Cavity design and marginal degradation of the occlusal part of class-II amalgam restorations

Jokstad, Asbjørn; Mjör, Ivar A.

doi:10.3109/00016359009029070

Cited by 6 publications

(5 citation statements)

References 19 publications

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“…An attempt to reduce the effect of the possible different treatment philosophies among the participating dentists was done by instructing the dentists to score the restorations using the USPHS criteria (29) and to retrieve the failed restorations for further metallographic examinations (30). Further details of the materials and methods have been described previously (26,27,31,32).…”

Section: Methodsmentioning

confidence: 99%

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

Jokstad

Mjör

1991

Acta Odontologica Scandinavica

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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.

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Section: Methodsmentioning

confidence: 99%

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

Jokstad

Mjör

1991

Acta Odontologica Scandinavica

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“…In more extensively destroyed teeth, the bevel improved the exposure angle of the enamel, but the effect was not so visible as in more conservative cavities ( One may question about the behavior and reliability of the restorative materials on the beveled area. It is noteworthy that, due to the mechanical properties, amalgam restorations should never be placed over thin (and/or beveled areas) (Boushell, Roberson, & Walter, 2013;Jokstad & Mjor, 1990). However, this is not necessarily true for polymers, such as resin composites, due to their modulus of elasticity being similar to the one observed for the dental structure (Jokstad & Mjor, 1990).…”

Section: Discussionmentioning

confidence: 99%

“…It is noteworthy that, due to the mechanical properties, amalgam restorations should never be placed over thin (and/or beveled areas) (Boushell, Roberson, & Walter, 2013;Jokstad & Mjor, 1990). However, this is not necessarily true for polymers, such as resin composites, due to their modulus of elasticity being similar to the one observed for the dental structure (Jokstad & Mjor, 1990). This said, resin composites can greatly benefit from the enhanced adhesion offered by the beveling procedures as previously discussed (Boushell et al, 2013), and the possibility of fracture due to reduced thickness is not concerning as the viscoelastic behavior of this class of material, more precisely deformation ( Considering that virtually no study assessed enamel prisms orientation and the only drawback consists on the additional removal of sound tooth structure, which is overcame by the above discussed benefits, it is important to reassess the indications for cavosurface angle beveling, as well as development and analysis of new cavity designs.…”

Section: Discussionmentioning

confidence: 99%

Effect of cavosurface angle beveling on the exposure angle of enamel prisms in different cavity sizes

Meurer¹,

Rizzante

Maenossono

et al. 2019

Microscopy Res & Technique

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The quality of the micromechanical retention between the enamel prisms exposed through acid etching and adhesive system can be influenced by the relationship between the angle of the exposed enamel prisms and the external surface/restorative material. Therefore, the aim of the present study was to determine the influence of the enamel cavosurface beveling in different cavity sizes on the angle relation between enamel prisms and the restorative material. For this research, 30 human permanent molars were used and divided into three groups according the isthmus aperture of class I cavities (1/4, 1/3, and 1/2 of the intercuspal distance). Cavosurface angle beveling was performed in each tooth buccal or palatal/lingual side, and a resin composite restoration was placed. Each restored tooth was sectioned in buccal/palatal direction followed by analysis in scanning electron microscope. Means of the angles observed between enamel prisms and the restorative material were registered and statistically analyzed by Kruskal‐Wallis test. Results showed higher mean angle values for beveled groups when comparing with the values observed in the unbeveled margins (p < .05) regardless of the isthmus aperture, being 1/4 (beveled = 48.36°; unbeveled = 20.71°), 1/3 (beveled = 39.75°; unbeveled = 29.15°), and 1/2 (beveled = 37.02°; unbeveled = 26.34°). It was also observed that in some unbeveled cavities, there were the presence of laterally exposed enamel prisms (0°), mainly in more conservative cavities. It was concluded that the presence of higher angles values occurred in the samples with beveled margins, without presence of laterally exposed enamel prisms.

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“…Restorations with technique codes MF and MC had, respectively, 11% and 13% of the measurable margins with CSAs less than 90°. These CSAs of less than 90° could result in fracture of potentially unsupported enamel at sites of occlusal loading, although it has been suggested (Jokstad & Mjor 1990) that enamel associated with CSAs smaller than 90° is not necessarily unsupported by sound dentine and should not be removed unless the enamel can be split off with a hand instrument. When cuspal inclines on the amalgam are carved/finished to be consistent with inclines on the adjacent tooth surface, a CSA of greater than 130° is likely to produce a small AMA (≈ 50°) and this has been shown to be undesirable (Elderton 1984).…”

Section: Discussionmentioning

confidence: 99%

The influence of modified cavity design and finishing techniques on the clinical performance of amalgam restorations: a 2‐year clinical study

Stratis

Bryant

1998

J of Oral Rehabilitation

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Use of modified cavo-surface angles (CSAs) and finishing techniques for amalgam restorations may influence the long term marginal fracture around these restorations. One operator placed 111 Tytin amalgam restorations in Class I and II preparations in the permanent teeth of 37 patients, each of whom received three restorations. One of these restorations was placed in a cavity prepared with a 'traditional' CSA and was finished more than 24 h after placement. Prepared cavities for the remaining two restorations for each patient were 'modified' with the aim of producing an occlusal CSA of 90-110 degrees. One restoration was carved-only and the other was finished more than 24 h after placement. Clinical evaluation of the restorations was carried out at baseline, 1 year and 2 years. At these times, the restorations were photographed and stone replicas were obtained from impressions taken at the cavity preparation stage to determine the cavo-surface angles. Careful application of the modified cavity design provided a mean cavo-surface angle of 109 degrees whereas a 'traditional' cavity design provided a mean cavo-surface angle of 126 degrees. Using the Mahler photographic method of evaluation, a combination of modification of the occlusal cavo-surface angle and finishing of the restoration was found to have an influence on the marginal fracture at 2 years. The clinical significance of these findings, with respect to the modified cavity design, is discussed.

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Cavity design and marginal degradation of the occlusal part of class-II amalgam restorations

Cited by 6 publications

References 19 publications

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

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

Effect of cavosurface angle beveling on the exposure angle of enamel prisms in different cavity sizes

The influence of modified cavity design and finishing techniques on the clinical performance of amalgam restorations: a 2‐year clinical study

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