3D analysis of upper airway morphology related to obstructive sleep apnea severity.

BACKGROUND: Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder characterized by repetitive collapse of the upper airway during sleep. However, little evidence is available on the differences between the sub-regions of the upper airway morphology and OSA severity. Since orthodontists frequently perform cone beam computed tomography (CBCT) in the neck area, we aimed to investigate the relationship and the differences between upper airway morphology and OSA severity using CBCT. MATERIALS AND METHODS: The medical records, CBCT imaging of 21 OSA patients diagnosed by polysomnography, and the apnea-hypopnea index (AHI) results were included to classify OSA severity as mild, moderate, or severe. The minimum cross-sectional areas (MCA) and volumes of the upper pharyngeal airway boundaries in four sub-regions: nasopharynx, retropalatal, retroglossal, and hypopharynx were measured. Dolphin Imaging software was used for upper airway segmentation. The correlation coefficient (r), one-way ANOVA, and the least significant difference post hoc multiple comparison test were applied to fulfill the objectives. RESULTS: A statistically significant relationship was found between the MCA of the nasopharynx and the AHI (r = -0.473, P < 0.05). Furthermore, a difference was found between mild and moderate and moderate and severe OSA severity in the MCA results of the retroglossal region (P < 0.05). However, no relationship was found between the upper airway volume and OSA severity. CONCLUSIONS: MCA was moderately negatively correlated to AHI only in the nasopharynx subregion. Moderate OSA presented significantly less MCA than mild and severe OSA only in the oropharynx and retroglossal subregions.

Relationship between Bilateral Landmarks of Facial Asymmetry in Skeletal Class II and Class III in Vertical Dimension: 3D Facial Scan and Cone-Beam Computed Tomography.

Significant facial asymmetry can lead to both functional and aesthetic issues. Often, such asymmetry originates from irregularities in the jaw structure. It is critical to recognize that asymmetries can be concealed by soft tissue, which may be overlooked. The aim of this study is to investigate the relationships between bilateral landmarks in the vertical dimension of facial asymmetry among individuals with skeletal Class II and Class III malocclusions. Fifty-two adult patients with a mean age of 24.4 ± 3.79 years with facial asymmetry who underwent orthodontic and orthognathic surgery were studied. Cone-beam computed tomography and facial scans were used to create 3D virtual head models which enhanced the accuracy in addressing facial asymmetry to ensure effective treatment planning. Each landmark was measured and digitized using the Dolphin Imaging program. The findings showed a correlation between gender and type of skeletal discrepancies with the menton deviation direction. In conclusion, the vertical discrepancy between bilateral landmarks was observable in both hard and soft tissues with more pronounced expression in soft tissues. This discrepancy was characterized by an elevation on the same side as the menton deviation, which was a feature observed in both skeletal Class II and Class III individuals.

Root resorption during maxillary molar intrusion with clear aligners: a randomized controlled trial.

OBJECTIVES: To compare changes in maxillary molar root resorption, intrusion amount, dentoskeletal measures, and maximum bite force (MBF) between clear aligners (CA) and fixed appliances with miniscrew (FM) during molar intrusion. MATERIALS AND METHODS: Forty adults with anterior open bite were randomized into either CA or FM groups. Lateral cephalograms, cone-beam computed tomography (CBCT), and MBF were collected at pretreatment (T0) and 6 months of treatment (T1). Maxillary molar intrusion in FM were intruded by nickel-titanium (NiTi) closed-coil spring delivered force (150 grams/side) while clear aligners combined with squeezing exercise were performed in CA. Parametric tests were used for statistical analysis. RESULTS: After 6 months of treatment, significant root resorption of 0.21-0.24 mm in CA and 0.38-0.47 mm in FM were found while maxillary molars were intruded 0.68 and 1.49 mm in CA and FM, respectively. CA showed significant less root resorption and intrusion than FM. Overbite, bite closing, and MBF increased significantly. CA showed significantly less overbite and SN-MP changes but more MBF increase than FM. MBF in CA was correlated with the amount of maxillary molar intrusion (r = 0.736, P < .05). CONCLUSIONS: Maxillary molar intrusion and root resorption in CA were half the amount in FM in 6 months. The amount of maxillary molar root resorption was one-third of the intrusion distance. CA displayed less overbite increase and bite closing but more MBF increase than FM. MBF in CA was positively correlated with the molar intrusion amount.

