Tooth agenesis: An overview of diagnosis, aetiology and management.

Patients with one or more developmentally absent teeth are routinely encountered in dental practice. Tooth agenesis can be associated with significant functional, aesthetic and psycho-social problems. The present article provides an overview of the prevalence and aetiology of tooth agenesis, as well as the condition's clinical characteristics and management options with reference to the evidence base. A timely diagnosis can facilitate the appropriate planning and management which might not be straightforward, and patient care will likely require multi- and inter-disciplinary input. It is critical that dental care practitioners are aware of the clinical characteristics and management options for tooth agenesis.

Evaluation of the predicted vs. achieved occlusal outcomes with the Invisalign® appliance: A retrospective investigation of adult patients.

INTRODUCTION: The aim of this study was to investigate the relationship between occlusal contacts, overbite, transverse expansion, and the buccolingual inclination of the teeth with reference to the predicted treatment outcomes and achieved outcomes related to the use of the Invisalign® appliance in mild-to-moderate Class I malocclusions. MATERIAL AND METHODS: The occlusal contacts, overbite, the buccolingual inclination and transverse expansion of the maxillary arch of adult patients satisfying inclusion and exclusion criteria were measured at the initial (pre-treatment), predicted, and achieved treatment stages using metrology software. Pearson correlation coefficients and regression equations were calculated to determine the association between the initial, predicted and achieved changes in occlusal contact against the other variables. RESULTS: Thirty-three patients, who commenced treatment between 2013 and 2018 and satisfied inclusion/exclusion criteria were evaluated. An overall loss of posterior contact was recorded and highlighted by a significantly greater loss of contact from the maxillary buccal occlusal surfaces compared to the palatal occlusal surfaces. The mean [SD] achieved overbite outcome (2.94mm [1.17]) was greater than the predicted (1.74mm [0.87), P<0.001). The buccolingual inclination was significantly increased for the lateral incisors and first and second molars despite a predicted decrease (P≤0.007). Achieved transverse expansion showed significant variation from the predicted. The loss of posterior occlusal contact was correlated with the buccolingual inclination (r=0.70) and transverse expansion (r=0.74) of the posterior teeth. CONCLUSIONS: In mild-to-moderate Class I malocclusions, treatment using the Invisalign® appliance resulted in an overall loss of posterior contact. The loss of occlusal contact was correlated with deficiencies in achieved buccolingual inclination and transverse expansion of the posterior teeth. Planned bodily expansion was ineffective as most expansion occurred due to unplanned buccal tipping.

How readable are orthognathic surgery consent forms?

BACKGROUND/OBJECTIVE: The valid consent process for medical intervention requires the disclosure of information in a format that is easily understandable by the patient. The aim of this investigation was to assess the readability of orthognathic surgery informed consent forms (OSICFs). METHODS: An online search methodology was conducted to identify OSICFs for analysis. The forms that satisfied inclusion/exclusion criteria were evaluated according to a standardised protocol. The readability of the content was assessed using three validated tools: the Simple Measure of Gobbledegook (SMOG) score, Flesch-Kincaid Grade-Level (FKGL) score and Flesch Reading Ease (FRE) score. RESULTS: Most of the 26 evaluated OSICFs were sourced from websites within the United States (69.2%) and from oral and maxillo-facial surgery practices (76.9%). Two of the assessed forms were template OSICFs available from oral and maxillo-facial professional societies to its members. The scores from the three tools found that the content of 84.6% to 92.3% of the forms were "difficult" to read. The mean (SD) SMOG score for all evaluated OSICFs was 12.31(2.22) [95% CI: 11.42 to 13.21]. The SMOG and FKGL scores were closely correlated (r=0.99, P < 0.0001; 95% CI: 0.9864 to 0.9973). There was no association between SMOG scores and the number of words contained within each consent form (r=-0.047;95% CI: -0.44 to 0.36). CONCLUSIONS: The OSICFs surveyed in this investigation failed to meet recommended readability levels. A significant number of patients are not likely to understand the information contained within the forms. Orthodontists are advised that poor literacy skills of their patients may preclude them from validly consenting to orthognathic surgery treatment procedures.

Analysis of the information contained within TikTok videos regarding orthodontic retention.

