Alterations on crown contour--effect on gingival health in man

The Relationships Between Tooth-Supported Fixed Dental Prostheses and Restorations and the Periodontium

PURPOSE

To search the literature and to critically evaluate the findings on the periodontal outcomes of restorations and tooth-supported fixed prostheses.

MATERIALS AND METHODS

PubMed was searched according to a systematic methodology, previously reported, but updated to include a larger database. Filters applied were: Case reports, clinical trial, review, guideline, randomized controlled trial, meta-analysis, systematic reviews, and English. A narrative review was then synthesized to discuss periodontal outcomes related to restorations and tooth-supported fixed prostheses. Relevant data was organized into four sections: Direct restorations, indirect restorations, biologic width or supracrestal tissue attachment and tooth preparation/finish line design.

RESULTS

While increased gingival index, bleeding on probing, probing depth and clinical attachment loss have been associated with subgingival restorations, intracrevicular margins do not cause periodontal diseases. Inflammation and bone loss occur, for both direct and indirect restorations, only with large overhangs. Different restorative materials are associated with different clinical responses when placed in the gingival sulcus or within the epithelial and connective tissue attachments. When the connective tissue attachment is removed, histological changes occur causing its apical shift and subsequent re-establishment. Gingival displacement during impression procedures can cause gingival recession. Emergence profile can have a range of values, not associated with periodontal diseases. Periodontal response appears to be clinically not different when compared among different finish line designs.

CONCLUSIONS

Contemporary procedures and materials used for the placement and fabrication of tooth-supported restorations and fixed prostheses are compatible with periodontal health when adequate patient education and motivation in self-performed oral hygiene are present. Periodontal diagnostic criteria should be thoroughly reviewed before fixed restorative treatments are planned and executed.

Waxing techniques to develop proper occlusal morphology in different occlusal schemes

Static and dynamic occlusal interferences frequently need to be corrected by selective grinding of the occlusal surface of conventional cast, porcelain fused to metal and all-ceramic restorations. Proper dimensional contours and occlusal morphologies of these restorations is an important consideration in overall success of the case. Various types of occlusal morphologies and contact relationships of posterior reconstructions are dependent on the occlusal schemes (Cusp-fossa or Cusp-marginal ridge) and the requirements of the patient's masticatory system. While much has been said and deliberated about the occlusal schemes, little is spoken about its development using intricate waxing techniques. There are various waxing techniques described in the literature which give a detailed description of the steps, methodology and instrumentation used for waxing of occlusal forms. The role of using such intricate waxing techniques cannot be overemphasized. Discussed in this article are the different techniques to be used in developing appropriate occlusal morphology and is supported by suitable case presentations.

Effect of different crown contours on periodontal health in dogs. Microbiological results

OBJECTIVES

In some clinical circumstances, i.e. in cases when the upper anterior region has to be restored by prosthetic means, it is necessary to place the margins of crowns and fixed partial dentures subgingivally. In addition, in periodontally compromised patients the restoration sometimes has to be overcontoured in order to replace the lost interdental papilla. The overcontoured crown margin may influence the subgingival bacterial composition. Therefore, the aim of the present investigation was to evaluate the effect of three different subgingival crown contours in dogs on the composition of the subgingival microbiota.

METHODS

In four adult beagle dogs the second and third premolars were prepared in three quadrants and restored with single gold crowns. The unprepared second and third premolars in the last quadrant served as controls. The crowns had three different emergence profiles including a normal contour, a 30 degrees and a 50 degrees over-contour. During the entire study period, professional oral hygiene was performed seven times a week. Microbiological samples were harvested from four sites of test and control teeth (mesial, distal, buccal and lingual) at baseline, after 3 months, and after 5 months.

RESULTS

The microbiological analysis (DNA-DNA hybridization technique) of the subgingival microbial flora revealed a dominance of P. intermedia, T. denticola and C. showae in all test and control groups at baseline. At three months, the total amount of bacteria increased and a broader variety of bacterial species could be detected. The detection frequency of most bacterial species increased from baseline to the 5-month evaluation. The frequency of detection of some species was higher in the 30 degrees and 50 degrees overcontoured test groups compared to the normal contour group and to the natural teeth.

CONCLUSIONS

It can be concluded within the limits of this investigation that overcontoured gold crowns placed subgingivally have only slight effects on the microbiological composition in dogs when an intensive oral hygiene regimen was executed.

Effect of different crown contours on periodontal health in dogs. Clinical results

OBJECTIVES

The aim of this study is to evaluate clinically the effect of different crown contours on the periodontium in beagle dogs.

