2023-2024 American Board of Orthodontics practice analysis study: Part 1.

As a specialty board, the American Board of Orthodontics (ABO) serves to protect the public and the orthodontic specialty by certifying orthodontists. The demonstration of commitment to lifelong learning and self-improvement is critical to achieving the highest level of patient care. The ABO completed a practice analysis study in 2023 to ensure all examinations represent current assessments of proficiency in orthodontics at a level of quality that satisfies professional expectations. The practice analysis is essential to providing a demonstrable relationship between the examination content and orthodontic practice and provides a critical foundation for ABO's examination programs.

Relapse and failure rates between CAD/CAM and conventional fixed retainers: a 2-year follow-up of a randomized controlled clinical trial.

BACKGROUND: Retention has been always considered a major challenge in orthodontics. Recently computer-aided design/computer-aided manufacturing (CAD/CAM) fixed retainers (FRs) have been introduced as a marked development in retainer technology, offering potential advantages. OBJECTIVE: The objective of this study was to compare the differences in relapse and failure rates in patients treated with FRs using CAD/CAM technology, lab-based technique, and chairside method. TRIAL DESIGN: A double-blinded, prospective, randomized controlled clinical trial was conducted over a 2-year period at a single centre. INTERVENTIONS: These patients were divided into three groups: CAD/CAM group with multistranded Stainless Steel wires (CAD/CAM, n = 14), lab group with the same multistranded wires (lab, n = 15), and a chairside group with Stainless Steel Ortho-FlexTech wires (chairside, n = 14). OUTCOMES: Inter-canine width (ICW) and Little's irregularity index were digitally measured from scans at the orthodontic debonding (T1), 6-month retention (T2), 1-year retention (T3), and 2-year retention (T4) visits. All forms of failure were documented and analyzed. RANDOMIZATION: Participants were randomly assigned to the three groups using online randomization software (randomization.com) by a statistician who was not involved in the study. BLINDING: Patients were blinded in terms of the FR group to which they were each randomly assigned. The principal investigator was blinded upon data analysis since patients' records were coded to minimize observer and measurement bias. RESULTS: Initially 81 patients were assessed for eligibility. Seventy-five patients were randomly allocated into the three study groups. After 2-year follow-up, 43 patients came back for the follow-up and were analyzed. The CAD/CAM group showed significantly less reduction in ICW compared to the chairside group at all time intervals (P < .05) and compared to the lab group at 6 months (P = .038). In terms of LII, the CAD/CAM group exhibited significantly less change than the chairside and lab groups at all time intervals (P < .05). The CAD/CAM group had the lowest failure rate (21.4%), followed by chairside group (28.6%) and then lab group (33.3%), however the differences were insignificant. No harms were observed in the current study. CONCLUSION: Within 2 years of fixed retention, CAD/CAM FRs showed significantly less relapse than lab-based and chairside FRs. However, there was no significant difference in failure rates among the groups. TRIAL REGISTRATION: NCT05915273.

The effect of maxillary first and mandibular second premolar extractions on the posterior Bolton ratio.

INTRODUCTION: The anterior and overall Bolton ratios and their application in orthodontics are widely known. However, little has been reported about the posterior Bolton ratio, how it is affected by the extraction of posterior teeth, and its application in orthodontic treatment planning. This study aimed to investigate how extracting maxillary first and mandibular second premolars affects the posterior Bolton ratio. METHODS: The sample included 55 patients with Class I occlusion within 1 standard deviation of ideal anterior and overall Bolton ratios. The digitized models were subjected to virtual extraction of maxillary first premolars and mandibular second premolars and setup of posterior teeth in ideal occlusion. If space closure compromised occlusion, the teeth were moved to achieve ideal cusp-fossa or cusp-marginal ridge occlusion. The ideal setups were measured for residual interproximal spacing. Statistical analysis used R statistical software (version 2018; R Core Team, Vienna, Austria). RESULTS: The ideal nonextraction posterior Bolton ratio was determined from the sample to be 105.77 ± 1.99%. The ideal expected posterior Bolton ratio for maxillary first and mandibular second premolar extraction patients was 106.52 ± 2.52%. This significantly differed from the expected posterior Bolton ratio for the 4 first premolar extractions. Patients finished with an average of 1.28 mm net residual spacing between mandibular first premolars and first molars; 38.2% of patients finished with at least 1.5 mm of residual space, and 9.1% of patients finished with at least 2 mm of residual space. CONCLUSIONS: A patient with ideal anterior, posterior, and overall Bolton ratios treated with maxillary first and mandibular second premolar extractions to ideal occlusion will likely finish with some spacing in the mandibular dentition.

