Gingival reaction on crowns with cast and sintered metal margins: a progressive report

Periodontal Behavior and Patient Satisfaction of Anterior Teeth Restored with Single Zirconia Crowns Using a Biologically Oriented Preparation Technique: A 6-Year Prospective Clinical Study

Objectives. The aim of this study was to analyze the behavior of the periodontal tissues around teeth in the anterior region when restored with zirconia single crowns, using a biologically oriented preparation technique (BOPT), over a 6-year follow-up. Methods. The study investigated tooth-supported single crowns in the anterior region that were fabricated with a zirconia core and feldspathic ceramic covering, in 34 patients. Follow-up analysis took place annually for 6 years, assessing periodontal responses by evaluating the following variables: plaque index (PI); probing depth (PD); gingival index (GI); gingival thickness adjacent to the restoration; and stability of the gingival margin (MS). Any (biological and mechanical) complications were also recorded, as well as the patients’ satisfaction with the treatment. Results. After 6 years’ follow-up, a low mean plaque index was obtained, probing depth was stable, and gingival thickness and margin stability had increased. Complications (biological and mechanical) did not present a statistically significant incidence and a crown survival rate of 97.2% was achieved. Patients’ satisfaction obtained a mean VAS score of 9.04 under 10. Conclusion. Teeth that are prepared with BOPT in the anterior region present good periodontal behavior around the restored teeth, particularly in terms of the stability of the gingival margin and increased gingival thickness. Single crowns prepared with BOPT obtain an excellent clinical survival rate, as well as a high score in patients’ satisfaction after 6 years.

Periodontal Behavior Around Teeth Prepared with Finishing Line for Restoration with Fixed Prostheses. A Systematic Review and Meta-Analysis

Background: The objective of this systematic review and meta-analysis was to analyze the periodontal behavior around teeth prepared with horizontal finishing crowns supporting fixed metal-ceramic and zirconia full coverage crowns and fixed partial dentures (FDPs). Materials and methods: An electronic search was conducted to locate relevant clinical trials in four databases: PubMed, Embase, Cochrane, and Scopus. A manual search was made in the reference sections of the articles identified for any additional articles. No restrictions were applied regarding year of publication or language. The following variables were considered in quantitative and qualitative analysis: probing pocket depth (PPD); probing attachment level (PAL); plaque control record (PCR); bleeding on probing (BOP); and gingival margin migration. Results: Twenty articles were selected for qualitative synthesis, and of these, nine underwent meta-analysis. Higher PCR was found in control teeth, while BOP, PPD, and PAL were higher around teeth prepared with horizontal finishing lines supporting complete coverage crowns/FDPs Gingival migration results were the clearest manifestation of compromised periodontal health around teeth prepared with horizontal finishing lines. Conclusions: Meta-analysis revealed that teeth prepared with horizontal finishing lines supporting crowns and FDPs present more periodontal disorders than untreated control teeth.

WITHDRAWN: Interventions for replacing missing teeth: partially absent dentition

BACKGROUND

Management of individuals presenting with partial loss of teeth is a common task for dentists. Outcomes important to the management of missing teeth in the partially absent dentition should be systematically summarized. This review recognizes both the challenges associated with such a summarization and the critical nature of the information for patients.

OBJECTIVES

To assess the effects of different prostheses for the treatment of partially absent dentition in terms of the following outcomes: long-term success, function, morbidity and patient satisfaction.

SEARCH METHODS

We searched the Cochrane Oral Health Group's Trials Register (to 21 March 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1), MEDLINE via OVID (1950 to March 2011) and EMBASE via OVID (1980 to March 2011). There were no restrictions regarding language or date of publication. We contacted several authors to identify non-published trials.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing different methods (including the design and materials used) of treating partial edentulism, with clinically relevant outcomes, were included in this review. Trials reporting only surrogate outcomes, such as plaque accumulation or gingival volume, were excluded from this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently carried out the screening of eligible studies, assessment of dimensions of quality of trials, and data extraction. Results were expressed as mean differences for continuous data, risk ratios for dichotomous outcomes, and hazard ratios with 95% confidence intervals for time-to-event data.

MAIN RESULTS

Twenty-one trials met the inclusion criteria for this review. Twenty-four per cent of these were assessed as being at high risk of bias and the remainder were at unclear risk of bias. The clinical heterogeneity among the included studies precluded any attempt at meta-analysis. There was insufficient evidence to determine whether one type of removable dental prosthesis (RDP) was better or worse than another. With fixed dental prostheses (FDPs), there was no evidence that high gold alloys are better or worse than other alloys, nor that gold alloys or frameworks are better or worse than titanium. There is insufficient evidence to determine whether zirconia is better or worse that other FDP materials, that ceramic abutments are better or worse than titanium, or that one cement was better or worse than another in retaining FDPs. There is insufficient evidence to determine the relative effectiveness of FDPs and RDPs in patients with shortened dental arch or to determine the relative advantages of implant supported FDPs versus tooth/implant supported FDPs.