The Accuracy of Lateral Cephalogram for Measuring Alveolar Bone Thickness and Root Diameter on Mandibular Incisors.

Background: The objective of the study was to ascertain whether the alveolar bone and root of the mandibular central incisor measured from cephalograms can represent the same measurements of both mandibular central and lateral incisors from CBCT. Methods: A total of 38 sets of CBCT images and cephalograms before treatment were selected for this study. Thicknesses included alveolar bone, cortical bone, and cancellous bone at the labial and lingual sides. Root diameter and total root-bone thickness were also evaluated. The measurements were performed at 3, 6, and 9 mm from the cemento-enamel junction. Heights included labial bone height and lingual bone height. All measurements were performed on cephalograms and CBCT images of the mandibular central incisor (L1CT) and mandibular lateral incisor (L2CT). The data were statistically analyzed using one-way ANOVA and Bonferroni tests (p < 0.01) to compare the cephalograms, L1CT, and L2CT. Results: The cephalograms presented thicker alveolar bone and cortical bone (labial: 0.16−0.31 mm, lingual: 0.14−0.29 mm; p < 0.001) as well as higher alveolar crest (labial: 0.46−0.48 mm, lingual: 0.38−0.39 mm; p < 0.001) than the CBCT images on both the labial and lingual sides, whereas lingual cancellous thicknesses were not significantly different (p = 0.257). The cephalograms presented greater total root-bone thicknesses than L1CT (0.19−0.30 mm; p < 0.001), whereas the cephalograms traced thinner roots than L1CT (0.18−0.23 mm; p < 0.001) and L2CT (0.39−0.59 mm; p < 0.001). Conclusion: Lateral cephalograms cannot represent both mandibular central and lateral incisor dentoalveolar thicknesses, heights, and root diameters the same as CBCT. However, the differences were less than 0.5 mm.

Effect of Extending Corticotomy Depth to Trabecular Bone on Accelerating Orthodontic Tooth Movement in Rats.

Corticotomy is a surgical procedure that induces injury to the cortical bone to accelerate tooth movement. This study aimed to increase the depth of corticotomy to the trabecular bone and to evaluate the amount and rate of tooth movement and alveolar bone changes in response to various degrees of cortical and trabecular bone injury. Seventy-eight male Wistar rats were randomly divided into four groups based on procedure used: (1) baseline control group of orthodontic tooth movement (OTM) only; (2) OTM + 4 corticotomies (CO); (3) OTM + 4 osteotomies (OS); and (4) OTM + 16 CO. A closed-coil nickel-titanium spring was placed to move the maxillary first molar mesially with a 10 g force. On days 0, 7, 14, and 21, alveolar bone alteration and tooth movement were measured using microcomputed tomography. Significant tooth movement was related to the number and the depth of the perforations. The OTM + 16 CO group showed a greater amount and rate of tooth movement than the OTM + 4 CO group. When osteotomy and corticotomy were compared with the same volume of bone removed, the OTM + 4 OS group had a faster rate of tooth movement than the OTM + 16 CO group during the first week, with significantly reduced bone volume. However, no significant difference was observed in the amount of tooth movement between the OTM + 4 OS and OTM + 16 CO groups at the end of the study. Extending the depth of corticotomy to trabecular bone increased the amount of tooth movement by accelerating the induction and completion of bone remodeling, which accelerated the rate of tooth movement during the initial stage.

Analysis of Osteoclasts and Root Resorption in Corticotomy-Facilitated Orthodontics with Ibuprofen Administration-An Animal Study.

