term outcome of implant overdentures and complications associated with different attachment systems may provide useful guidelines for the clinician in selecting the type of attachment system and overdenture design.

Benefits of dental implants installed during ablative tumour surgery in oral cancer patients: a prospective 5-year clinical trial

OBJECTIVE

This prospective study assessed treatment outcome and patient satisfaction of oral cancer patients with a mandibular overdenture on implants up to 5 years after treatment.

MATERIALS AND METHODS

At baseline, 50 consecutive edentulous oral cancer patients, in whom prosthetic problems were expected after oncological treatment, were evaluated by standardized questionnaires and clinical assessments. All implants were installed during ablative tumour surgery in native bone in the interforaminal area. About two-thirds of the patients (n=31) had radiotherapy post-surgery (dose >40 Gy in the interforaminal area).

RESULTS

At the 5-year evaluation, 26 patients had passed away and four patients had to be excluded from the analyses, because superstructures were not present, due to persistent local irritation (n=2), loss of three implants (n=1) and the impossibility of making an overdenture related to tumour and oncological surgery-driven anatomical limitations (n=1). In the remaining 20 patients, the prosthesis was still in function (76 implants). During the 5-year follow-up, total 14 implants were lost, 13 in irradiated bone (survival rate 89.4%, dose >40 Gy) and one in non-irradiated bone (survival rate 98.6%). Peri-implant tissues had a healthy appearance and remained healthy over time. Patients were satisfied with their dentures.

CONCLUSIONS

It was concluded that oral cancer patients can benefit from implants installed during ablative surgery, with a high survival rate of the implants, a high percentage of rehabilitated patients and a high denture satisfaction up to 5 years after treatment.

Factors associated with failure of surface-modified implants up to four years of function

OBJECTIVES

The relative impact of innovative treatment concepts on the failure of surface-modified implants is not well understood. This retrospective study aimed to explore this using data obtained in a university postgraduate training center.

MATERIAL AND METHODS

Patients treated with implants for a variety of indications over a 3-year period were included. All implants had been at least 1 year in function. Clinical records were evaluated for implant failure and in reference to implant length/diameter/location, time from tooth loss to implant placement, bone condition (native/grafted), surgical protocol (two-/one-stage), loading protocol (delayed/early/immediate), type of prosthesis (removable/fixed), surgeon's experience level (resident/trainee) and specialty (periodontist/oral surgeon). The impact of each covariate on failure was tested using the Fisher's exact test. Kaplan-Meier survival functions were constructed and Mantel-Cox log-rank tests were used to compare survival functions. To correct for possible interaction, Cox proportional Hazards regression was adopted.

RESULTS

Forty-one of 1,180 (3.5%) implants were lost in 34/461 (7.4%) patients (245 ♀, 216 ♂; mean age 51, range 18-90). Factors showing significant impact on failure on the basis of univariate analyses were implant location (p = .015), surgical protocol (p = .002), loading protocol (p = .002), surgeon's experience level (p = .035) and specialty (p = .001). When controlling for other covariates, only the loading protocol had a significant influence (p = .049) with early loading more prone to failure (p = .014) when compared with delayed loading. Immediate loading and delayed loading showed comparable implant survival (p = .311).

CONCLUSIONS

Implant therapy may be highly successful in a training center where inexperienced clinicians are strictly monitored and personally guided. Implant specific variables do not affect implant survival but early loading is a risk indicator for implant failure, whereas immediate loading is not.

Loading protocols for mandibular implant overdentures: a systematic review with meta-analysis

BACKGROUND

Mandibular overdentures are a successful treatment option for the edentulous patients with long-term predictable outcomes, using conventional loading protocols. Currently, both early and immediate loading protocols for mandibular implant overdentures are prevalent in the literature.

PURPOSE

A systematic review and meta-analysis of the current published literature on comparative studies using conventional versus either early and/or immediate loading protocols for mandibular implant overdentures.

MATERIALS AND METHODS

The review was carried out in accordance with the QUOROM (Quality of Reporting of Meta-Analyses) guidelines. The PICO (Population, Intervention, Comparisons, Outcomes) format was used in conjunction with predefined inclusion criteria. A literature search of PubMed (1969-October 2008), EMBASE (1998-October 2008), the Cochrane Database of Systematic Reviews, and the Cochrane Controlled Trial Register was conducted. In addition, hand searching through refereed dental journals was also performed for the years 2000 to 2008. The meta-analysis was conducted by using the MIX software v.1.7 (Kitasato Clinical Research Center, Kanagawa, Japan).

RESULTS

A total of 191 studies were identified through the electronic search. After full-text screening and cross-matching with the predefined inclusion criteria, only 10 studies with a minimum follow-up of 2 years were eligible for inclusion in this review. Of the 10 included studies, seven have compared the outcome of conventional versus early loading of implants supporting mandibular overdentures. The remaining three studies, on the other hand, compared the outcome of conventional versus immediate loading. The meta-analysis revealed no significant difference in the outcome between conventional and either early (p = .72) or immediate (p = .08) loading of implants supporting mandibular implant overdentures.