AUTHORS' CONCLUSIONS

Based on trials meeting the inclusion criteria for this review, there is insufficient evidence to recommend a particular method of tooth replacement for partially edentulous patients.

Interventions for replacing missing teeth: partially absent dentition

BACKGROUND

Management of individuals presenting with partial loss of teeth is a common task for dentists. Outcomes important to the management of missing teeth in the partially absent dentition should be systematically summarized. This review recognizes both the challenges associated with such a summarization and the critical nature of the information for patients.

OBJECTIVES

To assess the effects of different prostheses for the treatment of partially absent dentition in terms of the following outcomes: long-term success, function, morbidity and patient satisfaction.

SEARCH METHODS

We searched the Cochrane Oral Health Group's Trials Register (to 21 March 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1), MEDLINE via OVID (1950 to March 2011) and EMBASE via OVID (1980 to March 2011). There were no restrictions regarding language or date of publication. We contacted several authors to identify non-published trials.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing different methods (including the design and materials used) of treating partial edentulism, with clinically relevant outcomes, were included in this review. Trials reporting only surrogate outcomes, such as plaque accumulation or gingival volume, were excluded from this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently carried out the screening of eligible studies, assessment of dimensions of quality of trials, and data extraction. Results were expressed as mean differences for continuous data, risk ratios for dichotomous outcomes, and hazard ratios with 95% confidence intervals for time-to-event data.

MAIN RESULTS

Twenty-one trials met the inclusion criteria for this review. Twenty-four per cent of these were assessed as being at high risk of bias and the remainder were at unclear risk of bias. The clinical heterogeneity among the included studies precluded any attempt at meta-analysis. There was insufficient evidence to determine whether one type of removable dental prosthesis (RDP) was better or worse than another. With fixed dental prostheses (FDPs), there was no evidence that high gold alloys are better or worse than other alloys, nor that gold alloys or frameworks are better or worse than titanium. There is insufficient evidence to determine whether zirconia is better or worse that other FDP materials, that ceramic abutments are better or worse than titanium, or that one cement was better or worse than another in retaining FDPs. There is insufficient evidence to determine the relative effectiveness of FDPs and RDPs in patients with shortened dental arch or to determine the relative advantages of implant supported FDPs versus tooth/implant supported FDPs.

AUTHORS' CONCLUSIONS

Based on trials meeting the inclusion criteria for this review, there is insufficient evidence to recommend a particular method of tooth replacement for partially edentulous patients.

Comparison of the cytogenotoxicity induced by five different dental alloys using four in vitro assays

The purpose of present investigation was to compare the cyto-genotoxicity induced by five dental alloys in vitro. The cyto-genotoxicity induced by five dental alloy extracts on human B lymphoblast cells was assessed with neutral red uptake (NRU) , CCK-8, comet and micronucleus (CBMN) assays in vitro, respectively. The results of in vitro comet and CBMN assays indicated that DNA damage (% tail DNA) and micronucleus frequencies (MNFs) in all exposure groups did not significantly increase, as compared with the control group. However, the results of NRU and CCK-8 assays demonstrated that there were to some extent differences in the cytotoxicity among 5 dental alloy extracts in vitro. The cytotoxicity may be relevant to the Ni and Be ions released in the alloy extract.

Control of bias in randomized controlled trials published in prosthodontic journals

STATEMENT OF PROBLEM

Randomized controlled trials (RCTs) have become the gold standard for evaluating the effectiveness of treatment interventions. If not properly controlled, bias in the design of trial methodology can affect the validity of the study results.

PURPOSE

The purpose of this investigation was to assess the methodological quality of RCTs published in 3 prosthodontic journals over a 10-year period.

MATERIAL AND METHODS

Issues of The International Journal of Prosthodontics, The Journal of Prosthetic Dentistry, and The Journal of Prosthodontics published between 1988 and 1997 were searched manually to identify RCTs. Specific inclusion and exclusion criteria were established to identify articles about studies that qualified as RCTs. Two independent reviewers evaluated all qualified RCTs on the basis of how potential sources of bias in the trial methodology were controlled. Three areas-control of bias at entry, control of bias in assessment of outcome, and control of bias after entry-were evaluated with a scheme developed through the Cochrane Collaboration. A score of 1 or 0 was assigned for each of the 3 potential sources of bias, with the maximum quality score for an RCT being 3 (good bias control) and the minimum 0 (poor control). Frequencies were calculated for each dimension of trial methodology and overall quality scores of the RCTs.

RESULTS

Sixty-two RCTs were identified from 3631 articles screened. The method of randomization was explicit in only 47% of the RCTs. Forty percent of RCTs incorporated blinding in the assessment of outcome, and 76% accounted for all subjects at the end of the study. Overall quality scores revealed that only 16% of RCTs attempted to control bias in all 3 areas examined. Forty percent were deficient in 1 area, 34% were deficient in 2 areas, and 10% were deficient in all areas examined.

