Esthetics and smile characteristics evaluated by laypersons.

OBJECTIVE: To collect data regarding Canadian laypersons' perceptions of smile esthetics and compare these data to US data in order to evaluate cultural differences. MATERIALS AND METHODS: Using Adobe Photoshop 7, a digital image of a posed smile of a sexually ambiguous lower face was prepared so that hard and soft tissue could be manipulated to alter buccal corridor (BC), gingival display (GD), occlusal cant (OC), maxillary midline to face discrepancy (MMFD), and lateral central gingival discrepancy (LCGD). Adult Canadian laypersons (n  =  103) completed an interactive computer-based survey of 29 randomized images to compare smile preferences for these variables. The custom survey was developed to display fluid, continuously appearing modifiable smile variables using MATLAB R2008 for presentation. These data were compared with previously published data for US laypersons. Statistical inference was determined using Wilcoxon rank sum tests. RESULTS: Canadian laypersons were more sensitive in detecting deviations from ideal and had a narrower range of acceptability thresholds for BC, GD, OC, MMFD, and LCGD. Ideal esthetic values were significantly different only for BC. CONCLUSIONS: It appears that cultural differences do exist related to smile characteristics. Clinically significant differences in the preference of the smile characteristics were found between Canadian and US laypersons. Canadian laypersons, on average, were more discriminating to deviations from ideal and had a narrower range of acceptability.

Comparison of hand-traced and computer-based cephalometric superimpositions.

OBJECTIVE: To determine the ability to produce comparable superimpositions using hand tracing and digital methods (Dolphin v10). In addition, if the two methods were comparable, we wanted to determine if a difference existed between the best-fit cranial base superimposition and S-N superimpositions using the digital method. METHODS AND MATERIALS: Sixty-four initial (T(1)) and final (T(2)) cephalometric film radiographs were obtained. Cranial base and regional superimpositions were completed independently for each pair of radiographs by either hand tracing and digital methods. To quantitatively evaluate the differences between the two methods, the hand and digital superimpositions were digitized to obtain x-y coordinates of routine cephalometric landmarks at T(2). Linear distance between multiple corresponding (hand and digital) T(2) cephalometric landmark locations (e.g., A point) were measured and defined as the T(2) landmark distance (T(2) LD). Additionally, 61 patient records were used to compare the digital method for best-fit cranial base superimpositions versus S-N superimpositions. A Friedman test was applied to examine for differences. RESULTS: The upper 95% confidence limit for the mean of the T(2) LD for hand and digital superimposition methods was <1 mm for all landmarks except maxillary incisor tip and apex. The upper 95% confidence interval for best-fit vs S-N was >1 mm for most landmarks. CONCLUSION: This study validates the use of superimpositions produced by Dolphin Imaging version 10 and is a necessary step forward toward widespread acceptance of digital superimpositions.

The acceptability of variations in smile arc and buccal corridor space.

OBJECTIVES: To evaluate the esthetic acceptability range of computer-generated variations in smile arc and buccal corridor. DESIGN: Web-based descriptive study using available subjects. SETTING AND SAMPLE POPULATION: The World Wide Web. Subjects for the main study included 115 lay and 131 orthodontist raters. EXPERIMENTAL VARIABLES: Buccal corridors and smile arcs, each presented for a female and a male image. Buccal corridors were presented as none, ideal and excessive. The smile arc was presented as flat, ideal and excessive. The nine male and female variations, as combinations of the above variables, were each presented twice to evaluate reliability. OUTCOME MEASURE: Acceptability of buccal corridors and smile arcs using the web-based instrument. An arbitrary super majority threshold of acceptability was set at 67% approval. RESULTS: Both laypersons and orthodontists showed good reliability (k >or= 0.70). There was a broad range of acceptability, but laypersons and orthodontists showed no significant differences on the two variables tested. While orthodontists and laypersons both found smiles with excessive buccal corridors to be significantly less acceptable than those with ideal or absent buccal corridors, they were still acceptable over 70% of the time. Flat smile arcs were only acceptable 50-60% of the time, while smiles with ideal and excessive smile arcs were significantly more acceptable 84-95% of the time. When examining buccal corridors and smile arcs together, excessive buccal corridors were significantly less acceptable than ideal or absent buccal corridors regardless of the smile arc. A flat smile arc significantly reduced the acceptability of any buccal corridor to below the threshold of acceptability. CONCLUSIONS: Laypersons and orthodontists have similar preferences when acceptability of buccal corridors and smile arcs are considered. Flat smile arcs are more detrimental to smile esthetics than variations in buccal corridors. Clinicians must realize that although attractiveness may be reduced by variations in buccal corridors and smile arcs, the result may still be acceptable to a majority of people.

