Tooth Position Research Articles

ORTHODONTIC TREATMENT OF VERTICAL DEFORMATIONS OF THE POSTERIOR PART OF THE DENTAL ARCH, AS A PREPARATORY STAGE FOR PROSTHETICS

The numerical distribution of anomalies and deformations of dentition in the adult population of Ukraine actualizes the development of new methods of orthodontic treatment of maxillofacial deformations. The aim. To analyze dental occlusion in young patients who underwent orthodontic treatment before prosthetics to assess the distribution of vertical deformations of the dental rows in the buccal areas and investigate methods of their elimination. Materials and methods. A retrospective investigation of the medical histories of 427 young people (228 women (53.4%) and 199 men (46.6%)) was carried out; consent for treatment was signed by 254 people (179 women and 75 men), which was 59.5% of the number of examined people. The sample identified the following pathological conditions that required orthodontic correction: abnormalities in the number of teeth in 3 persons (1.2%); retention in 1 person (0.4%); an abnormal position of teeth on the upper jaw in 158 people (62.5%) and 198 people (78%) on the lower jaw; malformation of the shape of dental rows in 208 people (82%) on the upper jaw and 220 people (86.6%) on the lower jaw, sagittal malocclusion in 32 people (12.3%), transversal malocclusion in 44 people (17, 2%), vertical malocclusion in 75 people (29.5%). 61 individuals (24%) were identified with partially edentulous dental rows, which were localized, mainly, in the lateral areas of the upper and lower jaws. In the selected sample, men predominated (40 people 65.6%), and a significantly smaller number of women (21 people 34.4%). Spaces with missing two and three teeth were present in some patients on the lower and upper jaws (12.5% of men and 9.5% of women). Distally located edentulous spaces were lesser extent compared to included defects (41% compared to 59%). Dentoalveolar deformities prevailed (95.1%): 38 men 62.3% and 20 women 32.8%. The carried-out treatment with the appliance of the own design proved the effectiveness in the treatment of the II-III levels of vertical dentoalveolar distally located occlusal malformation, where it is difficult to provide anchorage for intrusion. Further research is important for a detailed study of the use of fixed orthodontic appliances depending on the general somatic condition of patients and the condition of the jaw bone.

Characteristics of rehabilitation for patients with severe asymmetric jaw deformities resulting from temporomandibular joint pathology

Relevance. Temporomandibular joint (TMJ) pathology, along with the resultant facial asymmetry, is a common condition within maxillofacial disorders. Addressing the rehabilitation of these patients within specialised medico-social care is a crucial and challenging task.Purpose. To develop a comprehensive rehabilitation protocol for patients with severe asymmetric jaw deformities caused by TMJ pathology.Materials and methods. From 2018 to 2023, ten patients with defects and deformities of the TMJ condylar process, presenting with severe asymmetric jaw deformities, were treated. An assessment of subjective and objective facial aesthetic parameters was conducted based on photographic protocols, as well as 2D and 3D cephalometric facial measurements. Comprehensive preparation for orthognathic surgery with simultaneous endoprosthesis replacement was performed based on the collected data. A regimen of postoperative therapeutic procedures was prescribed following the surgery.Results. All patients achieved the intended statistically significant outcomes: in the sagittal plane, an improvement in facial profile was noted based on the position of the chin (Pog) relative to the true vertical line passing through the subnasale point. In the frontal plane, alignment of the occlusal plane and normalization of the central line of the upper and lower incisors relative to the midline of the face were observed.Conclusion. The algorithm for the comprehensive preparation of patients with asymmetric jaw deformities, developed during growth, prior to performing orthognathic surgery with simultaneous TMJ endoprosthesis replacement should include: orthodontic treatment aimed at aligning teeth position and dental arches, eliminating rotations and pathological inclinations of teeth using a bracket system, fully restoring interocclusal height with temporary implant-supported structures, using occlusal splints and temporary composite restorations, as well as employing separating orthodontic plates. These stages enabled the achievement of good aesthetic results and improved patients' quality of life.

