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At least 289 records · Page 16Linked to original sources
PubMed2001

Burs with guide pins for standardized tooth preparation.

OBJECTIVE: The aim of this study was to develop and test self-limiting diamond burs to ease precise chamfer preparation and to fulfill the special requirements of computer-aided design/computer-aided manufacturing and all-ceramic restorations. METHOD AND MATERIALS: Rounded cylinder (based on ISO 881) and torpedo (based on ISO 879) diamond burs with a polished guide pin, 0.5 mm in length and 0.15 mm in radius, at the front end were developed in cooperation with an industrial partner. The in vitro testing involved a total of 140 human teeth. Experimental variables were the quality of the finish line, the microhardness of the enamel, and the thermal alteration of the dentin. Conventional diamonds served as a control. RESULTS: No mechanical or thermal damage related to the bur design was found in the hard tissues that had potentially been in contact with or in close proximity to the guide pin. Microhardness of the enamel at the finish line was significantly higher when prepared with burs with a guide pin compared to conventional burs. The results of using the guide pin might indicate the beneficial effect of reduced vibration. CONCLUSION: The guide pins of the self-limiting diamond burs reduce, rather than increase, the risk of hard tissue damage at the preparation margin. No adverse effects were found. Clinical use is justified.

Body Temperature↗
PubMed2001

Biomechanical effects of cervical lesions and restoration on periodontally compromised teeth.

OBJECTIVE: The purpose of this study was to photoelastically evaluate the effects of cervical root lesions and their restoration on stress distribution in periodontally compromised teeth. METHOD AND MATERIALS: Three-dimensional composite photoelastic models of a maxillary first premolar with buccal cervical root lesions were fabricated. Two different lesion configurations, wedge- and shallow saucer-shaped, at 20% alveolar bone height reduction were tested. A 35% reduction model was given a wedge-shaped lesion. The lesions were restored with microfine resin composite. Vertical loads of 7.5 lbs were applied to the unrestored and restored models at the tip of the buccal cusp and the tip of the lingual cusp. The resulting stresses within the tooth models were monitored and recorded photographically in the field of a circular polariscope arrangement. RESULTS: For buccal cusp loading of the unrestored models, stress concentrated at the apex of the lesion regardless of the lesion shape or periodontal support conditions. The highest stress concentration was observed around the apex of the wedge-shaped lesion on the 35% reduction model. Restoring the lesions changed stress distribution. Restoration of the lesions resulted in a marked stress reduction at the lesion apex. Stress along the gingival restoration-model interface was characteristic for the restored situation. The interfacial stress followed the contour of the restoration most closely for the wedge-shaped lesion on the 20% support reduction model. CONCLUSION: The shape and dimension of the lesion as well as periodontal support status has considerable influence on stress distribution, especially around the lesion, restored or not restored.

Alveolar Bone Loss↗
PubMed2001

Effect of sonic and mechanical toothbrushes on subgingival microbial flora: a comparative in vivo scanning electron microscopy study of 8 subjects.

OBJECTIVES: The purpose of this initial study was to evaluate the effects of both a sonic and a mechanical toothbrush versus the effects of no treatment on depth of subgingival penetration of epithelial and tooth-associated bacteria. METHOD AND MATERIALS: Eight adult subjects exhibiting advanced chronic periodontitis with at least 3 single-rooted teeth that were in separate sextants with facial pockets > or = 4 mm and < or = 8 mm and that required extraction constituted the experimental sample. Teeth were either subjected to 15 seconds of brushing with a mechanical toothbrush or a sonic toothbrush or left untreated. The test tooth and the associated soft tissue wall of the periodontal pocket were removed as a single unit. Samples were processed and coded for blind examination by scanning electron microscopy. Distributional and morphologic characteristics of dominant bacteria with specific emphasis on spirochetes were evaluated for both epithelial- and tooth-associated plaque. RESULTS: No differences were found in morphotypes or distributional and aggregational characteristics of epithelial-associated microbes in the 1- to 3-mm subgingival zone between the mechanical and sonic toothbrush-treated groups and the control group. Both toothbrush groups featured disruption of microbes that extended up to 1 mm subgingivally. Root surfaces on the sonic-treated samples appeared plaque-free at low magnification; however, at 4,700x, a thin layer of mixed morphotypes and intact spirochetes was found subgingivally and slightly subgingivally. In comparison, mechanical brush samples featured incompletely removed plaque, both subgingivally and subgingivally, with intact spirochetes present on subgingival root surfaces. CONCLUSION: Results suggest similar effects for both sonic and mechanical toothbrushes on epithelial- and tooth-associated bacterial plaque in periodontal pockets and adjacent root surfaces that extend up to 1 mm subgingivally. Further, the presence of intact subgingival spirochetes suggests limited exposure to acoustical or mechanical energy from the toothbrushes evaluated.