CONCLUSION

The quality of RCTs published in prosthodontic journals may be improved by minimizing potential sources of bias and adequately reporting trial methodology.

Nondestructive, in vitro quantification of crown margins

STATEMENT OF PROBLEM

It is important that artificial crowns fit the prepared tooth accurately, as marginal deficiencies are predisposed to plaque accumulation and lead to increased risk of periodontal disease. Various methods of evaluation for marginal fit are described in the literature, but most approaches are limited by destructive methods of assessment and/or small points of measurement.

PURPOSE

This study compared, in vitro, the marginal fit of 4 types of complete crowns on human premolar teeth with the use of nondestructive profilometry. This method determined whether fit was influenced by type of crown or surface morphology of the tooth, namely, grooved or ungrooved surfaces.

MATERIAL AND METHODS

Four groups of specimens were prepared for complete crowns: group BA, bonding alloy with chamfer finish line; group G, gold alloy with chamfer finish line; group PC, porcelain with a chamfer finish line; and group PS, porcelain with a shoulder finish line. Two profiles of grooved mesial and ungrooved distal surfaces of the teeth were performed: (1) teeth prepared for each type of crown and (2) teeth with crowns seated but not cemented. Marginal fit (absolute marginal discrepancy) from the finish line edge of the tooth preparations to crown edges (CE) and leading edges (LE) of crowns were measured.

RESULTS

A 2-way analysis of variance for crown type and tooth surface morphology revealed significant differences between crown types for all measurement parameters, except vertical LE. The effect of surface morphology was not significant, except for vertical LE (P<.05). For all parameters, except vertical LE, the ranking of marginal fit discrepancies from greatest to least was as follows: group PC, G, BA, and PS. For vertical LE distances, the ranking was PS, BA, G, and PC (P<.05).

CONCLUSION

Profilometry was used as a nondestructive, accurate method of evaluating the absolute marginal fit of different types of crowns. Marginal fits varied continuously around the circumference of each crown and made clinical assessment of fit accuracy subjective and arduous.

Biocompatibility of dental casting alloys: a review

STATEMENT OF PROBLEM

Dental casting alloys are widely used in applications that place them into contact with oral tissues for many years. With the development of new dental alloys over the past 15 years, many questions remain about their biologic safety. Practitioners must choose among hundreds of alloy compositions, often without regard to biologic properties.

PURPOSE

This article is an evidence-based tutorial for clinicians. Concepts and current issues relevant to the biologic effects of dental casting alloys are presented.

SUMMARY

The single most relevant property of a casting alloy to its biologic safety is its corrosion. Systemic and local toxicity, allergy, and carcinogenicity all result from elements in the alloy being released into the mouth during corrosion. Little evidence supports concerns of casting alloys causing systemic toxicity. The occurrence of local toxic effects (adjacent to the alloy) is not well documented, but is a higher risk, primarily because local tissues are exposed to much higher concentrations of released metal ions. Several elements such as nickel and cobalt have relatively high potential to cause allergy, but the true risk of using alloys containing these elements remains undefined. Prudence dictates that alloys containing these elements be avoided if possible. Several elements in casting alloys are known mutagens, and a few such as beryllium and cadmium are known carcinogens in different chemical forms. Despite these facts, carcinogenic effects from dental casting alloys have not been demonstrated. Prudent practitioners should avoid alloys containing these known carcinogens.

CONCLUSION

To minimize biologic risks, dentists should select alloys that have the lowest release of elements (lowest corrosion). This goal can be achieved by using high-noble or noble alloys with single-phase microstructures. However, there are exceptions to this generality, and selection of an alloy should be made on a case-by-case basis using corrosion and biologic data from dental manufacturers.

Developing a register for randomized controlled trials in prosthodontics: results of a search from prosthodontic journals published in the United States

STATEMENT OF PROBLEM

Treatment decisions are often made despite absence of evidence from well-conducted clinical trials. Conclusions about treatment efficacy derived from nonexperimental approaches often overestimate treatment effect. Randomized controlled trials (RCTs) provide the most reliable basis for evaluating effectiveness of treatment interventions.

PURPOSE

This study attempted to identify and catalog RCTs in prosthodontic journals published in the United States as an initial step in creating a register of clinical trials that would be a resource in setting up systemic overviews of prosthodontic literature.

METHODS

The International Journal of Prosthodontics, The Journal of Prosthetic Dentistry, and The Journal of Prosthodontics published between 1988 and 1997 were searched manually to identify clinical trials. Clinical trials had to meet the following criteria for inclusion in the register: the trial must involve human subjects, must include at least 2 treatment groups, and treatment group allocation must be randomized.

RESULTS

A total of 3,631 articles in 196 journal issues were screened. Sixty-two articles (1.7%) met the minimum criteria for inclusion in the RCT register.

CONCLUSION

Given the lack of randomized controlled trials in prosthodontic journals, a concerted effort by the organized prosthodontic community should be made to screen national and international journals and contribute to the development of a register of randomized controlled trials relevant to prosthodontics.