Maxillary basal arch forms in operated adult patients with cleft lip and palate using root apices: A pilot study.

OBJECTIVES: The purpose was to identify the maxillary basal arch forms utilizing the root apices and compare the maxillary basal arch form of groups with cleft lip and palate (CLP) and normal group. MATERIALS AND METHODS: This study included 30 patients (21.8 ± 3.5 years old) with unilateral CLP (ULCP group) and 30 patients (20.9 ± 2.2 years old) with bilateral CLP (BCLP group). The normal group consisted of 30 non-cleft patients (21.2 ± 2.3 years old) with normal occlusion. Three-dimensional (3D) Cartesian coordinates of the root apices of each tooth were determined using cone-beam computed tomography. The 3D coordinates were projected onto the palatal plane to create the 2D coordinates. Thereafter, the basal arch forms were constructed by the Procrustes superimposition. Finally, For the basal arch form comparisons among groups, the inter-root widths were measured. RESULTS: Both CLP groups had a narrower inter-root width than the normal group. The BCLP group had significantly narrower premolar and molar widths than the UCLP group (P < .05). Especially, the inter-first molar width of the UCLP and BCLP groups was 3.7 ± 0.7 (P < .001) and 6.6 ± 0.8 (P < .001) mm smaller than that of the normal group, respectively. CONCLUSIONS: We used the root apices to identify the basal arch forms. The basal arch form of patients with CLP was narrower than that of the normal group. The basal arch form of patients with BCLP was narrower than that of patients with UCLP. Our findings may help clinicians better comprehend basal arch forms in patients with CLP and transverse discrepancies.

Comparison of root apex's position between unilateral and bilateral palatally impacted canines: A pilot study.

INTRODUCTION: The purpose was to determine whether the location of the root apices of unilateral palatally impacted canines differs from that of bilateral palatally impacted canines using cone-beam computed tomography. METHODS: The subjects were divided into 3 groups: a bilateral palatally impacted canine group (BPG; n = 28), a unilateral palatally impacted canine group (UPG; n = 28), and a control group (CG; n = 28) that included contralateral normally erupted canines in the UPG. After selecting the root apex in the onDemand3D program, 3-dimensional coordinates were extracted. These 3-dimensional coordinates were converted using the MATLAB program to 2-dimensional coordinates via projection on the palatal plane. Procrustes analysis was used to superimpose these 2-dimensional coordinates. The x- and y-coordinates of the root apices were used to measure the distance between the origin and root apex. RESULTS: The distance between the root apex of the canine and the origin was 17.43 ± 1.78 mm in BPG, 17.96 ± 1.87 mm in UPG, and 13.96 ± 0.95 mm in CG. There was no statistically significant difference between UPG and BPG. However, there was a statistically significant difference between the CG and impacted groups (UPG and BPG). The same results were found for the x- and y-coordinates. CONCLUSIONS: The location of the root apices of unilateral palatally impacted canines is similar to that of bilateral palatally impacted. The location of root apices of palatally impacted canines differs from that of normally erupted canines.

Effect of Observer's Sex and Chin Prominences on the Perception of the Lower Lip-Chin Prominence Angle.

ABSTRACT: This study aimed to identify the preferred range of lower lip-chin prominence angles in the Korean population and evaluate the effect of the individual lower lip-chin prominence angle on perceptions of esthetic chin profile.Chin prominence silhouettes were used to assess the lower lip-chin prominence preference. The observers randomly categorized each image as (1) normal, (2) slightly abnormal but not requiring surgical correction, and (3) abnormal and requiring surgery. Individual lower-chin prominence angles of all observers were analyzed using standardized clinical photographs.The normal range of lower lip-chin prominence angle is 0° to 25°; socially acceptable range is 0° to -10°, 25° to 40°; range needing surgery is -10° to -30° and 40° to 45°. Women are more tolerant to chin protrusion. A protrusive chin is more acceptable in observers with retrusive chin profile.Skeletal Class II profile is more acceptable than skeletal Class III in the Korean population. The individual lower-chin prominence angle could affect perception of desired surgery. These findings indicate that patient-specific treatment planning is important in achieving satisfaction in chin surgery.

Methods in Genetic Analysis for Evaluation Mandibular Shape and Size Variations in Human Mandible.

ABSTRACT: The human mandible has been investigated from both clinical and evolutionary perspectives. Recent advances in genome science have identified the genetic regulation of human mandibular shape and size. Identification of genes that regulate mandibular shape and size would not only enhance our understanding of the mechanisms of mandibular growth and development but also help define a strategy to prevent mandibular dysplasia. This review provides a comprehensive summary of why and how the mandible was evaluated in the human mandible genome study. The variation in human mandibular shape and size has been progressively clarified, not only by focusing on the mandible alone but also by using extremely diverse approaches. The methods of data acquisition for evaluating human mandibular shape and size variation are well established. Furthermore, this review explains how to proceed with future research.