Following corticotomy surgery, patients experience moderate to severe post-operative pain that necessitates prescriptions of analgesics. The prostaglandin inhibitory effect of ibuprofen influences the mobility of teeth during orthodontic treatment. This study aimed to determine how ibuprofen affects histological reactions and dental root resorption during orthodontic tooth movement aided by corticotomy. Forty-two male Wistar rats were divided into three groups by random selection: (1) control group, (2) corticotomy group (CO), and (3) corticotomy with 0.6 mL of 15 mg/kg ibuprofen group (CI). On each buccal and palatal alveolar bone, two decortication points were made. Orthodontic tooth movement was induced on the maxillary first molar for 21 days utilizing a NiTi-closed coil spring with 10 g of force. Hematoxylin and eosin were used to prepare and stain the histological sections. The numbers of osteoclasts on days 0, 7, 14, and 21 were determined, and the root resorption area on days 0 and 21 was measured. Compared to the control group, the osteoclast counts in the CO and CI groups were considerably greater (p < 0.002). No significant differences were observed between the CO and CI groups in the numbers of osteoclasts or the percentages of root resorption (p > 0.05). The amounts of osteoclast activity and root resorption were unaffected by the administration of ibuprofen in corticotomy-facilitated tooth movement.

The Accuracy of Lateral Cephalogram in Representing the Anterior Maxillary Dentoalveolar Position.

Background: To evaluate the dentoalveolar position and root diameters of the maxillary incisors from cone beam computed tomograms (CBCT) compared with cephalometric tracings. Methods: A total of 64 sets of initial lateral cephalograms and CBCT images were enrolled. Measurements of dentoalveolar position included bone thicknesses and heights of alveolar, cortical, and cancellous bone. Root diameter and total root-bone thickness were also evaluated. All measurements were performed on cephalograms and CBCT images of the maxillary central incisor (U1CT) and maxillary lateral incisor (U2CT). The data were statistically analyzed using one-way ANOVA and Bonferroni tests (p < 0.01) to compare the cephalograms, U1CT, and U2CT. Results: The cephalograms presented thicker alveolar bone (labial: 0.20−0.67 mm, palatal: 0.41−0.60 mm; p < 0.001) and cortical bone (labial: 0.20−0.67 mm, palatal: 0.41−0.52 mm; p < 0.001) as well as higher alveolar crest (labial: 0.23−0.27 mm, palatal: 0.15−0.17 mm; p < 0.001) and cortical height (labial: 0.35−0.47 mm; p = 0.051, palatal: 0.14−0.18 mm; p < 0.001) than the CBCT images on both the labial and palatal sides, whereas palatal cancellous thickness was not significantly greater (p > 0.01). The cephalograms presented a greater total root-bone thicknesses (0.80−1.08 mm; p < 0.001), whereas the cephalograms traced thinner roots than the CBCT images (0.36−0.52 mm; p < 0.01). Conclusion: Routine lateral cephalograms are not suitable for alveolar bone evaluation in orthodontic treatment due to errors in representing dentoalveolar thicknesses and heights.

Maxillary anterior gingiva and dentoalveolar changes after en-masse retraction between thick and thin gingival biotypes.

INTRODUCTION: This study compared the changes of gingiva and alveolar bone parameters, including cortical and cancellous bones between thick and thin gingival biotypes after en-masse retraction. METHODS: Thirty-two adult subjects (mean age, 20.6 years) with maxillary anterior teeth protrusion and proclination were studied and divided into 2 equal groups: thick gingival biotype (TKB) and thin gingival biotype (TNB). Maxillary anterior teeth were retracted using nickel-titanium coil springs at 150 g of force bilaterally for 4 months. Lateral cephalograms, study models, and cone-beam computed tomography scans were taken before retraction and 3 months after 4 months of retraction. Nonparametric tests compared the changes within the groups at these periods and between the groups. RESULTS: The gingiva gained thickness and length (P <0.01) on the labial and palatal sides. The gingival thickness gained more on the palatal side (P <0.01), whereas the length gained equally in both groups. Labial alveolar bone showed increased thickness and height (P <0.01) as opposed to the palatal alveolar bone that presented with loss of thickness and height (P <0.01). The height loss occurred more in TNB (P <0.01). Labial cortical bone increased in thickness and height (P <0.01), whereas palatal cortical bone thinned (P <0.01) at levels in which no cancellous bone was present at the crestal level for TKB and the crestal and midroot levels for TNB. TKB showed slower incisor movement and less retroclination than the TNB (P <0.01) with minimal incisor extrusion. CONCLUSIONS: Favorable gingiva and labial bone responses after en-masse retraction were found in both gingival biotypes, whereas more palatal alveolar bone height loss was presented in TNB. Cortical bone thickness decreased when cancellous bone was absent.