Enhancing orthodontic precision: A comprehensive review of temporary anchorage devices

Temporary anchorage devices (TADs) have revolutionized orthodontic treatment by providing additional support for tooth movement, enabling precise control over tooth positioning, and expanding the scope of treatment options available to orthodontists. Temporary anchoring devices (TADs) provide a dependable means of accomplishing efficient and consistent tooth movement, and have emerged as a key breakthrough in modern orthodontic practice.: The present review aims to provide a comprehensive overview of TADs, including their types, applications, advantages, and limitations. : The review begins by elucidating the various types of TADs, such as mini-implants, miniplates, and microscrews, highlighting their differences in design, placement techniques, and biomechanical characteristics. Subsequently, it explores the diverse clinical applications of TADs, ranging from orthodontic tooth movement, space closure, intrusion, and extrusion to the management of skeletal discrepancies and complex cases requiring multidisciplinary approaches.: Moreover, the review examines the advantages offered by TADs, including enhanced treatment precision, reduced reliance on patient compliance, and the ability to achieve challenging tooth movements with minimal side effects. It also addresses the limitations and potential complications associated with TADs, such as risk of infection, mucosal irritation, and mechanical failure, emphasizing the importance of careful patient selection, proper placement techniques, and vigilant monitoring throughout treatment, highlighting their potential to further enhance orthodontic outcomes and patient satisfaction.: The significant role of temporary anchorage devices in modern orthodontic practice, emphasizing their versatility, efficacy, and potential to optimize treatment outcomes while minimizing the reliance on traditional anchorage methods and enhancing patient comfort and experience.

Proposal for an Anatomic Guide in Cortical Bone Window Technique for Endodontic Microsurgery: A Case Report

The success rate of endodontic microsurgery (EM) can be reduced for several reasons, including the tooth's position in the mouth. For this reason, using 3-dimensional (3D) computer-aided design/computer-aided manufacturing (CAD/CAM) guides has become common. Despite their great advantages, these guides have some limitations, including the difficulty of taking impressions and scanning in shallow vestibules. In this case report, we propose a design of an anatomical guide for endodontic microsurgery with a cortical bone window tailored for optimal accuracy from the patient's tomography, digital segmentation, and 3D printing.

A two-dimensional photographic and three-dimensional digital dental model comparative analysis in maxillary anterior teeth

Objective: To assess the accuracy of two-dimensional (2D) photographs in measuring esthetic parameters of the maxillary anterior teeth by comparing them with measurements obtained from three-dimensional (3D) dental models. Methods: A total of one hundred volunteers (49 males, 51 females, aged 18-23 years) were recruited from School and Hospital of Stomatology, Wuhan University from January to February 2024. 3D digital models of their dentitions were obtained using an intraoral scanner, and standardized frontal 2D intraoral photographs were captured with a digital camera. The lengths, widths and width/length ratio of the bilateral incisors, lateral incisors and canines were measured on both the 3D digital models and the 2D intraoral photographs. The width ratios of adjacent maxillary anterior were also calculated on the 2D intraoral photographs and the frontal view of 3D digital models. Results: The widths of lateral incisors [(5.85±0.60) mm] and canines [(4.73±0.71) mm] and the lengths of canines [(8.72±0.96) mm] in the 2D intraoral photographs were significantly lower than those in 3D digital models [(6.65±0.59), (7.76±0.60), (8.90±0.86) mm] (t=-18.24, P<0.001; t=-54.43, P<0.001; t=-4.40, P<0.001), while there were no significant differences in the lengths and widths of the other teeth (P>0.05). The width/length ratios measured from the 2D intraoral photographs for the lateral incisors and canines (0.74±0.08, 0.55±0.08) were significantly lower than those measured in the 3D digital models (0.84±0.09, 0.88±0.09) (t=-19.68, P<0.001; t=-50.21, P<0.001), and the width/length ratio of the central incisors showed no significant difference between the two groups (P>0.05). The width ratios of canines/lateral incisors and lateral incisors/central incisors measured on the 2D intraoral photographs (0.72±0.06, 0.85±0.11) were significantly smaller than those measured in the frontal view of 3D digital models (0.75±0.06, 0.89±0.11) (t=-9.31, P<0.001; t=-6.58, P<0.001). Conclusions: There is a difference between 2D and 3D measurement results of teeth in the esthetic area and the magnitude of the difference varies with their position in the dental arch. When analyzing the measurement of the anterior teeth, it is necessary to choose the appropriate method according to the target tooth position.

