Short-term stability of anterior open bite treatment with clear aligners in adults.

INTRODUCTION: This study aimed to examine the stability of anterior open bite (AOB) treatment with clear aligners. METHODS: This retrospective cohort study included 52 adult AOB patients (aged >18 years; 15 males, 37 females) who underwent nonextraction clear aligner treatment and were at least 1 year posttreatment. Eleven cephalometric measurements were evaluated at pretreatment, end of active treatment, and at least 1-year posttreatment. Overbite change, the primary outcome variable, and other cephalometric changes during treatment and retention were calculated, and repeated measures analysis of variance were performed. Stepwise multiple regression was used to make a prediction equation for open bite relapse. RESULTS: The mean retention period was 2.1 ± 1.1 years. The mean change in overbite during treatment was 3.3 ± 1.5 mm; 6% of patients presented relapse at least 1 year after treatment completion. The mean change of overbite (0.2 ± 0.5 mm) during the retention period was not statistically significant (P = 0.59). None of the 11 cephalometric measurements showed significant change during the retention period. The prediction model showed that only the coefficient for a tongue posture issue at the initial examination was statistically significant. CONCLUSIONS: AOB was successfully corrected in all 52 patients using only clear aligners with no additional adjunctive aids such as microimplants. When retained with maxillary and mandibular fixed retainers and maxillary and mandibular vacuum-formed retainers, there was no significant change in cephalometric measurements during the short-term retention period.

Comparison between a human judge and automatic landmark identification on digital models.

INTRODUCTION: Accurate landmark identification is a prerequisite for accurate and reliable biomedical image analysis. Orthodontic study models are valuable tools for diagnosis, treatment planning, and maintaining complete records. The purpose of this study was to evaluate the reliability and validity of a software program (Align Technology, Inc) as a tool for automatic landmark location. METHODS: Using digital intraoral scans of 10 dental arches, 4 calibrated human judges independently located cusp tips and interproximal contacts. The same landmarks were automatically identified by the software. Intraclass correlation coefficient (Cronbach α), absolute mean errors, and regression analysis were calculated. In addition, Bland-Altman 95% confidence limits were also applied to the data to graphically display agreement on landmark identification between the human judges and the software. RESULTS: The intraclass correlation coefficient between the software and the human judges' average for the x-, y-, and z-coordinates for all landmarks was excellent, at 1.0, 1.0, and 0.98, respectively. The regression analysis and Bland-Altman plots show no systematic errors for agreement on landmark identification between the human judges and the software. CONCLUSIONS: Landmark location was nearly identical between the software and the human judges, making the methods interchangeable.

Treatment of anterior open bites using non-extraction clear aligner therapy in adult patients.

Objective: The purpose of this study was to examine the effectiveness and mechanism of clear aligner therapy for the correction of anterior open bite in adult nonextraction cases. Methods: Sixty-nine adult patients with anterior open bite were enrolled and classified into Angle's Class I, II, and III groups. Fifty patients presented with skeletal open bite (mandibular plane angle [MPA] ≥ 38°), whereas 19 presented with dental open bite. Fifteen cephalometric landmarks were identified before (T1) and after (T2) treatment. The magnitudes of planned and actual movements of the incisors and molars were calculated. Results: Positive overbite was achieved in 94% patients, with a mean final overbite of 1.1 ± 0.8 mm. The mean change in overbite was 3.3 ± 1.4 mm. With clear aligners alone, 0.36 ± 0.58 mm of maxillary molar intrusion was achieved. Compared with the Class I group, the Class II group showed greater maxillary molar intrusion and MPA reduction. The Class III group showed greater mandibular incisor extrusion with no significant vertical skeletal changes. Conclusions: Clear aligners can be effective in controlling the vertical dimension and correcting mild to moderate anterior open bite in adult nonextraction cases. The treatment mechanism for Class III patients significantly differed from that for Class I and Class II patients. Maxillary incisor extrusion in patients with dental open bite and MPA reduction with mandibular incisor extrusion in patients with skeletal open bite are the most significant contributing factors for open bite closure.

Reliability of 3D dental and skeletal landmarks on CBCT images.