BACKGROUND: To analyze the content, reliability, and quality of relevant TikTok videos regarding orthodontic retention. METHODS: Six relevant terms were searched on the TikTok social media Web site. Uploaded videos satisfying inclusion/exclusion criteria were assessed for the presence of nine predetermined content domains and categorized as "high-content" (≥5) or "low-content" (<5). Reliability was determined using the DISCERN instrument and quality by the Global Quality Score (GQS). Layperson videos were evaluated for themes using discourse analysis. Intraclass coefficients for content, DISCERN scores, and GQS were calculated for intrarater reliability. Statistical analysis was via IBM SPSS Statistics (version 27.0.0.0; SPSS Inc. Chicago, IL). RESULTS: Orthodontists uploaded 37.8% and laypersons 34% of the 209 assessed videos. Just 22.1% of videos were considered to be 'high-content.' Quality of life issues related to retainer wear was the domain that was present least often in the videos provided by orthodontists (13.9%) and most often in those uploaded by laypersons (53.5%). High-content videos recorded greater mean GQS and DISCERN scores compared with low-content videos (P < 0.001). Strong positive associations existed between the number of domains present and DISCERN scores (rho = 0.808; P < 0.01) and between GQS and DISCERN scores (rho = 0.67; P < 0.01). Intraclass coefficient scores ranged between 0.92 and 0.98. Dissatisfaction with the need for long-term retainer wear was a prevalent negative theme in layperson videos. CONCLUSIONS: The content, reliability, and quality of TikTok videos regarding orthodontic retention were poor. The orthodontic profession must use TikTok effectively to ensure it delivers high-quality information relevant to laypersons' concerns.

Orthodontic clear aligners and TikTok videos: A content, reliability and quality analysis.

BACKGROUND AND OBJECTIVES: The social media platform, TikTok, has the potential to disseminate orthodontic information to an enormous global audience. The aim of this investigation was to assess the content, reliability and quality of videos regarding orthodontic clear aligners (OCAs) on the TikTok platform. METHODS: Three search terms were used to identify relevant videos. Characteristics such as video source and the number of views were documented. An 8-point information domain score was applied to categorise the videos as "not useful", "slightly useful", "moderately useful" and "very useful". The DISCERN tool and the Global Quality Score (GQS) were used to evaluate video reliability and quality. Intraclass coefficients (ICC) were computed for intrarater reliability. Statistical analyses were via IBM® SPSS®, version 27.0.0.0 (SPSS Inc. Chicago, IL, USA). RESULTS: Of the 117 videos that satisfied inclusion/exclusion criteria, most were uploaded by laypersons (44.4%) and orthodontists (35.9%). The assessed videos had over 300 million views. The overall mean (SD) number of information domains present in the videos was 1.85/8 (1.73). Most videos were deemed "slightly useful" (54.7%) or "not useful" (26.5%). The overall mean (SD) DISCERN score was 1.8/5 (1.28). The overall mean (SD) GQS was 2.48/5 (0.86). Higher DISCERN scores correlated with higher GQS (r=0.73; P<0.01). ICC scores (0.92-0.94) indicated excellent intrarater reliability. CONCLUSIONS: The content, reliability and quality of videos found on TikTok related to OCAs was poor. The orthodontic profession must direct patients to reliable and high-quality resources as well as uploading content onto TikTok to counteract the deficiencies highlighted in this study.

Ectopic and impacted maxillary canines: A quality evaluation of online information.

OBJECTIVE: To determine the quality of online information regarding ectopic and impacted maxillary canines (EIMCs). DESIGN: A cross-sectional survey on the Internet. MATERIAL AND METHODS: An online search using eight terms was carried out using four search engines. The relevant content of websites satisfying the inclusion and exclusion criteria were assessed for quality by applying three quality of information instruments and one readability tool. Statistical analyses were performed through GraphPad Prism 9.0. RESULTS: In total, 77 websites were evaluated. Most of the assessed content was associated with oral and maxillofacial surgery (49.35%) and orthodontic websites (31.18%). The overall mean DISCERN score was 38.05 ± 9.76/80 with 59.73% of websites recording a poor or very poor score. Three (3.9%) websites contained the HONCode seal. Twelve (15.58%) websites satisfied at least three out of a maximum four JAMA benchmarks and 11 (14.29%) satisfied none. The mean SMOG score was 9.81 ± 1.52 (95% confidence interval = 9.46-10.16; range = 6.7-15.1). CONCLUSION: The quality of online information related to EIMCs was poor and the content was difficult to read. Professional societies and clinicians should consider the use of quality of information and readability tools to enable the provision for reliable, high-quality and readable online information. This will assist EIMC treatment-related decision-making and management by patients and their families.