Comparative Analysis of Surgical Techniques for Wisdom Tooth Extraction.

Wisdom tooth extraction often requires various surgical techniques due to differences in tooth position, root morphology, and patient characteristics. This research aims to compare traditional surgical extraction with minimally invasive techniques such as piezo surgery and laser-assisted extraction, as well as extraction with the aid of 3D imaging and navigation systems. Patients requiring wisdom tooth extraction were randomly assigned to one of the surgical technique groups. Preoperative imaging assessed tooth position and root morphology. Intraoperative variables and postoperative outcomes were recorded, including pain levels, swelling, and healing time. Patient-reported outcomes were assessed using standardized questionnaires. Piezo surgery, 3D imaging, and navigation-guided extraction techniques demonstrated a shorter mean duration of surgery and lower incidence of intraoperative complications compared to traditional extraction and laser-assisted extraction. Postoperative outcomes were superior in the 3D imaging and navigation-guided extraction group, with lower pain scores, reduced swelling, and faster healing time. Advanced imaging-guided techniques, particularly 3D imaging and navigation-guided extraction, offer significant benefits for patients undergoing wisdom tooth extraction by improving surgical precision, minimizing complications, and enhancing postoperative outcomes. Incorporating these technologies into routine practice can optimize patient care and outcomes in oral surgery.

Endodontic Surgery and Post-Treatment Apical Periodontitis: A Systematic Review

Background It has been demonstrated that using innovative root-end filling materials speeds up the success of Endodontic Microsurgery (EMS) on teeth having root filling but still suffering from posttreatment Apical Periodontitis (AP). However, this has reopened the discussion about the long-term effectiveness of EMS conducted on such teeth. Objectives This study aimsto assess the long-term clinical and radiographic outcomes of endodontic surgical procedures in molars with radiographic evidence of secondary AP. Methodology A literature review was undertaken utilizing different databases, including MEDLINE (through PubMed), EMBASE, and Web of Science. The terms used for the search were ‘endodontic microsurgery,’ ‘apical microsurgery,’ ‘periapical disorders,’ ‘root canal therapy,’ ‘apicoectomy,’ ‘retreatment,’ ‘treatment result,’ “retrograde obturation,” and ‘success rate.’ In order to choose the most reliable longitudinal data, specific inclusion and exclusion criteria were established in advance. Only studies that met inclusion criteria for clinical and radiographic outcomes were considered, including prospective clinical studies and randomized clinical trials with at least two-year follow-ups. Results The study of the databases yielded 561 articles in total. From the 115 articles with full texts available, unrelated articles (105) were removed. Our inclusion criteria were met by an overall of ten studies (six prospective clinical studies and four randomized clinical trials). With intervals for follow-up ranging from two to thirteen years, a pooled success rate of 91% from all 451 treated teeth included in the randomized clinical trials and a pooled success rate of 79% from a total of 839 encompassed teeth in the prospective clinical studies were observed. During the same length of time of observation, survival rates ranged from 78% to 100%. Smoking status, tooth position and type, the presence or absence of dentinal abnormalities, the thickness of the bone between the teeth (interproximal bone), and the substance used to fill the space at the end of the roots are the five predictive variables revealed. Conclusion When EMS is performed by skilled endodontists who can deliver high success rates and reliable results, teeth afflicted by secondary AP have a good prognosis and can be preserved.

