The effects of dietary loading on the transdifferentiation of condylar chondrocytes.

INTRODUCTION: Transdifferentiation of chondrocytes into bone cells explains most condylar growth during prenatal and early postnatal stages, but the mechanisms regulating chondrocyte transdifferentiation during late postnatal growth remain unknown. This study aimed to quantify the effects of dietary loading on chondrocyte-derived osteogenesis during late postnatal condylar growth. METHODS: Two compound mouse lines were used to trace the fate of chondrocyte lineage in vivo. Twelve 3-week-old male Aggrecan-CreERT2 (AcanLineage); R26RTdTomato; 2.3 Col10a1-GFP and twelve 3-week-old male Col10a1-Cre (Col10a1Lineage); R26RTdTomato; 2.3Col1a1-GFP were randomly divided into experimental (soft-food diet, n = 6) and control (hard-food diet, n = 6) groups and kept for 6 weeks. One time, tamoxifen injections were given to AcanLineage mice at 3 weeks. Radiographic, microcomputed tomographic, and histomorphometric analyses were performed. RESULTS: Radiologic analysis showed that mice with a soft-food diet had smaller mandible lengths as well as decreased bone volume and density for their condylar process. Histologically, mice with soft diets had reduced activity in chondrocyte proliferation and maturation compared with the controls. Cell lineage tracing results showed the number of AcanLineage-derived bone cells (293.8 ± 39.8 vs 207.1 ± 44.6; P = 0.005), as well as total bone cells (445.6 ± 31.7 vs 360.7 ± 46.9; P = 0.004), was significantly higher in the hard-diet group than in the soft-diet group, whereas the number of non-AcanLineage-derived bone cells was not significantly different among groups (P = 0.938). Col10a1Lineage mice showed the same trend. CONCLUSIONS: Dietary loading directly affects condyle chondrogenesis and chondrocyte transdifferentiation, which alters the extent of condylar growth and remodeling.

Short-term skeletal and dentoalveolar effects of overexpansion.

OBJECTIVES: To evaluate whether the amount of rapid maxillary expansion differentially affects the skeletal and dentoalveolar changes that occur. MATERIALS AND METHODS: This randomized controlled trial included 23 patients who had rapid maxillary expansion (RME). Subjects were randomly assigned to a conventional expansion control group (n = 12) or an overexpansion group (n = 11), who started treatment at 13.2 ± 1.5 and 13.8 ± 1 years of age, respectively. Cone beam computed tomography scans (11 cm) were obtained prior to rapid maxillary expander (RME) delivery and approximately 3.7 months later. Initial hand-wrist radiographs were used to determine the participants' skeletal maturity. RESULTS: The RME screws were activated 5.6 ± 1.2 mm and 10.1 ± 0.6 mm in the conventional and overexpansion groups, respectively. Overexpansion produced significantly greater expansion of the nasal cavity (2.1X-2.5X), maxillary base (2.3X), buccal alveolar crest (1.4X), and greater palatine foramina (1.9X). Significantly greater intermolar width increases (1.8X) and molar inclination (2.8X) changes were also produced. The nasal cavity and maxillary base expanded 23%-32% as much as the screws were activated. Skeletal expansion was positively correlated with RME screw activation (R = 0.61 to 0.70) and negatively correlated (R = -0.56 to -0.64) with the patients' skeletal maturation indicators (SMIs). Together, screw activation and the patients' SMI scores explained 48%-66% of the variation in skeletal expansion. CONCLUSIONS: This pilot study shows that overexpansion produces greater changes than conventional expansion, with greater skeletal effects among less mature patients.

Keys to Class II correction: A comparison of 2 extraction protocols.