Orthodontic treatment consent forms: A readability analysis.

OBJECTIVE: To evaluate the readability of orthodontic treatment informed consent forms (ICFs). DESIGN: A cross-sectional observational investigation. METHODS: An online search strategy was adopted to identify ICFs for orthodontic treatment. The text of each form that satisfied inclusion criteria was modified to a standardised protocol. The readability was evaluated using three validated instruments. GraphPad Software (GraphPad Software Inc., La Jolla, CA, USA) was used for statistical analyses. RESULTS: A total of 59 ICFs were evaluated. The majority were available on the websites of orthodontists (66.1%) and general dentists (27.1%). The scores recorded from the three instruments indicated that the content of 93.2%-98.3% of ICFs was difficult to read. A strong correlation was observed between the Simple Measure of Gobbledegook (SMOG) and the Flesch Kincaid Grade level (FKGL) instruments (r = 0.9782; P < 0.0001). The mean SMOG score for all assessed forms was 11.19 (95% confidence interval [CI] 10.85-11.54). The ICFs authored by the manufacturers of orthodontic appliances provided by clinicians recorded a mean Flesch Reading (FRE) score of 40.14 (95% CI 33.91-46.37) out of a maximum 100. An analysis of the SMOG scores indicated that the content of ICFs authored by national orthodontic societies was more difficult to read than those written by all other authors (P=0.01; 95% CI -1.6 to -0.2). CONCLUSION: The readability of the ICFs was too difficult for a significant number of the population. Many patients will be unable to validly consent to treatment based solely on reading of the content of the evaluated ICFs. A greater effort is required to improve the readability of ICFs to help ensure patient autonomy regarding orthodontic treatment decision-making and management.

What's in a hashtag: A content evaluation of Instagram posts related to orthodontic retention and retainers.

OBJECTIVE: To evaluate and compare the content of posts placed on Instagram by orthodontic treatment providers (OTP) and patients regarding orthodontic retention and retainers. MATERIALS AND METHODS: Six "hashtag" terms related to orthodontic retention were searched on the social media Web site, Instagram. Relevant uploaded posts were evaluated for the presence of nine retainer and retention-related domains. Patient posts were also qualitatively evaluated for themes via discourse analysis. Descriptive and univariate statistical analyses were carried out. Cohen's kappa intrarater reliability testing was performed. RESULTS: Most of the 144 posts that satisfied inclusion criteria were uploaded by OTPs (81.9%). Text and image(s) comprised 86.8% of posts. The most frequently included domain posted by OTPs related to "what is a retainer" and "the importance of wearing a retainer" (49.2%). Posts by OTPs referred to a greater number of domains (P = 0.028), whereas posts by patients recorded comparatively more "quality-of-life"-related content (P = 0.027). Most patient posts were positive (53.8%). The main negative theme within patient posts related to retainer discomfort and the unhappiness associated with the requirement for indefinite retainer wear. The intrarater score was 0.89 for the presence of domains. CONCLUSIONS: OTPs appear to use Instagram for posting orthodontic retention-related information more often than patients. The content of Instagram posts differed between OTPs and patients. OTPs must ensure that the content of their Instagram posts is relevant to the concerns articulated in posts uploaded by patients.

Orthodontic temporary anchorage devices: A qualitative evaluation of Internet information available to the general public.

