Ben Balevi

Should warfarin be discontinued before a dental extraction? A decision-tree analysis

OBJECTIVE The aim of this study was to determine if warfarin should be withdrawn before a single tooth extraction on a patient with a prosthetic heart valve. STUDY DESIGN A quantitative decision tree was constructed to assess the expected utility values of 2 typical strategies to manage the dental extraction on a patient currently medicated with warfarin. Probabilities and utilities for a cardiovascular accident and major bleeding from a dental extraction were taken from the literature. RESULTS The decision slightly favors withholding warfarin: generating an optimal expected utility value of 0.976 utile. This was only 0.02 utile higher than the alternative option of continuing warfarin for a dental extraction. CONCLUSION The decision to withhold or continue warfarin before a dental extraction depends more on the relative risk of a major bleeding between the 2 medical management strategies than on the consequences of a cardiovascular accident.

Industry sponsored research may report more favourable outcomes

Data sourcesMedline and the Cochrane Database of systematic reviews between January 1993 and December 2008. Hand search of 12 different dental journals (Journal of Periodontology, International Dental Journal, British Dental Journal, Journal of the International Academy of Periodontology, Journal Canadian Dental Association, Swedish Dental Journal, Quintessence International, Journal of Clinical Periodontology, Periodontology 2000, Clinical Oral Implant Research, International Journal of Oral and Maxillofacial Implants, International Journal of Prosthodontic, Journal of Prosthetic Dentistry). Language restricted to English.Study selectionPrimary articles from systematic reviews that specifically studied the length of survival of dental implants.Data extraction and synthesisPrimary studies were extracted from reviews for which the following information was available: the failure rate of dental implants, publication year, journal Impact Factor, prosthetic design periodontal status, number of dental implants included in the study, methodological quality of studies, presence of a statistical advisor and financial sponsorship. Univariant quasi-Poisson regression and multivariate analysis were used to identity variables that were significantly associated with failure rates.ResultsTwo independent reviewers identified five systematic reviews from which 41 analysable trials were extracted (Kappa 0.90; 95%CI 0.77 - 1.00). The mean annual failure rate estimate for all trials was 1.09% (95%CI 0.84 - 1.42). The mean annual failure rate estimate of non-industry funded trials was 2.74% (95%CI 1.14 - 6.55). Four trials (10%) reported non-industry funding sources. The funding source was not reported in 26 trials (63%). 27 trials (66%) were considered to have a risk of bias. Given study age, both industry associated (OR= 0.21; 95%CI 0.12 - 0.38) and unknown funding sources trials (OR = 0.33; 95%CI 0.21 - 0.51) had a lower annual failure rate compared with non-industry associated trials. A conflict of interest statement was provided in 2 trials (5%).ConclusionsAfter controlling for other factors, the probability of annual implant failure reported in industry associated trials is significantly lower compared with non-industry associated trials. This bias may have significant impact on tooth extraction decision making, research on tooth preservation and government health care policies.

Implant-supported cantilevered fixed partial dentures

Data sourcesMedline was used to search for relevant material for the review.Study selectionSystematic reviews and longitudinal prospective/ retrospective studies (randomised controlled trials, controlled clinical trials and cohort studies) were chosen that reported outcomes following treatment with implant-supported fixed partial denture prostheses (FPDP) with cantilever extensions, after a mean function time of at least 5 years. Two independent reviewers preformed screening and data abstraction.Data extraction and synthesisFive-year survival and technical complication rates were extracted, which included: loss of prosthesis, loss of implants, complications with supra-construction (fractures or deformations of the framework or veneers, loss of retention and screw or abutment loosening) and marginal bone loss. Data from included studies were pooled and summarised as a weighted mean. Disagreement regarding data extraction was resolved by discussion and consensus.ResultsOnly three studies met the inclusion criteria for final analysis. Two of the studies had a prospective or retrospective case–control design, whereas the third was a prospective cohort study. The 5-year survival rate of cantilever FPDP varied between 89.9 and 92.7% (weighted mean, 91.9%), with implant fracture as the main cause for failure. The corresponding survival rate for FPDP without cantilever extensions was 95.3 to 96.2% (weighted mean, 95.8%). Technical complications related to the supra-construction in the three included studies were reported to occur at a frequency of 13–26% (weighted mean, 20.3%) for cantilever FPDP, compared with 0–12% (weighted mean, 9.7%) for noncantilever FPDP. The most common complications were minor porcelain fractures and bridge-screw loosening. For cantilever FPDP, the 5-year event-free survival rate varied between 66.7 and 79.2% (weighted mean, 71.7%) and between 83.1 and 96.3% (weighted mean, 85.9%) for noncantilever FPDP. No statistically significant differences were reported with regard to peri-implant bone-level change between the two prosthetic groups, either at the prosthesis or at the implant level.ConclusionsData on implant-supported FPDP with cantilever extensions are limited and therefore survival and complication rates should be interpreted with caution. The incorporation of cantilevers into implant-borne prostheses may be associated with a higher incidence of minor technical complications