Facial growth and management of orthodontic problems.

This article enables pediatricians to identify and understand the implications of common facial growth problems in children and adolescents. Problems with facial growth can result in aesthetic and functional concerns. Using a simple method of clinical evaluation, pediatricians can identify facial growth problems in the anteroposterior, vertical, and transverse dimensions. These problems can then be referred for evaluation and treatment by various means. Because facial growth is the result of the interaction of genetic and environmental factors (some of which are functional), growth modification may be a possibility. Some problems may be camouflaged or treated by combined surgical and orthodontic means. Continued growth in early adulthood may enhance or detract from treatment results obtained in childhood or adolescence. These dynamic properties of the face make management of facial growth challenging but generally rewarding and successful because of substantial aesthetic and functional improvements.

Prevalence of malocclusion and orthodontic treatment need in the United States: estimates from the NHANES III survey.

Data from the third National Health and Nutrition Examination Survey (NHANES III) provide a clear picture of malocclusion in the US population. Noticeable incisor irregularity occurs in the majority of all racial/ethnic groups, with only 35% of adults having well-aligned mandibular incisors. Irregularity is severe enough in 15% that both social acceptability and function could be affected, and major arch expansion or extraction of some teeth would be required for correction. About 20% of the population have deviations from the ideal bite relationship; in 2% these are severe enough to be disfiguring and are at the limit for orthodontic correction. In Mexican-Americans compared to the rest of the population, incisor irregularity and both severe Class II and Class III malocclusions are more prevalent, but deep bite and open bite are less prevalent. Application of the Index of Treatment Need to the survey data reveals that 57% to 59% of each racial/ethnic group has at least some degree of orthodontic treatment need. Over 30% of white youths, 11% of Mexican-Americans, and 8% of blacks report receiving treatment. Severe malocclusion is observed more frequently among blacks, which may reflect their lower level of treatment. Treatment is much more frequent in higher income groups, but approximately 5% of those in the lowest income group and 10% to 15% of those in intermediate income groups report being treated.

Treatment of Class III problems begins with differential diagnosis of anterior crossbites.

Etiology of Class III malocclusion can be genetic or environmental. Proclination of mandibular incisors and retroclination of maxillary incisors can cause posturing of the mandible in an anterior position due to incisal interference, a condition called pseudo Class III malocclusion that can be misleading in evaluating a patient with skeletal Class III malocclusion. Unfortunately, cephalometric evaluation may not be the most reliable tool in differentiating whether the maxilla or the mandible contributes to the skeletal disharmony. The most consistent findings seem to be the dental characteristics of Angle's Class III molars and canines, retroclined mandibular incisors, and the presence of an edge-to-edge or an anterior crossbite occlusion. This paper presents a diagnostic scheme to differentiate between dental and skeletal crossbites. Early treatment of Class III malocclusion can help to minimize the adaptations and limitations that are often seen in severe malocclusion of the late adolescence. However, treatment of skeletal crossbites remains a continuous challenge to the profession. Due to the diversity and variability in facial growth, accurate individualized growth prediction is not possible at the moment. Treatment directed at the mandible seems to invite relapse during the pubertal growth period. Treatment directed at the maxilla shows promising results and is awaiting long-term clinical results following early orthopedic interventions. Several intraoral appliances have proved to be successful in eliminating dental crossbites.

Open bite: a review of etiology and management.

Diagnosis and treatment of open bite malocclusion challenges pediatric dentists who attempt to intercept this malocclusion at an early age. This article updates clinicians on the causes and cures of anterior open bite based on clinical data. Patients with open bite malocclusion can be diagnosed clinically and cephalometrically, however, diagnosis should be viewed in the context of the skeletal and dental structure. Accurate classification of this malocclusion requires experience and training. Simple open bite during the exchange of primary to permanent dentition usually resolves without treatment. Complex open bites that extend farther into the premolar and molar regions, and those that do not resolve by the end of the mixed dentition years may require orthodontic and/or surgical intervention. Vertical malocclusion develops as a result of the interaction of many different etiologic factors including thumb and finger sucking, lip and tongue habits, airway obstruction, and true skeletal growth abnormalities. Treatment for open bite ranges from observation or simple habit control to complex surgical procedures. Successful identification of the etiology improves the chances of treatment success. Vertical growth is the last dimension to be completed, therefore treatment may appear to be successful at one point and fail later. Some treatment may be prolonged, if begun early. Long-term clinical outcomes are needed to determine treatment effectiveness and clinicians should consider the cost-effectiveness of these early initiated and protracted plans.

Skeletal jaw relationships: a quantitative assessment using elliptical Fourier functions.