INTRODUCTION: The evaluation of online information regarding orthodontic temporary anchorage devices (TADs) is lacking despite the increase in their use by orthodontists. This cross-sectional study aimed to investigate the quality of information regarding TADs available on the Internet to the general public. METHODS: Two search terms ("orthodontic temporary anchorage device" and "orthodontic miniscrew") were entered separately into a total of 5 search engines. The DISCERN instrument, Journal of the American Medical Association (JAMA) benchmarks, and Health on the Net Foundation Code of Conduct were used to evaluate the quality of information contained within Web sites that satisfied the inclusion and/or exclusion criteria. Web site readability was assessed via the Simple Measure of Gobbledygook and Flesch Reading Ease Score tools. Descriptive statistical analyses and Cohen's kappa intrarater reliability tests were performed. RESULTS: Thirty-one Web sites were evaluated. Most were authored by orthodontists (77.4%) and originated from the U.S. (38.7%). The mean (standard deviation [SD]) DISCERN score was 41.87 (8.45) out of 80, with a range of 27-57. Intrarater reliability testing for DISCERN scores was excellent (0.84). Four Web sites achieved all 4 JAMA benchmarks, and 2 achieved none. Referencing of content sources throughout the Web sites scored least via DISCERN (mean 1.49 out of 5 per Web site [SD, 0.77]) and JAMA (19.35% of Web sites). One Web site contained the Health on the Net Foundation Code of Conduct seal. The mean (SD) Simple Measure of Gobbledygook score was 8.75 (1.25), with a range of 6.5-11.3. The mean (SD) Flesch Reading Ease Score was 59.81 (7.17), with a range of 47.6-73.8. CONCLUSIONS: The quality of information related to TADs on the Internet is moderate. The usefulness of the information may be further reduced because it was beyond the readability of the average member of the general public. Web site authors should consider the use of additional expertise, quality of information tools, and readability formulas to ensure high-quality and easily readable content.

Orthodontic retention and retainers: Quality of information provided by dental professionals on YouTube.

INTRODUCTION: The evaluation of the quality of information (QOI) contained within oral health-related videos on the video-streaming Web site YouTube has been limited. This study aimed to determine the QOI regarding orthodontic retention and retainers contained within videos uploaded by dental professionals (DPs) to YouTube. METHODS: YouTube was systematically searched using 4 terms. The top 50 videos per search term by "number of times viewed" were stored in a specially created account. Following the application of inclusion/exclusion criteria, the videos were assessed for viewing characteristics, and a 4-point scoring system (0-3) was applied to evaluate QOI in 10 predetermined domains. Descriptive statistical analyses, intrarater, and interrater reliability tests were performed. RESULTS: Strong intrarater and interrater reliability scores were observed. Sixty-two videos from the top 50 most-viewed DPs were viewed a total of 1,367,810 times (range 77- 529,543). Most DPs originated from the United States (68%), and orthodontists (88%) uploaded most videos. The mean number (standard deviation [SD]) of reported domains was 5.5 out of 10 (SD, 2.2). The mean overall QOI score per domain was 1.14 out of 3 (SD, 0.64). The "importance of retention" domain scored highest (2.18; SD, 1.2). "The need for retention reviews" domain scored the lowest (0.3; SD, 0.65). The mean overall QOI score per DP was 11.72 out of 30.00 (SD, 5.85). CONCLUSIONS: The QOI related to orthodontic retention and retainers contained within videos provided by DPs through the YouTube Web site is deficient, particularly the need for retainer review. Orthodontists should be aware of the importance of YouTube as an information resource and ensure that videos related to orthodontic retention and retainers contain relevant, high-quality, and evidence-based information.

The influence of miniscrew insertion torque.

Objective: The aim of this in vitro study was to evaluate the progressive development of surface microdamage produced following the insertion of orthodontic miniscrews (OMs) into 1.5 mm thick porcine tibia bone using maximum insertion torque values of 12 Ncm, 18 Ncm, and 24 Ncm. Methods: Aarhus OMs (diameter 1.5 mm; length 6 mm) were inserted into 1.5 mm porcine bone using a torque limiting hand screwdriver set at 12 Ncm, 18 Ncm, and 24 Ncm. A custom rig equipped with a compression load cell was used to record the compression force exerted during manual insertion. A sequential staining technique was used to identify microdamage viewed under laser confocal microscopy. Virtual slices were created and stitched together to form a compressed two-dimensional composition of the microdamage. Histomorphometric parameters, including total damage area, diffuse damage area, maximum crack length, maximum damage radius, and maximum diffuse damage radius, were measured. Kruskal-Wallis Tests and Wilcoxon Rank-Sum Tests were used to analyse the generated data. Results: All OMs inserted using 12 Ncm failed to insert completely, while partial insertion was observed for two OMs inserted at 18 Ncm. Complete insertion was achieved for all OMs inserted at 24 Ncm. Histomorphometrically, OMs inserted using 24 Ncm produced a significantly larger diffuse damage area (P < 0.05; P < 0.05) and maximum diffuse damage radius (P < 0.05; P < 0.05), for both the entry and exit surfaces, respectively, compared with the 12 Ncm and 18 Ncm groups. Conclusions: Insertion torque can influence the degree of OM insertion and, subsequently, the amount of microdamage formed following insertion into 1.5 mm thick porcine tibia bone. An increase in insertion torque corresponds with greater insertion depth and larger amounts of microdamage.

