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Marginal fidelity of crowns fabricated from six proprietary provisional materials.

STATEMENT OF PROBLEM: The most important requirement for an interim crown is suitable marginal adaptation. PURPOSE: This in vitro study compared vertical discrepancies of margins for complete crowns made with six provisional materials (Provipont, Protemp Garant, Unifast LC, Triad VLC, Splintline, and Jet). MATERIAL AND METHODS: A direct technique was used to fabricate 60 provisional complete crowns on prepared molars with a polyvinyl siloxane impression and a vacuum-formed polypropylene sheet as matrices. A measuring microscope was used to measure vertical marginal discrepancies at x 100. Data were analyzed with Kruskal-Wallis one-way analysis of variance and Mann-Whitney U tests (alpha = 0.05). RESULTS: Significant differences were found between resinous materials tested (p = 0.0002) and multiple comparisons tests indicated no significant difference between Splintline and Protemp Garant; Provipont, Unifast LC, and Triad VLC; and Unifast LC, Triad and Jet provisional materials. CONCLUSIONS: This study indicated that provisional crowns fabricated with Splintline and Protemp Garant interim restorative materials recorded the least marginal discrepancies.

Acrylic Resins↗

Hypersensitivity to methyl methacrylate: mode of treatment.

This article describes the treatment of a patient who experienced a delayed hypersensitivity reaction associated with acrylic resin. Patch testing revealed an allergy to methyl methacrylate monomer. Patients with a known or suspected allergy of this type should be treated by alternative methods. Dental procedures in which negligible contact of the oral mucosa with methyl methacrylate are presented.

Acrylic Resins↗

Effect of water temperature on the fit of provisional crown margins during polymerization.

STATEMENT OF PROBLEM: When fabricating a provisional crown with the direct technique, dentists are concerned with margin discrepancies that result from polymerization shrinkage. PURPOSE: This in vitro study examined the effect of water temperature on the fit of provisional crown margins during resin polymerization. MATERIAL AND METHODS: The experiment was designed to simulate a direct technique to fabricate provisional crowns. After mixing autopolymerizing methyl methacrylate resin, the material was placed in a preformed polycarbonate crown. The crown was seated on a prepared premolar-shaped die with a shoulder margin. After 1 minute and 50 seconds, the crown was removed and polymerization was continued under the following conditions: 20 degrees C air, and water at 0 degrees C, 10 degrees C, 20 degrees C, 30 degrees C, 40 degrees C, 60 degrees C, and 80 degrees C. Six minutes after polymerization, the crown was trimmed and reseated on the die. Discrepancy of crown margin was measured with a 3-dimensional digitizer. RESULTS: Margin discrepancy varied with the condition during resin-polymerization (ANOVA, P <.001). The crowns polymerized in 20 degrees C and 30 degrees C water revealed the best margin fit, showing 3 times more accurate margin fit than those polymerized in 20 degrees C air (Bonferroni/Dunn procedure, P <.01). CONCLUSION: Conditions during resin polymerization were significant factors that affected margin fit of provisional crowns using the direct technique. Water temperatures of 20 degrees C and 30 degrees C produced the best fit at the margin of the provisional crown.

Analysis of Variance↗

A safe technique for removal of provisionally cemented crowns.

A technique is presented for removing full-cast crowns and porcelain crowns that have been temporarily or provisionally cemented. A rubber dam retainer clamp with rubber dam attached is placed on the crown and clamped near its margins. Steiglitz forceps are used to apply pressure and leverage. The assembled unit is removed with the Steiglitz and safely removes the loosened crown from the mouth.

Crowns↗

Microleakage of intermediate restorative materials.

This study compares the microleakage of a glass ionomer cement, Ketac Fil, used without cavity conditioning, with the established intermediate restorative materials, Cavit-W, and a reinforced zinc oxide-eugenol cement, Kalzinol. Microleakage was assessed using an electrochemical technique. At the end of 30 days, the materials tested, listed in decreasing order of microleakage, were Cavit-W, Ketac Fil inserted without cavity conditioning, Kalzinol, and the control group of Ketac Fil inserted into conditioned cavities. There was no significant difference in the microleakage observed in Ketac Fil restorations inserted without cavity conditioning and Kalzinol (p = 0.450), while the differences between the other groups were highly significant (p less than 0.001).

Calcium Sulfate↗

Solving endodontic isolation problems with interim buildups of reinforced glass ionomer cement.

A technique is presented for the expedient placement of interim buildups of type II glass ionomer cement as an aid for endodontic isolation of broken down teeth. The bond strength of glass ionomer cement to tooth structure is sufficient to withstand the forces of endodontic manipulation without the need for reinforcing pins. The material also shows promise as an intermediate endodontic seal. Variations of this technique are presented to address some other common isolation problems and the esthetic needs of the patient.

