• CAMBRA and its effect on surface roughness of various restorative materials

      Bolding, Lauren Mills; Masri, Radi, 1975-; Driscoll, Carl F. (2012)
      Purpose: The purpose of this study was to investigate the effect of various anti-caries agents on the surface roughness of three different restorative materials. Materials and Methods: Sixty-four specimens of each material (porcelain, base metal and titanium alloy) were prepared and separated into four groups for soaking in anti-caries agents (Prevident, ACT, chlorhexidine and water). A profilometer was used to measure surface roughness before and after soaking for two years simulated usage. The change in surface roughness for each specimen was calculated. Statistical analysis was completed using a factorial analysis of variance (two-way ANOVA) followed by Tukey's HSD test. A p value ≤0.05 was considered significant. Results: The results demonstrate that there was no significant difference in mean change in surface roughness between the three materials, porcelain, base metal, and titanium. The results further demonstrate that there was a significant difference in mean change in surface roughness between Prevident Dental Rinse and chlorhexidine gluconate. There was no significant difference between water, ACT, and chlorhexidine gluconate. There was also no significant difference between Prevident Dental Rinse, water, and ACT. There was a significant interaction between Prevident Dental Rinse and chlorhexidine within the porcelain samples. Prevident Dental Rinse produced a negative change in surface roughness while chlorhexidine gluconate produced a positive change in surface roughness. Conclusion: Within the limitations of this study, it can be concluded that Prevident Dental Rinse and chlorhexidine gluconate may cause a change in surface roughness of porcelain when used for a period of two years. Prevident Dental Rinse may cause an increase in surface roughness of porcelain while chlorhexidine gluconate may cause a decrease in surface roughness of porcelain.
    • The Effect of CAMBRA Recommended Anti-Caries Agents on Surface Roughness of Lithium Disilicate Ceramics

      Ghunaim, Dima Hanna; Masri, Radi, 1975-; Driscoll, Carl F. (2014)
      Purpose: The purpose of this study was to explore the clinical importance of the effect of Prevident and chlorhexidine on the surface roughness of three commonly utilized lithium disilicate ceramics: pressed (Press), milled (CAD), milled and veneered with fluorapatite (CAD/CERAM). Methods and Materials: Seventy-six rectangular specimens in each group of Press, CAD, and CAD/CERAM were fabricated. A profilometer was used to measure the surface roughness prior to and after soaking. The samples were immersed in the assigned anti-caries solution in an airtight plastic container. For the simulation of 2 years use the samples were soaked in chlorhexidine for 3 hours, Prevident, 6% alcohol and distilled water for 12 hours. Statistical analysis was completed using a two-way ANOVA followed by Tukey's HSD test. A p value ≤.05 was considered significant. Results: The results demonstrated that Press samples became significantly rougher. In addition to that, the surface roughness of CAD and CAD/CERAM was significantly decreased. However, CAD was significantly less rough than CAD/CERAM. Water did not significantly change the surface roughness of ceramics, while 6% alcohol, Prevident, and chlorhexidine significantly decreased the roughness of the ceramics. There was no significant difference in the increase of surface smoothness among the three solutions. A significant interaction was found only with water, the control. Conclusion: Within the limitations of this study, it can be concluded that Prevident and chlorhexidine can change the surface roughness of lithium disilicate ceramics when used for a period of 2 years. The surface roughness of Press increased, while that of CAD and CAD/CERAM decreased.
    • The effect of electrical stimulation on success of bone grafts: an in vivo study