OBJECTIVES: To quantify reliability of three-dimensional skeletal landmarks and a comprehensive set of dental landmarks in cone-beam computed tomography (CBCT) and to determine the shapes of envelope of error. MATERIALS AND METHODS: Three judges located 31 skeletal landmarks and 60 dental landmarks on the pre- and posttreatment CBCT images of 22 patients. Landmark error was determined by calculating the distance of deviation of landmark locations around their average. Standard deviation and mean radial spherical error were calculated. Scatterplots were constructed to characterize envelope of error. RESULTS: The midline landmarks of the cranial base were highly reliable. Bilateral skeletal landmarks tended to have larger error than midline landmarks. Among the nonconventional landmarks, fronto-zygomatic suture, condyle, and mental foramen showed relatively high reliability. However, foramen spinosum and temporal fossa showed larger errors. Gonion was the least reliable landmark. Most dental landmarks were located more reliably than skeletal landmarks. The highest reliability was found at incisal edges. Mesiobuccal cusp of first molars also showed high reliability. CONCLUSIONS: There were differences in the size and shape of the distributions of errors of different landmarks. Most landmarks showed elongated envelopes. Bilateral structures tended to show greater errors than midline structures. Most dental landmarks were more reliable than skeletal landmarks.

The northern "Black Metropolis" of the early twentieth century: a reappraisal.

The new perspective of the "Black Metropolis" implies that conditions created by the Great Migration helped blacks in northern cities to establish themselves in professional, entrepreneurial, and artistic, entertainment and mass media occupations. The present study evaluates this argument with Census data, focusing on the nation's largest black communities, Harlem (New York) and Bronzeville (Chicago), at time points that capture the first wave of the Great Migration. Contrary to expectations, the odds of black employment in the aforesaid occupations declined or remained essentially unchanged in both communities over the study period. Harlem and Bronzeville were surprisingly limited in their potential to offer opportunities for blacks to become professionals, entrepreneurs, and artists, entertainers and writers, perhaps because these communities were saturated by the tremendous influx from the South. Accordingly, it is recommended that the Black Metropolis perspective be modified, to provide a more accurate view of the consequences of the Great Migration.

Randomized clinical trial comparing control of maxillary anchorage with 2 retraction techniques.

INTRODUCTION: The objective of this pilot randomized clinical trial was to investigate the relative effectiveness of anchorage conservation of en-masse and 2-step retraction techniques during maximum anchorage treatment in patients with Angle Class I and Class II malocclusions. METHODS: Sixty-four growing subjects (25 boys, 39 girls; 10.2-15.9 years old) who required maximum anchorage were randomized to 2 treatment techniques: en-masse retraction (n = 32) and 2-step retraction (n = 32); the groups were stratified by sex and starting age. Each patient was treated by a full-time clinic instructor experienced in the use of both retraction techniques at the orthodontic clinic of Peking University School of Stomatology in China. All patients used headgear, and most had transpalatal appliances. Lateral cephalograms taken before treatment and at the end of treatment were used to evaluate treatment-associated changes. Differences in maxillary molar mesial displacement and maxillary incisor retraction were measured with the before and after treatment tracings superimposed on the anatomic best fit of the palatal structures. Differences in mesial displacement of the maxillary first molar were compared between the 2 treatment techniques, between sexes, and between different starting-age groups. RESULTS: Average mesial displacement of the maxillary first molar was slightly less in the en-masse group than in the 2-step group (mean, -0.36 mm; 95% CI, -1.42 to 0.71 mm). The average mesial displacement of the maxillary first molar for both treatment groups pooled (n = 63, because 1 patient was lost to follow-up) was 4.3 ± 2.1 mm (mean ± standard deviation). Boys had significantly more mesial displacement than girls (mean difference, 1.3 mm; P <0.03). Younger adolescents had significantly more mesial displacement than older adolescents (mean difference, 1.3 mm; P <0.02). CONCLUSIONS: Average mesial displacement of the maxillary first molar with 2-step retraction was slightly greater than that for en-masse retraction, but the difference did not reach statistical significance. This finding appears to contradict the belief of many clinicians that 2-step canine retraction is more effective than en-masse retraction in preventing clinically meaningful anchorage loss.

