Cavosurface Margin Research Articles

Marginal adaptation and fit of adhesive ceramic inlays

This in vitro study compared the marginal adaptation of CAD/CAM and laboratory-made ceramic inlays before, during and after loading. Six MOD inlay preparations of standardized design with one cervical margin in dentine and the other in enamel were prepared for each inlay type: CAD/CAM fabricated MGC-glass ceramic inlays, CAD/CAM fabricated feldspathic porcelain inlays, laboratory-made glass ceramic inlays and laboratory-made feldspathic porcelain inlays. Appropriate luting composite materials were used. The restored teeth were subjected to occlusal loading, thermal cycling, toothbrush-toothpaste abrasion and chemical degradation in vitro. Marginal adaptation was quantitated along the entire length of the cavosurface margin and along selected sections of the margin using SEM, following in vitro testing corresponding to 0, 0.5, 1.0, 2.7 and 5.0 years of clinical service. In addition, marginal fit of the cemented inlays was evaluated in the SEM. The initial marginal adaptation in enamel was excellent in all groups. After in vitro testing, significant marginal discrepancies were found in all groups. A high percentage of marginal openings was recorded, notably in the cervical portions of the margins in both enamel and dentine.

The effects of dentine bonding agents on marginal leakage of composite restorations--long-term studies.

The aim of this study was to compare the effects upon marginal leakage of a number of dentine bonding agents when used with a posterior composite resin, Occlusin, after storage for periods of up to 2 years. The bonding agents used were Gluma, Scotchbond, Topaz and an experimental material. The results were compared with a glass ionomer, Chemfil II. Class V cavities with or without a bevelled cavo-surface margin were prepared in the buccal surfaces of extracted premolar teeth. Following restoration, the teeth were stored for periods of up to 2 years and then thermally cycled. Marginal leakage was subsequently demonstrated using a radioactive isotope containing 45Ca, and an auto-radiographic technique. Image analysis was used to determine the total amount of linear leakage for each specimen. The results showed that some leakage occurred for all materials at each time interval. The bevelled design of cavity allowed significantly less leakage than the unbevelled cavity. Overall, there was little difference between the various dentine bonding agents. The glass ionomer restorations showed significantly less leakage than the composite resin and dentine bonding agent combinations in unbevelled cavities.

Sealing effectiveness of light-cured glass ionomer cement liners

Glass ionomer materials have been used as liners or bases beneath restorations, but light-cured varieties have recently been introduced. Microleakage at the restoration/tooth interface in cervical cavities was used to test the adhesion to dentin of two new light-cured glass ionomer cement lining materials, XR-Ionomer and Fuji Lining LC. Wedge-shaped cervical cavities were prepared on extracted teeth with a gingival cavosurface margin involving dentin, and the specimens were assigned randomly to three groups. The experimental groups were restored with two light-cured glass ionomer cements, the controls were restored with a chemically cured glass ionomer cement; and marginal leakage was assessed by dye penetration. The two light-cured glass ionomer cements displayed some adhesion to dentin in class V test cavities, but there was no significant difference between the two materials.

Clinical correlations of dentin structure and function

Dentin, a porous, fluid-filled mineralized tissue, may provide critical mechanical support to overlying enamel. Once the enamel or cementum surface seals are lost by disease or trauma, the same organization that provided critical mechanical support then becomes a liability, offering millions of fluid-filled diffusion channels from the periphery directly to the pulp. If restorative materials placed in cavities do not seal the dentin, there is a fluid-filled continuum from the cavosurface margins, around gaps between the restorative material and the tooth, to dentin surfaces, then through dentin via its tubules to the pulp. Under most conditions these channels permit bidirectional diffusion of exogenous and endogenous substances across dentin. Occasionally, hydrodynamic stimuli will produce transient, rapid movement of dentinal fluid that will induce pain. The tubules are sometimes so close together in deep dentin that their intrinsic wetness interferes with the bonding of adhesive resins. This permits the formation of gaps, microleakage, dentin sensitivity, and, occasionally, pulpal irritation. Many clinical problems such as poor dentin bonding, microleakage, dentin sensitivity, and pulpal irritation have a common denominator in the structure and function of dentin.

Using Composite Resin as a Posterior Restorative Material

Composite resins have been improved dramatically over the last few years. Some of the newest formulations are nearly as wear resistant as amalgam. Under the appropriate conditions, they may be used to restore Class I and Class II cavity preparations. Their use, however, must be in accordance with the conditions described in this paper. The following conditions should be followed: The selection of a posterior composite resin should be based on well-documented clinical data, not physical and mechanical properties. Complete moisture control is essential for the successful restoration of posterior teeth with composite resin. Always use a glass ionomer as a liner. The material should cover all the dentin. Cavity preparations should be minimal in dimension. Avoid unnecessary removal of tooth structure. Do not bevel the occlusal cavosurface margin. Insert the composite in increments. Minimize introduction of trauma during the finishing procedure. Use a surface penetrating sealant to reduce wear rate and to enhance margin integrity. Evaluate carefully the clinical performance of the restored tooth at least once a year. Discuss possible limitations of posterior composite resins as compared with amalgam restorations.