      Talwar, Garima Kaur; Masri, Radi, 1975-; Driscoll, Carl F. (2012)
      Purpose: Bone grafting is often unpredictable and is associated with reduced success rate, extended healing times and morbidity. Methods that expedite healing and increase predictability will contribute to the overall success of reconstructive efforts. In this project, the effect of electrical stimulation on bone graft healing in rat calvaria was examined. Materials and Methods: Fifteen adult male Sprague-Dawley rats were used. A 7 mm diameter bone defect at the midline of the calvarium was grafted using freeze-dried mineralized bone. Bipolar platinum stimulating electrodes were overlaid on top of the periosteum on the center of the graft. Animals were divided randomly into two groups. The experimental group (n=8) received electrical stimulation (3 times/day for 10 days) and the control group (n=7) received no stimulation. At 6 weeks, the grafted areas together with the surrounding bone were harvested from the cranium. Tissue sections (5-7 μm) were prepared and stained using hematoxylin and eosin. Mounted slides were analyzed and for each animal, the grafted area was marked and the percent of new bone, remaining graft material and connective tissue was calculated. Data was analyzed using ANOVA. A p≤.05 was considered significant. Results: There were statistically significant differences between the experimental and control group. The electrical stimulation group had significantly more (p=0.034) bone (3.81+3.6 %) compared to the control group (0.47+0.52%). The amount of remaining graft material was also significantly higher (p=0.024)in the control group (26.11+6.54%) compared to the stimulation group (16.64+5.28%). No significant difference (p=0.15) was found between the 2 groups in the amount of connective tissue (stimulation: 79+5.47%; control: 73.2+6.82%). Conclusion: In this animal model of bone graft healing, electrical stimulation resulted in significantly more bone formation and less remaining graft material. These findings suggest that electrical stimulation expedites bone graft healing.
    • The Golden Proportion In Denture Teeth

      Rivera, Elias M.; Driscoll, Carl F. (2011)
      Purpose: The purpose of this study was to investigate the proportion of anterior to posterior denture teeth manufactured by two major manufacturers (Ivoclar and DENTSPLY) and determine if they follow the suggested Golden Proportion. Materials and Methods: Sixty-six maxillary denture teeth from two different companies (Ivoclar and DENTSPLY) were set using a standardized technique. The most popular small, medium and large moulds were tested from each company (n=11). 30-degree posterior teeth were used. All the samples were photographed and the images were analyzed using computer software to measure the visible widths of the maxillary anterior and posterior teeth. The existence of the golden proportion was investigated. Results: The golden proportion was not found to exist between maxillary anterior and posterior denture teeth. Conclusion: The measured width of anterior and posterior denture teeth did not equal the calculated width based of the Golden Proportion in either Ivoclar or DENTSPLY denture teeth.
    • Radiographic Evaluation of All Ceramic Crown Margins

      Wahle, William Maxwell; Driscoll, Carl F.; Masri, Radi, 1975- (2016)
      Statement of Problem: Radiographs aid in clinical determination of crown fit, specifically interproximal margins where tactile and visual methods can fail us. With the use of all ceramic materials surpassing ceramometal, it is beneficial to understand what limitations are present with this method to determine the correct marginal adaptation. Purpose: The purpose of this study was to assess if we can accurately identify crown margin closure via radiographs for all ceramic and ceramometal crown margins, and if not, to understand where the error lies. Materials and Methods: Individual IPS e.max, ZirPress, and ceramometal crowns were fabricated using a single prepared maxillary premolar and measured with light microscopy to ensure fit at the margin to below 20μm. The crowns were set up on a margin opening jig, and radiographs were made at 20μm increments starting at 0μm and finishing at 180μm for a total of 10 marginal adaptations. The threshold for closed versus open was >80μm. 80° and 90° radiographs were also made for each discrepancy to account for clinician variation in radiograph making. The 60 radiographs were then randomized and evaluated by prosthodontists and general dentists. Results: Individual evaluation accuracy of marginal adaptation was 48.8% for ceramometal crowns, 72.1% for e.max, and 76.9% for ZirPress. The scientific hypotheses were found to be true. When incorrectly evaluated, ceramometal crowns were significantly more likely to be evaluated acceptable when open margins were present, or as false positives. E.max and ZirPress were found to be more likely evaluated unacceptable with closed margins present. No significant difference was seen between general dentists and prosthodontists or between 80° and 90° variations except for ceramometal crowns which were more accurate for 90°. Conclusions: Within the limitations of this in vitro study, accuracy of marginal adaptation evaluations without clinical examination is not as high as would be expected. Ceramometal crowns tend to be incorrectly evaluated closed. Ceramic crowns (IPS e.max lithium disilicate and ZirPress) tend to be incorrectly evaluated open. No difference between prosthodontists and general dentists was evident in this study with relation to accuracy of evaluations. The goal of this study was to provide information to aid in marginal closure determination when evaluating crowns radiographically and guidance when examining crowns of different radiopacities with relation to the common inaccuracies found in the study.