Influence of cortical bone thickness on miniscrew microcrack formation.

INTRODUCTION: The aim of this in-vitro study was to investigate the influence of cortical bone thickness on the amount of surface microdamage produced after insertion of orthodontic miniscrews (OM) in porcine tibia bone. METHODS: Aarhus OMs (Medicon, Tuttlingen, Germany; diameter, 1.5 mm; length, 6 mm) were inserted into 1.0 mm (group A; n = 10), 1.5 mm (group B; n = 10), and 2.0 mm (group C; n = 10) of porcine cortical bone using a torque-limiting hand screwdriver set at 18 Ncm. A sequential staining technique was used to identify microdamage under laser confocal microscopy. Virtual slices were stitched together using ImageJ software (National Institutes of Health, Bethesda, Md) to form a compressed 2-dimensional composition of the microdamage. The ImageJ software was used to quantify the total damage area, diffuse damage area, maximum crack length, maximum damage radius, and maximum diffuse damage radius. Kruskal-Wallis tests and Wilcoxon rank sum tests were used to analyze the data. RESULTS: All OMs in group A (1.0 mm) were inserted completely; however, 2 OMs from group B (1.5 mm) and all OMs in group C (2.0 mm) failed to insert completely. The entry surface of group C (2.0 mm) exhibited significantly higher amounts of total damage, diffuse damage area, maximum crack length, and maximum crack damage radius compared with groups A (1.0 mm) and B (1.5 mm). The maximum crack length observed on the entry and exit surfaces ranged from 1.03 to 3.06 mm. CONCLUSIONS: In this study, we demonstrated a higher level of microdamage after the insertion of OMs into 2.0-mm thick cortical bone compared with 1.0-mm thick cortical bone. Therefore, clinicians need to consider the thickness of the cortical bone at the insertion site, because mechanisms to reduce cortical bone thickness would likely reduce the amount of microdamage formed. A safety zone of 3.5 mm from the OM is also recommended for OMs inserted into 1.0- and 1.5-mm cortical bone thicknesses to minimize any detrimental effects after targeted remodeling.

Malocclusions in young children: Does breast-feeding really reduce the risk? A systematic review and meta-analysis.

BACKGROUND: Researchers have purported that breast-feeding can decrease the risk of malocclusions. The authors studied the relationship of breast-feeding on malocclusions in young children by means of conducting a systematic review of association (etiology). TYPES OF STUDIES REVIEWED: The authors used a 3-step search strategy, including electronic searches. They considered studies whose investigators included healthy children with primary dentition with a history of breast-feeding and in which the study investigators had assessed specific malocclusion outcomes to be eligible for inclusion in this review. The authors considered prospective and retrospective (longitudinal) studies, case-control studies, and analytical cross-sectional studies. Two of the authors, using standardized instruments, independently assessed the methodological quality and extracted data from the included studies. For situations for which there were a sufficient number of studies, the authors conducted meta-analyses using the random-effects model, supplemented with the fixed-effects model in situations for which statistical heterogeneity was 50% or less, assessed using the I2 statistic. RESULTS: The authors identified 7 studies that were included in the review. They found that children who had breast-fed suboptimally had an increased risk of developing malocclusions and that a strong and significant association existed between a shorter duration of breast-feeding (less than 12 months) and the development of an anterior open bite (n = 1,875; risk ratio, 3.58; 95% confidence interval, 2.55 to 5.03; P < .00001) and a class II canine relationship (n = 1,203; risk ratio, 1.65; 95% confidence interval, 1.38 to 1.97; P < .00001). CONCLUSIONS: Young children with a history of suboptimal breast-feeding have a higher prevalence and risk ratio for malocclusions. These children have an increased risk of developing a class II canine relationship, posterior crossbite, and anterior open bite. PRACTICAL IMPLICATIONS: Dental health care professionals should continue to encourage and promote breast-feeding; however, patients should be aware that children still can develop malocclusions, despite having received optimal breast-feeding, owing to the multifactorial etiology of malocclusions.