Construction and Evaluation of an AI-based CBCT Resolution Optimization Technique for Extracted Teeth

IntroductionIn dental clinical practice, cone-beam computed tomography (CBCT) is commonly used to assist practitioners to recognize the complex morphology of root canal systems; however, because of its resolution limitations, certain small anatomical structures still cannot be accurately recognized on CBCT. The purpose of this study was to perform image super-resolution (SR) processing on CBCT images of extracted human teeth with the help of a deep learning model, and to compare the differences among CBCT, super-resolution computed tomography (SRCT), and micro-computed tomography (Micro-CT) images through three-dimensional reconstruction. MethodsThe deep learning model (Basicvsr++) was selected and modified. The dataset consisted of 171 extracted teeth that met inclusion criteria, with 40 maxillary first molars as the training set and 40 maxillary first molars as well as 91 teeth from other tooth positions as the external test set. The corresponding CBCT, SRCT, and Micro-CT images of each tooth in test sets were reconstructed using Mimics Research 17.0, and the root canal recognition rates in the 3 groups were recorded. The following parameters were measured: volume of hard tissue (V1), volume of pulp chamber and root canal system (V2), length of visible root canals under orifice (VL-X, where X represents the specific root canal), and intersection angle between coronal axis of canal and long axis of tooth (∠X, where X represents the specific root canal). Data were statistically analyzed between CBCT and SRCT images using paired sample t-test and Wilcoxon test analysis, with the measurement from Micro-CT images as the gold standard. ResultsImages from all tested teeth were successfully processed with the SR program. In 4-canal maxillary first molar, identification of MB2 was 72% (18/25) in CBCT group, 92% (23/25) in SRCT group, and 100% (25/25) in Micro-CT group. The difference of hard tissue volume between SRCT and Micro-CT was significantly smaller than that between CBCT and Micro-CT in all tested teeth except 4-canal mandibular first molar (P < .05). Similar results were obtained in volume of pulp chamber and root canal system in all tested teeth (P < .05). As for length of visible root canals under orifice, the difference between SRCT and Micro-CT was significantly smaller than that between CBCT and Micro-CT (P < .05) in most root canals. ConclusionsThe deep learning model developed in this study helps to optimize the root canal morphology of extracted teeth in CBCT. And it may be helpful for the identification of MB2 in the maxillary first molar.

Precise maxillofacial soft tissue reconstruction: A combination of cone beam computed tomography and 3dMD photogrammetry system

IntroductionThe reconstruction of both extra- and intra-oral soft tissue defects, particularly in restoring the morphology of the lip and the corners of the mouth, has posed a significant challenge for surgeons. Inappropriate methods often lead to maxillofacial deformity which then causes psychological and functional problems. This study aimed to address the challenge of reconstructing extensive and complex maxillofacial soft tissue defects, mainly focusing on the lip, the corners of the mouth, and the surrounding areas. Materials and methodsWe developed a reconstruction approach by combining the 3dMDface System (3dMD) with the cone beam computed tomography (CBCT). Firstly, with the extra-oral incision line, we evaluated the shape and the size of the extra-oral defect with 3dMD digitally. Then we used the corresponding maxillary and mandible tooth positions to record the intra-oral defect, which was then converted to digital images by combining 3dMD and CBCT. The islands of the anterolateral thigh perforator flap were then designed after the locations of the perforators were detected with Doppler ultrasonography. ResultsA clinical case diagnosed as dermatofibrosarcoma protuberans was presented to illustrate the approach. The patient's tumor resection and the size of multiple defects were measured and simulated via the virtual surgery system. A three-island perforator flap from the descending branch of the lateral femoral circumflex artery was designed accurately. Two weeks postoperatively, the flap was healed as anticipated and the patient was satisfied with the profile. ConclusionThe combination of the 3dMD and CBCT technologies improves the accuracy and fitness of extra- and intra-oral soft tissue reconstruction.