Periodontal and restorative considerations with clear aligner treatment to establish a more favorable restorative environment.

Although standard fixed appliances are better suited to control difficult tooth movement in three planes of space, clear aligner orthodontic treatment may be requested by patients because of the superior esthetics compared with conventional fixed appliances when clear aligners can be considered. Several clinical trials have shown improved periodontal status during orthodontic treatment with clear aligners while fixed appliances have almost always been associated with increased inflammation and mild periodontal breakdown despite preventive measures performed during treatment. There have been no reports of decalcification and only one reported case of root resorption with clear aligners, whereas with fixed appliances, numerous incidents of both decalcification and root resorption have been reported. In addition, studies have also shown significantly less pain from soft-tissue injuries and muscle soreness from parafunctional habits with computer-aided clear aligners. Restorative advantages include improved esthetics and comfort during treatment for better case acceptance and the ability to bleach teeth throughout treatment. Improving tooth alignment with orthodontic treatment with fixed or clear appliances increases the clinician's potential capability to perform more conservative restorative procedures, requiring less tooth structure removal and less endodontic involvement because of better tooth positions. In those cases in which clear aligner appliances may be appropriate, less damage may occur to existing porcelain restorations than might transpire from bonding of fixed appliances and their removal, as well as potentially reduced tooth wear during treatment. This article presents three case reports that demonstrate the periodontal and restorative aspects of treatment using the computer-aided clear appliances, which have either eliminated the need for certain restorative procedures or created a better periodontal and tooth position environment for performing these procedures.

Esthetic orthodontic treatment using the invisalign appliance for moderate to complex malocclusions.

In this report, three patients were treated with a new treatment protocol for Invisalign to demonstrate that a variety of complex malocclusions can be successfully treated using this protocol, including correction of moderate crowding, correction of moderate Class II division 1, and deep overbite. Previous studies of Invisalign showed significant limitations for more complex orthodontic treatment, although a few recent case reports have shown successfully completed moderate to difficult orthodontic malocclusions. One reason for the discrepancy is that the earlier studies were done during the first four years of the appliance development (now ten years of clinical use), when significant problems existed with accomplishing bodily movement, torquing of roots, extrusions, and rotations of premolars and canines. The new protocol included new methods for anterior/posterior corrections, showing on the computer the effect of elastics for Class II treatment simulated as a one-stage anterior/posterior movement at the end of treatment. Staging for interproximal reduction (IPR) is now automatically staged when there is better access to interproximal contacts to avoid IPR where significant overlap between teeth is present to avoid performing IPR on surfaces that may be damaged by instruments such as burs, strips, and disks when cut on a sharp angle. Staging for tooth movements is now also done to enable combination movements to occur simultaneously for each tooth with the tooth that needs to move the most (the lead tooth) determining the minimum number of stages required. All other teeth move at a slower rate than the lead tooth throughout the duration of treatment. Attachments are now placed in the middle of the crown automatically for rotation and automatically sized in proportion to the clinical crown. Use of 1 mm thick (buccal-lingual dimension) horizontal beveled rectangular attachments is standard on premolars for retention of aligners during intrusive movements, such as leveling the lower curve of Spee in deep overbite for extrusions and for control of the tooth long axis during torquing movements. Staging of tooth movements now track linear and rotational velocities of teeth separately with the number of treatment stages determined by the lead tooth based on its rotational or linear maximum velocities at no more than two degrees of rotation per stage. Simultaneous movements are done for all teeth providing visible space (approximately 0.05 mm) between teeth during movements past other teeth using expansion instead of IPR as a primary way to increase space available for correction of crowding.

. Facial attractiveness: ranking of end-of-treatment facial photographs by pairs of Chinese and US orthodontists.

