Repair or Observation of Resin Margin Defects: Clinical Trial After Five Years.

OBJECTIVE: To assess the effectiveness of repair/resealing of stained composite margins as an alternative to controlled observation without treatment in a randomized clinical trial after five years. METHODS AND MATERIALS: Each patient recruited had from one to three composite restorations with visible margin discoloration. Initially, the characteristics of each defect were recorded with direct vision through a surgical microscope at 20× magnification. Clinical evaluation was done by two independent examiners using modified USPHS criteria for color, margin discoloration, and margin adaptation. Each restoration was then randomly assigned to a control or treatment group. Control restorations were observed yearly for the presence of recurrent caries; treatment restorations were resealed by exposing the margin with a » round bur, removing all interfacial stain, acid etching, placing an adhesive bonding agent, and a flowable composite to restore margin integrity. There were 152 patients recruited, with 360 restorations (180 control and 180 treatment). RESULTS: At five years, 104 patients were recalled (68%) with 271 restorations (76%): 136 untreated control and 135 resealed restorations. At that time, 61 restorations had been lost or replaced for nonrelated reasons. Clinical evaluation of the remaining 210 restorations determined penetrating discoloration (control = 81%, resealed = 46%) and margin crevice formation (control = 21%, resealed = 11%). Recurrent caries was diagnosed cumulatively in only six control and five treatment restorations (<5%). Microscopically, 49 control restorations (49%) and 36 resealed restorations (33%) had crevice formation. Discoloration was distributed as follows: 9% vs 47% with no discoloration, 30% vs 33% in the composite, 49% vs 18% in the interface, and 12% vs 2% in tooth structure. CONCLUSIONS: Resealing of restorations with margin discoloration reduced the occurrence of penetrating stain from 81% in controls to 46% in resealed margins and crevicing from 21% to 11% after five years. Both controlled observation and resealing of margins resulted in a similar very low incidence (<6%) of recurrent caries.

Grand rounds for dental students: an exploration.

Grand Rounds are widely used in medicine for educating students comprehensively about clinical issues. The aim of this study was to explore the value of Grand Rounds for introducing first- (D1) and second-year (D2) dental students to an interdisciplinary approach to dental care. The objectives were to explore how interested students were in various topics, which topics they would like to see addressed in future sessions, which aspects they liked/disliked, how they evaluated the program components, and how they evaluated the outcomes. Data were collected from D1s at the end of the Year 1 fall term and from D1s and D2s at the beginning and end of the Year 1 winter term and at the end of Year 2. Response rates for most of the groups ranged from 88% to 100%, but response rates for surveys at the end of the study period fell to 40% and 32%. The results showed that the students were most interested in clinical topics that were presented in an interdisciplinary way. Their suggested topics ranged from specialty-specific issues to treatment-related topics such as implants and cosmetic dentistry. The open-ended responses showed that students liked learning differing perspectives on these topics, but disliked the course-related assignments and the preparation work in small groups. The closed-ended responses showed that the students appreciated the in-class presentations by experts and evaluated the course as helpful in informing them about the complexity of issues and the importance of the interplay between basic and clinical sciences. Educating future dentists in a way in which they embrace interdisciplinary approaches is challenging. Using the Grand Rounds concept could be one approach to increasing students' awareness of the importance of interdisciplinary work.

Accuracy of CAD/CAM crown fit with infrared and LED cameras.

PURPOSE: The intraoral recording of digital images is a critical component of fabricating accurate Cerec restorations. This study evaluated the marginal fit and internal adaptation of Cerec ceramic crowns fabricated using different cameras, alternative powdering materials, and multiple image capture sequences. MATERIALS AND METHODS: A master epoxy resin model was fabricated using a polyvinylsiloxane (PVS) impression of a typodont with an all-ceramic crown preparation on tooth 14. A titanium dioxide powder/mechanical sprayer and an aerosol contrast spray were used to create a uniformly reflective surface. An infrared laser Cerec 3/RedCam unit and LED Cerec AC/BlueCam unit were used to record images for crown fabrication. Three different image capture sequences were performed to record the data. Crowns were made for each test group using a Cerec AC unit with V3.80 software. The crowns were milled from blocks of IPS EmpressCAD. Marginal fit and internal adaptation of the crowns to the master model of the preparation was assessed with a measuring microscope at 20X. The data was analyzed using a two-way ANOVA. RESULTS: No significant differences were found in the marginal fit, axial wall adaptation, or occlusal wall adaptation between any of the test groups (p < 0.05). CONCLUSION: Within the confines of this in vitro study, there were no significant differences between the marginal fit and internal adaptation of Cerec CAD/CAM ceramic crowns fabricated with: 1) the infrared laser camera (RedCam) and the LED camera (BlueCam), 2) titanium dioxide powder or aerosol contrast spray, or 3) multiple imaging sequences for recording the preparation and adjacent teeth.

Marginal ridge strength in Class II tunnel restorations.

This in vitro study evaluated the compressive fracture resistance of marginal ridges of teeth with Class II tunnel preparations. Tunnel preparations were completed in extracted human bicuspid and molar teeth (bicuspids, bur size: #2, #4, #6; molars, bur size: #4, #6, #8). Control teeth in both the molar and bicuspid groups remained unprepared. Half the preparations in each group were restored with a glass ionomer cermet. After thermocycling, each marginal ridge was loaded in compression in an Instron Universal testing machine. Fracture values were compared with a two-factor ANOVA. A Dunnet post hoc test was used to compare the strength of each group to its control. Results indicated that up to a certain size, tunnel preparations could be completed without diminishing the strength of the undermined marginal ridges. Placement of a glass-ionomer cermet in the tunnel preparations restored the strength of all but the largest preparations (#6 bur in the bicuspid group) to a level which was not statistically significantly different from the controls.

Tensile bond strength of dental adhesives to dentin and enamel.

This study compared the tensile bond strengths of an unfilled resin bonding agent and four proprietary dentin bonding agents to dentin and acid-etched enamel. Forty-eight hours after bonding, 10 dentin-bonded teeth and 10 enamel-bonded teeth for each material were loaded in tension in an Instron Universal Testing Machine until bond failure. The remaining specimens were stored in a water bath for six months and then tested in a similar manner. At the end of six months, Universal Bond and Tenure (3-step) had bond strengths significantly greater than those of the other agents. All bonding agents, except Tenure (3-step), showed a significant decrease in tensile bond strength to both dentin and enamel after six months (p less than 0.0001).