INTRODUCTION: The purpose of this study was to evaluate the effects of 2 extraction patterns on incisor and molar movements in patients with growing Class II Division 1. METHODS: The sample included 54 patients 10-17 years of age treated by 2 private practice orthodontists using Tweed directional force mechanics, 4 premolar extractions, J-hook headgears, and Class II elastics or Saif springs. The sample was divided on the basis of having maxillary and mandibular first premolars (4/4) or maxillary first and mandibular second premolars (4/5) extracted. Each group included 27 patients. Treatment lasted 2.8 ± 0.60 years and 2.6 ± 0.54 years for the 4/4 and 4/5 groups, respectively. Pretreatment (T1) and posttreatment lateral cephalograms and dental casts were evaluated. Cranial base, mandibular, and maxillary superimpositions were performed to quantify tooth movements and displacements. RESULTS: There were no statistically significant T1 between-group differences in crowding or in the SNA, SNB, ANB, and MPA angles. Analyses of covariance, controlling for statistically significant (P <0.05) differences in T1 mandibular incisor position, showed that mandibular first premolars extractions produced greater (1.6 mm) mandibular incisor retraction than second premolar extractions. The mandibular first molars were protracted significantly more (0.7 mm) after the second premolar than the first premolar extractions. Within-group changes of the MPA, between-group differences in the changes in MPA, and the amount of vertical eruption of the maxillary and mandibular molars were not significantly different between the 2 extraction patterns. CONCLUSIONS: Extraction of mandibular second premolars enhances Class II molar correction, with greater mesial first molar movement and less distal incisor movement. Neither extraction pattern has an effect on the MPA or the vertical dimension (ie, there was no "wedge effect").

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.

Is there a relationship between dental crowding and the size of the maxillary or mandibular apical base?

OBJECTIVE: To determine whether apical base size is related to dental crowding. MATERIALS AND METHODS: Digital scans of dental casts were taken of 75 untreated Class I adults to measure maxillary and mandibular tooth size, dental arch perimeters, intermolar widths, and intercanine widths. Cone beam computed tomography (CBCT) images were used to measure the apical base of the maxilla and mandible, including the total cross-sectional area, five basal arch perimeters and five basal arch widths. Principal components factor analyses were performed to evaluate the relationships between the apical base size and tooth-size-arch-length discrepancies (TSALD). RESULTS: The dental arch and maxillary apical base measures were significantly larger in males than females. There were only limited sex differences in mandibular apical base size. The dental arch measurements were smaller in subjects with greater upper and lower TSALD. Maxillary and mandibular apical base dimensions were positively interrelated. Low-to-moderate correlations were found between the size of the maxillary apical base and TSALD. The size of the mandibular apical base was not related to upper or lower TSALD. Tooth size showed little to no relationship with TSALD. CONCLUSIONS: Although maxillary apical base size is related to maxillary and mandibular crowding in subjects with Class I malocclusion, mandibular apical base size is not.

The prevalence of clinically meaningful malocclusion among US adults.

OBJECTIVE: The primary purpose of this study was to statistically evaluate age, ethnic and sex differences in the prevalence of clinically meaningful malocclusions among adults. SETTING AND SAMPLE POPULATION: A random sample of 8804 untreated US adults between 17 and 46 years of age was selected from the Third National Health and Nutrition Examination Survey data. MATERIALS & METHODS: Three ethnic (non-Hispanic White, non-Hispanic Black and Mexican Americans) and three age (17-26, 27-36 and 37-46 years) groups were evaluated. Subjects with and without clinically meaningful malocclusions were categorized based on the established cut-off values. Chi-square analyses were performed to determine differences in prevalence. RESULTS: The prevalence of clinically meaningful mandibular incisor irregularity, overjet and overbite increased significantly (P < 0.05) with age, while posterior crossbite decreased. There were statistically significant ethnic differences in the prevalence of incisor irregularity, overbite, overjet, open bite and reverse overjet. Males had a significantly higher prevalence of clinically meaningful mandibular incisor irregularity, overbite, open bite and reverse overjet than females. One-third of US adults exhibited no clinically meaningful malocclusions. CONCLUSIONS: There are age, ethnic and sex differences in the prevalence of clinically meaningful malocclusions that characterize approximately two-thirds of untreated US adults.

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.

