Publications (91) View all
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Article: Influence of recasting different types of dental alloys on gingival fibroblast cytotoxicity.
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ABSTRACT: Surplus alloy from the initial casting is commonly reused with the addition of new alloy. This recasting procedure could affect the cytotoxicity of dental alloys. The purpose of this in vitro study was to evaluate the effect of repeated casting of high-noble and base metal alloys on gingival fibroblast cytotoxicity. Disk-shaped specimens (5 × 2 mm, n=60) of a high-noble (Au-Pt) and 2 base metal (Ni-Cr and Cr-Co, n=20) alloys were prepared with 100% new alloy and 50%, 65%, and 100% once recast alloy. The elemental composition of specimens was analyzed with X-ray energy-dispersive spectroscopy. Five specimens from each group were conditioned in saline with 3% fetal bovine serum albumin. The conditioning media were analyzed for elemental release with atomic absorption spectroscopy. Cytotoxic effects were assessed on human gingival fibroblast with a 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyl tetrazolium bromide (MTT) colorimetric assay. The data were analyzed with 1-way and 2-way ANOVA and Tukey's HSD multiple comparison test (α-=.05). Elemental compositions of Co-Cr and Au-Pt alloys were significantly different among casting protocols. Elemental release of Co-Cr and Ni-Cr alloys was significantly different between new and recast specimens (P<.001). Nickel release increased with recast alloy addition. The 2-way ANOVA showed a significant effect of the casting procedure (P<.001) alloy group (P<.001) and their interaction for cytotoxicity (P<.001). The Ni-Cr alloy groups with 65% and 100% recast alloy had lower cellular activity than all other specimens (P<.001). The results of this study indicated that alloys containing nickel have increased cytotoxic effects and that composition of the alloys affected the cytotoxicity. Furthermore, recasting nickel-containing alloys with 65% surplus metal addition significantly increased the cytotoxic activity.The Journal of prosthetic dentistry 01/2012; 107(1):24-33. · 1.22 Impact Factor -
Article: Smile esthetics from patients' perspectives for faces of varying attractiveness.
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ABSTRACT: Delivering an attractive smile is a key element in orthodontic patient satisfaction. Smile characteristics can be affected by the facial context. The purpose of this study was to investigate smile esthetics related to facial attractiveness and sex of the model. Attractive, average, and unattractive model faces (2 of each; 3 male, 3 female) determined by peer ratings were combined with 10 smile variables (buccal corridor, smile arc, maxillary gingival discrepancy, gingival display, incisal-edge discrepancy, cant, overbite, central-incisor gingival margin discrepancy, and maxillary midline to face, and maxillary midline to mandibular midline). Each smile characteristic was altered digitally and presented with slider technology to allow a continuous range of choices. Raters chose the ideal and the limits of acceptability. The variables were divided into 6 separate surveys and rated 96 times. Reliability was assessed by answering each question twice. Individual smile variable reliability ranged from fair to excellent, except for the buccal corridor. Clinically significant values were defined as greater than 1.0 mm with statistical significance (P <0.05). Rater sex did not make a difference. Clinical significance was found for smile arc, gingival display, and maxillary midline to face. For females, accentuated smile arcs were preferred for the unattractive and attractive models compared with the average models. The opposite was found for male models. More gingival display was preferred for the attractive and unattractive male and female models compared with the average models. Attractive models were allowed less midline deviation. Facial attractiveness and model sex impacted smile variables with a facial context, except for occlusal cant. These smile characteristics with a facial context should be considered when diagnosing and planning treatment for an orthodontic patient.American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 10/2011; 140(4):e171-80. · 1.33 Impact Factor -
Article: Smile esthetics from the layperson's perspective.