Elliptical Fourier functions (EFF) were generated for the boundary outlines of the hard tissue craniofacial complex including the maxilla, mandible, and cranial base in order to quantitatively describe adult patients (n = 98) who were initially classified into nine skeletal groups by a combination of conventional cephalometric measures and clinical judgement. The mean residual fit of the EFF-predicted points and the original digitized data for the individual subjects ranged from .42 mm to .61 mm with a mean of .52 mm suggesting an accurate fit. Visual inspection of the individual plots confirmed this. Predicted classifications from a step-wise discriminant analysis based on EFF amplitudes were compared with the original classifications. The discordance rates for A-P and vertical plane classification were 21% and 13% respectively with an overall discordance rate of 33%. In general, a cluster analysis using EFF amplitudes did not identify clusters very similar in membership to the original groups; however, it was marginally successful in identifying members of the more severe groups and, like discriminant analysis, appeared to be more sensitive to vertical morphological differences. The overall lack of agreement between classifications and clusters based on EFF amplitudes and the original classifications may indicate that traditional skeletal categories such as those used in this study do not actually represent discrete groups.

Stability of surgical maxillary expansion.

Stability after transverse expansion of the maxilla via Le Fort I osteotomy with segments was evaluated in 39 patients. The average expansion was 5.4 mm at the second molars, decreasing almost linearly to 2.8 mm at the first premolars. Postsurgical relapse also was greatest at the second molars, averaging 2.6 mm. The percentage of relapse was greatest posteriorly, decreasing from 49% at the second molars to 30% at the first premolars. Considerable variability in stability followed surgery: Three-fourths of the patients had some relapse at the first molars (greater than 3 mm in 28%), but one fourth were stable. Sixty-two percent of the patients had a net posttreatment gain in arch width at the first molars. No correlation was found between transverse relapse and the type of presurgical orthodontic tooth movement, the use of rigid fixation, or the use of an auxiliary stabilizing arch wire. The amount of postsurgical relapse was significantly greater in those who had concurrent mandibular surgery. To improve clinical results with surgical expansion, we recommend (1) moderate overexpansion at surgery for major transverse changes, (2) maintenance of the occlusal splint for at least 6 weeks, and (3) use of a lingual arch wire or auxiliary labial arch wire to maintain molar width during postsurgical orthodontics.

Craniofacial growth from infancy through adulthood. Background and clinical implications.

The purpose of this article was to enable the pediatrician to identify and understand the implications of common facial growth problems in children and adolescents. Problems with facial growth can result in aesthetic and functional complaints. Using a simple method of clinical evaluation, the pediatrician can identify facial growth problems in the anteroposterior, vertical, and transverse dimensions. These problems can then be referred for evaluation and treatment by a variety of means. By adopting a contemporary view that facial growth is the result of genetic and environmental factors (some of which are functional), growth modification becomes a real possibility. Unfortunately, some problems must be camouflaged or treated by combined surgical and orthodontic means. Continued growth in early adulthood can enhance or detract from treatment results obtained in childhood or adolescence. These dynamic properties of the face make management of facial growth challenging but generally rewarding and successful because of substantial aesthetic and functional improvements.

Parental attitudes toward behavior management techniques used in pediatric dentistry.

Previous studies evaluating parents' attitudes toward behavior management techniques used in pediatric dentistry suggest that parental attitudes are generally negative. The purpose of this study was to reexamine this issue by comparing the effect of prior explanation on parental acceptance of eight behavior management techniques. Videotaped segments were made of children's dental appointments containing examples of eight behavior management techniques. One group of 40 parents viewed a videotape which provided no explanation for each technique before it was shown. Another group of 40 parents viewed a videotape which provided no explanation of the techniques. The parents then were asked to rate the acceptability of each technique using a visual analogue scale. Results indicated that the informed parents were significantly more accepting of behavior management techniques than the uninformed parents but both groups were generally positive about the techniques studied. Further, parents reporting greater stress were less accepting of the techniques studied.

Relationship between vertical dentofacial morphology and respiration in adolescents.

The relationship between vertical dentofacial morphology and respiration has been debated and investigated from various approaches. The purpose of this study was to use contemporary respirometric techniques to compare the breathing behavior of normal and long-faced adolescents. Sixteen normal and 32 long-faced subjects 11 to 17 years of age were chosen clinically and verified by means of a discriminant function. Vertical and anteroposterior facial form was assessed from lateral cephalometric radiographs according to the following measurement criteria: six skeletal angular, eight skeletal linear, four dental linear, and three skeletal ratios. Breathing behavior was quantified according to tidal volume, minimum cross-sectional nasal area, and percent of nasal breathing as assessed by pneumotachography, measurement of differential pressures, and inductive plethysmography. The data indicated that the normal and long-faced groups were significantly different with respect to lower face form, and each group in the study was comparable to groups that had been chosen by previous investigators. Multiple regression analysis demonstrated that the normal and long-faced groups had similar tidal volumes and minimum nasal cross-sectional areas, but the long-faced subjects had significantly smaller components of nasal respiration. These results illustrate that groups without significant differences in airway impairment can have significantly different breathing modes that may be behaviorally based, rather than airway-dependent.