CONCLUSIONS

Short-term outcomes of early or immediate loading protocols for mandibular implant overdentures achieved comparable success to conventional loading ones. No evidence was found of long-term studies to support or refute either early or immediate loading protocols for mandibular implant overdentures.

Edentulism and comorbid factors

INTRODUCTION

Complete edentulism is the terminal outcome of a multifactorial process involving biological factors and patient-related factors. It continues to represent a tremendous global health care burden, and will for the foreseeable future. The purpose of this review is to determine what comorbid factors exist for the completely edentulous patient.

METHODS

This literature review evaluated articles obtained via the National Library of Medicine's PubMed Website, using keywords of edentulism with various combinations of the terms comorbidity, incidence, health, nutrition, cancer, cardiovascular health, diabetes, osteoporosis, smoking, asthma, dementia, and rheumatoid arthritis. Abstracts were selected and screened, and selected full-text articles were reviewed. Articles were limited to those with adequate patient cohorts and a minimum of 2-year follow-up data.

RESULTS

Edentulism was found to be a global issue, with estimates for an increasing demand for complete denture prostheses in the future. Completely edentulous patients were found to be at higher risk for poor nutrition, coronary artery plaque formation (odds ratio 2.32), to be smokers (odds ratio 2.42), to be asthmatic and edentulous in the maxillary arch (odds ratio 10.52), to being diabetic (odds ratio 1.82), to having rheumatoid arthritis (odds ratio 2.27), and to having certain cancers (odds ratios varying from 1.54 to 2.85, depending on the type of cancer). Chronic residual ridge resorption continues to be the primary intraoral complication of edentulation, and there appear to be few opportunities to reduce bone loss in the edentulous patient.

CONCLUSIONS

While the completely edentulous patient seems to be at risk for multiple systemic disorders, whether development of these disorders is causal or casual has not been determined. To minimize the loss of residual alveolar ridges, exemplary complete denture therapy, along with the establishment of routine recall systems, should be the ultimate goal of treatment of this patient cohort.

Changes in inflammatory mediators in peri-implant fluid after implant insertion

BACKGROUND

Endosseous dental titanium implants have revolutionized restorative dentistry and have made a significant impact on improved patient care. The aim of this study was to compare and evaluate the influence of the placement technique on periodontal health.

METHODS

A baseline examination was performed in patients with submerged and non-submerged titanium implants, including an evaluation of plaque index (PI), gingival index (GI), periodontal probing depth (PD), clinical attachment level (CAL), and bone level, as well as histamine and arachidonic acid metabolite concentrations, in the peri-implant crevicular fluid. Examinations were repeated after 12, 24, and 36 months.

RESULTS

Bone loss was significantly higher in the submerged group relative to the non-submerged group at 3 years (P <0.01), with a slight increase at 24 months. All clinical parameters were significantly higher in the submerged group relative to the non-submerged group at 24 and 36 months (P <0.05 for PI; P <0.01 for GI, PD, and CAL). The mean levels of histamine and other inflammatory mediators were significantly higher, whereas 15(S)-hydroxy-5,8,11,13-eicosatetraenoic acid concentrations were significantly reduced in the submerged group, with a high correlation with periodontal indices at 24 and 36 months (P <0.001).

CONCLUSION

This longitudinal study suggested that submerged implants present a number of risks for periodontal complications compared to non-submerged implants, which can be evidenced by inflammatory mediator variations in the peri-implant crevicular fluid.

Evaluation of aesthetics of implant-supported single-tooth replacements using different bone augmentation procedures: a prospective randomized clinical study

OBJECTIVES

The aim of this study was to evaluate the aesthetics of implant-supported single-tooth replacements using different augmentation procedures in a prospective study with the use of an objective rating index and with a subjective patient questionnaire, and to compare the results with each other.

MATERIAL AND METHODS

Ninety-three patients with a single-tooth gap in the anterior zone of the maxilla were selected for the study. All patients had a local bone defect that needed augmentation before placement of an endosseous implant with sufficient initial stability. Aesthetics of the implant-supported crown and adjacent mucosa was rated by a prosthodontist 1 year after placement of the porcelain crown. Aesthetics was rated using the Implant Crown Aesthetic Index. A subjective appreciation of the final result was assessed with a patient questionnaire.

RESULTS

The Implant Crown Aesthetic Index reveals a mean overall score of 4.8, with an acceptable result in 66% of the cases. Results of the satisfaction questionnaire reveal a mean overall score of 8.5 with an acceptable result in 100% of the cases. There is no correlation between results of the Index and the questionnaire for the overall and the crown score. The patients' opinion and the professionals' opinion about the peri-implant mucosa do show a significant correlation.

CONCLUSIONS

The peri-implant mucosa is rated as less satisfactory than the implant-supported crown by both the dental professional and patients. The dental professional was less satisfied with respect to the total result and results of the crown than the patients.