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ABSTRACT: Computer-based smile esthetic surveys based on slider technology allow more precise control of variables and the possibility of obtaining continuous data. Variations in the perception of smiles from different facial perspectives have not been resolved. The objective of this study was to quantify the ideal and the range of acceptable values for smile variables judged by laypersons from a full-face perspective for comparison with lower-face data. Mirrored and symmetric male and female full faces previously determined by peers to be of average attractiveness were used. Ninety-six laypersons judged these smile variables: smile arc, buccal corridor fill, maxillary gingival display, maxillary midline to face, maxillary to mandibular midline discrepancy, overbite, central incisor gingival margin discrepancy, maxillary anterior gingival height discrepancy, incisal edge discrepancy, and cant. The judges manipulated the variables using adjustable image technology that allowed the variable to morph and appear continuous on a computer monitor. Medians for each smile variable were compiled, and the Fleiss-Cohen weighted kappa statistic was calculated to measure reliability. Multiple randomization tests with adjusted P values were used to compare these data with those for lower-face views. Reliability ranged from 0.25 for ideal overbite to 0.60 for upper midline to face, except for upper and lower buccal corridor limits, which each had a kappa value near 0. There were no statistically significant differences between the ratings of male and female raters. The following variables showed statistically and clinically significant differences (>1 mm) when compared with the lower-face view: ideal smile arc, ideal buccal corridor, maximum gingival display, upper to lower midline, and occlusal cant. Although the smile arc values differed because of model lip curvature variations, the principle of tracking the curve of the lower lip was confirmed. For the full-face view, the raters preferred less maximum gingival display, less buccal corridor, more upper to lower midline discrepancy, and less cant of the occlusal plane. Reliability was fair to moderate with the exception of the buccal corridor limits. Most variables showed no clinically meaningful differences from the lower-face view. The acceptable range was quite large for most variables. Detailed knowledge of the ideal values of the various variables is important and can be incorporated into orthodontic treatment to produce an optimal esthetic smile.American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 01/2011; 139(1):e91-e101. · 1.33 Impact Factor -
Article: Esthetics and smile characteristics from the layperson's perspective: a computer-based survey study.
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ABSTRACT: The paradigm shift from occlusion to esthetics places more emphasis on the subtle relationships among the teeth and the interplay with the soft tissues. The authors of this study quantified the ideal and maximum acceptable deviations for smile characteristics. The authors created a survey by using a digital image editing software package, which enabled raters to manipulate intraoral photographs featured in the survey. They altered smile characteristics in photos of a sex-neutral face showing nasal tip to mentolabial fold. The authors administered an electronic survey in Boston (n = 78); Columbus, Ohio (n = 81); and Seattle (n = 84). An interactive interface allowed raters to select the ideal for each smile characteristic presented and identify the range of acceptability for the variables. Raters were reliable (kappa = 0.34-0.88). Survey location was not significant except that raters from the West accepted a broader smile than did those from the Midwest and the East. Raters identified ideals and thresholds for the following smile characteristics: smile arc; buccal corridor; gingival display; canine and posterior crown torque, ideal and large corridor; maxillary midline to face; maxillary to mandibular midline; overbite; maxillary central incisor gingival height discrepancy; maxillary lateral incisor gingival height discrepancy; maxillary central to lateral incisal step; maxillary central incisor crown width-to-height ratio; maxillary central-to-lateral incisal ratio; and occlusal cant. Generally, the values for ideal paralleled existing data, and new guidelines for some variables emerged. The ranges of acceptability were large. The ideal and an acceptable range for each smile characteristic can be identified reliably. Laypeople can reliably identify ideal smile characteristics. The ranges of acceptable deviations for smile characteristics are large, and practitioners should avoid unnecessarily sensitizing patients to minor discrepancies.Journal of the American Dental Association (1939) 11/2008; 139(10):1318-27. · 1.77 Impact Factor -
Article: Attractiveness of variations in the smile arc and buccal corridor space as judged by orthodontists and laymen.
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ABSTRACT: To evaluate changes in attractiveness on the basis of computerized variations of smile arcs and buccal corridors for male and female smiles judged by orthodontists and laypersons. Using a visual analog scale in a Web-based survey, orthodontists and laypersons rated the attractiveness of nine digitally altered smile arc and buccal corridor variations of male and female smiles. The variations were accomplished in a clinically relevant manner and based on standards set by experienced orthodontists in a pilot web-based survey. The results indicate that both laypersons and orthodontists prefer smiles in which the smile arc parallels the lower lip and buccal corridors are minimal. Significantly lower attractiveness ratings were found for smiles with flat smile arcs and excessive buccal corridors. Flattening of the smile arc overwhelms the deleterious effects of excessive buccal corridors on attractiveness ratings. On the basis of the results of this study, care should be taken not to produce an excessively flat smile arc during orthodontic treatment.The Angle Orthodontist 08/2006; 76(4):557-63. · 1.21 Impact Factor