The effect of 4 first premolar extractions on the posterior Bolton ratio.

INTRODUCTION: Overall and anterior Bolton ratios have been well covered in the orthodontic literature; however, little has been reported on posterior Bolton ratios. Considering the frequency of premolar extractions in the specialty, it would be relevant to know how the posterior occlusion is affected by premolar extractions. This study aimed to investigate how the posterior Bolton ratio is affected by the extraction of the 4 first premolars. METHODS: Fifty-five patients with Class I occlusion within 1 standard deviation of ideal anterior and overall Bolton ratios models were selected and digitized. Tooth widths were measured. Virtual extractions of 4 first premolars were performed, and a digital setup of anterior and remaining posterior teeth observing ideal occlusion relationships was executed. When space closure compromised the occlusion, preference was given to the latter. Residual interproximal spacing was digitally measured on the setups. Analysis of variance and linear regression tests were used to identify factors contributing to interproximal spacing. RESULTS: An average of 1.1 mm of net residual spacing between mandibular second premolars and first molars was observed. In 27% of the sample, at least 1.5 mm of residual space was found. In addition, 16% showed at least 2 mm of residual space. The ratio of the maxillary second premolars to the mandibular second premolars and the width of the maxillary second premolars best explain residual space (r = 0.554; r2 = 0.307). A regression equation for predicting residual space is offered. CONCLUSIONS: Ideal anterior, posterior, and overall Bolton ratios treated with extraction of 4 first premolars and ideal occlusion will likely finish with some spacing in the mandible.

Class II malocclusion correction with Invisalign: Is it possible?

INTRODUCTION: This research aimed to determine whether Class II malocclusion can be treated with clear aligners after completing treatment with the initial set of aligners. METHODS: A sample of 80 adult patients were divided into Group 1 with Class I molar malocclusions (n = 40 [11 men and 29 women]; 38.70 ± 15.90 years) and Group 2 with Class II molar malocclusions (n = 40 [11 men and 29 women]; 35.25 ± 15.21 years). All patients had finished treatment with the initial set of Invisalign aligners (Align Technology, Santa Jose, Calif) without known centric occlusion-centric relation discrepancies, issues of compliance, or overcorrection. The 7 measurements using the American Board of Orthodontics (ABO) Model Grading System and millimetric measurements for anteroposterior (AP) and vertical dimensions were assessed and compared between the 2 groups at pretreatment, posttreatment ClinCheck (Align Technology) prediction, and posttreatment. RESULTS: No improvements were observed in the AP correction. The amount of AP correction in patients with Class II malocclusion was 6.8% of the predicted amount. The amount of overbite correction achieved was 28.8% and 38.9% of the predicted amounts in patients with Class I and Class II malocclusion, respectively. Significant improvements in alignment and interproximal contact scores were observed, with only slight improvements in total ABO scores. An increase in mean occlusal contacts score was observed after treatment. No patient with Class II malocclusions would meet the ABO standards after Invisalign treatment. CONCLUSIONS: The Invisalign system successfully achieves certain tooth movements but fails to achieve other movements predictably. No significant Class II correction or overjet reduction was observed with elastics for an average of 7-month duration in the adult population. Additional refinements may be necessary to address problems created during treatment, as evidenced by a posterior open bite incidence.

American Board of Orthodontics: Progress of the scenario-based clinical examination.

In 2017, the directors of the American Board of Orthodontics (ABO) decided to move forward with a new clinical examination format-a scenario-based examination. The first examination of this type was administered in February 2019, and 2 more exams have been given since then. Each examination consisted of at least 6 scenarios with 4-7 questions for each scenario. Questions came from 4 domains or categories-data gathering and diagnosis, treatment objectives and planning, treatment implementation and management, and critical analysis and outcomes assessment. As of today, 49% of members of the American Association of Orthodontists are ABO certified. For more information about the scenario-based examination and ABO certification or certification renewal processes, go to AmericanBoardOrtho.com.

American Board of Orthodontics: Update on the new scenario-based clinical examination.

The American Board of Orthodontics has updated its clinical examination process to remove barriers to the case-based examination, strengthen the specialty, and further distinguish board-certified orthodontists from other dental practitioners providing orthodontic care. The ABO adopted a scenario-based clinical examination and discontinued case requirements. The first new exam was administered in February 2019. It consisted of 6 scenarios with 4-7 questions for each scenario. The scenarios represent a variety of problems and patients, and the questions relate to data gathering and diagnosis, treatment objectives and planning, treatment implementation and management, and critical analysis and outcomes assessment. Feedback from the February 2019 exam was positive, and 4 more have been scheduled. For more information about the ABO certification process, go to AmericanBoardOrtho.com.

