Quality assessment of randomised controlled trials of dental implant surgery and prosthodontics published from 2004 to 2008: a systematic review

Randomized clinical trials in dentistry: Risks of bias, risks of random errors, reporting quality, and methodologic quality over the years 1955-2013

OBJECTIVES

To examine the risks of bias, risks of random errors, reporting quality, and methodological quality of randomized clinical trials of oral health interventions and the development of these aspects over time.

METHODS

We included 540 randomized clinical trials from 64 selected systematic reviews. We extracted, in duplicate, details from each of the selected randomized clinical trials with respect to publication and trial characteristics, reporting and methodologic characteristics, and Cochrane risk of bias domains. We analyzed data using logistic regression and Chi-square statistics.

RESULTS

Sequence generation was assessed to be inadequate (at unclear or high risk of bias) in 68% (n = 367) of the trials, while allocation concealment was inadequate in the majority of trials (n = 464; 85.9%). Blinding of participants and blinding of the outcome assessment were judged to be inadequate in 28.5% (n = 154) and 40.5% (n = 219) of the trials, respectively. A sample size calculation before the initiation of the study was not performed/reported in 79.1% (n = 427) of the trials, while the sample size was assessed as adequate in only 17.6% (n = 95) of the trials. Two thirds of the trials were not described as double blinded (n = 358; 66.3%), while the method of blinding was appropriate in 53% (n = 286) of the trials. We identified a significant decrease over time (1955-2013) in the proportion of trials assessed as having inadequately addressed methodological quality items (P < 0.05) in 30 out of the 40 quality criteria, or as being inadequate (at high or unclear risk of bias) in five domains of the Cochrane risk of bias tool: sequence generation, allocation concealment, incomplete outcome data, other sources of bias, and overall risk of bias.

CONCLUSIONS

The risks of bias, risks of random errors, reporting quality, and methodological quality of randomized clinical trials of oral health interventions have improved over time; however, further efforts that contribute to the development of more stringent methodology and detailed reporting of trials are still needed.

An overview of characteristics of registered studies on dental implants

OBJECTIVE

Clinical trials serve as the empirical basis for clinical decision making. The objective of the current study is to provide an overview of clinical trials examining dental implant outcomes.

METHOD

All registered studies on Dental Implants were selected for analysis. The clinicaltrials.gov<http://clinicaltrials.gov/> website was used to query the characteristics of registered studies. The search term used was dental implants.

RESULTS

As of the study conduct date (01/01/2014), a total of 205 studies on dental implants were registered. These included 168 interventional and 37 observational studies. Results were available for only 14 studies. All observational studies and 98.8% of interventional studies included both male and female subjects. Close to 60% of studies had sample sizes between 1 and 50. NIH was listed as funding source in only 5 interventional studies and 3 observational studies. 80% of interventional studies were randomized. However, double masking was reported in only 15% of interventional studies with majority being open labeled.

CONCLUSION

ClinicalTrials.gov registry was created with the intention of increasing the transparency of conducted or ongoing clinical studies and to minimize publication bias commonly seen with industry-sponsored studies. Results of the current study showed that a predominating number of registered studies are funded by industry and other sources, very few registered studies have made their results public, and the ClinicalTrials.gov registry does not provide sufficient information on the quality of study design and thus precluding the public and researchers to judge on the quality of registered studies and publication bias.

A systematic review of outcome measurements and quality of studies evaluating fixed tooth-supported restorations

PURPOSE

The purpose of this systematic review was to review clinical studies of fixed tooth-supported prostheses, and to assess the quality of evidence with an emphasis on the assessment of the reporting of outcome measurements. Multiple hypotheses were generated to compare the effect of study type on different outcome modifiers and to compare the quality of publications before and after January 2005.

MATERIALS AND METHODS

An electronic search was conducted using specific databases (MEDLINE via Ovid, EMBASE via Ovid, Cochrane Library) through July 2012. This was complemented by hand searching the past 10 years of issues of the Journal of Oral Rehabilitation, Journal of Prosthetic Dentistry, Journal of Prosthodontics, and the International Journal of Prosthodontics. All experimental and observational clinical studies evaluating survival, success, failure, and complications of tooth-supported extracoronal fixed partial dentures, crowns, and onlays were included. No restrictions on age or follow-up time were placed.

RESULTS

The electronic search generated 14,869 papers, of which 206 papers were included for full-text review. Hand-searching added 23 papers. Inclusion criteria were met by 182 papers and were included for the review. The majority were retrospective studies. Only 8 (4.4%) were randomized controlled trials. The majority of the studies measured survival and failure, and few studies recorded data on success; however, more than 60% of the studies failed to define survival, success, and failure. Many studies did not use any standardized criteria for assessment of the quality of the restorations and, when standardized criteria were used, they were modified, thereby not allowing for comparisons with other studies. There was an increase of 21.8% in the number of studies evaluating outcome measurements of all-ceramic restorations in past 8 years.