Microleakage in three designs of glass ionomer under composite resin restorations

Three Class V cavity configurations with walls above and below the cemento-enamel junction were compared when 'sandwich' technique restorations with glass ionomer and composite resin were used. No dye penetration occurred at the occlusal cavosurface margin when the latter was bevelled and light-cured Scotchbond was applied to the etched enamel before restoration with Durafil composite resin. The least dye penetration at the gingival margin was observed when Ketac bond glass ionomer covered the entire non-bevelled wall. No configuration entirely eliminated dye penetration at the gingival margin.

Replacement reasons and service time of class-II amalgam restorations in relation to cavity design

Four hundred and sixty-eight class-II amalgam restorations were placed in 210 patients. The restorations had been inserted by seven Scandinavian dentists in their clinics, among their regularly attending patients. Impressions of the teeth with cavity preparations had been made, and epoxy casts fabricated. The designs and qualities of the cavities were assessed in accordance with an evaluation system for class-II cavities designed for use on models. The restorations were observed yearly and scored in accordance with the USPHS criteria. In case of replacement the reason was recorded, and the service time calculated. The restorations were observed throughout a period varying from 8 to 10 years. At the end of the observation period, 212 restorations had been lost owing to dropout patients, 68 restorations had been replaced, and 188 restorations remained functional. The commonest criteria for replacement were secondary caries (n = 30) and restoration bulk fractures (n = 24). Using univariate statistics and multivariate discriminant analyses, the time of service and the reasons for replacement were correlated with different clinical variables, including different indices for the dimensions and qualities of the cavity preparation. Several features of the cavity design could be associated with the service time of the restoration or with the reason for replacement, or both. Secondary caries was primarily associated with cavity design features gingivally on the proximal surface (p less than 0.001). At the patient level the rate of secondary caries correlated with the total number of restorations placed during the observation period, irrespective of the quality of the cavosurface margins or the size of the cavity. Restoration bulk fractures could be related to cavities with narrow and deep occlusal parts, or deep proximal parts (p less than 0.001). The discriminant functions predicted correctly between 70% and 93% of the actually failed restorations in the failure groups. The good prediction performance indicates that a linear discriminant analysis that includes aspects of the prepared cavity may be applied to predict the reasons for failure of restorations.

The effects of dentine bonding agents on marginal leakage of composite restorations

The aim of this study was to compare the effects upon marginal leakage of a number of dentine bonding agents: Gluma, Scotchbond, Topaz and an experimental material when used with a posterior composite resin, Occlusin. The results were also compared with composite used without a dentine bonding agent and with a glass ionomer, Chemfil II. Class V cavities with or without a bevelled cavo-surface margin were prepared in the buccal surfaces of extracted premolar teeth. Following restoration, the teeth were stored for periods of up to 3 months and then thermally cycled. Marginal leakage was subsequently determined using a radioactive isotope containing 45Ca, and an autoradiographic technique. Image analysis was used to determine the total amount of linear leakage for each specimen. The results showed that some leakage occurred for all materials at each time interval. The bevelled design of cavity allowed significantly less leakage than the non-bevelled type. The use of dentine bonding agents did not improve the marginal seal of the composite restorations, and the glass ionomer restorations showed significantly less leakage than the composite resin and dentine bonding agent combinations.

Efficacy of Beveling Posterior Composite Resin Preparations

A clinical study was conducted to evaluate the controversy over the need to bevel the occlusal cavosurface margins of posterior composite resin preparations. A total of 43 standard amalgam type cavity preparations were generated. On a randomized basis the preparations were either beveled or left unmodified. The width of the bevel in each case approximated 1 micron. Impressions were made of each preparation to verify occlusal dimension. Each preparation was restored with Estilux Posterior (Kulzer, Inc.) using conventional techniques. Polyvinyl siloxane impressions were generated and then cast with die stone. These casts were evaluated for wear at baseline, 6 months, 1, and 2 years. The loss of composite resin in the beveled preparation at 2 years averaged 81.2 microns while the nonbeveled averaged 69.8 microns. On the basis of this study, it was concluded that beveling of the occlusal cavosurface did not enhance the wear resistance of the composite resin restoration nor any of the other clinical characteristics evaluated in the study.

Clinical requirements for a successful 'sandwich'--dentine to glass ionomer cement to composite resin.

