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At least 811 records · Page 45Linked to original sources
PubMed2003

Color measurements as quality criteria for clinical shade matching of porcelain crowns.

STATEMENT OF PROBLEM: The ability of a dentist to select and communicate an acceptable shade match to a dental laboratory may be the most important factor in esthetic restorative dentistry. PURPOSE: The purpose of this study was to evaluate the use of instrumental color measurement in clinical shade matching of porcelain-fused-to-metal (PFM) and all-porcelain crowns. The relative effects of clinical and laboratory factors related to shade matching for PFM and all-porcelain crowns were also evaluated. MATERIALS AND METHOD: Forty patients treatment planned to receive PFM or all-porcelain crowns made up the study population. The patients were randomly divided into two groups for shade selection: conventional visual assessment and photocolorimetric analysis. At the preparation appointment, a photograph was taken of the target tooth along with four shade guide tabs selected by the two visual observers. The crown was fabricated by either visual selection or by the lowest E* values determined from the photographs and a spectrophotometer. The same dental laboratory fabricated all 40 restorations. At the cementation appointment, clinical criteria were used to evaluate anatomy/contour, surface texture, and the amount of glaze as it relates to color perception before the restoration was cemented. RESULTS: The mean E* between the reference tooth before preparation and the crown before cementation in the visual assessment group was 10.49 (+/- 14.6), whereas the mean E* in the photocolorimetric group was 8.99 (+/- 5.7). Analysis of data showed that the observers and the colorimetric technique were perfect (E* = 0) 41% of the time and varied (E* = 0.1 or higher) 59% of the time. Data collected further showed no significant difference or correlation between shade selection methods and the evaluated clinical criteria. CONCLUSIONS: These results provide evidence that there is no significant difference in shade selection using the conventional visual assessment by two experienced clinicians or the photocolorimetric technique. CLINICAL SIGNIFICANCE: The use of photocolorimetric analysis in shade selection can serve as a reliable alternative to conventional visual shade selection. This method is useful for clinicians who have difficulty with shade selection.

Color↗
PubMed1998

Criteria for the predictably restorable endodontically treated tooth.

This paper outlines criteria which allow the clinician to identify endodontically treated teeth that can be restored with a high level of predictability. The intent of the article is not to preclude the restoration of teeth that do not meet these criteria; it is to provide a science-based approach for identifying those teeth with a high probability of long-term success upon restoration. For an endodontically treated tooth not requiring a post, the requirements are for biologic width + ferrule length, (i.e. 4.5 mm of supra-bony solid tooth--dentin a minimum of 1 mm thick after preparation). A tooth requiring a post needs, in addition, enough root length to allow a 4 mm apical seal and a post length--apical to the crown margin, equal to the length of the crown. It is essential to assess the functional loads to which the restored tooth would be subjected. Teeth that are endodontically treated, or are likely to be in future, should be avoided as abutments supporting precision attachment RPDs, distal extension RPDs or cantilever FPDs.

Crowns↗
PubMed2001

The influence of preparation technique and sodium hypochlorite on removal of pulp and predentine from root canals of posterior teeth.

AIM: To test the null hypothesis that removal of pulp tissue and predentine from root canals of multirooted teeth is not significantly different when performed by one of two mechanical preparation techniques in conjunction with either water or 3% sodium hypochlorite (NaOCl) irrigation. METHODOLOGY: Forty-six freshly extracted premolar or molar teeth, with pulps vital at the time of extraction, were assigned to four groups balanced by anatomy (group 1, step-back filing/NaOCl; group 2, step-back filing/water; group 3, automated rotary/NaOCl; group 4, automated rotary/water). Preparation was undertaken by a single operator and the volumes of irrigant recorded for each tooth. One root from each tooth was prepared for transverse histological assessment at eight levels, including one at and two apical to the working length. A validated index was used to measure the presence and location of residual pulp tissue and predentine. RESULTS: No statistically significant differences were found in the frequency with which residual pulp tissue or predentine were observed amongst the groups. Coronal parts were more frequently devoid of pulp tissue and predentine than the apical. Canals were frequently occluded with residual pulp tissue apical to the working length. There was a trend for better pulp and predentine removal in accessible parts of the canal as a function of rotary preparation and NaOCl irrigation. The isthmus had residual pulp tissue less frequently in the NaOCl groups. Accessory anatomy was unaffected regardless of technique or irrigant. CONCLUSIONS: Pulp tissue and predentine removal were not significantly different between a step-back filing and an automated rotary preparation technique in conjunction with water or NaOCl.

Bicuspid↗
PubMed1995

Fixed bonded prosthodontics: a 10-year follow-up report. Part I: Analytical overview.

