Intervention for replacing missing teeth: Different types of implants - evidence summary of updated Cochrane review.

Around 1300 different types of dental implants are available worldwide and the implant manufacturers are resorting to aggressive marketing strategies; claiming their implants to provide a superior outcome. The clinician is left with a constant dilemma on which implant to choose for better clinical outcome and welfare of the patient. Moreover, in India, economical consideration is a concern too. The dentist has to select an implant that provides a good result and is economical. Cochrane systematic reviews provide the gold standard evidence for intervention, diagnosis, etc., and follow a strict quality control. A Cochrane systematic review was done to shed light on whether the different implant surface modifications, shapes or materials significantly influence clinical outcomes. All randomized controlled trials (RCTs) till January 17, 2014 were searched and out of the 81 trials, only 27 met the inclusion criteria. This evidence summary from the review concludes that based on the available literature; there is no evidence of any one type of implant being superior to another. There is weak evidence showing roughened dental implants are more prone to bone loss due to periimplantitis. This review indicated that there is a need for well-designed RCTs, with long-term follow-up and low bias. Moreover, none of the included studies was from India, which also points out the need for improving the quality of RCTs conducted in India.

INTRODUCTION

Cochrane database of systematic reviews, published by the Cochrane Library provides the gold standard evidence for intervention, diagnosis, etc., The standard of systematic review is maintained by uniform criteria of the research question, selection of studies, and data analysis including interpretation. After publishing in the database, each systematic review has to be updated every 2 years to include studies if followed the inclusion and exclusion criteria.

Although the prevalence of tooth loss is decreasing,[12] a large proportion of patients visiting the dentists consist of partially or completely edentulous patients. Osseointegrated dental implants have revolutionized the treatment of these patients. They can be used to treat a variety of patients ranging from single tooth loss to complete oral rehabilitation. Dental implants have shown promising success rate and have now become a routine treatment when dealing with the replacement of teeth. However, as the use of dental implants is increasing, so is the research. Around 1300[3] different types of dental implants are available worldwide, with their manufacturers claiming their implants to be more successful than others. The clinicians are put in a perplexing situation to decide the ideal body shape of the implant, the ideal platform design, the ideal surface of the implant or the ideal material of the implant.

It is important for the clinician to understand the difference between the facts and the marketing gimmicks by various implant manufacturers. This updated Cochrane review[4] presents evidence-based guidelines regarding different types of implants and their comparison in terms of various surface preparations, different shapes, and different materials. It attends to the question “whether the different surface modifications or coatings or different shapes of implants or different implant materials lead to better clinical outcomes?”[4]

METHODOLOGY

The Cochrane handbook for systematic reviews of interventions is used as a guide to form the methodology of this review. Randomized controlled trials (RCTs) of the parallel group and split-mouth design in participants who received osseointegrated root form dental implants with at least 1-year of follow-up were included in this review. Comparison was done between identical implants placed following the same protocol, but differing only in terms of (1) surface modification or (2) implant shape or (3) implant material or (4) any combination of these. Nonrandomized/quasi-randomized trials were excluded. The primary outcome was described in terms of biological or mechanical failure, and the occurrence of periimplantitis was the secondary outcome.

Electronic search was conducted in the Cochrane Oral Health Group's Trial Register, the Cochrane Central Register of Controlled Trials, MEDLINE through Ovid and EMBASE via Ovid; without any language filter, until January 17, 2014. A hand search of selected journals was also conducted. The titles and abstracts of the reports identified through electronic and hand search were scanned by two independent reviewers and full report to check if they met the inclusion criteria. Any disagreement was resolved by discussion and contacting a third reviewer. Data extraction forms were modified as needed and used to collect data. The risk of bias assessment was done using the recommended approach for Cochrane reviews. Risk ratio and 95% confidence interval (CI) were used to describe the measurement of treatment effect for dichotomous data and mean difference along with 95% CI was used for continuous outcomes. Heterogeneity assessment and sensitivity analyses were performed as per the Cochrane handbook for systematic reviews of interventions.

Eighty-one trials were identified in the search; however, most of them were nonrandomized or quasi-randomized studies, and many studies had a short follow-up, or the data were presented in an unusable way. Twenty-seven RCTs with either parallel group design or split mouth design, which met the inclusion criteria, were included in the review [Tables 1 and 2].

Table 1

Available evidence from the included trials comparing implant surfaces and implant shapes

Table 2

Available evidence from trials comparing different implant materials and combination

Critical analysis of included trials

Critical analysis of the included trials revealed that most of the studies were at unclear risk of bias for allocation concealment and low-risk of bias for sequence generation while a considerable number of studies were at high-risk of bias for blinding. Meta-analysis was performed among studies of similar comparisons reporting the same outcome measures. However, a sensitivity analyses could not be performed due to the lack of a sufficient number of trials in the meta-analyses. The severity of the risk of bias on the final results could not be assessed due to the lack of sensitivity analyses.

Based on the data from the included trials, this Cochrane review failed to show any superiority of a particular implant surface, shape or material over others in terms of implant failure and bone level changes. The review found 81 trials during the search but, only 27 fulfilled the inclusion criteria which clearly indicates a lack of properly designed and reported RCTs. Even after an extensive review and a meta-analysis, a definitive guideline on which implant system should be chosen by the clinician could not be established. Nonetheless, it did become clear from the review that clinical outcomes are not significantly altered by various modifications put forth by different manufacturers. However, a strong evidence to support this statement is still missing [Table 3]. The review did fulfill its secondary objective and found weak evidence that roughened dental implants are more susceptible to periimplantitis than turned implants [Tables 4 and 5].

Table 3

Summary of findings

Table 4

Turned implants compared with roughened implants

Table 5

Turned implants compared with roughened implants-individual data

Future implications and research

A very prominent fact that came to light in the review was that only one-third of the searched trials (27/81) met the inclusion criteria. Those that did meet the inclusion criteria were at unclear or high-risk of bias. The number of studies included in the meta-analysis was too low to carry out sensitivity analyses which could have been significant. Moreover, the included studies were from European, Australian and, East-Asian countries; while none was an Indian study. Many of the different implant systems that formed the intervention group in these studies are not even available in India; while those that are available and commonly used in India were not presented in the review. This clearly indicates the need for properly designed RCTs with adequate sample size, a follow-up period of at least 5 years and a low-risk of bias; that are reported according to the consolidated standards of reporting trials guidelines.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.