American Board of Orthodontics: Time for change.

The American Board of Orthodontics (ABO) works to certify orthodontists in a fair, reliable, and valid manner. The process must examine an orthodontist's knowledge, abilities, and critical thinking skills to ensure that each certified orthodontist has the expertise to provide the highest level of patient care. Many medical specialty boards and 4 American Dental Association specialty boards use scenario-based testing for board certification. Changing to a scenario-based clinical examination will allow the ABO to test more orthodontists. The new process will not result in an easier examination; standards will not be lowered. It will offer an improved testing method that will be fair, valid, and reliable for the specialty of orthodontics while increasing accessibility and complementing residency curricula. The ABO's written examination will remain as it is.

Common errors observed at the American Board of Orthodontics clinical examination.

The American Board of Orthodontics has developed tools to help examinees select patients to be used for the Board examination. The Case Management Form can be used to evaluate aspects of a patient's treatment that cannot be measured by other tools. The Case Management Form is a structured treatment-neutral assessment of orthodontic objectives and outcomes associated with a patient's treatment. Despite the availability of this form, examiners continue to see problems, including lack of attention to finishing details, inappropriate treatment objectives, excessive proclination of mandibular incisors due to treatment mechanics, excessive expansion of mandibular intercanine width, closing skeletal open bite with extrusion of anterior teeth leading to excessive gingival display, and failure to recognize the importance of controlling the eruption or extrusion of molars during treatment. In addition, some examinees exhibit a lack of understanding of proper cephalometric tracing and superimposition techniques, which lead to improper interpretation of cephalometric data and treatment outcomes.

Quality of occlusal outcome in adult class II patients after maxillary total arch distalization with interradicular mini-screws.

BACKGROUND: The aim of the investigation was to evaluate if a Class II malocclusion in adult patients can be successfully corrected by maxillary total arch distalization with interradicular mini-screws in combination with completely customized lingual appliances (CCLA). METHODS: Two patient groups were matched for age and gender to determine differences in the quality of final treatment outcome. The treatment results of 40 adult patients with a Class I malocclusion (Group 1) were compared with those of 40 adult patients with a moderate to severe Class II malocclusion (Group 2). All patients had completed treatment with a CCLA (WIN, DW Lingual Systems, Bad Essen, Germany) without overcorrection in the individual treatment plan defined by a target set-up. To compare the treatment results of the two groups, 7 measurements using the American Board of Orthodontics Model Grading System (ABO MGS) and linear measurements for anterior-posterior (AP) and vertical dimensions were assessed at the start of lingual treatment (T1), after debonding (T2B), and compared to the individual target set-up (T2A). RESULTS: A statistically significant AP correction (mean 4.5 mm, min/max 2.1/8.6, SD 1.09) was achieved in Group 2, representing 99% of the planned amount. The planned overbite correction was fully achieved in both the Class I and Class II groups. There was a statistically significant improvement in the ABO scores in both groups (Group 1: 39.4 to 17.7, Group 2: 55.8 to 17.1), with no significant difference between the two groups at T2B. 95% of the adult patients in Group 1 and 95% in Group 2 would meet the ABO standards after maxillary total arch distalization with a CCLA and interradicular mini-screws. CONCLUSIONS: CCLAs in combination with interradicular mini-screws for maxillary total arch distalization can successfully correct moderate to severe Class II malocclusions in adult patients. The quality of the final occlusal outcome is high and the amount of the sagittal correction can be predicted by the individual target set-up.

Forces and moments generated by 3D direct printed clear aligners of varying labial and lingual thicknesses during lingual movement of maxillary central incisor: an in vitro study.