Intracoronal radiolucencies within unerupted teeth. Case report and review of literature.

A panoramic radiograph obtained during orthodontic treatment revealed an intracoronal radiolucency within an unerupted permanent second molar. This unusual entity was successfully treated by surgical and endodontic intervention, followed by restorative and orthodontic treatment. These treatments enabled the tooth to maintain pulpal vitality, erupt, complete root formation, and function. This report will review the proposed etiologies for this condition, discuss the need for surgical intervention, and present the details of the case.

Failure to thrive: review of the literature, case reports, and implications for dental treatment.

The symptom failure to thrive (FTT) is increasing in the general population, and has a prevalence of 9.6% among infants in the United States. Other factors occur in association with growth failure such as medical and dental anomalies and developmental delays that influence the management of these children. Four cases are presented to demonstrate the spectrum of problems and interdisciplinary management required to provide successful dental treatment.

Dentofacial growth and development.

Theoretical growth and development, and practical aspects are explored in an overview of how growth has been considered by investigators and clinicians during the past twenty years, to the beliefs held today. Diagnostic and treatment methods, where technical innovations are the most apparent, are considered in the context of classical orthodontic thinking. New diagnostic techniques will be introduced that will require changes in our basic understanding of growth and treatment. Orthodontics will continue to be integrated into total patient diagnosis and treatment.

Screening panoramic radiographs in children: prevalence data and implications.

The purpose of this paper was to review the rationale for the radiographic screening of asymptomatic pediatric patients and to report the prevalence of selected pathologic and developmental conditions using panoramic radiographs. Three observers participated in this retrospective study that utilized panoramic radiographs from 849 subjects, aged 3-9 years, chosen randomly from the School of Dentistry treatment records of the University of North Carolina at Chapel Hill. Findings indicated that 2.4% of the subjects had supernumerary teeth, 7.8% were missing permanent teeth, 9.1% had ectopic eruption, 0.1% had radiolucencies of the jaws, and 0.1% had radiopacities of the jaws. These prevalences are discussed in light of recent evidence concerning the risk/benefit ratio of the panoramic radiograph. We conclude that the panoramic radiograph is a poor projection for screening the dental needs of asymptomatic healthy children; alternative screening protocols should be examined.

The effect of orthognathic surgery on occlusal force.

To investigate the effect of orthognathic surgery on occlusal force, such force was measured during maximum effort, chewing, and swallowing in 70 patients who had superior repositioning of the maxilla and/or mandibular advancement or setback. Larger changes in occlusal force than could be accounted for by the altered geometry were observed in all groups. Of 15 patients who had only superior repositioning of the maxilla, ten had greater than 20% increase in occlusal force, three had little change, and two showed a greater than 20% decrease. When the mandible was advanced, 11 of 34 patients had greater than 20% increase in maximum biting force, 11 had little or no change, and 12 had greater than 20% decrease. When the mandible was set back, six of the 21 patients had greater than 20% increase, nine had little or no change, and six had greater than 20% decrease. It appears that considerable change in bit force, which is not primarily related to jaw geometry, occurs after orthognathic surgery.

Variables affecting measurements of vertical occlusal force.

Previous studies of occlusal force have provided conflicting results. The purpose of these studies was to determine whether the extent of vertical opening, contralateral occlusal support, or head posture influenced vertical occlusal forces during swallowing, simulated chewing, and maximum biting effort. Three samples of subjects with normal vertical facial proportions--one each of children, adolescents, and young adults--were evaluated to determine the effects of changes in small (2.5 vs. 6.0 mm) vertical separation of the first molars. A sample of young adults was used to evaluate changes in large (10-40 mm) vertical openings, and a sample of adolescents was used to investigate the effect of contralateral support and head posture. All between-group comparisons were evaluated using non-parametric statistics. For the small vertical openings, there was significantly more vertical occlusal force at 6.0 than 2.5 mm in children during swallowing and chewing but not during maximum biting effort. In adults, there was significantly more force during swallowing at 6.0 than at 2.5 mm separation, but no differences in chewing or maximum biting. Increasingly large vertical openings resulted in a progressive increase in maximum bite force to a maximum at about 20 mm, followed by a decrease and then a second increase to near-maximum force at about 40 mm for young adults. There were no significant differences in vertical force with or without contralateral support or between flexed, normal, and extended head postures at either of the small openings.