INTRODUCTION: In this study, we assessed agreement and disagreement among pairs of Chinese and US orthodontists in the ranking for "facial attractiveness" of end-of-treatment photographs of growing Chinese and white orthodontic patients. METHODS: Two groups of orthodontist-judges participated: from the University of the Pacific, School of Dentistry, in California and from Peking University School and Hospital of Stomatology in China. Each judge independently ranked standard clinical sets of profile, frontal, and frontal-smiling photographs of 43 white patients and 48 Chinese patients. Pearson correlations were generated for a total of 1980 rankings by pairs of judges. RESULTS: The resulting correlations ranged from +0.004 to +0.96 with a median of +0.54. Of these, 18.7% were lower than 0.4; 41.0% were lower than 0.5; 68.8% were lower than 0.6; 91.6% were lower than 0.7; and only 8.4% were greater than 0.7. As had been anticipated, correlations between judges were higher when they ranked patients of their own ethnicity than when they ranked patients of different ethnicity, but the differences were smaller than had been expected. The rankings of no pair of judges correlated negatively. This is to say that no pair of judges, whether of the same or different ethnicity, ranked the patients so that those 1 judge tended to find attractive were consistently found unattractive by the other. CONCLUSIONS: The distribution of levels of agreement between pairs of orthodontists did not differ substantially whether the pairs included 2 US orthodontists, 2 Chinese orthodontists, or 1 US and 1 Chinese orthodontist. As might be expected, the pairs of Chinese orthodontists agreed with each other slightly better on average when ranking Chinese patients, and the pairs of US orthodontists agreed with each other slightly better on average when ranking white American patients, but the overall differences were small. These findings appear consistent with the inference that, on average, judgments of "facial attractiveness" by orthodontists at the 2 venues are more similar than had been expected for patients of Chinese and white ethnicity.

Evaluation of facial attractiveness from end-of-treatment facial photographs.

INTRODUCTION: Orthodontists typically make judgments of facial attractiveness by examining groupings of profile, full-face, and smiling photographs considered together as a "triplet." The primary objective of this study was to determine the relative contributions of the 3 photographs-each considered separately-to the overall judgment a clinician forms by examining the combination of the 3. METHODS: End-of-treatment triplet orthodontic photographs of 45 randomly selected orthodontic patients were duplicated. Copies of the profile, full-face, and smiling images were generated, and the images were separated and then pooled by image type for all subjects. Ten judges ranked the 45 photographs of each image type for facial attractiveness in groups of 9 to 12, from "most attractive" to "least attractive." Each judge also ranked the triplet groupings for the same 45 subjects. The mean attractiveness rankings for each type of photograph were then correlated with the mean rankings of each other and the triplets. RESULTS: The rankings of the 3 image types correlated highly with each other and the rankings of the triplets (P <.0001). The rankings of the smiling photographs were most predictive of the rankings of the triplets (r = 0.93); those of the profile photographs were the least predictive (r = 0.76). The difference between these correlations was highly statistically significant (P = .0003). It was also possible to test the extent to which the judges' rankings were influenced by sex, original Angle classification, and extraction status of each patient. No statistically significant preferences were found for sex or Angle classification, and only 1 marginally significant preference was found for extraction pattern. CONCLUSIONS: Clinician judges demonstrated a high level of agreement in ranking the facial attractiveness of profile, full-face, and smiling photographs of a group of orthodontically treated patients whose actual differences in physical dimensions were relatively small. The judges' rankings of the smiling photographs were significantly better predictors of their rankings of the triplet of each patient than were their rankings of the profile photographs.

Effect of cephalometer misalignment on calculations of facial asymmetry.

INTRODUCTION: In this study, we evaluated errors introduced into the interpretation of facial asymmetry on posteroanterior (PA) cephalograms due to malpositioning of the x-ray emitter focal spot. We tested the hypothesis that horizontal displacements of the emitter from its ideal position would produce systematic displacements of skull landmarks that could be fully accounted for by the rules of projective geometry alone. METHODS: A representative dry skull with 22 metal markers was used to generate a series of PA images from different emitter positions by using a fully calibrated stereo cephalometer. Empirical measurements of the resulting cephalograms were compared with mathematical predictions based solely on geometric rules. The empirical measurements matched the mathematical predictions within the limits of measurement error (x= 0.23 mm), thus supporting the hypothesis. Based upon this finding, we generated a completely symmetrical mathematical skull and calculated the expected errors for focal spots of several different magnitudes. Quantitative data were computed for focal spot displacements of different magnitudes. RESULTS AND CONCLUSIONS: Misalignment of the x-ray emitter focal spot introduces systematic errors into the interpretation of facial asymmetry on PA cephalograms. For misalignments of less than 20 mm, the effect is small in individual cases. However, misalignments as small as 10 mm can introduce spurious statistical findings of significant asymmetry when mean values for large groups of PA images are evaluated.