Do preoperative antibiotics prevent dental implant complications

Data sourcesThe Cochrane Oral Health Groups Trials Registry, the Cochrane Central Register of Controlled Trials, Medline and Embase were consulted to find relevant work. Searches were made by hand of numerous journals pertinent to oral implantology. There were no language restrictions.Study selectionRandomised controlled clinical trials (RCT) with a followup of at least 3 months were chosen. Outcome measures were prosthesis failures, implant failures, postoperative infections and adverse events (gastrointestinal, hypersensitivity, etc.).Data extraction and synthesisTwo reviewers independently assessed the quality and extracted relevant data from included studies. The estimated effect of the intervention was expressed as a risk ratio together with its 95% confidence interval (CI). Numbers-needed-to-treat (NNT) were calculated from numbers of patients affected by implant failures. Meta-analysis was done only if there were studies with similar comparisons that reported the same outcome measure. Significance of any discrepancies between studies was assessed by means of the Cochrans test for heterogeneity and the I2 statistic.ResultsOnly two RCT met the inclusion criteria. Meta-analysis of these two trials showed a statistically significantly higher number of patients experiencing implant failures in the group not receiving antibiotics (relative risk, 0.22; 95% CI, 0.06–0.86). The NNT to prevent one patient having an implant failure is 25 (95%CI, 13–100), based on a patient implant failure rate of 6% in people not receiving antibiotics. The following outcomes were not statistically significantly linked with implant failure: prosthesis failure, postoperative infection and adverse events (eg, gastrointestinal effects, hypersensitivity).ConclusionsThere is some evidence suggesting that 2 g of amoxicillin given orally 1 h preoperatively significantly reduces failures of dental implants placed in ordinary conditions. It remains unclear whether postoperative antibiotics are beneficial, and which is the most effective antibiotic. One dose of prophylactic antibiotics prior to dental implant placement might be recommended.

Caries risk and number of restored surfaces have impact on the survival of posterior composite restorations

Data sourcesCochrane Library, PubMed, the Web of Science (ISI) and Scopus.Study selectionLongitudinal studies of direct class II or classes I and II restorations in permanent dentition of at least five years duration, a minimum of 20 restorations at final recall and the original datasets available were considered. Only English language studies were included. Two reviewers screened titles independently.Data extraction and synthesisMultivariate Cox regression method to analyse the variables of interest and hazard ratios with respective 95% confidence intervals were determined. The annual failure rate (AFR) of the investigated restorations and subgroups was calculated.ResultsTwelve studies, nine prospective and three retrospective were included. A total of 2,816 restorations (2,585 Class II and 231 Class I restorations) were included in the analysis. Five hundred and sixty-nine restorations failed during the observation period, and the main reasons for failure were caries and fracture. Regression analyses showed a significantly higher risk of failure for restorations in high-caries-risk individuals and those with a higher number of restored surfaces. The overall annual failure rate at five years and ten years was 1.8% and 2.4% respectively. The rates were higher in high-caries-rate individuals at 3.2% and 4.6% respectively.ConclusionsThe conclusion of the present meta-analysis of 12 clinical studies based on raw data is that caries risk and number of restored surfaces play a significant role in restoration survival, and that, on average, posterior resin composite restorations show a good survival, with annual failure rates of 1.8% at five years and 2.4% after ten years of service.

Lasers may reduce pain arising from dentin hypersensitivity.

A critical summary of Sgolastra F, Petrucci A, Severino M, Gatto R, Monaco A. Lasers for the treatment of dentin hypersensitivity: a meta-analysis. J Dent Res 2013;92(6):492-499.