Acoustics↗
PubMed2002

Marginal bone loss and tooth loss in a sample from the County of Stockholm--a longitudinal study over 20 years.

The purpose of the study was to assess the degree of marginal alveolar bone loss and tooth loss in a longitudinal study over a period of 20 years. In 1970 a medical and odontological study on a stratified sample of the population of the County of Stockholm aged 18-65 years started. Twenty years later a new odontological investigation was performed on the 513 subjects who wanted to take part once more and who had at least five remaining teeth. The mean distance between the marginal bone level and the cemento-enamel junction measured on the radiographs in 1970 (MBL) was 13.8% of the root length. The mean bone loss during the 20-year period (MBD) was about 10%, corresponding to a mean annual marginal bone loss of about 0.1 mm. The MBD-values were significantly positively correlated to the MBL-values. The mean number of remaining teeth was 24.7 in 1970 and 21.8 in 1990. A significant positive correlation existed between the number of teeth lost between 1970 and 1990 and the mean MBD-value. In stepwise multiple regression analyses, the MBL-value was the only independent variable positively correlated to the MBD-value, while the number of teeth lost between 1970 and 1990 was significantly correlated to age and the MBL-value.

Adolescent↗
PubMedDate not supplied

Clinical evaluation of a resin-modified glass ionomer adhesive system: results at five years.

One hundred non-carious, non-undercut cervical lesions were restored with Silux Plus or Estio LC and bonded with Fuji Bond LC. The restorations were evaluated yearly for retention and marginal discoloration. After five years, the overall retention rate was 96%. Of the 41 restorations examined at five years, five had clinically evident marginal discoloration.

Chi-Square Distribution↗
PubMed2002

Reliability of different techniques to assess marginal defects of Class II restorations in retrieved primary molars: a visual-tactile, SEM, dye penetration and polarized light microscopy study.

The aims of the present article were to assess the reliability of different techniques to assess marginal defects in Class II restorations in retrieved primary molars, and to determine the degree of agreement between the various assessment modalities. The material evaluated was comprised of 18 exfoliated primary molars that had been restored 20 to 22 months previously with a resin-modified glass ionomer (Vitremer--7 teeth), a hybridized composite resin (Z100 + Scotchbond Multipurpose--9 teeth), and amalgam (Dispersalloy--2 teeth). No significant differences could be observed between the groups. The majority of the restorations rated A at the buccal and lingual margins, but poor adaptation was disclosed at the cervical margin of the three types of restorations. SEM evaluation revealed that the highest percentage of defects was seen at the cervical margins with no statistically significant difference between the groups. No or minimal leakage was present at the occlusal margins and severe penetration of dye was seen at the cervical margins in all groups. Significantly less demineralization was seen adjacent to the Vitremer and Z100 restorations when compared to the Dispersalloy but no difference was found between the esthetic restorations. Except for the visual tactile examination, small marginal defects could be disclosed by the three assessment techniques (SEM, dye penetration, and polarized light microscopy). A good degree of agreement was observed between the three evaluation techniques.

Child↗
PubMed2002

Three-year clinical evaluation of One-Step in non-carious cervical lesions.

PURPOSE: To clinically evaluate the 3-year performance of a one-bottle dentin adhesive in the restoration of non-carious cervical lesions (NCCLs) with resin composite. MATERIALS AND METHODS: 105 NCCLs were restored with either AElite Flow, Bisco Glaze (both flowable resin-based composites) or Silux (a microfilled resin-based composite), using One-Step dentin adhesive. The cavities were cleaned with pumice and water slurry, the dentin lightly roughened with a fine diamond bur, and the restorations placed according to the manufacturer's instructions. Patients were recalled at 6 months, 1 year, 2 years and 3 years, and restoration integrity and marginal discoloration assessed. RESULTS: The overall retention rates were: 6 months, 100%; 1 year, 95%; 2 years, 87%; 3 years, 75%. Marginal discoloration was negligible, and there was no significant difference among the materials, although there was a trend for it to be greater around the Bisco Glaze restorations.