An update on present and future considerations of aligners.

This report reviews the orthodontic treatment of six different patients who received removable aligners. These cases include correction of deep overbite, open bite, mild-to-moderate crowding, large overjet, cases requiring premolar extractions, the presence of multiple restorations, and cases requiring periodontal-restorative treatments, the improved periodontal status with aligners compared to fixed appliances and the use in teenagers. This report demonstrates that a wide range of cases can be effectively treated, provided the cases are thoroughly reviewed at an early stage process using Invisalgn's ClinCheck software, which will show the specific details of all consecutive appliances prior to any treatment being started so as to determine the biologic and biochemical feasibility of treatment.

Pacific Craniofacial Team and Cleft Prevention Program.

There is no doubt modern genetics have greatly influenced our professional and personal lives during the last decade. Uncovering genetic causes of many medical and dental pathologies is helping to narrow the diagnosis and select a treatment plan that would provide the best outcome. Importantly, having an understanding of multifactorial etiology helps direct our attention toward prevention. We now understand much better our own health problems. In some cases, we can modify our lifestyle and diet in order to prevent "environmental factors" from triggering the mutated genes inherited from our parents. Good examples are diabetes and cardiovascular diseases. If we realize we might have inherited genes for cardiovascular problems from several ancestors who had heart attacks, we already know that these genes will make us only "susceptible" for disease. Those who exercise, watch one's weight, diet, and carefully monitor one's lifestyle will very likely--though possessing "susceptibility genes"--stay healthier and, maybe, will never experience any cardiovascular problems. In principle, the same applies for craniofacial anomalies, especially for nonsyndromic cleft lip and palate. One needs to understand genetic and environmental causes of nonsyndromic orofacial clefts in order to prevent them. With all this in mind, the Pacific Craniofacial Team and Cleft Prevention Program have been established at the Department of Orthodontics, University of the Pacific Arthur A. Dugoni School of Dentistry in San Francisco. A partnership with Rotaplast International, Inc., has made it possible for the faculty, orthodontic residents, and students to participate in 27 multidisciplinary cleft medical missions in underdeveloped and developing countries by donating professional and educational services, and, last but not least, by collecting valuable data and specimens to further research. A significant number of research studies, including 15 master of science theses, have been accomplished in UOP's Craniofacial Genetics Laboratory, with contributions by faculty, undergraduate and graduate students. It has been leading to a better understanding of etiology of nonsyndromic orofacial clefts. It has been learned that genetic factors and environmental factors are ethnicity-specific and, in many places throughout the world, location-specific. Thus, a specific protocol for cleft prevention has to be worked out based on genetic and nutritional studies of each specific population group in order to be effective. This is our ultimate goal.

Consolidating molecular AND logic with two chemical inputs.

A novel molecular AND logic gate 1 is demonstrated based on the competition between fluorescence and photoinduced electron transfer (PET). It is constructed according to a 'receptor2-spacer-fluorophore-spacer-receptor1-spacer-fluorophore-spacer-receptor2' format where receptor1 is a tertiary amine, receptor2 is a benzo-15-crown-5 ether and the fluorophore is an anthracene moiety, which are separated from each other by methylene spacers. The fluorescence response in methanol is significantly enhanced only when both H+ and Na+ are the inputs at high enough concentrations in accordance with AND logic. Cs+ behaves similarly to Na+, but with a lower fluorescence enhancement, whereas the other alkali metal cations are not effective. Electrospray ionization mass spectrometry provides evidence for formation of 1:1 and 1:2 (1:metal) complexes with alkali cations, and formation of a 1:2:1 (1:metal:proton) complex in the additional presence of acid.