In vitro comparison of peak polymerization temperatures of 5 provisional restoration resins.
BACKGROUND: The heat produced by provisional restoration materials may injure the dental pulp. This study measured and compared peak temperatures during polymerization of 5 materials used in the fabrication of provisional restorations. METHODS: The tested materials were 2 self-curing resins (Integrity and Protemp) and 3 dual-cure resins (Iso-Temp, TCB Dual Cure and Provipont DC). A mould the size of a maxillary molar tooth was fabricated to contain 0.5 cc of resin. The temperature rise of the different materials was recorded every 10 seconds over a 10-minute period. RESULTS: The rise in temperature of Integrity (peak temperature of 33.8 degrees C) and Protemp Garant (35.6 degrees C) was significantly higher than the rise in temperature of Iso-Temp (29.5 degrees C), TCB Dual Cure (28.4 degrees C) and Provipont DC (29.5 degrees C). CONCLUSION: Use of the dual-cure resins in provisional restorations may reduce the risk of pulp injury. (+info)
The use of resin cements in restorative dentistry to overcome retention problems.
The use of resin cements in combination with dentin bonding agents can result in superior attachment of prostheses to tooth structure. This paper describes four clinical cases in which dentin-bonded resin cements were used to overcome retention problems. In the first case, a detached fixed partial denture, which was in good condition when separated, was recemented to abutment teeth prepared with less-than-ideal angle of convergence. In the second case, a detached all-porcelain crown was recemented with a dentin-bonded resin cement after appropriate surface treatment. In the third case, a porcelain-fused-to-metal crown made for a molar tooth was cemented to a short clinical crown, avoiding crown-lengthening surgery. In the fourth case, a 3-unit fixed partial denture was recemented to abutments with less-than-ideal supporting features. Dentin-bonded resin cements can help to extend the life of detached prostheses until the patient is financially prepared for replacement or it can help to avoid crown-lengthening surgery. (+info)
The use of real time video magnification for the pre-clinical teaching of crown preparations.
OBJECTIVE: To investigate the effect on the undergraduate learning process of using an alternative method designed to enhance the visual demonstration of taper on full veneer crown preparations (better understanding of the value of taper on preparations early in the teaching programme in restorative dentistry). DESIGN: A comparison between the conventional teaching of full veneer crown preparations and the same teaching with the additional use of a magnified real time video display using a surgical microscope was investigated in this study. OUTCOME MEASURES: The degree of taper was measured for replica full crown preparations and results compared between different cohorts of undergraduates and experimental conditions. RESULT: Undergraduates taught using the real time video produced more accurately tapered preparations. This ability was retained over one year. CONCLUSIONS: A possible explanation for the result was that the use of magnification improved the undergraduates' precise understanding of taper by enhancing their ability to evaluate this critical measurement during the teaching process. (+info)
An unusual case of talon cusp on geminated tooth.
A rare case of talon cusp on geminated permanent central incisor is described. These developmental anomalies cause clinical problems including unsightly dental appearance, occlusal interference, displacement of the affected tooth, attrition, periodontopathy, irritation of the tongue, loss of space and malocclusion. Clinical and radiographic characteristics of these anomalies and modes of treatment are presented. Recognition of this condition and early diagnosis are important to avoid complications. (+info)
Adverse reactions triggered by dental local anesthetics: a clinical survey.
One hundred and seventy-nine patients completed a questionnaire focusing on adverse reactions to dental local anesthetics as manifested by 16 signs and symptoms. Twenty-six percent of the participants reported having at least 1 adverse reaction. It was found that most of the adverse reactions occurred within the first 2 hours following the injection of local anesthetics. Pallor, palpitations, diaphoresis, and dizziness were the most common adverse reactions reported in the study. The results pointed to a significant relationship between anxiety, gender, injection technique, and procedure with a higher incidence of adverse reactions. (+info)
Casting accuracy of experimental Ti-Cu alloys.
The purpose of the present study was to investigate the casting accuracy and the dimensional change of experimental titanium-copper alloys (3.0 and 5.0 mass% Cu; hereafter, only "%" will be used) and to compare the findings with those of pure titanium. Castings were made using an argon-arc melting/pressure difference-casting unit. The fit of the metals cast in both full crown and MOD inlay dies was evaluated by measuring the distance between the shoulder margin and the cervical shoulder of the die. The changes in the inner diameter of castings were determined. In addition, surface roughness measurements inside the castings were carried out using a conventional profilometer, and thermal expansion measurements were made on cast cylindrical specimens using a differential dilatometer. There were no significant differences in dimensional change between pure titanium and the titanium-copper alloys. The fit of the titanium-copper alloys was inferior to pure titanium. The results of surface roughness measurements showed significance differences between the roughness of the pure titanium and titanium-copper alloys. (+info)
Integrating posterior crowns with partial dentures.
This article outlines those considerations which are important in integrating posterior crowns with partial dentures. Planning the support and retention of the denture prior to crown construction will enhance patient treatment. Modification of the crown preparation to incorporate rest seats, retentive areas, guide planes and a planned path of insertion may be necessary. (+info)
The shear bond strength of composite brackets on porcelain teeth.
Recent advances in materials and techniques suggest that direct bonding of orthodontic attachments to surfaces other than enamel may now be possible. To test the effectiveness of bonding orthodontic attachments to porcelain teeth, composite brackets (Spirit MB) were bonded to 64 porcelain teeth by means of a self-cure non-mixed resin system (Unite). The 64 porcelain teeth were divided into groups of eight and after roughening with a green stone they were subjected to a combination of treatments. Some were etched, some primed with a silane coupling agent and some received both treatments before the brackets were bonded to them. Half of the teeth were then thermally-cycled 500 times between 4 and 60 degrees C before all the brackets were removed in a shear test. The shear data was analysed by one way analysis of variance and the Student-Newman-Keul test. The results showed that the highest bond strength existed in the group which had been both etched and primed but not thermocycled (P < 0.05). The factors that affected the bond strength, beginning with the most significant, were acid etching, primer application, and then thermocycling. A mechanical based composite bracket can offer good bond strength to porcelain teeth. (+info)