OBJECTIVE: The objective of this study was to measure the forces and moments exerted by direct printed aligners (DPAs) with varying facial and lingual aligner surface thicknesses, in all three planes of space, during lingual movement of a maxillary central incisor. MATERIALS AND METHODS: An in vitro experimental setup was used to quantify forces and moments experienced by a programmed tooth to be moved and by adjacent anchor teeth, during lingual movement of a maxillary central incisor. DPAs were directly 3D-printed with Tera Harz TC-85 (Graphy Inc., Seoul, South Korea) clear photocurable resin in 100-µm layers. Three multi-axis sensors were used to measure the moments and forces generated by 0.50 mm thick DPAs modified with labial and lingual surface thicknesses of 1.00 mm in selective locations. The sensors were connected to three maxillary incisors (the upper left central, the upper right central, and the upper left lateral incisors) during 0.50 mm of programmed lingual bodily movement of the upper left central incisor. Moment-to-force ratios were calculated for all three incisors. Aligners were benchtop tested in a temperature-controlled chamber at intra-oral temperature to simulate intra-oral conditions. RESULTS: The results showed that increased facial thickness of DPAs slightly reduced force levels on the upper left central incisor compared to DPAs of uniform thickness of 0.50 mm. Additionally, increasing the lingual thickness of adjacent teeth reduced force and moment side effects on the adjacent teeth. DPAs can produce moment-to-force ratios indicative of controlled tipping. CONCLUSIONS: Targeted increases in thickness of direct 3D-printed aligners change the magnitude of forces and moments generated, albeit in complex patterns that are difficult to predict. The ability to vary labiolingual thicknesses of DPAs is promising to optimize the prescribed orthodontic movements while minimizing unwanted tooth movements, thereby increasing the predictability of tooth movements.

Evaluation of enamel thickness of mandibular incisors.

OBJECTIVE: To measure enamel thickness at the proximal surfaces of the mandibular incisors, using micro-computed tomography (micro-CT) scans. MATERIAL AND METHODS: Forty-one single-rooted mandibular incisors were selected and analyzed according to anatomical characteristics, to form three groups: Group 1 - central incisors (n = 18); Group 2 - right lateral incisors (n = 10); and Group 3 - left lateral incisors (n = 13). First, enamel thickness at the proximal contact areas of the mandibular incisors was measured. Second, the mesial and distal surfaces of the lateral incisors were compared. Finally, the relationship between the tooth width and the mean enamel thickness was determined. Each tooth was scanned with a micro-CT scanner, and the image was processed with SCANCO micro-CT onboard analysis software. RESULTS: There were no statistically significant differences in mean enamel thickness between the mesial and distal surfaces for each lateral incisor, or between contralateral lateral incisors. In all surfaces analyzed, the upper zones had statistically significantly thinner enamel (0.52 ± 0.10 mm) when compared to the middle and lower zones (0.60 ± 0.08 mm and 0.59 ± 0.08 mm, respectively). There was no correlation (r =0.07) between enamel thickness of the mandibular incisor and the tooth width. CONCLUSIONS: The enamel thickness of the mandibular incisors is similar on the mesial and distal surfaces, with the thinnest layer located at the upper zone.

Comparative assessment of relapse and failure between CAD/CAM stainless steel and standard stainless steel fixed retainers in orthodontic retention patients.

OBJECTIVES: To compare relapse and failure rates of computer-aided design/computer-aided manufacturing (CAD/CAM) and standard fixed retainers. MATERIALS AND METHODS: This single-center, single-blinded, prospective randomized clinical trial included 46 patients who completed active orthodontic treatment and complied with retention visits. The patients were randomly assigned to three groups: CAD/CAM group with multistranded stainless steel wires (CAD/CAM, n = 16), Lab group with the same multistranded wires (lab, n = 16), and control group with stainless steel Ortho-FlexTech wires (traditional, n = 14). Intraoral scans were obtained at placement of fixed retainers (T1), 3-month visit (T2), and 6-month visit (T3) and measured for intercanine width and Little's Irregularity Index. Failures were recorded. RESULTS: The CAD/CAM group experienced less intercanine width decrease than the traditional group at 3 months (mean difference, 0.83 ± 0.16 mm; 95% confidence interval [CI], 0.44-1.22; P < .001) and 6 months (mean difference, 1.23 ± 0.40 mm; 95% CI, 0.19-2.27; P < .05). The CAD/CAM group experienced less increase in Little's Irregularity Index compared with the lab group within 3 months (mean difference, 0.81 ± 0.27 mm; 95% CI, 0.12-1.49; P < .05). Failures from greatest to least were experienced by the lab group (43.8%), the CAD/CAM group (25%), and the traditional group (14.3%). CONCLUSIONS: Within 6 months of bonding fixed retainers, CAD/CAM fixed retainers showed less relapse than lab-based and traditional chairside retainers and less failures than lab-based retainers.

Three-dimensional cone-beam computed tomography comparison of shorty and standard Class II Carriere Motion appliance.