Cast or fiber posts a summary of evidence from vitro studies

Data sourcesMedline, the Cochrane Controlled Trials Register, China National Knowledge Infrastructure and China Biology Medicine disc were searched.Study selectionOnly randomised studies were included.Data extraction and synthesisData were independently extracted. Standardised mean differences were combined and analysed using meta-analysis.ResultsThirteen studies were included; premolars were used as specimens in six studies, central incisors in five studies and canines in three articles. There was considerable variation in both alloy and fibre materials used between studies. The standardised mean difference of the combined data was 0.64 (95% confidence interval, 0.08–1.20; P < .001), indicating that the cast post group displayed significantly higher fracture resistance than the fibre post group.ConclusionsOn the basis of the current best available evidence, we concluded that cast posts had higher fracture resistance than fibre posts.

No difference in the 5-year survival rates between the resin-bonded cantilever bridge and the removable partial denture for the restoration of the shortened dental arch

DesignThis was a randomised controlled trial (RCT) in a dental hospital.InterventionResin-bonded fixed partial dentures (RBFPD) or removable partial dentures (RPD) were compared. The RBFPD restored 1 occlusal unit, up to but not beyond the second premolar, by means of single pontics cantilevered from single abutments whenever possible. Bilateral lower free-end saddle RPD were constructed on cast metal frameworks that incorporated rests, retainers and a rigid connector. The trials participants were reviewed 3 months and 1 year after insertion of the new lower prosthesis, and thereafter at yearly intervals. Additional review and maintenance appointments were scheduled as clinically required.Outcome measureSurvival of the prosthesis was assessed at each review according to specified criteria. Survival analysis was performed using a Cox proportional hazard regression ratio.ResultsEleven fixed partial dentures and 15 RPD failed. Debonding was the most common cause of failure in the RBFPD group, with non-use and loss of teeth most common in the RPD group. Although the RPD group required rather more maintenance visits, the difference in prosthesis survival rates was not statistically significant [hazard ratio (HR), 0.59; 95% confidence intervals (CI), 0.27–1.29].ConclusionsThe absence of a significant difference in 5-year survival, the reported advantages of fixed partial dentures, and the greater maintenance need for those in the RPD treatment group support the use of RBFPD.

