Agenesis of maxillary first molars is rare. Four young children referred by their pediatric dentist for lack of eruption of the maxillary first molars are presented. The dental age- and root development of the developing tooth germs in the maxillary permanent molar region was compared with that of the mandibular first and second molars. It was determined that the developing molars distal of the maxillary primary second molars were second molars and that the first molars were congenitally missing. A correct diagnosis of congenitally missing first molars avoids erroneous surgical exposure of unerupted second molars in young children.

IntroductionThis study used digital intraoral scans to evaluate how clear aligner treatment affects occlusal contacts and to determine the influence of sex and age on contact changes. Results were compared with contact changes that occur during fixed appliance therapy.MethodsPatients included in this study were treated in a University setting and private practice. Inclusion criteria were a Class I malocclusion treated nonextraction with clear aligners and the presence of pretreatment and posttreatment digital intraoral scans. Scans were imported into specialized software, and occlusal contacts were analyzed. The effects of age and sex on contact changes during clear aligner treatment were determined. Changes in occlusal contacts were compared with changes that occur during nonextraction treatment of patients with a Class I relationship using fixed edgewise appliances.ResultsA total of 45 clear aligner patients fit the eligibility criteria. Clear aligner treatment reduced the percentage of tight, near, and approximating contacts, whereas the percentage of open and no contacts increased. These changes in occlusal contacts were greater for the older age group studied. Genderinfluenced occlusal contact changes in the anterior dentition only where the decrease in near contacts and increase in open contacts were greater for males. These results for patients treated with clear aligners were similar to those for patients treated with fixed appliances; both treatment modalities reduced close occlusal contacts at the time active treatment was completed.ConclusionsThese results indicated that when clear aligners or fixed appliances are used to treat a Class I malocclusion, the resulting occlusion immediately after debonding is not as “tight” as it was at pretreatment.

Birth season has been inconsistently associated with anthropometrics, bone fractures, and malocclusion. Our aim was to assess the association between birth season and anthropometrics (height, weight, birth weight), bone fractures and dental malocclusion in the United States.

Objective: To evaluate cone-beam computed tomography (CBCT) image quality via cephalometric measurement variability while reducing radiation exposure by altering the radiographic technique. Materials and Methods: A human cadaver was imaged using a Morita Accuitomo 170 CBCT machine at various technique parameters: tube voltages of 60, 70, 80, and 90 kV, tube currents of 1, 2.5, and 5 mA, and rotational arcs of 180 degrees and 360 degrees. From the rotation data, standard cephalogram views were generated. Point radiation dose measurements were recorded at the entry of three key radiosensitive regions. Ten examiners measured seven cephalometric parameters on the conventional cephalogram and each derived view. Measurement error and dose were compared between radiographic techniques and a standard cephalometric procedure. Results: Generally insignificant differences in measurement error were observed when rotation arc was reduced from 360 degrees to 180 degrees, when tube current was reduced from 5 mA to 2.5 mA, and when tube voltage was reduced from 90 kV to 80 kV and 70 kV. Radiation dose could be halved for either of the rotation arc or tube current reductions; reducing both yielded dose comparable to standard cephalometric imaging. Using 1 mA or 60 kV rendered nondiagnostic images. Discussion: The study's cadaver included embalming fluid, a lack of patient-motion-induced image blur, and lesser bone density relative to a typical adolescent orthodontic patient, which can yield images not wholly representative of live patients. Conclusion: Orthodontists could image with CBCT using a 180 degrees arc of rotation, 2.5 mA, and 70 or 80 kV to reduce radiation dose while yielding images of adequate quality that are derived from three-dimensional data. (C) 2019 World Federation of Orthodontists.