OBJECTIVES: To compare treatment effects of the standard and shorty Class II Carriere Motion appliances (CMAs) on adolescent patients. MATERIALS AND METHODS: Fifty adolescents with Class II malocclusion formed group 1, who were treated with shorty CMA (n = 25, 12.66 ± 1.05 years), and age- and sex-matched group 2, who were treated with standard CMA (n = 25, 12.73 ± 1.07 years). Treatment effects were analyzed by tracing with Invivo software to compare pretreatment (T1) cone-beam computed tomography (CBCT) images with post-CMA (T2) CBCT images. A total of 23 measurements were compared within and between groups. RESULTS: In groups 1 and 2, maxillary first molars showed significant distal movement from T1 to T2 (1.83 ± 2.11 mm and 2.14 ± 1.34 mm, respectively), with distal tipping and rotation in group 1 (6.52° ± 3.99° and 3.15° ± 7.52°, respectively) but only distal tipping (7.03° ± 3.45°) in group 2. Similarly, in both groups, the maxillary first premolars experienced significant distal movement with distal tipping but no significant rotation. In group 1, maxillary canines did not undergo significant distal movement. In both groups 1 and 2, mandibular first molars experienced significant mesial movement (1.85 ± 1.88 mm and 2.44 ± 2.02 mm, respectively). Group 1 showed statistically significantly less reduction in overjet and less canine distal movement with less distal tipping than group 2 (α < .05). CONCLUSIONS: The shorty CMA achieved Class II correction similarly to the standard CMA, with less change in overjet and distal tipping movement of the maxillary canines.

Evaluation of enamel thickness of mandibular incisors

ABSTRACT Objective: To measure enamel thickness at the proximal surfaces of the mandibular incisors, using micro-computed tomography (micro-CT) scans. Material and Methods: Forty-one single-rooted mandibular incisors were selected and analyzed according to anatomical characteristics, to form three groups: Group 1 - central incisors (n = 18); Group 2 - right lateral incisors (n = 10); and Group 3 - left lateral incisors (n = 13). First, enamel thickness at the proximal contact areas of the mandibular incisors was measured. Second, the mesial and distal surfaces of the lateral incisors were compared. Finally, the relationship between the tooth width and the mean enamel thickness was determined. Each tooth was scanned with a micro-CT scanner, and the image was processed with SCANCO micro-CT onboard analysis software. Results: There were no statistically significant differences in mean enamel thickness between the mesial and distal surfaces for each lateral incisor, or between contralateral lateral incisors. In all surfaces analyzed, the upper zones had statistically significantly thinner enamel (0.52 ± 0.10 mm) when compared to the middle and lower zones (0.60 ± 0.08 mm and 0.59 ± 0.08 mm, respectively). There was no correlation (r =0.07) between enamel thickness of the mandibular incisor and the tooth width. Conclusions: The enamel thickness of the mandibular incisors is similar on the mesial and distal surfaces, with the thinnest layer located at the upper zone.

RESUMO Objetivo: Medir a espessura do esmalte nas superfícies proximais dos incisivos inferiores, usando imagens de microtomografia computadorizada (micro-CT). Material e Métodos: Quarenta e um incisivos inferiores com raiz única foram selecionados e analisados de acordo com as características anatômicas, formando três grupos: Grupo 1 - incisivos centrais (n = 18); Grupo 2 - incisivos laterais direitos (n = 10); e Grupo 3 - incisivos laterais esquerdos (n = 13). Primeiro, foi medida a espessura do esmalte nas áreas de contato proximal dos incisivos inferiores. Em segundo lugar, as faces mesial e distal dos incisivos laterais foram comparadas. Por fim, foi determinada a relação entre a largura do dente e a espessura média do esmalte. Cada dente foi escaneado com um scanner micro-CT, e a imagem foi processada com o software de análise SCANCO micro-CT. Resultados: Não houve diferenças estatisticamente significativas na espessura média do esmalte entre as superfícies mesial e distal de cada incisivo lateral, ou entre os incisivos laterais contralaterais. Em todas as superfícies analisadas, as zonas superiores apresentaram esmalte significativamente mais fino (0,52 ± 0,10 mm) quando comparadas às zonas média e inferior (0,60 ± 0,08 mm e 0,59 ± 0,08 mm, respectivamente). Não houve correlação (r = 0,07) entre a espessura do esmalte do incisivo inferior e a largura do dente. Conclusões: A espessura do esmalte dos incisivos inferiores é semelhante nas faces mesial e distal, com a camada mais fina localizada na zona superior.