Quintessence International, 07/1990

Periodontal curettes are used extensively for root preparation in periodontal therapy. The traditional method of root scaling and planing is found in standard periodontics textbooks. A modification of the clinical usage of periodontal curettes that might he useful to clinicians in daily dental practice is described.

Five methods for the treatment of teeth with an incompletely formed apex (open apex) and a necrotic pulp are discussed. The methods discussed include the use of (1) a customized cone (blunt-end, rolled cone): (2) a short-fill technique: (3) periapical surgery (with or without a retrograde seal). (4) apexification (apical closure induction) , and (5) one-visit apexification. The apexification techniques, which use various formulations of calcium hydroxide to induce closure, are stressed. Based on the review of the literature and clinical experience of the authors, it was concluded hat successfull treatment of an immature puipless tooth can partly result from the antibacterial and calcificationinducing action of calcium hydroxide.

The heat generated at the apical 2 mm of the outer root surface of extracted human canine teeth during three obturation procedures was measured. The rise in temperature was found to be less when a sealer was used in all obturation techniques. Temperatures as high as 44.02 °C were recorded with warm gutta-percha with no sealer, and the lowest temperature rise occurred with a thermoplasticized gutta-percha technique with sealer. The thickness of the remaining dentin and cementum after cleaning and shaping were found to have no effect in reducing temperature rise. The results of this investigation indicated that temperature rise on the outer surface of the root as a result of heat-generating obturation procedures is negligible and will not have an effect on the supporting attachment apparatus.

A technique is presented for repair of fatigue-fractured fixed partial dentures with an overlaid, bonded porcelain/metal repair. The repair techniques utilize recent advances in resin-to-metal and resin-to-porcelain adhesion. Clinical procedures are given for adhesion of repair castings to intraoral porcelain or metal surfaces. Metal surface preparation techniques depend on the chemistry of the metal and include intraoral tin plating of noble metals. Direct adhesion of composite resin luting agents is used for base metals.

Dental twinning results from abnormal events in the embryologic development of teeth. This paper describes the impossibility of assigning precise diagnostic terms. such as gemination, fusion, macrodontia, and concrescence, to dental twinning anomalies because the entire course of odontogenesis cannot he witnessed. Traditional nomenclature is reviewed and seven cases that exemplify the principle are presented. Modification of nomenclature to describe dental twinning defects is suggested.

The effect of defined stresses on cantilevered prostheses attached to osseointegrated implants was assessed by finite element analysis. The effect of stress on a cantilever, consisting of a ductile alloy in contact with a brittle polymer, was demonstrated to be complex. The distribution of applied stresses also influenced the results. Possible fracture and distortion of both materials were demonstrated. Finite element analysis is a particularly useful system for predicting stress behavior and can be employed to produce an optimal prosthetic design that reduces the potential for clinical failure.

The technique for fabrication of complete dentures in two visits was described in part I. The purpose of the present study was to evaluate both the clinical methods used and patients' acceptance of tile resulting dentures. Eleven general practitioners were taught to use the technique and then asked to complete a questionnaire. Most practitioners had some difficulty with some aspects of tile technique. The consensus was that the two-visit denture technique would have some application in providing low-cost dentures, provided that the esthetic demands of the patient could he satisfied within the limitations of the technique. The second part of the evaluation was provided by patients, who were asked to indicate a preference between two sets of dentures, one made using a four-visit technique and the other using the two-visit technique. Preferences were divided, but all patients were able to wear both sets of dentures. The final responsibility for providing an adequate denture service remains with the practitioner.

Certain difficulties exist that make it hard to construct a complete set of dentures for the Class III edentulous patient. With the advent of osseointegrated implants, many of these difficulties can be overcome and patients can now look forward to stable and retentive prostheses that do not have to be removed. By careful assessment of the patient and meticulous attention to detail during the surgical and prosthodontic phases of treatment, predictable long-term results can be achieved.

Two groups of maxillary premolars with Class I cavities were prepared with one marginal ridge thickness to a width of 1.0 mm. One group was restored with amalgam and the other group with composite resin. Two groups of Class II cavities also were prepared and restored with amalgam and composite resin. The teeth in the four treatment groups were subjected to a centric load at the marginal ridge until fracture occurred. A two-factor analysis of variance revealed a statistically significant difference between the class of preparation (Class I preparations were weaker than were Class II preparations) but differences in strength between restorative materials (composite resin versus amalgam) and the interaction effect (class of preparation x restorative materials) were not found to be statistically significant (α = .05). A Newman-Keuls sequential range test found no statistically significant differences in strength between groups (α = .05). Fracture patterns were observed under scanning electron microscope. Fractures extended into the enamel and into the material in the Class 1 composite resin, Class I amalgam, and Class II composite resin restorations. Fractures extended only into the material in Class II amalgam restorations.

To determine the fluoride uptake in enamel and dentin, a fluoridating composite resin was fixed at a 100-µn distance from bovine enamel and dentin for 2 weeks. The results revealed a substantial increase in the level of fluoride in both enamel and dentin. This model investigation showed that the fluoride released by the composite resin was effectively taken up by the surrounding tissues. The fluoride released from the composite resin and the subsequent uptake by the tissues would be expected to protect against secondary caries.

This study was designed to assess the feasibility and practicability of the employment of endoscopic methods for the diagnosis of dental caries and to compare the diagnostic performance, in posterior teeth, of visual endoscopic caries diagnosis (with and without the benefit of differential fluorescence) with that of conventional visual diagnosis, bitewing radiographi, and conventional transillumination. The two endoscopic methods were found to be clinically practicable, to be able to demonstrate the presence of small carious lesions, and to have both advantages and disadvantages compared to conventional methods. When all tooth sites were compared, the results indicated that the endoscopic methods may detect a greater number of carious lesions than do conventional visual, radiographic, or fiber-optic transilluminational methods of caries diagnosis. Further investigations involving histologic validation of diagnoses as well as larger numbers of patients and multiple examiners are indicated.

en dentists were sudied to determine the effects of work posture on their muscles and circulatory system. Each dentist prepared four teeth in two different work postures, while being measured for systolic and diastolic arterial pressure, heart rate, and muscular electrical activity. Results indicated that muscular and circulatory stress was reduced when the dentists worked at the 12-o 'clock position with the mannikin positioned horizontally in front of them.