Reports from recent evidence-based conferences

The 1st International Conference on Evidence-Based Dentistry (EBD) was recently held in Atlanta, Georgia. Over 200 delegates from 12 countries representing many significant stakeholders, such as: clinicians, researchers, academics, lawyers, statisticians, ethicists, regulatory bodies, product manufacturers and private insurance companies, attended this 2-day conference. Dr Jim Bader began the conference by trying to answer the simple question: Is EBD a new word for an old concept? He argued that what makes EBD a new concept is that for the first time, an attempt is being made to objectively synthesize all current available information for the sake of optimizing the efficiency and efficacy of clinical practice. Susan Sutherland followed Dr Bader by reviewing the concept of Systematic Reviews (SR). This process differs greatly from the traditional expert reviews, in that SR’s follow a standard and rigorous scientific methodology that objectively gathers and critically appraises all sources of information available. Professor Kay Dickersin reminded the audience that even SR’s can be subjected to the bias that research with positive outcomes are more likely to be published and thus gathered in a systematic search. Dr Hodge then reviewed the methods presently used to assess the quality of the literature. Although no single method seemed to be favorable he tended to put more credence on the reliability of ‘‘component assessment methods’’ as compared to ‘‘quantitative scale methods’’. The concurrent afternoon sessions dealing with the perceptive of EBD to the dental product development and the private dental insurance provider resulted in much discussion and debate amongst the delegates. Another session presented by William Giannobile, James Summitt, David Cagna and William Shaw summarized ‘‘what evidence’’ is currently available in the field of periodontics, the management of initial carious lesion, prosthodontics and orthodontics respectively. The presenters did not hide the fact that there is a dearth of good quality evidence available for them to make significant conclusion from. But moderator Dr James Bader urged the audience not to become ‘‘EBD elitist‘‘ by condemning all data generated short of the ‘‘gold standard’’ of the RCT methodology. Random Controlled Trials are not always feasible in dentistry. He suggested that a better way of extracting valid information from such so-called ‘‘inferior quality’’ studies need to be developed by the critical appraisers. A highlight of the conference was Dr Phillip Hujoel who introduced a four-level scale to assess clinical significance. This should not be confused with levels of clinical evidence or statistical significance. In other words, how should clinicians interpret clinical significance in the face of a well-designed clinical study that, may or may not, have statistical significance? Level 1 of Clinical Significance — There exists a ‘‘tangible benefit’’ with a ‘‘large treatment effect’’. At this level, statistical significance is irrelevant because the difference and thus the benefit (or harm) are so obvious from the study that the results ‘‘hit you on the head like a two-by-four block of wood’’. An example of this would be the clinical findings of osseointegration dental implants in human mandibles. The overwhelming success rate of over 90% is obvious and does not necessarily need the support of statistical analysis. Level 2 of Clinical Significance — There exists a ‘‘tangible benefit’’ with a ‘‘small treatment effect’’. In such studies, statistical analysis is needed to support any difference in any mild benefit measured. An example of this would be the benefit of occlusal splint on TMD. Studies may show a small but measurable benefit that nevertheless generates a statistically significant outcome. Level 3 of Clinical Significance — A ‘‘large significant therapeutic effect on the surrogate end point’’ (i.e. dental varnish that drastically reduces oral strep. Mutans levels) but no or questionable evidence of a ‘‘tangible clinical benefit’’ (ie lower caries levels). Level 4 of Clinical Significance — A ‘‘small to moderate therapeutic effect on the surrogate end-point’’ (ie, Listerine reducing gingival index) with no or questionable evidence of a ‘‘tangible clinical benefit’’ (i.e., lower future tooth loss) Statistical analysis helps to determine the reliability of the data in a clinical study, especially when the measure outcome is mild or moderate (Level 2 and 4 of clinical significance) but it does not determine clinical significance. Clinical significance is a subjective matter determined by the patient in consultation with the dentist. Concurrent sessions in the role of the educator in EBD and cutting edge meta-analysis methodology were presented by expert speakers in their fields. The Ethical and Legal obligations in the use of EBD were presented by Dr Mary McNally (a dental ethicist) and Ms. Elaine Gibson (a lawyer). The ethical role of EBD must be assessed in the context on the major stakeholder, including the patient. Ms. Gibson believes that the positive implication of EBD to the law is that better clinical evidence means better clinical and legal decisions. The final session reviewed the use of evidence in dental product advertising in the lay media. Representatives from ColgatePalmolive, a major American television network’s advertising department (ABC Inc.) and the National Advertising Division (an industry watch-dog which reviews the validity of national advertising) were on the panel to discuss their ethical duty to using evidence in the way they deliver their message in the media. Dr Bader commented that there may be a difference in the way evidence is used for commercial use. In EBD, evidence is synthesized by many sources in the hope of getting the overall truth while advertisers seek only the evidence that supports their claims, regardless of quantity or quality of the evidence, an approach that harks back to the traditional approach to evidence rather than the one EBD espouses. The conference ended with a keynote speech from Dr Roman Jaeschke, a professor from McMaster’s University and a pioneer in the EBM movement. He remarked that the power of evidence-based practice is in medical decision-making. The patients in consultation with the clinician make the decision using clinical evidence. Many dimensions of EBD were introduced and successfully presented in a concise and clear manner. The meeting was also

Commentary on two reviews of anterior composite restorations

ed from Demarco FF, Collares K, Coelho-de-Souza FH, Correa MB, Cenci MS, Moraes RR, Opdam NJ. Anterior composite restorations: A systematic review on long-term survival and reasons for failure. Dent Mater 2015; 31: 1214-1224. pii: S0109-5641(15)00214-6. doi: 10.1016/j.dental.2015.07.005. [Epub ahead of print] Review. PubMed PMID: 26303655 Heintze SD, Rousson V, Hickel R. Clinical effectiveness of direct anterior restoration – a meta-analysis. Dent Mater 2015; 31: 481-495. doi: 10.1016/j.dental.2015.05.015. Epub 2015 Mar 13. PubMed PMID: 257731887 Address for correspondence: Flávio F. Demarco, Graduate Program in Dentistry, Federal University of Pelotas Rua Goncalves Chaves 457, Room 506 96015-560, Pelotas-RS, Brazil. E-mail: flavio.demarco@pq.cnpq.br; ffdemarco@gmail.com Heintze SD, Ivolar Vivadent, Bendererstr. 2, 9494 Schaan, Leichtenstein E-mail: siegward.heintze@ivoclarvivadent.com SUMMARY REVIEW/RESTORATIVE