New mammals from the Upper Cretaceous Allen Formation (Patagonia, Argentina) and reassessment of meridiolestidan diversity

Dryolestoid mammals are classical members of the Jurassic faunas of Laurasia but mostly absent during the Cretaceous. The reverse is true in Gondwana in general and South America in particular, where meridiolestid dryolestoids are dominant in the Late Cretaceous. We describe here 21 new mammalian specimens from the Upper Cretaceous locality Cerro Tortuga (Allen Formation, Patagonia, Argentina) collected via screenwashing, which we identify as meridiolestid dryolestoids. We recognize a new species of meridiolestid and reassign a previously described specimen to the new taxon. The morphology of these new remains represents a new morphotype in the spectrum of meridiolestid diversity, recording a broadening of trophic adaptations from the ancestral insectivory to the more derived herbivory observed among the later and more derived members of the group. The novel dental morphology helps bridge the anatomy of the plesiomorphic sharp-toothed meridiolestidans with that of the more derived and bunodont mesungulatoids. The new taxon suggests that development of both broad cingulids and complex crown morphology precede the development of the wide compressed roots, bunodonty, and thickened enamel characteristic of derived mesungulatids. Other specimens from the collection are referable to taxa previously known from the same locality. These provide new information about tooth positioning, dental formula, and overall dental morphology. The new material suggests that Groebertherium, previously regarded as a dryolestid taxon, is in fact a likely member of Meridiolestida.

Cone-beam CT evaluation of post-extraction alveolar bone changes at the maxillary incisor sites in an East Asian population: A cross-sectional study

ObjectiveUnderstanding the characteristics of alveolar bone resorption in an East Asian population after maxillary incisor extraction and providing a reference for implant treatment plans. Study designCone-beam computerized tomography (CBCT) data of 125 East Asian patients with unilateral extraction of maxillary incisors for 3 months were collected. The alveolar bone width and height in the extraction sites were measured and compared with the corresponding contralateral sites. ResultsThe differences in alveolar bone width between the extraction site and contralateral site were as follows: 4.11 mm, 2.68 mm, and 2.09 mm (3 mm, 5 mm, 7 mm apical from CEJ of the contralateral tooth). Data are expressed as the median. The horizontal resorption ratio of alveolar bone was 49.94 %, 31.5 %, and 24.46 %. The difference in alveolar bone height was 0.78 mm. The vertical resorption ratio was 7.78 %. The resorption did not differ significantly between sexes and was not significantly affected by tooth positions. ConclusionsIn the studied East Asian population, significant horizontal and vertical alveolar bone resorption occurs after natural healing of maxillary incisor extraction for 3 months. The closer to the alveolar ridge crest, the more significant the horizontal resorption, resulting in an “inverted triangle” shape residual alveolar bone.

Accuracy assessment between computer-guided surgery planning and actual tooth position during tooth autotransplantation.

This study aims to evaluate the precision and efficacy of utilizing computer-aided design (CAD) in combination with three-dimensional printing technology for tooth transplantation. This study analysed 50 transplanted teeth from 48 patients who underwent tooth transplantation surgery with the aid of CAD and positional guides. A consistent coordinate system was established using preoperative and postoperative cone-beam computed tomography images. Linear displacements and angular deviations were calculated by identifying key regions in both virtual designs and actual transplanted teeth. Additionally, an analysis was conducted to explore potential factors influencing these deviations. The mean cervical deviation, apical deviation, and angular deviation among the 50 transplanted teeth were 1.16 ± 0.57 mm, 1.80 ± 0.94 mm, and 6.82 ± 3.14°, respectively. Cervical deviation was significantly smaller than apical deviation. No significant difference in deviation was observed among different recipient socket locations, holding true for both single-root, and multi-root teeth. However, a significant difference was noted in apical deviation between single-root and multi-root teeth. Our analysis identified a correlation between apical deviation and root length, leading to the development of a prediction model: Apical deviation = 0.1390 × (root length) + 0.2791. The postoperative position of the donor teeth shows discrepancies compared to preoperative simulation when utilizing CAD and 3D printed templates during autotransplantation procedures. Continual refinement of preoperative design is a crucial endeavour.

