Cone-beam computed tomography integration in clear aligner treatment planning: A cross-sectional study exploring practices and perceptions among orthodontists and general practitioners.

ABSTRACTObjectivesThe primary aim of the investigation was to survey clear aligner therapy (CAT) use among general dentists in Australia. A secondary aim was to evaluate the factors that influenced general dentists in Australia not to provide CAT.Material and MethodsGeneral dentists registered with the Australian Health Practitioner Regulation Agency were invited to participate in a structured cross‐sectional electronic survey. The survey covered demographics, preferred CAT systems and practices, relevant treatment planning and retention protocols, patient‐reported CAT issues, pertinent respondent opinions, and reasons for not providing CAT. Descriptive statistics were computed via GraphPad Prism v10 (GraphPad Software Inc., La Jolla, CA, USA).ResultsMost of the 264 (n = 172; 65.2%) respondents indicated that they provided CAT. The majority (n = 82; 58.6%) reported that they treated between 1 and 20 patients with CAT annually. Invisalign was the most used system (n = 83; 61.2%), with 55 (41.7%), indicating that they used more than one system. Most (n = 124; 98.4%) were comfortable using CAT for mild crowding, whereas 73.4% (n = 94) were not comfortable in treating severe crowding with CAT. The median (IQR) number of patients per respondent treated with extraction of a permanent incisor or premolar was 0 (0). Issues regarding tooth positions were reportedly always or mostly in need of change in the initial treatment plan by 68.7%. Problems regarding patient compliance with CAT wear protocols (n = 67; 45.6%) and the predictability of treatment outcomes (n = 31; 21.1%) were the most identified themes of the free‐text comments. Over 80% of those who did not provide CAT indicated that they preferred to refer to an orthodontist for management.ConclusionAlmost two‐thirds of the respondents provided CAT. Invisalign was the most used system. The majority use CAT combined with nonextraction treatment. Most of those who did not provide CAT preferred to refer to an orthodontist for patient management.

Authors' response.

Extraoral (EO) diagnostic radiography is an essential part of clinical dentistry. It is widely used as part of the clinical repertoire for diagnosis and treatment planning. Panoramic radiography (PR) is the mainstay of 2D EO imaging and cone beam computed tomography (CBCT) is now becoming widely adopted for 3D EO imaging.This research is composed of a literature review and special project investigations. The review focuses on the general development of extraoral radiography modalities, the diagnostic uses of such modalities, the medical and legal ramifications of ionising radiation, and summarises the legislations and regulations for operation of CBCT and PR machines across Australian jurisdictions. Project investigations were conducted to analyse the baseline number of PR and CBCT machines across Australian jurisdictions for the year ending 2014, and to examine the distribution of Medicare-rebated PR and CBCT scans after changes to the Medicare Benefits Schedule (MBS) in 2014 in limiting access to CBCT rebated scans. The main research results include:1. A total number of 1,913 EO X-ray machines made up of 1,681 PR machines and 232 CBCT machines were recorded nationally in 2014.2. Based on gross data, Queensland recorded the largest number of CBCT and PR machines, whereas NT recorded smallest number of CBCT and PR.3. The Australian Capital Territory had the highest accessibility to CBCT machines and Western Australia (WA) had the highest accessibility to PR machines relative to both the populationsize and the number of dental practitioners.4. The use-licensing regulations set out by each Radiation Regulator influences the adoption of CBCT and PR machines across Australian states and territories, particularly notable in WA.5. Increases in either the population size or the number of dentists could contribute to a positive growth in the adoption of PR and CBCT modalities.6. The underlying rationales imposed for restricting access to rebates for CBCT scans in the 2014 MBS were controversial, but were effective in reducing the number of rebated CBCT scans.7. During December 2014nNovember 2015 (under the new MBS), females received on average more Medicare-rebated CBCT and PR scans than males.8. Overall, the reduction in the number of Medicare-rebated CBCT scans provided significant cost savings for Medicare and also helped to reduce the ionisation load to the community during December 2014nNovember 2015.