Objective: Dental Monitoring (DM) is a software system that allows orthodontists to remotely monitor a patient's treatment. This study evaluated the accuracy of DM software in assessing the achievement of treatment goals in patients undergoing rapid palatal expansion treatment and patient acceptance of DM. Methods: Consecutively treated patients undergoing rapid palatal expansion were invited to participate. Participants were trained to capture intraoral photos/videos using the DM app. Maxillary intermolar width (mm) and posterior crossbite correction measured by DM were compared with digital models and intraoral measurements. Patient acceptance of the DM app was evaluated with a survey. Results: Of the 30 patients enrolled, 20 patients completed the study. DM accurately assessed the correction of posterior crossbite. There was no significant difference in intermolar width measurements obtained with DM, digital model, or intraoral examination. Overall, 71% of the participants found the DM app "easy" to work with and 43% of the patients preferred DM over a clinical visit. Conclusion: In-person evaluation of maxillary expansion with a Hyrax expander can be replaced with remote monitoring using the DM software, yet challenges associated with digital imaging hinder the use of this remote evaluation for some patients. (C) 2019 World Federation of Orthodontists.

The book's goal is to provide an update on the use of clinical cephalometrics, a goal that it more than adequately reaches. True to its title, the book provides a detailed description of both 2-dimensional (2D) and 3-dimensional (3D) analysis of the craniofacial skeleton.

Introduction: Tooth size and morphology of anterior teeth influence interarch relationships. The Bolton analysis uses tooth width to calculate a sum of mandibular to maxillary tooth width ratios necessary for proper occlusion. Several parameters not factored in the Bolton analysis influence occlusion, such as tooth thickness. This study sought to use 3D modeling to develop and assess a tooth size analysis that encompasses labioligual thickness as well as mesiodistal width of anterior teeth. Methods: The role of tooth thickness in interarch relationships was studied using simulations in a 3D modeling software (Suresmile). To develop a new chart of interarch ratios based on tooth thickness, a series of simulations were produced with varying tooth thicknesses and widths. The new ratios were evaluated on records from 50 patients. Results: Findings from the simulations suggest that the ideal tooth thickness remains approximately 2 mm if the overall tooth width of the dentition increases and the interarch anterior ratio is maintained. The thickness-adjusted anterior mandibular to maxillary tooth ratio ranges from 0.70-0.79 depending on the tooth thickness. This thickness-adjusted ratio provides a superior prediction for the sum of anterior tooth width compared with the Bolton analysis. Conclusion: Tooth thickness affects interarch tooth width ratios and anterior occlusion. A thickness-adjusted ratio can be used to more accurately predict anterior tooth dimensions necessary to achieve proper occlusion.

In a research article in the January 2017 issue, the feasibility of yttria-stabilized zirconia in fixed lingual retention as an alternative to stainless steel was explored (Stout MM, Cook BK, Arola DD, Fong H, Raigrodski AJ. Assessing the feasibility of yttria-stabilized zirconia in novel designs as mandibular anterior fixed lingual retention after orthodontic treatment. Am J Orthod Dentofacial Orthop 2017;151:63-73). I found the use of zirconia in this new application to be very innovative and interesting. The authors gave many advantages of this technique among which I found the lack of inadvertent activation of the retainer to be the most clinically useful. I applaud the authors for the detailed study, which is the first of its kind. My only concern is a biologic one, about the fundamental requirement that a retainer should not inhibit the physiologic mobility of teeth. Zachrisson1Zachrisson B.U. Multistranded wire bonded retainers: from start to success.Am J Orthod Dentofacial Orthop. 2015; 148: 724-727Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar explained that the composite bridges over many neighboring teeth became too rigid and would not allow the individual teeth to exert their normal physiologic mobility; hence, it was evident that a bonded retainer must have some elastic properties. Considering this, won't the inherent stiffness of zirconia prevent or at least reduce the physiologic mobility of the teeth. If the authors can throw some light on the stiffness of the material they used and if its resiliency is sufficient to allow physiologic mobility, it will be very enlightening. Assessing the feasibility of yttria-stabilized zirconia in novel designs as mandibular anterior fixed lingual retention after orthodontic treatmentAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 151Issue 1PreviewThe purpose of this study is to explore the feasibility of yttria-stabilized zirconia (Y-TZP) in fixed lingual retention as an alternative to stainless steel. Full-Text PDF Authors’ responseAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 151Issue 5PreviewThank you for reading our article and bringing up an important question regarding the material stiffness and its effects on physiologic tooth movement (Stout MM, Cook BK, Arola DD, Fong H, Raigrodski AJ. Assessing the feasibility of yttria-stabilized zirconia in novel designs as mandibular anterior fixed lingual retention after orthodontic treatment. Am J Orthod DentofacialOrthop 2017;151:63-73). We measured the material's flexibility with a 4-point bend test (results are presented in the Results section on page 66). Full-Text PDF