Effect of Orthodontic Treatment on the Outcomes of Endodontically Treated Teeth: A Cone-Beam Computed Tomography Analysis

IntroductionOften there is the need of moving endodontically treated teeth. Orthodontic movement may have no effect on the prognosis of teeth with root canal treatment (RCT). To verify this subject, we evaluated the effect of orthodontic movement on the prognosis of RCT teeth using cone-beam computed tomography (CBCT) and further explored the influence of orthodontic movement on the prognosis of RCT teeth with and without apical periodontitis (AP). MethodsThis retrospective study was conducted by evaluating 169 RCT teeth of 100 patients who had undergone fixed orthodontic treatment. AP was assessed and classified using the CBCT periapical index. Univariate analysis of RCT outcome was performed for the total RCT group, RCT without AP group and RCT with AP group. Multivariate logistic regression was performed for the total RCT group and RCT without AP group, respectively, but not for the RCT with AP group. Variables related to the prognosis of RCT were included, such as age, gender, tooth position, RCT quality, coronal restoration quality, periodontal condition, orthodontic traction distance, and orthodontic rotation angle. ResultsThe orthodontic traction distance and rotation angle were not significantly correlated to the RCT outcomes, regardless of the presence of AP. Among the total RCT group, teeth with unqualified RCT (odds ratio = 3.42, P = .004) and inadequate coronal restoration (odds ratio = 4.40, P = .031) had a lower success rate. Of the 97 RCT teeth without AP, unqualified RCT was a risk factor for treatment failure (odds ratio = 3.55, P = .041). Of the 72 RCT teeth with AP, the univariate analysis showed that RCT quality were significantly related to the outcome (P = .042). ConclusionsOrthodontic movement had no effect on the prognosis of RCT teeth regardless of the presence of AP.

Cirurgia de Recobrimento Radicular com Enxerto Conjuntivo Subepitelial no Tratamento de Recessão Gengival: Relato de Caso Clínico

Gingival recession, a common periodontal condition, occurs when the gingival margin migrates apically to the cementoenamel junction (CEJ), exposing the root and potentially causing dental hypersensitivity, caries, and aesthetic dissatisfaction. Causes include bacterial biofilm, frenulum and frenum insertions, band of keratinized gingiva, gingival phenotype, alveolar morphology, tooth positioning, and mechanical trauma. It is classified into three types: RT1 (no CEJ exposure), RT2 (interproximal loss equal to or less than buccal loss), and RT3 (interproximal loss greater than buccal loss). Among root coverage techniques, the subepithelial connective tissue graft (SCTG) is highlighted for its predictability, color compatibility with adjacent gingival tissue, and good blood supply, reducing the likelihood of necrosis. This qualitative and descriptive study reported a clinical case of root coverage surgery with SCTG in a 60-year-old female patient with Miller class III and Cairo RT2 recessions on teeth 31 and 41. The palate was chosen as the donor site for the graft due to its adequate thickness. The SCTG technique combined with a laterally positioned flap and double papilla was used. The procedure resulted in reduced dentinal hypersensitivity and patient satisfaction with aesthetics, along with an increase in keratinized tissue, despite not achieving total root coverage. The success of the treatment was attributed to the precise indication of the case and professional skill.

Radiation exposure during orthodontic treatment: risk to children and adolescents.

To estimate radiation risk to children and adolescents during orthodontic treatment by retrieving number and type of radiographs from the patient records. Radiographs, along with justifications for radiation exposure, were obtained retrospectively from the patient records of 1,790 children and adolescents referred to two Swedish orthodontic clinics. Data were grouped according to treatment stage: treatment planning, treatment, and follow-up. Estimated risk was calculated using the concept of effective dose. Each patient had received around seven radiographs for orthodontic purposes. The most common exposures during treatment planning were one panoramic, one lateral, and three intraoral periapical radiographs. A small number of patients received a tomographic examination (8.2%). Few justifications for treatment planning and follow-up, but more in the actual treatment stage, had been recorded. The most common examinations were to assess root resorption and the positions of unerupted teeth, or simply carry out an unspecified control. The estimated risk of developing fatal cancer was considered low. The radiation risk from orthodontic treatment was equivalent to about 5-10 days of natural background radiation. Children and adolescents sometimes undergo multiple radiographic examinations, but despite the low radiation burden, accumulated radiation exposure should be considered and justified in young patients.

Digital Planning to Enhance Diagnosis and Precision in Correcting Excessive Gingival Display in the Presence of Asymmetrical Maxillary Position: A Case Report.