Effect of breastfeeding on different features of malocclusions in the primary dentition: a systematic review protocol.

REVIEW QUESTION/OBJECTIVE: The objective of this review of association (etiology) is to identify the association of breastfeeding with the development of different features of malocclusions in the primary dentition. The specific review questions are: What is the risk of developing different features of malocclusions in the primary dentition.

Qualitative evaluation of pretreatment patient concerns in orthodontics.

INTRODUCTION: A discrepancy exists between objective and subjective measures of orthodontic treatment need, highlighting the importance of patients' perceptions. Limited qualitative information is available regarding patients' perceptions and orthodontic concerns. For the first time, patient facial images and qualitative methodology were used to assess patients' orthodontic concerns, which are incorporated into and are important in treatment planning and consent. METHODS: An interview-based, cross-sectional study of adolescent patients eligible to receive orthodontic treatment in a public dental hospital was conducted with 105 adolescents (42 boys, 63 girls) aged between 12 and 17 years. Each patient's face was video recorded, and 3 images were selected from each recording to assess the patient's orthodontic concerns. The initial chief concerns were compared with concerns articulated after the patients assessed their facial images. In addition, patient concerns were compared with occlusal features visible on smiling using the Dental Aesthetic Index and patient study casts. RESULTS: For 37% of the adolescent patients, smiling images helped to identify additional concerns. For 87%, their smiling images helped them to describe their concerns in more detail. In addition, a few patients did not articulate any concern about features measurable on the Dental Aesthetic Index that were visible on smiling. CONCLUSIONS: Showing adolescent patients images of their face and smile helped them to identify and better describe their concerns. Adolescents are not always overly concerned about visible and quantifiable malocclusion features. This might influence orthodontic treatment planning and consent.

The psycho-social impact of malocclusions and treatment expectations of adolescent orthodontic patients.

OBJECTIVES: To evaluate the short- and long-term orthodontic treatment (OT) expectations, malocclusion severity, and oral health-related quality of life (OHRQoL) status of adolescent patients using qualitative and quantitative methodology. MATERIALS AND METHODS: Adolescents (n = 105; 42 males and 63 females) aged between 12 and 17 years participated in this interview and questionnaire-based study. The Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) and the Oral Impacts on Daily Performances (OIDP) scale evaluated OHRQoL status. Study casts were analysed using the Dental Aesthetics Index (DAI) and the Index of Complexity, Outcome and Need (ICON). Mann-Whitney test and Spearman's correlations tested various univariate variables. RESULTS: With similar index-determined OT need (DAI, P = 0.371 and ICON, P = 0.932) females tended to have worse OHRQoL status (PIDAQ scores, P-values ranged from 0.006 to 0.0001 and scores for the OIDP question related to smiling, laughing, and showing teeth without embarrassment, P-value = 0.015). Occlusal index scores did not have statistically significant associations with the OHRQoL scales. Better dental appearance was expected by 85 per cent of the adolescents in the short-term and by 51 per cent in the long-term after OT. The associated psycho-social expectations were: 1. improved dental self-confidence, 2. positive psychological impact/improved self-worth, and 3. positive social impact. CONCLUSIONS: Female adolescent patients tended to experience worse psycho-social impacts related to their malocclusions compared with males with similar index-determined OT need. Index-determined OT need scores did not correlate with the OHRQoL scales. Adolescent patients expected OT to improve their dental appearance and QoL aspects.

A qualitative investigation of RANKL, RANK and OPG in a rat model of transient ankylosis.