Cermet Cements↗

Effects of calcium hydroxide paste as an intracanal medicament on apical seal.

Seventy-six extracted human permanent canines and premolars with single canals were used in this study. The crowns were removed, the canals were instrumented, and the roots were randomly divided into four groups of 18 each. Three groups were medicated with Ca(OH)2 USP, Calasept, and Vitapex, respectively, while the control group was not medicated. The roots were incubated in 100% relative humidity at 37 degrees C for 1 wk, after which the medicaments were removed and the canals were enlarged to the next file size. One tooth in each group was examined in the scanning electron microscope while the remaining roots were filled with gutta-percha using a lateral condensation technique. The roots were placed in 2% methylene blue solution for 2 wk and both linear and volumetric dye penetration evaluated. A highly significant correlation between linear and volumetric leakage was observed. The leakage among the experimental groups was not significantly different, but was significantly less than in the control group.

Bicuspid↗

Reactive oxygen species generation and photo-cytotoxicity of eugenol in solutions of various pH.

In order to clarify the mechanism of photo-damage caused by eugenol (4-allyl-2-methoxyphenol), we measured cell survival in the presence of eugenol at concentrations of 10(-3) - 10(-7) M, with and without VL (visible light) irradiation by a VL dental lamp and at various pHs (7.2, 7.8 and 8.2) using two different cells (HSG, a human submandibular gland tumor cell line; HGF, a human gingival fibroblast in primary culture). Also, ROS (reactive oxygen species) generation in the above adherent single cells was measured by ACAS laser cytometry combined with CDFH-DA, a peroxide probe. The survival of both HSG and HGF cells treated with eugenol was significantly decreased as the VL irradiation time and/or the pH of the medium was increased. The amount of ROS generated from eugenol was also enhanced by increasing the VL irradiation time and elevating the pH of the medium. Cytotoxicity and ROS generation of HGF cells were significantly lower than that of HSG cells. Glutathione (1 mM) or cysteine (1 mM) protected the photo damages. We conclude that the cytotoxicity of VL-irradiated eugenol possibly was caused by the generation of eugenol radicals and additionally by ROS, both of which were produced dependent on the dose of eugenol, length of irradiation time, and pH of the medium.

Carcinoma, Squamous Cell↗

Comparison of antibacterial activity of two dentin bonding systems using agar well technique and tooth cavity model.

OBJECTIVE: This study compared the antibacterial activities of two dentin bonding systems (ABF, Kuraray and Reactmer Bond, Shofu) by a conventional agar well technique and a newly designed in vitro test using tooth model. METHODS: In the agar well technique, the test materials were filled in the wells of Muller Hinton agar plates inoculated with Streptococcus mutans NCTC10449, and the diameters of inhibition zones produced around the materials were measured after 24h of incubation. For the tooth model test, three cavities (diameter 1mm, depth 2mm) were prepared in the flat occlusal dentin of human extracted molar. After sterilization, the teeth were left in broth culture of 1.56 x 10(8)CFU/ml of S. mutans at 37 degrees C for 72h for allowing bacteria to invade the cavity. The dentin bonding systems were applied separately to each of the two infected cavities, and the third cavity was left unapplied for control. After sealing the occlusal surfaces, the teeth were kept in physiologic saline solution at 37 degrees C for 72h. The standardized amounts of dentin chips (120+/-5mg) were obtained from the cavity walls and the number of bacteria recovered was determined. The results were analyzed by One Way ANOVA, Kruskal Wallis and Mann-Whitney's U tests. RESULTS: The primer of ABF and Reactmer Bond produced inhibition zones with similar sizes (p>0.05), but the bonding resin of ABF did not produce any inhibition. When tested by the model cavity method, the application of ABF resulted in significantly less bacterial recovery than Reactmer Bond (p<0.05), demonstrating substantial antibacterial effects. CONCLUSIONS: The tooth model method used in this study was effective for evaluating the substantial antibacterial effects of dentin bonding agents, and the experimental dentin bonding system ABF was demonstrated to be able to inactivate the bacteria in the cavity effectively in comparison with little antibacterial activity shown by Reactmer Bond.

Agar↗

Immediate loading of single-tooth implants in the anterior maxilla. Preliminary results after one year.