Effects of micro-osteoperforations on tooth movement and bone in the beagle maxilla.

PURPOSE: The purpose of this study was to determine how micro-osteoperforations (MOPs) affect tooth movements, bone turnover, bone density, and bone volume. METHODS: A split-mouth experimental design with 7 beagle dogs was used to evaluate bone surrounding maxillary second premolars that had been retracted for 7 weeks. One month after the maxillary third premolars were extracted, 8 MOPs (1.5 mm wide and 7 mm deep) were created without flaps with the use of the Propel device (6 were placed 3 mm distal to the second premolar and 2 were placed in the premolar furcation) on one randomly chosen side. The maxillary second premolars were retracted bilaterally with the use of 200 g nickel-titanium closed coil springs. Tooth movements were measured intraorally and radiographically. Microscopic computed tomography was used to evaluate the material density and volume fraction of bone distal to the premolars. Hematoxylin and eosin-stained and fluorescent sections were used to examine the bone remodeling. RESULTS: Neither the intraoral (P = 0.866) nor radiographic (P = 0.528) measures showed statistically significant side differences in tooth movements. There also were no statistically significant differences in the density (P = 0.237) or volume fraction (P = 0.398) of bone through which the premolars were being moved. Fluorescent and histologic evaluations showed no apparent differences in osteoblasts, osteoclasts, or mineralization of bone near the teeth being moved. Bone healing was evident in and near the MOP sites, which had nearly but not completely healed after 7 weeks. Regions of acellular bone were evident extending ∼0.8 mm from the MOP sites. CONCLUSIONS: MOPs placed 3 mm away from teeth do not increase tooth movements and have limited and transitory effect on bone.

Effect of automated messaging on oral hygiene in adolescent orthodontic patients: A randomized controlled trial.

OBJECTIVE: To determine whether automated text messages sent daily to adolescent orthodontic patients improves oral hygiene more than weekly reminders. MATERIALS AND METHODS: A blinded, prospective, randomized controlled trial was designed to evaluate the effects of automated messages on oral hygiene. Subjects were recruited from patients undergoing orthodontic treatment at the Texas A&M University College of Dentistry, Department of Orthodontics. They were being treated with a variety of fixed full appliances in both arches. Subjects were randomly assigned to either a once-a-week text message group or a daily text message group. There were 52 females and 27 males who were 12 to 17 years of age. Oral hygiene was measured at the beginning of the study and again 8.6 ± 0.9 weeks later. RESULTS: The daily reminder group (N = 42) had significantly greater improvements in oral hygiene compliance than the weekly reminder group (N = 37). The daily score decreases were 48%, 21% and 19% for the bleeding index (BI), plaque index (PI), and gingival index (GI), respectively. The weekly score decreases were 27%, 14% and 13% for the BI, PI, and GI. There were no sex differences in hygiene changes during the study. The 42% of patients who completed the survey at the end of the study wanted more frequent messages and reported that messages related to decreasing treatment time were the most effective, while those related to oral hygiene were the least effective. CONCLUSIONS: Daily text messages are more effective at improving oral hygiene than weekly text messages.

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.

Prevalence of gingival recession after orthodontic tooth movements.

INTRODUCTION: This study was designed to evaluate the long-term prevalence of gingival recession after orthodontic tooth movements, focusing on the effects of mandibular incisor proclination and expansion of maxillary posterior teeth. METHODS: Records of 205 patients (162 female, 43 male) were obtained from 2 private practice orthodontists. Using pretreatment (age, 14.0 ± 5.9 years) and posttreatment (age, 16.5 ± 6.0 years) lateral cephalograms and dental models, mandibular incisor proclination and maxillary arch widths were measured. Gingival recession was measured based on posttreatment and postretention (age, 32.3 ± 8.5 years) intraoral photographs and models. Associations between tooth movements and gingival recession were evaluated statistically. RESULTS: Only 5.8% of teeth exhibited recession at the end of orthodontic treatment (only 0.6% had recession >1 mm). After retention, 41.7% of the teeth showed recession, but the severity was limited (only 7.0% >1 mm). There was no relationship between mandibular incisor proclination during treatment and posttreatment gingival recession. Incisors that finished treatment angulated (IMPA) at 95° or greater did not show significantly more recession than did those that finished less than 95°. There were weak positive correlations (r = 0.17-0.41) between maxillary arch width increases during treatment and posttreatment recession. CONCLUSIONS: Orthodontic treatment is not a major risk factor for the development of gingival recession. Although greater amounts of maxillary expansion during treatment increase the risks of posttreatment recession, the effects are minimal.