The composite resins are now being used extensively in restorative dentistry although there are still some problems remaining. Long-term prevention of microleakage continues to be an area of controversy particularly in relation to the margins between dentine and composite resin. Chemical adhesion between glass ionomer cement and dentine is accepted as being a long-term union and it has recently been shown that a mechanical union is possible between composite resin and glass ionomer cement. This has led to the development of the so-called 'sandwich technique' where glass ionomer cement is used as a lining under composite resin restorations particularly where the cavo-surface margin is in dentine. This paper discusses the various levels of adhesion in the 'sandwich' and suggests the best methods of obtaining optimum results from the clinical application of the technique. Particular attention is drawn to the wide variation in the strength of the union depending on the materials used and the methods of handling.

Marginal fracture of posterior composite resins

This study assesses the early cavomarginal breakdown of the newer posterior composite resin restorations compared with that of amalgam restorations. A total of 432 posterior composite restorations and 73 amalgam restorations were examined: 121 composite restorations (28%) and 44 amalgam restorations (60%) clinically showed a marginal crevice at some point on the cavosurface margin of the restoration at 6-month, 1-year, and 2-year recalls. The largest single reason for poor marginal adaptation was marginal fracture. Up to 2 years, the marginal integrity of the studied posterior composites was superior to that of an amalgam alloy. It was determined that smaller cavities, greater bulk of resin at the margin (especially at functional cusp areas), and well-finished margins without overfiling seem to reduce the occurrence of marginal fracture on composite resin restorations.

An analysis of margin adaptation of all-porcelain facial margin ceramometal crowns

E limination of the metal collar or metal substructure at the facial margin of a ceramometal crown will greatly improve the esthetic result of the completed restoration. A number of techniques for fabrication of facial porcelain margins for these restorations (platinum foil, refractory die, and direct lift-off) have been described.‘-’ The least complicated of these, the direct lift-off technique, has certain potential disadvantages such as the displacement of the metal coping during shoulder buildup and pyroplastic deformation during firing. Although these discrepancies have been measured and reported by several authors5s 9 scarce data exist relative to the margin adaptation of the all-porcelain facial margin. The purpose of this study was to measure the cavosurface margin adaptation of all-porcelain margins fabricated with a lift-off technique and to measure changes in the metal coping margin during the stages of porcelainization.

Two-year clinical evaluation of light-cured composite resin restorations in primary molars

The restorations were evaluated at baseline, and at 6, 12, and 24 months by two trained examiners. In the system used, the highest, most desirable rating is Alfa. Of the restorations evaluated at 24 months, 99% had Alfa ratings for color match, 87% had Alfa ratings for no discoloration at cavosurface margins, and 86% had Alfa ratings for no loss of anatomic form. In addition, 75% of the restorations had Alfa ratings for margin adaptation, and 91% had Alfa ratings for no recurrent caries at the 24-month evaluation. In conclusion, the light-cured composite resin restorative material functioned well at the 12- and 24-month evaluation periods, when used in primary molars.

A varnish to prevent etching unrestored enamel

The prognosis of acid-etched enamel was investigated in both laboratory and clinical experiments. Acid etching produced irregularities even on the prismless layer that covers prism enamel. The irregularities produced by etching are not remineralized in vivo but are filled with organic debris. Brushing reduced the depth of the irregularities but did not eliminate them. A protective varnish against acid etching was developed. The varnish also serves as a guide to facilitate removal of excess resin beyond the cavosurface margin.

Microleakage of direct gold restorations: An in vitro study

lhe adaptation of restorative materials to the walls of cavity preparations has been considered clinically important for many years.’ A chemical bond between a restorative material and tooth structure with no marginal leakage would be ideal. However, at the present time no available material possesses this criterion. Early studies of the microleakage of conventional amalgam alloys, using autoradiographs, showed that the initial sealing properties of amalgam were greatly improved by the use of copal resin cavity liner.‘> ’ More recently, it has been reported that corrosion-resistant amalgam restorations placed after coating the cavity walls with cavity varnish showed no leakage at 48 hours and after 3 months.4 These same authors reported similar results in a study using dogs as experimental animals5 The most recent study of leakage of direct gold restorations used a crystal violet dye technique.” In this study amalgam and compacted gold were found to have less leakage than composite resins using an acid-etch technique. Cohesive gold restorations have long been considered the epitome of clinical restorations in a general practice. Textbooks list adaptation to cavity walls and cavosurface margins as one of the attributes of cohesive direct gold restorations. Pure gold foil, electrolytically deposited mat gold, powdered gold encased in gold foil, and alloyed filling gold are in current use for conservative restorations. The purpose of this study was to evaluate the adaptation to cavity walls of four types of direct filling golds by studying the microleakage around restorations placed with and without a copal resin liner.