This case report addresses the treatment of excessive gingival display (EGD) in the context of maxillary asymmetry, zenith irregularities, and occlusal plane inclination. Digital planning was pivotal in formulating a precise treatment strategy by incorporating facial photographs, digital models, and cone-beam computed tomography data. Parameters, including occlusal plane inclination, teeth position, and lip-to-gingival margin relationships, were considered to ensure treatment alignment with the patient's facial characteristics. Notably, during the planning phase, it was evident that the conventional approach using the cementoenamel junction as the apical limit for incisions would result in asymmetry. Consequently, the gingival margin position was defined in accordance with facial and lip features. The chosen treatment, flapless crown lengthening, was tailored to the patient's thin phenotype and guided by measurements derived from digital planning. Postsurgery, the patient experienced a swift and painless recovery. A harmonious smile with a stable gingival margin position was achieved at the 1-year follow-up, seamlessly complementing the patient's facial attributes. This case underscores the importance of personalized EGD treatment and the value of digital planning in enhancing diagnostic accuracy and precise treatment planning, ultimately facilitating optimal treatment strategies.

Accuracy of the novel digital non-cross-arch surgical guides with integration of tooth undercut retention and screw-bone support for implant placement in mandibular free-end

BackgroundLarge cross-arch free-end surgical guides can obscure the visual field, compromising surgical accuracy due to insufficient stability at the free-end. This in vitro study aims to evaluate the accuracy of novel digital non-cross-arch surgical guides designed for implant placement at the mandibular free-end, incorporating tooth undercut retention and screw-bone support.Materials and methodsA mandibular dental model lacking left molars was utilized to fabricate unilateral (cross-arch) tooth-supported surgical guides (GT I, n = 20). Subsequently, two additional types of surgical guides were fabricated: GT II (covering two teeth, n = 20) and GT III (covering three teeth, n = 20). These novel surgical guides were designed to utilize the undercut of the supporting teeth for retention and enhance stability with screw-bone support at the guide’s free-end. Furthermore, 60 identical guiding blocks were assembled on the three types of surgical guides to facilitate the implants’ insertion. On a phantom head, 120 implant replicas were placed at the Federal Dentaire Internationale (FDI) teeth positions #36 and #37 on the dental model, employing a combination of surgical guides and guiding blocks. To assess accuracy, planned and placed implant positions were compared using intraoral optical scanning. Discrepancies in angulation and linear deviations, including the coronal/apical 3D deviations, lateral deviation as well as depth deviation, were measured. Statistical analysis was performed using two-way ANOVA and Bonferroni test (α = 0.05).ResultsGT I exhibited significantly largest discrepancies, including angular and linear deviations at the crest and apex at every implant site. Especially in depth, at implant site #36, the mean deviation value of GT I (0.27 ± 0.13 mm) was twice as large as GT III (0.13 ± 0.07 mm), and almost twice as large as GT II (0.14 ± 0.08 mm). However, at implant site #37, this deviation increased to almost a five-fold relationship between GT I (0.63 ± 0.12 mm) and II (0.14 ± 0.09 mm), as well as between GT I and III (0.13 ± 0.09 mm). No significant discrepancies existed between the novel surgical guides at either implant site #36 or #37.ConclusionThis study provides a practical protocol for enhancing accuracy of implant placement and reducing the size of free-end surgical guides used at mandibular molar sites.

Comparison of treatment effects between clear aligners and fixed appliances in patients treated with miniscrew-assisted molar distalization.