METHODS

One month after commencing oral hygiene procedures the second and third premolars in three quadrants of four adult beagle dogs were prepared for receiving crowns. The unprepared second and third premolars in one quadrant served as controls. Crowns with three different emergence profiles (normal (=tooth) contour, 30 degrees and 50 degrees over-contour) were cemented where one quadrant received the same treatment. Clinical parameters were recorded on all four sites (mesial, buccal, distal and lingual) of test and control teeth at baseline, after 3 and 5 months. During the entire study period, professional oral hygiene was performed seven times a week.

RESULTS

The Plaque Index increased for the 30 degrees and 50 degrees over-contour groups, although no statistically significant differences could be observed. For the normal contour and control group minor changes occurred. Similar results could be depicted for the Gingival Index. The changes regarding the variables Plaque and Gingival Index were correlated to the Gingival Crevicular Fluid Flow. Here, significant differences for the Gingival Crevicular Flow were observed between the treatment groups and over the treatment period for the 30 and 50 degrees over-contour groups. Only slight differences for this parameter were observed in and between the control and normal contour groups. In the control group, the Pocket Probing depth remained stable during the entire study but increased in the crowned treatment groups over time. At 3 and 5 months the probing depth was significant greater in the 30 degrees and 50 degrees over-contour groups compared to the control group. There was a higher loss of clinical attachment levels for the test groups than for the control group. There were statistically significant differences at each timepoint between groups and also within groups except for the control group.

CONCLUSIONS

Within the limits of this study it can be concluded that over-contoured subgingival crowns seem to affect clinical periodontal health only slightly in dogs over 5 months when an intensive oral hygiene regimen is executed.

Interactions between the gingiva and the margin of restorations

An adequate understanding of the relationship between periodontal tissues and restorative dentistry is paramount to ensure adequate form, function, esthetics, and comfort of the dentition. While most clinicians are aware of this important relationship, uncertainty remains regarding specific concepts such as the biologic width and indications and applications for surgical crown lengthening. This review discusses the concept of the biologic width and its relationship to periodontal health and restorative dentistry. The importance of restorative margin location, materials, and contours related to periodontal health is also addressed. The rationale and indications for surgical crown lengthening are elaborated. Particular surgical principles of crown lengthening are examined in detail.

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.

Periodontal prosthesis: creating successful restorations

When the dentition is mutilated by periodontal disease, it's hard to restore. The authors outline the mechanical and biological problems to overcome in treating advanced periodontal disease.

Splinting: a retrospective 17-year follow-up study

A retrospective 17-year, longitudinal study monitoring 66 patients with fixed partial denture and removable partial denture restorations revealed that perceptive splinting was beneficial and enhanced the longevity of the restoration. The study discussed the advantages and disadvantages of splinting, the survival rate of splints and splinted teeth, and the importance of oral hygiene and a periodic maintenance program.

Gingival crown margin configurations: a review and discussion. Part I: Terminology and widths

The terms bevel, chamfer, and shoulder are widely used to describe crown margin designs. However, as no clear definition of the essential feature(s) of each design has been universally accepted, the same term often describes margins of widely differing width and/or configuration. Similarly "bevel angles" are not consistently defined. While tradition favors the use of thinner marginal designs, many of the reasons advanced for their superiority are questionable in the light of contemporary research. Use of marginal widths beyond the absolute minimum demanded of the material may contribute to overcoming some of the persistent problems identified with fixed prosthodontic replacement of natural teeth. These include overcontour, porcelain debonds, poor esthetics, and fit. It is suggested that the problems associated with underpreparation and the potential advantages of wider preparations need reemphasis.

Clinical crown contours: contemporary view

Crown contours represent a group of characteristics critical for the longevity and success of dental restorations. This article presents the theories that have been developed about crown contours, describes each feature in detail, and clarifies potential interrelationships with all components of the mouth. When identified early, crown contours can be incorporated in treatment planning and restorative procedures.

Full crown restorations and gingival inflammation in a controlled population

The volume of crevicular fluid around full crown restorations was measured with a Periotron instrument to compare the gingival inflammation between restored and nonrestored teeth in the same patient. Thirty-eight full crown restorations were compared to nonrestored teeth used as controls in 26 patients. Forty-six full crown restorations in 28 patients were also evaluated according to gingival margin placement to determine if there was a difference in inflammation in gingival tissues. The highly motivated patients were selected from a private practice because of their interest and investment in long-term dental health. The results revealed the following findings. 1. Full crown restorations have the potential for causing gingival inflammation. However, they need not be associated with a significant increase in gingival inflammation when placed in the oral environment of a highly motivated patient in a rigid dental recall program. 2. Gingival inflammation surrounding full crown restorations may be controlled regardless of gingival margin placement when the gingiva is healthy, the restorations are adequate, and the patient is in a strict recall program.