Certification renewal process of the American Board of Orthodontics.

The American Board of Orthodontics was established in 1929 and is the oldest specialty board in dentistry. Its goal is to protect the public by ensuring competency through the certification of eligible orthodontists. Originally, applicants for certification submitted a thesis, 5 case reports, and a set of casts with appliances. Once granted, the certification never expired. Requirements have changed over the years. In 1950, 15 cases were required, and then 10 in 1987. The Board has continued to refine and improve the certification process. In 1998, certification became time limited, and a renewal process was initiated. The Board continues to improve the recertification process.

IBC: índice Board CES / The IBC: CES Board Index

Resumen La medición de resultados de los tratamientos de ortodoncia es fundamental para evaluar objetivamente la calidad de la finalización y el éxito logrado por la terapia, y a su vez en la evaluación de los residentes del posgrado de ortodoncia. En la literatura se han reportado varios sistemas que permiten analizar dichos resultados, pero algunos no integran suficientes criterios o ayudas diagnósticas. La Universidad CES, basada en el American Board of Orthodontics-Objetctive Grading System (ABO-OGS), ha desarrollado un índice con 16 criterios analizados en modelos, radiografías y fotografías, que integran una medición objetiva de la finalización de los tratamientos. El propósito de este artículo fue describir el índice Board CES (IBC) como herramienta de evaluación de resultados clínicos de la ortodoncia y generar retroalimentación para el tratamiento de casos futuros mejorando la calidad de los mismos. Dicho índice podría ser empleado en universidades y en prácticas privadas.

The measurement of orthodontic treatment results is crucial to objectively assess the quality of the completion and success of therapy, and in turn in the evaluation of graduate orthodontic residents. The literature has reported several systems that analyze these results, but some do not integrate sufficient criteria or diagnostic aids. CES University, based on the American Board of Orthodontics - Objective Grading System (ABO - OGS), has developed an index with 16 criteria analyzed in models, radiographs and photographs, which allow an objective measurement of the completion of treatments. The purpose of this article was to describe the CES Board Index (IBC) as a tool for assessing clinical outcomes in orthodontics and generate feedback for the treatment of future cases improving their quality. This index could be used in Universities and in private practices.

Effects of high-speed curing devices on shear bond strength and microleakage of orthodontic brackets.

This study evaluated the shear-peel bond strength and mode of bond failure of 3 curing devices (plasma arc light, argon laser, and conventional halogen light) and 2 orthodontic bracket adhesives with different filler contents (Transbond XT and Adhesive Precoated [APC]). Observations of microleakage were also reported. Ninety human adolescent premolars were randomly divided into 6 groups, and standardized brackets were bonded according to the manufacturers' recommendations. The plasma arc light produced significantly (P =.006) higher bond strength than did the halogen light or the argon laser when Transbond was used. When APC was used, the plasma arc light and the halogen light produced similar results, and they both produced significantly (P =.015) higher bond strengths than did the argon laser. Overall, the APC showed substantially less variation in bond strength than did the Transbond. Although all curing methods showed significant microleakage (P <.001), differences among the 3 curing lights occurred only when APC was used. Microscopic evaluations demonstrated that 95% of the specimens failed for adhesion at the bracket or tooth surface; the argon laser produced the highest adhesive remnant index scores. On the basis of bond strength and microleakage results, the plasma arc light was comparable with or superior to the other curing devices, depending on the adhesive used.