Periodontal effects of fixed partial denture retainer margins: configuration and location

Revolution of Current Dental Zirconia: A Comprehensive Review

The aim of this article is to comprehensively review the revolution of dental zirconia (Zir), including its types, properties, applications, and cementation procedures. A comprehensive search of PubMed and Embase was conducted. The search was limited to manuscripts published in English. The final search was conducted in October 2021. Newly developed monolithic Zir ceramics have substantially enhanced esthetics and translucency. However, this material must be further studied in vitro and in vivo to determine its long-term ability to maintain its exceptional properties. According to the literature, monolithic translucent Zir has had promising results and a high survival rate. Thus, the utilization of this material is indicated when strength and esthetics are needed. Both the materials and methods used for cementation of monolithic Zir have significantly improved, encouraging dentists to use this material, especially when a conservative approach is required. Zir restorations showed promising outcomes, particularly for monolithic Zir crowns supported with implant and fixed dental prostheses.

Effectiveness of porcine-derived xenograft with enamel matrix derivative for periodontal regenerative treatment of intrabony defects associated with a fixed dental prosthesis: a 2-year follow-up retrospective study

Purpose

Due to the difficulty of the hygienic care and sanitary management of abutment teeth and subpontic areas associated with fixed dental prostheses (FDPs), intrabony defects occur and accelerate due to the accumulation of plaque and calculus. This study aimed to evaluate the efficacy of regenerative periodontal surgery for intrabony defects associated with FDPs.

Methods

The study inclusion criteria were met by 60 patients who underwent regenerative treatment between 2016 and 2018, involving a total of 82 intrabony defects associated with FDPs. Periodontal osseous lesions were classified as 1-, 2-, and 3-wall intrabony defects and were treated with an enamel matrix derivative in combination with bone graft material. The changes in clinical (pocket probing depth [PPD] and clinical attachment level [CAL]) and radiographic (defect depth and width) outcomes were measured at baseline and at 6, 12, and 24 months.

Results

Six months after regenerative treatment, a significant reduction was observed in the PPD of 1-wall (P<0.001), 2-wall (P<0.001), and 3-wall (P<0.001) defects, as well as a significant reduction in the CAL of 2-wall (P<0.001) and 3-wall (P<0.001) intrabony defects. However, there was a significant increase in the CAL of 1-wall intrabony defects (P=0.003). Radiographically, a significant reduction in the depth of the 3-wall (P<0.001) defects and a significant reduction in the width of 2-wall (P=0.008) and 3-wall (P<0.001) defects were observed. The depth decreased in 1-wall defects; however, this change was not statistically significant (P=0.066).

Conclusions

Within the limitations of the current study, regenerative treatment of 2- and 3-wall intrabony defects associated with FDPs improved clinical and radiological outcomes. Additional prospective studies are necessary to confirm our findings and to assess long-term outcomes.

Biologic perspectives in restorative treatment

One of the primary goals of a long term successful restorative therapy is to establish a physiologic periodontal climate that facilitates the maintenance of periodontal health. The contemporary clinician has a host of alternatives for the restoration of teeth. It is now possible to mimic nature and provide restorations that defy detection but the most challenging procedure in clinical dentistry is fabricating a restoration in gingival harmony. Periodontal health is the basis of all restorative dentistry. Because periodontal disease is a major cause of tooth loss in adults, the clinician must be aware of the biological variables relevant to restorative therapy, basic concepts and clinical modes of therapy available, to be able to develop an appropriate diagnosis and treatment plan. A natural looking prosthesis within a healthy periodontium should represent the ultimate goal. This article addresses the interactions between periodontal tissues and restorative procedures. It reviews the essentials of soft tissue management inherent in restorative dentistry that will increase the probability of a successful restoration.

Clinical evaluation of fiber-reinforced fixed bridges

BACKGROUND

This study evaluated the clinical performance of 39 light and heat polymerized fixed partial bridges made with a substructure of preimpregnated, unidirectional fiber-reinforced composite, or FRC, veneered with a hybrid particu late composite.

METHODS

The authors evaluated 22 extracoronal, full-coverage retainer prostheses and 17 intracoronal, partial-coverage retainer prostheses placed over a 37-month period. All substructures initially were fabricated with a low-volume FRC. The authors reevaluated this design after early failures occurred, leading to a substructure with a higher volume of FRC. All prostheses were assessed for surface integrity, anatomical contour, marginal integrity and structural integrity at several intervals.

RESULTS

The data show that survival was associated primarily with substructure design volume. When patients with severe parafunctional habits were excluded, the survival rate was 95 percent for prostheses made with a high-volume substructure (survival range, 2.77 to 4.30 years; mean +/- standard deviation survival, 3.75 +/- 0.4 years). Retainer configuration did not have a statistically significant influence on clinical survival. For all surviving prostheses, the authors observed few changes in any clinical parameters from baseline to 48 months. A loss of surface luster was observed in the majority of cases. Repairable surface defects were detected on two prostheses at 24 months. Scanning electron microscopic analyses indicated no exposed fibers on the occlusal surface and minimal wear.