According to the standard protocol, a load-free healing period is one of the most emphasized requirements for implant integration. Recent studies have encouraged a progressive shortening of the healing period for single-tooth implants and immediate loading has been proposed for the aesthetic zone in the maxilla. The present study evaluated clinical outcomes of immediately loaded FRIALIT-2 Synchro implants 12 months after placement in the maxillary incisal region. In the course of our investigation, nine patients have been treated following an immediate loading protocol. The stepped-screw type implants were inserted with an increasing torque up to 45 Ncm, thus measuring the primary stability of the implants. All implants were immediately restored with unsplinted acrylic resin provisional crowns and the patients provided with occlusal splints. Regular controls were performed at monthly intervals, intraoral radiographs were taken directly after implant placement, 6 and 12 months post insertion. The survival rate, clinical stability (Periotest) and radiographic coronal bone defects (CBD) were evaluated at delivery of the definitive superstructures (CBD 6) and 6 months later (CBD 12). Twelve FRIALIT-2 Synchro stepped screws of 3.8, 4.5 and 5.5 mm diameter and 13 and 15 mm length were placed in the incisal maxillary region. The median Periotest value 6 months post insertion was -2 with a minimum of -5 and a maximum of +2. The mean coronal bone level changes (CBD) at 6 and 12 months were 0.45 and 0.75 mm. No implant failed up to 12 months after insertion, resulting in a 100% survival rate. The presented results showed promising data for immediately loaded single-tooth implants in the anterior maxilla. Periotest values were within the range published for submerged implants. The radiographic coronal bone resorption after 6 and 12 months was even less than evaluated for implants placed in a standard two-stage procedure. It is evident that successful immediate loading protocols require a careful and strict patient selection aimed at achieving the best primary stability and avoiding any excessive functional or non-functional loading. Additional research needs to be done to provide data in situations where problems of poor bone quality, multiple implants or augmentation procedures must be overcome.

Acrylic Resins↗

Influence of polymerization conditions on monomer elution and microhardness of autopolymerized polymethyl methacrylate resin.

Residual monomer contents and surface hardness are important factors in determining the serviceability of provisional restorations. The intent of this study was to systemically evaluate the effects of curing conditions on provisional polymethyl methacrylate (PMMA) resins which utilize a free-radical polymerization reaction. Combinations of the three curing factors of temperature, pressure, curing environment (water/air) were adjusted during the fabrication of autopolymerized specimen disks. The initial hardness of tested materials was measured with a microhardness tester 1 h after disc fabrication, and the amounts of residual methyl methacrylate (MMA) released into water were analyzed by reverse-phase HPLC after 7 d of water immersion. Results from multiple regressions showed that curing temperature was the dominant factor in improving resin surface hardness, whereas curing in water was the key factor for reducing the quantity of residual monomer. The pressure factor, which was thought to be critical for managing autopolymerized resins, showed no significant influences on the properties tested. ANOVA results showed that provisional PMMA resins cured in hot water, with or without pressure, significantly reduced the amount of residual MMA elution (up to 80%) and increased the microhardness values (up to 50%).

Acrylic Resins↗

Socio-economic correlates of traumatic injuries to the permanent incisors in schoolchildren aged 12 years in Blumenau, Brazil.

This study aimed to assess the prevalence of injuries to the permanent incisors in Blumenau, Brazil. In addition, the relationship between dental injuries and socio-economic indicators was examined. A cross-sectional survey was carried out. It included a random sample of 652 children aged 12 years, from both sexes, attending public and private primary schools in Blumenau, Brazil. Multi-stage sampling technique and proportional representation were adopted. A trained and calibrated dentist collected the data through clinical examinations and interviews. Clinical examination included type of damage, treatment provided and needed, size of incisal overjet and type of lip coverage. The response rate was 82.5%. The prevalence of dental injuries was 58.6%. Boys experienced more injuries than girls, 67.2% and 50.2% (P=0.001), respectively. Children from mothers with higher schooling experienced more dental injuries than those from of mothers with lower schooling, 68.2% and 56.6% (P=0.03). Father's level of education, parents' employment status and family income were not statistically significantly associated with dental injuries (P>0.05). There was a tendency for children with incisal overjet greater than 5 mm (P=0.2) and inadequate lip coverage (P=0.1) to have more dental injuries, but differences were not statistically significant. Nearly all (97.3%) children who had dental injuries needed treatment. In conclusion, the prevalence of dental injuries in Blumenau, Brazil, was very high, treatment of dental injuries was severely neglected, and boys and children from mothers with high schooling were more likely to have experienced dental injuries.

Brazil↗

An interdisciplinary approach to treatment planning in implant dentistry.

The practice of implant dentistry requires an interdisciplinary approach that integrates the knowledge, skills and experience of all the disciplines of dentistry into a comprehensive treatment plan. This article outlines a comprehensive interdisciplinary treatment philosophy designed for developing the foundation of optimal aesthetics in implant dentistry. Cases are presented to illustrate the utility of interdisciplinary treatment in which specialists are recruited to enhance and improve a patient's dental function and aesthetics.

Adult↗