CONCLUSIONS

Prosthodontic literature presents with a reduced percentage of RCTs compared to other disciplines in dentistry. The overall quality of recording prosthodontic outcome measurements has not improved greatly in the past 8 years.

Comprehensive Comparison of the 5-Year Results of All-on-4 Mandibular Implant Systems With Acrylic and Ceramic Suprastructures

The objective of the present study was to evaluate the comprehensive 5-year results of fixed mandibular dentures fabricated from metal-acrylic or metal-ceramics according to the All-on-4 protocol. Twenty-seven patients who received immediately loaded All-on-4 fixed mandibular dentures in 2006 were included in the study, and they were evaluated up to 5 years after denture integration. Endpoints were chosen in accordance with the 2007 Pisa consensus and included bone resorption, the Oral Health Impact Profile (OHIP), the sulcus fluid flow rate (SFFR), and prosthodontic complications. The initial situation in both groups was largely identical. Bone loss remained under 2 mm after 5 years in all implants and showed no group difference. The SFFR showed a gradual increase in both groups, and acrylic-bearing implants showed a substantially and significantly higher flow rate from the third year onward. The subjective improvement as expressed by the OHIP score was immediate and dramatic, and it showed no group differences. All acrylic restorations showed some extent of abrasion, and veneer fractures occurred in 4 patients (28.6%). Besides a single fracture of a fixation screw, there were no prosthetic complications in patients with ceramic suprastructures. According to bone loss and subjective outcome, acrylic and ceramic suprastructures appeared to be equivalent after 5 years; however, sulcus flow and prosthodontic complications suggest that the economic advantage of acrylic dentures may be specious. The rational choice of implant suprastructures requires comprehensive, long-term observation. Short-term economic benefits might be cancelled out in the long term.

Occlusal overload and bone/implant loss

AIM

The aim of this search was to assess the biological consequences that overload might have on already osseointegrated oral implants through a systematic screening of the scientific literature.

METHOD

Detailed searches through PUBMED, OVID, EMBASE and LILACS databases were made. Articles published up to December 2011 and those reported on the clinical, radiographic and/or histological outcome of oral implants subjected to so-called overload were considered eligible for inclusion. Identified studies were assessed by one non-blinded reviewer according to well-defined inclusion and exclusion criteria. When doubt arose, the co-authors were counselled until final agreement was obtained. The PICO questions formulated was:"what is the effect of overload vs. no overload on bone/implant loss in clinically stable implants?"

RESULTS

The database searches as well as additional hand searching, resulted in 726 potentially relevant titles. Eventually, 16 clinical and 25 animal studies were considered relevant to the topic. After inclusion/exclusion criteria assessment, all clinical studies and all but three animal studies and one systematic review were considered at high risk of bias and excluded. The included animal studies did not reveal an association between overload and peri-implant bone loss in the absence of peri-implant inflammation, whereas in its presence, overload seemed to aggravate the peri-implant tissue breakdown.

CONCLUSIONS

The effect of implant overload on bone/implant loss in clinically well-integrated implants is poorly reported and provides little unbiased evidence to support a cause-and-effect relationship. The PICO question remained unanswered. At the animal level, "overload", mimicked by supra-occlusal contacts acting in an uninflamed peri-implant environment, did not negatively affect osseointegration and even was anabolic. In contrast, supra-occlusal contacts in the presence of inflammation significantly increased the plaque-induced bone resorption.

Methodological quality and descriptive characteristics of prosthodontic-related systematic reviews

Ideally, healthcare systematic reviews (SRs) should be beneficial to practicing professionals in making evidence-based clinical decisions. However, the conclusions drawn from SRs are directly related to the quality of the SR and of the included studies. The aim was to investigate the methodological quality and key descriptive characteristics of SRs published in prosthodontics. Methodological quality was analysed using the Assessment of Multiple Reviews (AMSTAR) tool. Several electronic resources (MEDLINE, EMBASE, Web of Science and American Dental Association's Evidence-based Dentistry website) were searched. In total 106 SRs were located. Key descriptive characteristics and methodological quality features were gathered and assessed, and descriptive and inferential statistical testing performed. Most SRs in this sample originated from the European continent followed by North America. Two to five authors conducted most SRs; the majority was affiliated with academic institutions and had prior experience publishing SRs. The majority of SRs were published in specialty dentistry journals, with implant or implant-related topics, the primary topics of interest for most. According to AMSTAR, most quality aspects were adequately fulfilled by less than half of the reviews. Publication bias and grey literature searches were the most poorly adhered components. Overall, the methodological quality of the prosthodontic-related systematic was deemed limited. Future recommendations would include authors to have prior training in conducting SRs and for journals to include a universal checklist that should be adhered to address all key characteristics of an unbiased SR process.