Adult↗
PubMed2002

On dental erosion and associated factors.

The aim of this thesis was to explore aspects of dental erosion by investigating its prevalence among young Saudi men and young children, develop a system for its assessment and to evaluate various tentative background factors that may be associated with its occurrence. Saudi military inductees (n = 95) were subjected to questionnaire and clinical examination, including recordings of severity of dental erosion and a number of other oral health parameters. The system applied for grading the severity of dental erosion showed an intraexaminer agreement of 78%. Around one-fourth of the maxillary anterior tooth surfaces exhibited pronounced dental erosion and the average soft drink consumption was 247 liters/year. High level of soft drink consumption and long retention time of the drink in the mouth before swallowing, intensified oral hygiene, mouth breathing and low gingival bleeding index were found to have significant correlations with the presence of dental erosion. Furthermore, less plaque on maxillary palatal tooth surfaces, increased numbers of buccal cervical defects, first permanent molar "cuppings", missing teeth, and lower salivary urea content had significant correlations with the severity of dental erosion. High intake of acidic drinks and fruits, upper respiratory tract problems and frequent taking of medication were common findings in young Saudi children (n = 16) with severe dental erosion. The clinical diagnosis of erosion in deciduous teeth was confirmed by SEM. Enamel from various healthy teeth were subjected to microhardness measurements before and after in vitro exposure to citric acid. Deciduous enamel was found to be softer and relatively more prone to erosion than permanent enamel but the potential for erosion was about the same regardless of the origin of the teeth. Six methods of drinking a sugar-free cola-type drink were assessed in two groups of healthy volunteers. Intraoral pH was measured at specific locations and at predetermined time points using the microtouch method (n = 12), and continuously by using telemetric measurement (n = 6). Of the six methods tested, those in which the drink was in contact with the tooth surface for a prolonged period of time were found to strongly affect intraoral pH. It may be concluded from this thesis that dental erosion is common among young Saudi men and that erosion is associated with many etiological, aggravating and modifying factors. Consumption of soft drinks, amount of palatal plaque on maxillary anterior teeth and salivary urea concentration are some factors related to erosion. The presence of dental erosion in children is likely to be associated with a number of general health and dietary factors but is also aggravated by the relatively more rapid progression of erosion in the deciduous teeth. Drinking method seems to be an important factor in the risk of developing dental erosion.

Adult↗
PubMedDate not supplied

[Histopathological and therapeutical aspects of cervical lesions].

The term "cervical lesions" definies all the alterations consisting in a loss of hard dental tissues located along the cement-enamel junction, and may be more specifically defined as carious lesions (LCC) and non-carious lesions (NCCL). The non-carious cervical lesions are characterized by the loss of mineralised dental tissue in the absence of a carious process. This definition includes three different lesion categories: abrasion, erosion and the cervical lesions caused by stress (abfractions). In this paper the authors explain the histological, clinical, preventive findings of NCCL and try to give some guidelines to choose the appropriate material to restore different types of non carious cervical lesions.

Dental Caries↗
PubMed2002

Micro-shear bond strength of resin-bonding systems to cervical enamel.

PURPOSE: To evaluate the micro-shear bond strength of current adhesive systems to cervical and mid-coronal enamel. MATERIALS AND METHODS: Two commercially available resin adhesives were investigated; a self-etching primer system (Clearfil SE Bond) and a one-bottle adhesive system (Single Bond) intended for use with the total-etch wet-bonding technique were employed. Two regions of enamel, cervical and mid-coronal regions, were chosen from the buccal surface of extracted molars and were then bonded with each adhesive system and submitted to the micro-shear bond test. In addition, the conditioned enamel surfaces without any bond and the enamel-resin adhesive interfaces were studied morphologically using scanning electron microscopy (SEM). RESULTS: No significant differences were found between the adhesive systems used (P > 0.05). However, for both bonding systems, cervical enamel showed significantly lower bonding than mid-coronal enamel (P < 0.05). The relatively lower bond strengths obtained from cervical enamel probably resulted from its aprismatic structure, which appears to be more resistant to dissolving in acids than prismatic mid-coronal enamel.