CONCLUSIONS

This study shows that a unidirectional, preimpregnated FRC can be used successfully to make bridges of variable retainer designs that last up to four or more years when a high-volume substructure is used.

CLINICAL IMPLICATIONS

Short-span polymer prostheses made with particulate composite and unidirectional glass FRC can be used in certain clinical situations in which a metal substructure is not desired.

Crowns and other extra-coronal restorations: aesthetic control

A pleasing dental appearance is the subjective appreciation of the shade, shape and arrangement of the teeth and their relationship to the gingiva, lips and facial features. Achieving such a pleasing appearance in our patients is not always easy but is critical, not least because our work is effectively on display and this has implications for patients' perceptions of our practice. To be successful, thorough assessment, careful planning and precise clinical execution is required. Every bit as important though, is good communication, both with the dental laboratory and particularly with the patient. In few areas of dentistry can effective communication be as critical as it is here.

Effect of posterior crown margin placement on gingival health

STATEMENT OF PROBLEM

The clinical impact of posterior crown margin placement on gingival health has not been thoroughly quantified.

PURPOSE

This study evaluated the effect of posterior crown margin placement with multivariate analysis.

MATERIAL AND METHODS

Ten general dentists reviewed 240 patients with 480 metal-ceramic crowns in a prospective clinical trial. The alloy was randomly selected from 2 high gold, 1 low gold, and 1 palladium alloy. Variables were the alloy used, oral hygiene index score before treatment, location of crown margins at baseline, and plaque index and sulcus bleeding index scores recorded for restored and control teeth after 1 year. The effect of crown margin placement on sulcular bleeding and plaque accumulation was analyzed with regression models (P<.05).

RESULTS

The probability of plaque at 1 year increased with increasing oral hygiene index score before treatment. The lingual surfaces demonstrated the highest probability of plaque. The risk of bleeding at intrasulcular posterior crown margins was approximately twice that at supragingival margins. Poor oral hygiene before treatment and plaque also were associated with sulcular bleeding. Facial sites exhibited a lower probability of sulcular bleeding than lingual surfaces. Type of alloy did not influence sulcular bleeding.

CONCLUSION

In this study, placement of crown margins was one of several parameters that affected gingival health.

Effect of pH on endotoxin affinity for metal-ceramic alloys

STATEMENT OF PROBLEM

Crevicular pH may modify bacterial endotoxin affinity for high-noble metal-ceramic alloys.

PURPOSE

Porphyromonas gingivalis lipopolysaccharide (LPS) affinity for 3 metal-ceramic alloys at 3 different pH levels was compared in vitro by measuring adsorption to and release from the alloy surface.

MATERIAL AND METHODS

Metallographically polished disks were fabricated from Pd-Ag-Sn, Au-Pd-Ag-Sn-In, and Au-Pd-In-Ga alloys. Clean disks were placed individually into 1 mL at pH 6.5, 7.0, or 7.5 phosphate-buffered saline solution containing 0.9 endotoxin units per square millimeter tritiated LPS (n = 3 disks per alloy-pH group). The disks were incubated for 24 hours at 37 degrees C before being transferred to LPS-free buffer and incubated, again for 24 hours at 37 degrees C, to evaluate elution. This transfer continued at 24-hour intervals up to 96 hours total elution incubation. Lipopolysaccharide adsorption to and elution from disks was determined through liquid scintillation spectrometry. Adsorption data were evaluated with a 2-way analysis of variance (alpha=.05) and the post hoc Tukey honestly significant difference test.

RESULTS

Lipopolysaccharide adsorption values ranged from 0.48 +/- 0.04 EU/mm(2) for the Au-Pd-Ag-Sn-In alloy at pH 7.5 to 0.75 +/- 0.04 EU/mm(2) for the Pd-Ag-Sn alloy at pH 6.5. Alloy type (P=.0001) and environmental pH (P=.0001) significantly influenced adsorption. Adsorption to the Pd-Ag-Sn and Au-Pd-In-Ga alloys at pH 6.5, 7.0, and 7.5 were similar and decreased with increasing pH. In contrast, adsorption to the Au-Pd-Ag-Sn-In alloy was significantly less than to other alloys at pH 6.5 but did not differ at other pH levels. Lipopolysaccharide release from the alloy surface could not be detected.

CONCLUSION

P. gingivalis LPS affinity for metal-ceramic alloys was modified by environmental pH. The degree of LPS adsorption depended on the composition and surface chemistry of each alloy.