Developments in biomaterials in the field of adhesion have made possible a less invasive dentistry. Improvements in adhesive polymers along with the analysis of certain failures in resin-bonded prostheses have suggested the micropreparation of abutment teeth. A long-term study of resin-bonded prostheses and splints was undertaken. The success rate of this protocol is presented for a study period of 10 years (1984 to 1993). These results indicated that the resin-bonded prosthesis is a viable option in patients who are missing one or two teeth. Of 145 prostheses, 11 failed, resulting in an overall survival rate of 83% (Kaplan-Meier test). Furthermore, the study confirmed that, for splints, preparation is important to counter the major stresses related to tooth mobility in patients with periodontal disease.

Dental Stress Analysis↗
PubMed1992

Modulation by peripheral conditioning stimuli of the responses of trigeminal brain stem neurones and of the jaw opening reflex to tooth pulp stimulation in chronically prepared, anaesthetized cats.

The effects of peripheral conditioning stimuli on the thresholds of the jaw opening reflex (JOR) and of trigeminal brain stem neurones to tooth pulp stimulation were examined in chronically prepared, anaesthetized cats. High intensity electrical conditioning stimuli applied to the ipsilateral forepaw produced an increase in the thresholds of both responses, with the JOR thresholds being elevated significantly more, and remaining elevated for significantly longer, than those of the neurones. These findings suggest that the elevation of the JOR cannot be explained just by inhibitory effects on the brain stem neurones.

Animals↗
PubMed2001

The emotional effects of tooth loss in partially dentate people attending prosthodontic clinics in dental schools in England, Scotland and Hong Kong: a preliminary investigation.

AIM: To compare the emotional effects of tooth loss in three partially dentate populations. DESIGN: A questionnaire survey. MATERIALS AND METHODS: A questionnaire was completed by 150 partially dentate subjects undergoing routine prosthodontic care at Guy's, King's and St Thomas's Dental Institute, London; the Dental School, Dundee, Scotland; and the Faculty of Dentistry, University of Hong Kong. Data were analysed using the Chi-square test. RESULTS: Forty nine per cent of all participants reported difficulties in accepting the loss of some of their teeth. People from Dundee were less likely to have difficulties accepting tooth loss (P = 0.001). People from London took longer to come to terms with their tooth loss and were more likely to feel less confident (P < 0.001). Fifty five per cent of all participants restricted their choice of foods and 54 per cent had not enjoyed their food as much as before. Fewer people in Dundee restricted their choice of food (P < 0.001) and were more likely to enjoy their food (P = 0.009). People in Hong Kong were most likely to restrict their choice of food (P = 0.006). Thirty five percent of all subjects felt unprepared for the effects that tooth loss had upon them. People in Hong Kong were more prepared for tooth loss than those in Dundee and London (P = 0.003). In addition, they were less concerned about leaving their dentures out overnight (P = 0.024). CONCLUSIONS: The emotional effects of tooth loss were significant in all groups. People from London took longer to come to terms with their tooth loss.

Attitude to Health↗
PubMed2003

Possible role of immunocompetent cells and the expression of heat shock protein-25 in the process of pulpal regeneration after tooth injury in rat molars.

Recent studies have established that heat shock proteins (HSPs) potentially play a role in immunosurveillance. The purpose of the present study was to clarify the relationship between the chronological changes of immunocompetent cells and the expression of HSP-25 in the process of pulpal regeneration after tooth injury in rat molars by immunocytochemistry for HSP-25 and class II major histocompatibility complex (MHC) antigen. In untreated control teeth, intense HSP-25 immunoreactivity was found in the cell bodies of odontoblasts. Both cavity preparation and tooth replantation caused the degeneration of the odontoblast layer to result in the loss of HSP-25 immunoreactions in the suffered dental pulp at the early stages after tooth injury. Numerous class II MHC-positive cells appeared along the pulp-dentin border and extended their cell processes into the dentinal tubules at 12-24 h after cavity preparation and 3 days after tooth replantation. Newly differentiated odontoblast-like cells with HSP-25 immunoreactivity were arranged at the pulp-dentin border and the class II MHC-positive cells retreated towards the subodontoblastic layer by post-operative days 3-5 after tooth injury. Thus, the common cellular events occur during pulpal regeneration following two different experimental injuries. These findings indicate that the time course of changes in the expression of HSP-25 immunoreactivity reflects the degeneration/regeneration process of odontoblasts and that the temporal appearance of the class II MHC-positive cells at the pulp-dentin border suggests their participation in odontoblast differentiation as well as in initial defence reactions during the pulpal regeneration process.

Animals↗
PubMedDate not supplied

Auxiliary retention and the role of the core in fixed prosthodontics.

Extensively damaged teeth frequently require placement of a core before preparation to receive an indirect restoration. Dentine pins have traditionally been used to enhance retention and resistance form when coronal dentine is significantly reduced; however, pins are invasive and may produce pulpal or periodontal problems. Cavity design features such as grooves, boxes or retentive pits may be better alternatives. The choice of the core material may also influence the outcome although reliable research data are scarce. Large cores should be considered to have a structural role in supporting the final restoration.

Adhesives↗