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/).

Prosthodontic rehabilitation of oral function in head-neck cancer patients with dental implants placed simultaneously during ablative tumour surgery: an assessment of treatment outcomes and quality of life

The aim of this prospective study was to assess treatment outcome and impact on quality of life of prosthodontic rehabilitation with implant-retained prostheses in head-neck cancer patients. Fifty patients were evaluated by standardized questionnaires and clinical assessment. All received the implants during ablative tumour surgery in native bone in the interforaminal area. About two-thirds of the patients (n=31) needed radiotherapy post-surgery. Both in irradiated and non-irradiated bone two implants were lost 18-24 months after installation. Peri-implant tissues had a healthy appearance. No cases of osteoradionecrosis occurred. In 15 patients no functional implant-retained lower dentures could be made for various reasons. The other 35 patients all functioned well, with an improvement in quality of life. Major improvement was observed in the non-irradiated patients. In the irradiated patients, less improvement in many functional items was observed, while items related to the oral sequelae of radiotherapy did not improve. Similar to the quality-of-life assessments, denture satisfaction was improved and tended to be higher in non-irradiated than irradiated patients. Implant-retained lower dentures can substantially improve the quality of life related to oral functioning and denture satisfaction in head-neck cancer patients. This effect is greater in non-irradiated than irradiated cancer patients.

Supportive therapy and the longevity of dental implants: a systematic review of the literature

OBJECTIVE

To review systematically whether supportive implant treatment during a follow-up of at least 10 years after functional loading is effective in prevention of biological complications and fixture loss.

METHODS

A MEDLINE search was conducted for the period of 1965 to April 2006 of longitudinal clinical studies with follow-up periods after implant function of at least 10 years. Sixty-two studies were initially screened for inclusion and read in full text. Nine studies remained for the final assessment and 53 articles were thus excluded for the following reasons: (1) no information on implant maintenance was presented, (2) the number of patients/implants assessed at 10-year follow-up/final evaluation was not presented (3) fixture loss and marginal bone loss during function were not assessed at 10-year evaluation and (4) residual inflammation and/or probing pocket depth (PPD) not assessed at 10-year examination.

RESULTS

Fifty-six percent of 62 initially screened studies did not assess clinical inflammation and PPD around implants at long-term evaluation of implants. This was the most common reason for exclusion of studies. In 28% of excluded studies, there was no information on implant maintenance during follow-up. A total of 749 fixtures were included and followed for more than 10 years of functional load. Five of the included studies gave no detailed information of the assessments or the treatment at follow-up visits during the 10 years. Only in two of the included cohorts were patients enrolled in an individualized supportive program on a 3-6-month recall interval.

CONCLUSION

There are, to date, few available studies evaluating the long-term effect of supportive programs for implant patients. Based on the nine studies included, no evidence is available to suggest the frequency of recall intervals or to propose specific hygiene treatments. There is an urgent need for such studies to be initiated.

How do patients perceive the benefit of reconstructive dentistry with regard to oral health-related quality of life and patient satisfaction? A systematic review

BACKGROUND

Reconstructive dentistry encompasses an enormous range of treatment modalities from the restoration of single teeth to the reconstruction of the whole dentoalveolar complex in edentulous patients. Some treatment modalities have been assessed in terms of quality-of-life (QoL) outcomes and satisfaction

OBJECTIVES

The aim of the present investigation was to search and review studies published between 1996 and 2006 in which the impact of the treatment was measured in terms of QoL outcome, ideally, oral health-related quality of life (OHRQoL). Patient satisfaction was also accepted as an outcome.

MATERIALS AND METHODS

The primary search engine used was NICB PubMed based on MeSH headings. Hand searching of the cited references in the included papers identified a number of additional studies. The primary focus of the search was to link treatment to QoL outcomes.

RESULTS

The majority of included studies involved the treatment of edentulous patients, particularly the mandible. The preponderance of the studies comparing conventional dentures (CDs) and implant-supported overdentures (IODs) were randomized-controlled trials (N = 18). There was compelling evidence that patients were more satisfied with IODs than CDs. There was strong evidence that OHRQoL can be significantly improved using IODs. Evidence suggesting that one retention system is superior to another needs further clarification. Although high satisfaction ratings have been reported for maxillary implant prostheses, the overall ratings given to the maxillary implant prostheses were not significantly greater than for CDs. There was only sparce information regarding QoL or satisfaction outcomes for the majority of other forms of reconstructive dentistry.

CONCLUSION

Apart from the restoration of the edentulous mandible with IODs or CD, where there is an accumulating body of evidence on the effect of treatment choice, there are many procedures for which there are little or no such data at all. As yet, the entire range of reconstructive treatment has witnessed insufficient investigations relating treatment to its effect on QoL or satisfaction. This is an area that needs to be expanded as a way of quantifying the effect of treatment choices.