OBJECTIVE:To determine whether, in Class I borderline cases, experienced orthodontists choose nonextraction treatment more frequently than do orthodontists with less experience. A secondary aim was to evaluate whether clinicians' gender and place of education play a role in extraction decision making. MATERIALS AND METHODS:An online survey was developed using three Class I borderline patient cases. The survey included questions about clinicians' demographics as well as questions about the selected cases. The survey was distributed to approximately 2000 clinicians through the American Association of Orthodontics. RESULTS:Of the 253 responses collected, a trend was observed wherein clinicians with more than 15 years of experience preferred an extraction treatment option more frequently than did clinicians with less than 5 years of experience. There was no association between gender and place of education and the decision to extract in the selected borderline cases. Crowding, patient's profile, and mandibular incisor inclination were among the top three reasons chosen by clinicians for both the extraction and nonextraction treatment decisions. CONCLUSIONS:A trend was observed in which clinicians with more experience chose an extraction treatment option more frequently in borderline cases than did those with less experience. Clinicians' gender did not play a role in extraction decision making.

Introduction: We assessed the relationship between race and orthodontic service use for Medicaid-enrolled children. Methods: This cross-sectional study focused on 570,364 Medicaid-enrolled children in Washington state, ages 6 to 19 years. The main predictor variable was self-reported race (white vs nonwhite). The outcome variable was orthodontic service use, defined as children who were preauthorized for orthodontic treatment by Medicaid in 2012 and subsequently received orthodontic records and initiated treatment. Logistic regression models were used to test the hypothesis that nonwhites are less likely to use orthodontic care than are whites. Results: A total of 8223 children were approved by Medicaid for orthodontic treatment, and 7313 received records and began treatment. Nonwhites were significantly more likely to use orthodontic care than were whites (odds ratio [OR] = 1.18; 95% confidence interval [CI] = 1.02, 1.36; P = 0.031). Hispanic nonwhite children were more likely to use orthodontic care than were non-Hispanic white children (OR = 1.42; 95% CI = 1.18, 1.70; P < 0.001). Conclusions: In 2012, nonwhite children in the Washington Medicaid program were significantly more likely to use orthodontic care than were white children. The Washington Medicaid program demonstrates a potential model for addressing racial disparities in orthodontic service use. Future research should identify mechanisms underlying these findings and continue to monitor orthodontic service use for minority children in Medicaid.

Introduction: The purpose of this study is to explore the feasibility of yttria-stabilized zirconia (Y-TZP) in fixed lingual retention as an alternative to stainless steel. Methods: Exploratory Y-TZP specimens were milled to establish design parameters. Next, the specimens were milled according to ASTM standard C1161-13 and subjected to 4-point flexural tests to determine material properties. Finite element analysis was used to evaluate 9 novel cross-sectional designs, which were compared with stainless steel wire. Each design was analyzed under loading conditions to determine von Mises and bond stresses. The most promising design was fabricated to assess the accuracy and precision of current CAD/CAM milling technology. Results: The superior design had a 1.0 x 0.5 mm semielliptical cross-section and was shown to be fabricated reliably. Overall, the milling indicated a maximum percent standard deviation of 9.3 and maximum percent error of 13.5 with a cost of $30 per specimen. Conclusions: Y-TZP can be reliably milled to dimensions comparable with currently available metallic retainer wires. Further research is necessary to determine the success of the bonding protocol and the clinical longevity of Y-TZP fixed retainers. Advanced technology is necessary to connect the intraoral scan to an esthetic and patient-specific Y-TZP fixed retainer.