Analysis of Variance↗
PubMedDate not supplied

Abfraction: 3D analysis by means of the finite element method.

OBJECTIVE: Tooth deflections under functional loads are considered to be the etiologic factor of noncarious cervical lesions. There are several studies on the materials used to restore these lesions; however, there are few discussing this phenomenon's etiology from a biomechanic point of view. This study was undertaken to evaluate tooth behavior when forces were applied from different directions. METHOD AND MATERIALS: A 3D finite element model of a maxillary central incisor was designed. A distributed force of 1.5 N was applied on the palatal side of the crown in five stages, with varying directions progressing from tipping to intrusion. Two separate approaches (displacement and stress) were considered to evaluate the cervical area from a stress perspective. RESULTS: The displacement approach resulted in a curved path when compared to a straight line connecting the apical and incisal areas. The maximum deflections were in the cementoenamel junction area. The same area was shown to undergo the maximum of von Mises stress and stress intensity. Patterns of the von Mises stress when evaluated in a mesiodistal direction were in complete agreement with the shape of the cervical lesions (except for the application of the intrusive force, which rules out its effect in producing such lesions). CONCLUSION: Force applications, except for intrusive force, can produce increases in the von Mises stress and tooth deflections that can answer the question of the etiology of noncarious cervical lesions. The highest amounts of deflection and von Mises stress were produced by the 45-degree force application.

Computer Simulation↗
PubMedDate not supplied

Two-year clinical performance of Class V resin-modified glass-lonomer and resin composite restorations.

While a one-year report had been previously published, this study was undertaken to evaluate the clinical performance and appearance of a resin-modified glass ionomer and a resin composite over two years. Thirty-seven pairs of restorations of FujI II LC and Z 250/Single Bond were placed in caries-free cervical erosion/abfraction lesions without tooth preparation. Restorations were clinically evaluated at baseline, 6, 12, 18 and 24 months using modified Ryge/USPHS criteria. No statistically significant difference (p = 0.13) was observed in the overall performance of the materials. Retention was 96% for the resin-modified glass ionomer and 81% for the resin composite, with no additional restorations of either material lost after one year. As previously reported, retention of the Z 250 restorations at six months was below the minimum specified in the ADA Acceptance Program for Dentin and Enamel Adhesives. The resin composite restorations generally had a better appearance, with a 100% alpha rating in color match, versus 85% for the resin-modified glass ionomer.

Adult↗
PubMedDate not supplied

Effect of resin viscosity and enamel beveling on the clinical performance of Class V composite restorations: three-year results.

This study evaluated the effect of the elastic modulus and margin configuration on the clinical performance of resin-based composite restorations in Class V non-carious defects. One hundred and five cervical non-carious defects on buccal surfaces of canines and premolars were included in this study. Defects were randomly divided into three Groups and restored according to the following techniques: Group 1--no enamel bevel was placed and the defect was restored with a microfilled resin-based composite (Durafill VS); Group 2--the enamel margin was beveled and the defect restored as in Group 1; Group 3-the enamel margin was beveled and the defect was restored with a flowable resin-based composite (Natural Flow). Each group comprised 35 lesions. A total-etch, one-bottle adhesive (One-Step) was used in all groups. Retention rate, pre- and post-operative sensitivity, marginal discoloration and secondary caries were determined over a three-year period and the data were analyzed statistically. At six months post-insertion, the restorations placed with beveled enamel margins resulted in 100% retention regardless of the composite used compared to a 66% retention of the non-beveled margins. At two and three years, no significant difference in retention rate was found among the three groups. Post-operative sensitivity, marginal discoloration and secondary caries were not affected by enamel beveling and restorative material. Beveled enamel margins resulted in significantly better clinical retention in the first six months only. Enamel beveling and composite viscosity appeared to not significantly affect the clinical performance of Class V non-retentive composite restorations after three years.

Adult↗