INTRODUCTION: Previous studies have found ankylosis occurs as a part of the inflammatory process of aseptic root resorption initiated in a rat model. The physiologic mechanisms behind the development of dentoalveolar ankylosis and healing response are still unclear. While receptor activator of nuclear factor-κß ligand (RANKL), receptor activator of nuclear factor-κß (RANK) and osteoprotegerin (OPG) have gained momentum in the understanding of resorption, no study to date has investigated their role in dentoalveolar ankylosis. AIMS: The aims of this study were to investigate if, and when, ankylosis occurred in the rat PDL, whether the resolution of ankylosis occurred with time and, finally, to observe the expression of RANKL, RANK and OPG during the ankylotic process. MATERIALS AND METHODS: Dry ice was applied for 20 minutes to the upper right first molar crown of 15 eight-week-old, male Sprague-Dawley rats. An additional three rats served as untreated external controls. Groups of three rats were sacrificed after the thermal insult on day 0, 4, 7, 14 and 28 respectively. Each maxilla was dissected out and processed for histological examination and RANKL, OPG and RANK immunohistochemistry. RESULTS: By the use of light microscopy and H&E staining, no ankylosis was detected in the external control group and the experimental groups at days 0 and 4. On day 7, disruption within the periodontal ligament was observed in the interradicular region and the initial signs of ankylosis were seen in the form of finger-like projections extending from the alveolar bone towards the cementum. Fourteen days after the thermal insult, all animals exhibited extensive ankylosis that spanned the entire interradicular periodontal space. At 28 days, the development of ankylosis appeared to have ceased and repair was observed, together with an intact periodontal ligament in all but one rat. Positive staining results were obtained with RANKL, RANK and OPG antibodies. The expressions of RANKL, RANK and OPG were similar in the external control group, 0-, 4-, and 28-day experimental groups. In the 7- and 14-day experimental groups, RANKL, RANK and OPG were expressed in the blood vessels within the ankylotic regions. CONCLUSIONS: During the development of ankylosis and its resolution, it was concluded from their simultaneous presence that there is a complex interaction between RANKL, RANK and OPG that requires further investigation.

Accelerating orthodontic tooth movement with the aid of periodontal surgery--the practitioner viewpoint.

INTRODUCTION: There has been a revival of interest in the acceleration of orthodontic tooth movement (OTM) by inducing injury to dentoalveolar cortical bone. Termed corticotomy, the procedure offers an advantage to adult patients whose bone metabolism is such that any reduction in treatment time would be welcomed. The procedure has been refined for over 100 years and recent research indicates treatment duration may be reduced often by as much as a third, but it is not clear how widely the method is applied in practice. For the procedure to be successful, careful interdisciplinary management by orthodontists and periodontists is required. However, information regarding the attitude and knowledge of practitioners and the frequency of the procedure performed in Australia and New Zealand is lacking. METHODS: A questionnaire was formulated and tested in a pilot study on postgraduate orthodontic and periodontic students at The University of Adelaide. As a consequence of the responses, the wording of several questions was clarified and the sequence modified to produce the final format. Separate questionnaires were developed for specialist orthodontists and periodontists in keeping with their different backgrounds and were distributed at two relevant conferences. RESULTS AND CONCLUSIONS: The number of practitioners who had been involved with at least one corticotomy per annum was low for orthodontists (12%) and periodontists (18%). The majority of those surveyed believed that more research was required on corticotomy-facilitated OTM and would not recommend the procedure to patients without greater investigation of the technique. More than half of the sampled orthodontists indicated that they would never recommend corticotomy-facilitated orthodontics to their patients. The minority who were willing to recommend the procedure would limit involvement to adult patients, the management of ankylosed teeth, impacted canines and patients susceptible to root resorption. Over 90% of the sampled periodontists believed that there were adverse side effects.

Craniofacial and upper airway morphology in pediatric sleep-disordered breathing and changes in quality of life with rapid maxillary expansion.