Self-etch primers and conventional acid-etch technique for orthodontic bonding: a systematic review and meta-analysis. Fleming PS, Johal A, Pandis N. Am J Orthod Dentofacial Orthop 2012;142:83-94. Anne-Marie Bollen, DDS, MS, PhD To assess the risk of attachment failure, bonding time, and demineralization adjacent to attachments between 1-stage (self-etch) and 2-stage (acid etch) bonding in orthodontic patients over a minimum follow-up period of 12 months Information not available Systematic review and meta-analysis Level 1: Good-quality, patient-oriented evidence Grade A: Consistent, good-quality patient-oriented evidence

Objectives: Deep bite occurs in about 15% to 20% of the US population. Currently, it is unknown which types of correction are most efficient or stable. The purpose of this systematic review was to investigate factors related to stability of deep-bite correction.Materials and Methods: An electronic search of 4 databases was performed from January 1, 1966 to June 27, 2012. Studies were considered for inclusion if they reported on deep bite samples that underwent orthodontic treatment in the permanent dentition. Records were required at the initial, posttreatment, and 1-year posttreatment times. Hand searching of reference lists of the included studies was performed. Data were abstracted using custom forms, and risk of bias was assessed using a modified Newcastle-Ottawa Scale.Results: Twenty-six studies met the inclusion criteria. Most were case series, with considerable potential for bias. The significant heterogeneity of the studies precluded meta-analyses, and only descriptive statistics and stratified comparisons were reported. On average, patients underwent significant overbite improvement during treatment, and most of the correction was maintained long-term. Across all studies, the mean initial overbite, posttreatment overbite, and long-term overbite were 5.3, 2.6, and 3.4 mm, respectively. Initial severity appeared to be related to long-term stability. However, this relationship was difficult to isolate from other factors. The length of follow-up did not appear to be related to the amount of relapse.Conclusions: Although the quality of the current evidence is not high, patients with deep-bite malocclusion appear to undergo relatively successful treatment, and most of the correction appears to be stable. (C) 2012 World Federation of Orthodontists. (C) 2012 World Federation of Orthodontists.

Effectiveness of early treatment of Class II malocclusion. Wheeler TT, McGorray SP, Dolce C, Taylor MG, King GJ. Am J Orthod Dentofacial Orthop 2002;121:9-17. Anne-Marie Bollen, DDS, MS, PhD To investigate the success of early treatment with a headgear/biteplate or a bionator in patients with Class II malocclusion and compare this to changes over a similar time period in untreated observation subjects. Government: National Institute of Dental Craniofacial Research Grant No. DE08715 Randomized controlled trial Level 1: Good-quality, patient-oriented evidence Grade B: Inconsistent or limited-quality patient-oriented evidence

This chapter contains sections titled: Introduction Methods Results Discussion Conclusions Acknowledgments

Some treatment options for impacted maxillary canines can lead to unfavorable outcomes. Autotransplantation is an option that involves atraumatic surgical removal of the canine and reimplantation into a previously created socket. The aim of this study was to evaluate survival and success rates after autotransplantation of maxillary permanent canines with closed apices. The sample consisted of 49 patients (mean age at transplantation, 21.8 years), who had autotransplantation of impacted maxillary canines. The sample was divided into 2 categories: 63 autotransplanted maxillary canines with no controls and 27 unilateral transplanted canines with a nontransplanted canine on the contralateral side as a control. Success was determined by using the following criteria: survival, mobility, probing pocket depth, gingival bleeding, vitality, color, internal and external inflammatory resorption, bone level, and signs of pathology. Thirty-eight percent of the sample was considered successful, and the overall survival rate was 83%, with an average duration of 14.5 years (range, 1.4-27.8 years). In the case control sample, the transplanted teeth had unfavorable differences compared with the nontransplanted teeth for probing pocket depth, gingival bleeding, vitality, and color, all of which were statistically significant. The results of this study indicate that autotransplanted canines with closed apices have a low complete success rate but can have a favorable survival rate over the long term. The technique should be considered as an interim measure to maintain bone level before placement of implants in patients who are unwilling to undergo lengthy orthodontic treatment to align ectopic canines.

This chapter contains sections titled: Background and Etiology Prevalence Evidence on the Relationship Between Malocclusion and Periodontal Health Evidence on the Relationship Between Orthodontic Treatment and Periodontal Health Future Directions Acknowledgments