To investigate the accuracy and reliability of cone beam computed tomography (CBCT) measurements of buccal alveolar bone height (BBH) and thickness (BBT) using custom acquisition settings. School of Dentistry, Oregon Health & Science University. Twelve embalmed cadavers. Cadaver heads were imaged by CBCT (i-CAT® 17-19, Imaging Sciences International, Hatfield, PA) using a 'long scan' (LS) setting with 619 projection images, 360° revolution, 26.9 s duration, and 0.2 mm voxel size, and using a 'short scan' (SS) setting with 169 projection images, 180° rotation, 4.8 s duration, and 0.3 mm voxel size. BBH and BBT were measured with 65 teeth, indirectly from CBCT images and directly through dissection. Comparisons were assessed using paired t-tests (p≤0.05). Level of agreement was assessed by concordance correlation coefficients, Pearson's correlation coefficients, and Bland-Altman plots. Mean differences in measurements compared to direct measurements were as follows, LS 0.17±0.12 (BBH) and 0.10±0.07 mm (BBT), and SS 0.41±0.32 (BBH) and 0.12±0.11 mm (BBT). No statistical differences were found with any of BBH or BBT measurements. Correlation coefficients and Bland-Altman plots showed agreement was high between direct and indirect measurement methods, although agreement was stronger for measurements of BBH than BBT. Compared to the LS, the similarity in results with the reduced scan times and hence reduced effective radiation dose, favors use of shorter scans, unless other purposes for higher resolution imaging can be defined.

Three-dimensional C-arm Cone-beam CT: Applications in the Interventional Suite

Lateral cephalograms have the inherent drawback of superimposition of bilateral structures, while landmarks are more reproducible on CBCT scans. Yet no studies in the literature have utilized 3D imaging to investigate the effects of clear aligners on anterior open bite. Therefore, The aim is to measure the skeletal and dental changes that contribute to anterior open bite closure with clear aligner therapy on CBCT scans. It is a single-arm retrospective study that included 40 cases of anterior open bite who were treated using Invisalign. Pre- and post-treatment CBCT scans were traced to record 13 dental and 3 skeletal measurements. A paired t-test was conducted to compare the mean values of pre- and post-treatment measurements. Combined intrusion of the maxillary right and left molars was statistically significant, meanwhile mandibular molars maintained their vertical position. Maxillary incisors were extruded and retroclined significantly, whereas mandibular incisors were only extruded. While anterior facial height was decreased insignificantly, both lower anterior facial height and mandibular plane angle showed a significant decrease. Clear aligner (Invisalign) therapy is effective in the management of anterior open bite through vertical control, maxillary molars intrusion, maxillary incisors extrusion, maxillary and mandibular incisors retroclination, and mandibular autorotation.

Transposition of a maxillary canine and a lateral incisor and use of cone-beam computed tomography for treatment planning

Maxillary molar distalization with clear aligner therapy and infrazygomatic temporary skeletal anchorage devices.

The increasing adoption of clear aligner therapy (CA) has highlighted contrasting viewpoints between orthodontists and general dentists concerning its application and management. This study investigates these divergent perspectives, focusing on the advanced training and expertise of orthodontists, which enables them to conduct thorough evaluations of intricate dental alignments and aesthetic factors. Conversely, general dentists perceive CAs as a more user-friendly and less invasive treatment option, allowing them to offer these services in a more accessible manner. Such disparities prompt important considerations regarding treatment efficacy, patient outcomes, and the delineation of professional responsibilities within dentistry. To assess these differences, a web-based survey was conducted among 64 dental practitioners, exploring their demographics, experiences with CA, types of patients treated, and specific malocclusions addressed. The data were analyzed using SPSS software version 23. Results revealed that 57% of respondents reported incorporating CA into their practices, with a significantly higher percentage of orthodontists (P = 0.001). Orthodontists primarily treated Class I malocclusions characterized by crowding, spacing, deep bites, and open bites. The majority of CA patients were employed adults, with an equal distribution of males and females seeking treatment; notably, the prevailing source of information about CA was external media advertising. In conclusion, the study identifies significant differences in the utilization of CA between orthodontists and general dentists, particularly regarding practitioner numbers, experience levels, and case selection strategies. As clear aligner therapy continues to develop, understanding these distinctions will be crucial for optimizing patient care. Keywords: clear aligner, Orthodontists, General dentists

Management of the anterior open bite using clear aligner therapy and surgery-first: Case example and scoping review of the literature

Computed gray levels in multislice and cone-beam computed tomography

Orthodontically induced external apical root resorption is a common iatrogenic effect of tooth movement. With the increasing use of clear aligner therapy, it is important to evaluate whether its biomechanics reduce root resorption compared with fixed orthodontic appliances. To compare apical root resorption in patients treated with clear aligners and fixed appliances using cone-beam computed tomography (CBCT). A retrospective comparative CBCT-based analysis was conducted on 120 orthodontic patients. Root volumes and lengths were measured from the cementoenamel junction to the apex using pre- and post-treatment CBCT scans. Apical root resorption was quantified as percentage volume loss and absolute root length reduction. Primary analyses employed linear mixed-effects models adjusted for clustering of teeth within patients and for tooth type, arch, extraction status, and treatment duration. Clear aligner therapy was associated with significantly lower apical root resorption than fixed appliances. Mean percentage root volume loss was lower in the aligner group (6.1 ± 4.8%) than in the fixed appliance group (8.4 ± 6.1%) (p = 0.004). Mean root length reduction was also smaller with aligners (p = 0.001). Clinically significant root resorption occurred less frequently in the aligner group (p = 0.048). Longer treatment duration increased resorption risk. Clear aligner therapy is associated with less apical root resorption than fixed orthodontic treatment, while treatment duration remains an independent risk factor.