INTRODUCTION: The association between pediatric sleep-disordered breathing caused by upper airway obstruction and craniofacial morphology is poorly understood and contradictory. The aims of this study were to evaluate the prevalence of children at risk for sleep-disordered breathing, as identified in an orthodontic setting by validated screening questionnaires, and to examine associations with their craniofacial and upper airway morphologies. A further aim was to assess the change in quality of life related to sleep-disordered breathing for affected children undergoing rapid maxillary expansion to correct a palatal crossbite or widen a narrow maxilla. METHODS: A prospective case-control study with children between 8 and 17 years of age (n = 81) at an orthodontic clinic was undertaken. The subjects were grouped as high risk or low risk for sleep-disordered breathing based on the scores from a validated 22-item Pediatric Sleep Questionnaire and the Obstructive Sleep Apnea-18 Quality of Life Questionnaire. Variables pertaining to a screening clinical examination, cephalometric assessment, and dental cast analysis were tested for differences between the 2 groups at baseline. Ten children who underwent rapid maxillary expansion were followed longitudinally until removal of the appliance approximately 9 months later with a repeated Obstructive Sleep Apnea-18 Quality of Life Questionnaire. All data were collected blinded to the questionnaire results. RESULTS: The frequency of palatal crossbite involving at least 3 teeth was significantly higher in the high-risk group at 68.2%, compared with the low-risk group at 23.2% (P <0.0001). Average quality of life scores in the high-risk group indicated reduced quality of life related to sleep-disordered breathing by 16% compared with children in the low-risk group at baseline (P <0.0001). Cephalometrically, mean inferior airway space, posterior nasal spine to adenoidal mass distance, and adenoidal mass to soft palate distance were reduced in the high-risk group compared with the low-risk group by 1.87 mm (P <0.03), 2.82 mm (P <0.04), and 2.13 mm (P <0.03), respectively. The mean maxillary intercanine, maxillary interfirst premolar, maxillary interfirst molar, mandibular intercanine, and mandibular interfirst premolar widths were reduced in the high-risk group compared with the low-risk group by 4.22 mm (P <0.0001), 3.92 mm (P <0.0001), 4.24 mm (P <0.0001), 1.50 mm (P <0.01), and 1.84 mm (P <0.01), respectively. Children treated with rapid maxillary expansion showed an average improvement of 14% in quality of life scores in the high-risk group compared with the low-risk group, which showed a slight worsening in quality of life related to sleep-disordered breathing by an average of 1% (P <0.04), normalizing the quality of life scores in the high-risk children to the baseline scores compared with the low-risk group. CONCLUSIONS: Children at high risk for sleep-disordered breathing are characterized by reduced quality of life, reduced nasopharyngeal and oropharyngeal sagittal dimensions, palatal crossbite, and reduced dentoalveolar transverse widths in the maxillary and mandibular arches. No sagittal or vertical craniofacial skeletal cephalometric predictors were identified for children at high risk for sleep-disordered breathing. In the short term, rapid maxillary expansion might aid in improvement of the quality of life for children with a narrow maxilla in the milder end of the sleep-disordered breathing spectrum.

Masseter length determines muscle spindle reflex excitability during jaw-closing movements.

INTRODUCTION: The masticatory muscles are considered to be important determinants of facial form, but little is known of the muscle spindle reflex characteristics and their relationship, if any, to face height. The aim of this study was to determine whether spindle reflexes, evoked by mechanical stimulation of an incisor and recorded on the masseter muscle, correlated with different facial patterns. METHODS: Twenty-eight adult volunteers (16 women; ages, 19-38 years) underwent 2-N tap stimuli to their maxillary left central incisor during simulated mastication. Reflexes were recorded during local anesthesia of the stimulated tooth to eliminate the contribution from periodontal mechanoreceptors. Surface electromyograms of the reflex responses of the jaw muscles to these taps were recorded via bipolar electrodes on the masseter muscle and interpreted by using spike-triggered averaging of the surface electromyograms. Lateral cephalometric analysis was carried out with software (version 10.5, Dolphin, Los Angeles, Calif; and Mona Lisa, Canberra, Australia). RESULTS: Two-newton tooth taps produced principally excitatory reflex responses beginning at 17 ms poststimulus. Correlation analysis showed a significant relationship between these muscle spindle reflexes and facial heights: specifically, shorter face heights were associated with stronger spindle reflexes. This correlation was strongest between the derived measure of masseter length and the spindle reflex strength during jaw closure (r = -0.49, P = 0.008). CONCLUSIONS: These results suggest that a similar muscle spindle stimulus will generate a stronger reflex activation in the jaw muscles of patients with shorter faces compared with those with longer faces. This finding might help to explain the higher incidence of clenching or bruxism in those with short faces and also might, in the future, influence the design of orthodontic appliances and dental prostheses.