The biomechanics in achieving molar distalization may differ between fixed appliances and clear aligners in the control of tooth movement. The objective of this study was to compare the treatment effects between clear aligners (CA) and fixed appliances (FA) in patients treated with miniscrew-assisted molar distalization. The sample consisted of 46 subjects with mild-to-moderate crowding. A total of 22 patients treated with clear aligners (age, 25.66 ± 6.11 years old) and 24 patients treated with fixed appliances (age, 24.04 ± 4.95 years old) for miniscrew-assisted molar distalization were included in this study. The dental and skeletal changes were evaluated by the pre- and post-treatment lateral cephalograms. Significant changes were found with the vertical variables SN-OP angle (2.24 ± 3.22°, P < .05) and SN-MP angle (0.73 ± 1.15°, P < .05) for the FA group when compared with the CA group (SN-OP angle 0.41 ± 2.26° and SN-MP angle -0.21 ± 1.38°, P > .05). Both treatment groups achieved a 2-3mm. molar distalization with significant intrusion of the upper molars. The CA group showed significantly less distal tipping of molars (U6^PP angle -2.29 ± 3.29° and L6^MP angle -2.92 ± 2.49°, P < .05) compared to the FA group (-5.24 ± 4.28° and -5.53 ± 5.03°, P < .05). In addition, significant retraction and lingual inclination of the upper and lower incisors were found in both groups. The changes of tooth position were evaluated by 2D lateral cephalograms, not 3D measurements. Compared to fixed appliances, clear aligners seemed to have better control of vertical dimension and distal tipping of molars in patients treated with miniscrew-assisted molar distalization.

Correlation between Depth of the Curve of Spee and Some Specific Malocclusion Characteristics in a Population from Sibiu County, Romania-A Cross-Sectional Study.

Background: This study aimed to investigate the relationship between the Curve of Spee (COS) depth and malocclusion characteristics in a population from Sibiu County, Romania. The research sought to understand how the COS's anatomical dimensions correlate with different classes of malocclusion and the position of the frontal teeth. Methods: A total of 265 participants from the Dentistry Ambulatory of the Military Hospital of Sibiu were included in this study. It employed digital intraoral scanning technology to measure the COS, overjet, and overbite, with malocclusion classification. Statistical analyses, including correlation and regression, were conducted to examine the relationships between COS depth, frontal teeth position, and malocclusion characteristics. Results: The average COS depth measured was 1.0564 mm, presenting variability when compared to existing literature. Most of the study participants had Class I malocclusion. A significant positive correlation between COS depth and overjet was identified, with no notable gender-based differences in these occlusal parameters. Conclusions: The findings affirm the integral role of COS in occlusal dynamics and malocclusion diagnosis. The COS measurement of a mean of 1.0564 mm, when compared to other results emphasizes the differences in occlusal curvature among various populations. The results contribute to a refined understanding of occlusal relationships, supporting the need for personalized orthodontic and prosthetic treatments based on precise anatomical measurements.

AI model to detect contact relationship between maxillary sinus and posterior teeth

ObjectivesTo establish a novel deep learning networks (MSF-MPTnet) based on panoramic radiographs (PRs) for automatic assessment of relationship between maxillary sinus floor (MSF) and maxillary posterior teeth (MPT), and to compare accuracy of MSF-MPTnet, dentists and radiologists identifying contact relationship. Study designA total of 1035 PRs and 1035 Cone-beam computed tomographys （CBCT）images were collected from January 2018 to April 2022. The relationships were classified into class I and II by CBCT. Class I represents non-contact group, and class II represents contact group. 350 PRs were randomly selected as test dataset and accuracy of MSF-MPTnet, dentists, and radiologists was compared. ResultsThe intraclass correlation coefficient of dentists was 0.460–0.690 and it was 0.453–0.664 for radiologists. Sensitivity and accuracy of MSF-MPTnet were 0.682–0.852and 0.890–0.951, indicating that the output performance of MSF-MPTnet was reliable. Accuracy of maxillary premolars and molars were 79.7%–90.3 %, 76.2%–89.2 % and 72.9%–88.3 % in MSF-MPTnet model, dentists and radiologists. Accuracy of class I relationship in the MSF-MPTnet model (67.7%–94.6 %) was higher than that of dentists (56.5%–84.6 %) in maxillary first premolars and right second premolar, and accuracy of class I relationship in the MSF-MPTnet model is also higher than radiologists (40.0%–78.1 %) in all teeth positions (p < 0.05). ConclusionsMSF-MPTnet model could increase detecting accuracy of the relationship between MSF and MPT, minimize pseudo contact relationship and reduce frequency of CBCT use.