To investigate the epidemiology and risk factors of open gingival embrasures (OGE) in adult patients after clear aligner therapy (CAT). A total of 518 adult patients were recruited to evaluate the prevalence and severity of OGE between central incisors through intraoral photographs; 281 patients with complete lateral cephalometric radiographs and cone-beam computed tomography (CBCT) were selected above to investigate mainly mesiodistal anatomical indicators regarding the occurrence and severity of OGE; and 186 non-extraction (NE) patients were selected from 281 patients to further investigate the relationship between tooth movement or labial-palatal/lingual anatomical indicators with OGE. The prevalence of OGE was relatively high and significantly associated with tooth extraction. The prevalence and severity of OGE decreased as follows: one-lower-incisor-extraction>two-premolar-extraction>NE types. The interproximal contact point-alveolar crest (ICP-AC)>5mm, ΔICP-AC>0.5mm, cemento-enamel junction-alveolar crest (CEJ-AC)>2mm, and ΔCEJ-AC>0.2mm were significantly associated with the occurrence of OGE. ΔCEJ-AC may more sensitively reflect bone loss, meanwhile, CEJ-AC in distal sites was significantly associated with moderate or severe OGE in mesial sites. Intrusion movement<2mm and labial inclination<5° were the warning limits for incisor movement. Furthermore, we found that bone dehiscence and root resorption were significantly associated with OGE. OGE of varying severity could be accompanied by different degrees of three-dimensional alveolar bone resorption. Moderate-to-severe OGE may occur alongside other complications in orthodontic treatment. This research also provided valuable clinical insights and treatment guidance in CAT. Clear aligner therapy (CAT) is a favored orthodontic choice for adults, yet it can carry hidden risks to periodontal health. Open gingival embrasure (OGE), or "black triangles" between teeth, can affect aesthetics, promote food impaction, and potentially relate to underlying bone loss. Our large-sample study investigated the incidence of OGE, identified the treatment alternatives associated with increased risk, how OGE related to alterations in tissue loss and tooth movement, and what risks OGE may indicate. The prevalence of OGE is relatively high in adult patients after CAT. Patients with a single lower incisor removed had the highest rates and severity of OGE, followed by those with two premolars extracted, and finally those with no extractions. Detailed imaging revealed that the occurrence and severity of OGE are significantly associated with bone loss, not only between teeth but also from the front-back directions. Additionally, specific thresholds for tooth movement that may elevate OGE risk include excessive incisor intrusion or forward tilting. Importantly, OGE often occurred along with other complications like bone dehiscence or root resorption. Our findings provide anatomical data on the potential three-dimensional tissue loss associated with different severities of OGE and further provide clinical guidance in CAT.

2849

Introduction: Impacted single-rooted teeth present a diagnostic and therapeutic challenge due to their topographic and morphological variability. A thorough understanding of their position, root morphology, and associated pathologies is essential. The aim of this study was to investigate the anatomical characteristics of impacted single-rooted teeth using Cone Beam Computed Tomography (CBCT). Materials and Methods: This study included 96 impacted single-rooted teeth in 64 patients. CBCT scans were obtained from the dentomaxillofacial radiology department of the IOS, and images were analyzed using CS 3D Imaging software. The parameters assessed included the frequency of impacted teeth by type, root morphology, position in the transverse and sagittal planes, the presence of anatomical obstacles, and associated pathologies, particularly resorption of adjacent teeth. Results: The maxillary canine was the most frequently impacted tooth (49%), followed by the maxillary central incisors (23%). Root morphology was normal in 80.2% of cases, with dilaceration observed in 19.8%. In the transverse plane, teeth were mainly positioned buccally (45.8%) or palatally/lingually (44.8%). In the sagittal plane, the vertical position was the most common (39.6%), followed by oblique and horizontal positions (30.2% each). Anatomical obstacles to eruption were present in 12.5% of cases, while 19.8% of teeth exhibited associated pathologies. Resorption of adjacent teeth was noted in 12.5% of cases, mostly mid-root resorption (83.3%). Conclusion: These results confirm the value of CBCT in accurately evaluating impacted single-rooted teeth and highlight the need for comprehensive three-dimensional analysis to optimize diagnosis and treatment planning.