Periodontal tissue responses after insertion of artificial crowns and fixed partial dentures

PURPOSE

The purpose of this review was, first, to critically evaluate published evidence on the effects of artificial crowns and fixed partial dentures (FPDs) on adjacent periodontal tissue health, and second to synthesize this evidence into meaningful summaries. Restoration qualities that contribute to inflammatory responses were identified based on strength of evidence, and variables that should be controlled in future investigations were outlined. Such information is necessary to accurately predict the prognosis of periodontal tissues adjacent to crowns or FPDs.

METHODS

Clinical trial and epidemiologic evidence published in English was collected. The effects of crowns or FPDs on gingival inflammation, probing depths, and bone loss were evaluated based on accuracy of measurement, reliability of measurement, and/or appropriateness of data analysis.

RESULTS

Crowns and FPDs increased the incidence of advanced gingival inflammation adjacent to restorations, particularly if restorations had intracrevicular finish line placement, poor marginal adaptation, or rough surfaces. However, because of the limitation in the accuracy and reliability of probing depth measurements, reports of greater mean probing depths of crowned teeth, which tended to be less than 1 mm greater than control teeth, should be questioned. Finally, crowns and FPDs in general did not accelerate the rate of adjacent bone loss.

CONCLUSION

Clinically deficient restorations, as well as clinically acceptable restorations, can contribute to gingival inflammation. However, with the limitations of the applied methods of measurement, current evidence has not shown an increased attachment loss adjacent to crowns or FPDs. Future trials should document periodontal health before therapy and periodically after restoration insertion so that each tooth serves as its own control. In future studies, the periodontal disease history of the patient, the influence of the restoration on plaque formation, and the composition of the crevicular microflora must be recorded.

Marginal adaptation of implant-supported metal-ceramic crowns fabricated with gold cylinders

PURPOSE

The purpose of this investigation was to determine the mean marginal discrepancy of metal-ceramic crowns fabricated with gold cylinders and cemented on implant abutments. These discrepancies were then compared with those measured previously for implant-supported ceramic crowns.

MATERIALS AND METHODS

Fifteen Nobel BioCare CeraOne abutments were connected to implant fixtures embedded in acrylic resin blocks. Marginal discrepancies were determined for gold cylinders, gold cylinders plus ceramic alloy (metal frameworks), completed metal-ceramic crowns, and cemented metal-ceramic crowns using a stereomicroscope equipped with a video camera linked to a computer. A Hotelling's T2 test (p < or = .05) was used to evaluate potential differences in mean marginal discrepancies among groups.

RESULTS

The mean marginal discrepancies were: 1) gold cylinders, 7.56 +/- 2.73 microns; 2) metal frameworks, 6.21 +/- 1.34 microns; 3) metal-ceramic crowns, 11.06 +/- 3.21 microns; and 4) zinc-phosphate cemented crowns, 31.47 +/- 6.65 microns. No significant difference between gold cylinders and metal frameworks was found. Mean marginal discrepancies for metal-ceramic crowns were significantly greater than discrepancies for cast gold cylinders. Cemented-crown mean marginal discrepancy was significantly greater than all other means.

CONCLUSIONS

Cemented metal-ceramic crowns fabricated using proprietary gold cylinders exhibited well-fitting margins (31.47 microns).

10-year periodontal response to resin bonded bridges

The purpose of this study was to evaluate the long-term (10 years +/- 15 months) periodontal response to resin bonded bridges (RBRs). A total of 103 patients who had RBRs bonded between 1980 and 1984 were recalled. Periodontal evaluations were made by two clinicians for all abutment teeth and for selected control teeth with intact, non-restored lingual surfaces. Periodontal indices consisted of: plaque index (PI), gingival index (GI), gingival recession, probing depth, and loss of attachment. Paired t tests indicated no significant difference in overall GI between experimental and control sites, but a significant difference in PI and probing depth with experimental sites (abutment teeth) showing higher PI and greater probing depths. Significant differences were found in overall recession and attachment loss, again with more recession and attachment loss observed on the abutment teeth as compared to the controls. Site specific analyses for PI, probing, and loss of attachment showed small but significant differences between experimental and control teeth in 15 of 21 sites. Although these findings may be statistically significant, the clinical impact for resin bonded restorations functioning for over 10 years is minimal and is comparable to periodontal response to other types of restorations.

Annual review of selected dental literature: report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The annual review of selected dental literature this year cites 384 published papers and reports. This year's review contains more editorial comment than reviews of years passed. New data on the biological responses to materials is emphasized in several sections. Observations on new compounds able to prevent plaque formation are presented. Clinically relevant advances in knowledge concerning the etching of different tooth structures are reported along with the effect of etching procedures on the dental pulp. Evaluation of periodontal diseases in all age groups is a topic. Limitations of current diagnostic techniques in periodontal disease, temporomandibular disorders, and implant therapy are included. There are new views on the use of dental amalgam. The future use of dental mercury is predicted. Interest in new ceramic systems is indicated as the demand for esthetics continues. Clinical information is emphasized over scientific information throughout this year's review.