Microleakage of conventional and microfilled composite restorative resins

Microfilled composite resins have been introduced in clinical dentistry because of the difficulty in finishing conventional composite resins satisfactorily. Owing to the difference in coefficients of thermal expansion of the two resin systems, the objective of this in vitro study was to evaluate microleakage of a conventional and a microfilled composite resin. Class V cavities with butt cavosurface margins were prepared in the middle third of the facial surfaces of the crowns of 80 noncarious human premolar teeth; they were acid etched within the preparations only. Forty preparations were restored with Concise composite and forty with Silar microfilled resin. Ten teeth from each group were subjected to cyclic temperature changes between 5 and 55 degrees C for 1000, 2500, or 5000 cycles, respectively, and ten teeth from each group were not cycled (controls). After suitable preparation, the teeth were immersed in 45Ca solution for 18 h and contact radiographs were prepared. Microleakage was scored 0-3 at both the cervical and occlusal margins of the restorations. Microleakage was significantly greater at the cervical margins than at the occlusal margins. Differences within occlusal and cervical microleakages among the two resins were not significant.

Early and delayed finishing of amalgam with different polishing procedures

T he finishing of amalgam restorations should include the carving of anatomy and cavosurface margins at the time of placement and should be followed by refinement of anatomy and margins and by polishing at a later time. Excess material, usually called flash, frequently extends beyond the cavosurface margins. This excess material should always be removed since it will eventually fracture leaving an undesirable margin. The clinical performance of amalgam restorations is improved by finishing and polishing.’ Burnishing reduces porosity and residual mercury content in amalgam restorations2 Better marginal integrity of burnished restorations has been demonstrated.3 The feasibility of immediate polishing of high-copper content amalgam alloys has also been reported.4 In the past finishing and polishing procedures have been done at a subsequent appointment by necessity. There have been several different techniques advocated for the finishing and polishing of amalgam restorations. The purpose of this study was to examine amalgam surfaces finished after 30 minutes and after 24 hours.

Quality assessment of amalgam restorations provided by Israeli dentists

Abstract The purpose of the present study was to assess the quality of silver amalgam restorations rendered by Israeli dentists. A group of 433 new army recruits, 18–20 years of age was selected for the study. A total of 707 amalgam restorations were examined in an army dental clinic, under standardized conditions by the same observer. The quality of amalgam restorations was assessed according to an index devised for this purpose. The quality of restorations was relatively low. Approximately two‐thirds of the fillings exhibited satisfactory quality when marginal adaptation of the filling material was examined. Three‐fifths of the fillings followed the principles of extension for prevention. A relatively high percentage (75%) of the fillings did not extend beyond the cavosurface margin at any point or did not fall short of it. However, in only 47% of all fillings was appropriate occlusion restored. The fillings were found to be porous in about 60% of the cases and almost none of the fillings were polished. Overhangs were detected in about one‐quarter of the restorations (22.8%); inflammatory reactions of the gingival tissue were noticeable in more than half of the cases (51.3%). An attempt was made to study the various characteristics of the amalgam filling as categorized by the index presented in this study, and discuss its effect on the filling's overall quality. It was suggested that lack of standardization of performance levels in Israel is reflected, in part, in the observed low quality of amalgam restorations. The conclusions of this investigation point to interventions which can be initiated through the dental education, financing and public health planning sectors of the society, to increase awareness of this problem and define specific interventions to improve the quality of restorative dental cave delivered in general practice in Israel.

Standardized sequence for carving and finishing amalgam restorations

This method of amalgam carving and finishing, described in a step-by-step sequence, is fast and effective. The initial step of using the acorn burnisher eliminates the great bulk of excess amalgam and contours the restoration. A simple armamentarium is all that is required for carving, burnishing, and polishing. A general scheme for reestablishing original or ideal occlusal morphology has been discussed, emphasizing distinct triangular and marginal ridges and convex contour. Attention was focused on the prevention of ditching at the cavosurface margin, thus ensuring full benefit of the improved physical properties of silver amalgam.

Cross-Sectional Clinical Evaluation of Recurrent Enamel Caries, Restoration of Marginal Integrity, and Oral Hygiene Status

Both marginal quality and oral hygiene status have strong effects on the risk of recurrent caries. Although there was no statistically significant interaction between these two parameters in this study, the influence of each variable was dependent on its severity. There is a difference between the behavior or the likelihood of recurrent caries on occlusal surfaces as compared with smooth surfaces. On the smooth surfaces, there is a continued increased risk with decreasing marginal quality; the occlusal surfaces, however, show no change in vulnerability beyond a modified marginal quality score of 3. Variation in oral hygiene had a more pronounced effect on the probability of recurrent caries of restorations with moderate margin scores than it did on restorations with either very poor or very good cavosurface margins. This work further emphasizes the importance of technically good restorative care at the operative visit, which, coupled with conscientious oral hygiene, should have a positive effect on increasing the longevity of restorations and decreasing the need for replacement.