Anatomical relationship between the maxillary posterior teeth and the sinus floor according to an anterior overbite.

OBJECTIVE: To evaluate the vertical relationship between the maxillary sinus floor (MSF) and the maxillary posterior teeth (MPT) according to an anterior overbite. SETTINGS AND SAMPLE POPULATION: The patients were divided into three groups according to an anterior overbite. The open bite group (OBG) included patients with an anterior overbite of ≤0 mm, the normal overbite group (NBG) included patients with an overbite of 0-3 mm, and the deep bite group (DBG) included patients with an overbite ≥3 mm. Thirty patients were randomly matched into each group based on age and sex. MATERIALS AND METHODS: The distances and vertical relationship between the MSF and the MPT was analysed using cone-beam computer tomography. The vertical relationship between the two was classified as either favourable or unfavourable for the intrusion of the posterior teeth. RESULTS: A higher ratio of patients in the OBG had MPT positioned close to the MSF than the DBG. Intrusion of the posterior teeth was unfavourable for an average of 87.2%, 77.2% and 70.2% molars in the OBG, NBG and DBG, respectively. CONCLUSIONS: The vertical distance between the MSF and the MPT is associated with an anterior overbite. The posterior teeth were in an unfavourable position for the orthodontic intrusion in the OBG as compared to the other groups. Additional caution is needed when planning orthodontic intrusion treatment for patients with an anterior open bite. But, there were some individual variations within each group.

Comparison of maxillary basal arch forms using the root apex in adult women with different skeletal patterns: A pilot study.

INTRODUCTION: This study aimed to establish maxillary basal arch forms using the root apices and to determine the differences in the basal arch forms in adult women with different sagittal skeletal patterns. METHODS: This retrospective study included 91 adult women, with either a Class I (n = 24), Class II Division 1 (n = 22), Class II Division 2 (n = 23), or Class III (n = 22) malocclusion, who underwent cone-beam computed tomography. Three-dimensional coordinates of the root apices were determined using the multiplanar reformation mode of OnDemand3D software (Cybermed Inc, Seoul, South Korea). Two-dimensional coordinates were converted from acquired 3-dimensional coordinates via projection on the palatal plane, and the Procrustes superimposition method was used to build the basal arch form. Finally, interroot width measurements were performed for basal arch form comparisons. RESULTS: There were significant differences among the 4 groups (P <0.05) with respect to the intercanine width. The intercanine width of Class II Division 1 group was significantly narrower than that of the other groups. The Class II Division 1 and Class II Division 2 groups tended to have tapered arch forms and squared arch forms, respectively. CONCLUSIONS: We established maxillary basal arch forms using the root apices. The Class II Division 1 group had a significantly narrower intercanine distance. The use of the root apex to depict the basal arch form seems reasonable.

Cone-Beam Computed Tomography Evaluation of Pharyngeal Airway Space Changes After Bimaxillary Orthognathic Surgery in Patients With Class III Skeletal Deformities: A 6-Year Follow-Up Study.

PURPOSE: The aim of the present study was to investigate the volumetric and 2-dimensional (2D) changes in the pharyngeal airway space (PAS) after bimaxillary orthognathic surgery (maxillary advancement and mandibular set back) in patients with skeletal Class III deformities. PATIENTS AND METHODS: In the present retrospective study, patients with skeletal Class III deformities were treated at Pusan National University Hospital (Busan, South Korea) and had undergone cone-beam computed tomography examination preoperatively, immediately postoperatively, 6.0 ± 0.6 months postoperatively, and 6.2 ± 1.3 years postoperatively. The anteroposterior length (APL), largest transverse width (LTW), and cross-sectional area (CSA) at 4 reference planes and the PAS volume were measured. Spearman's correlation analysis was used to assess the correlation between the PAS changes and skeletal movements. RESULTS: The subjects included 11 men and 12 women. Their mean age was 22.7 ± 4.7 years (range, 18 to 33 years). The APL and CSA on the PNS-Vp, CV1, and CV2 planes, the LTW on the CV1 plane, and the oropharyngeal and total volume had decreased at 6 months postoperatively. However, thereafter, no significant 2D or volumetric changes were observed until 6.2 years postoperatively. The long-term change of the LTW on the CV3 plane correlated negatively with mandibular relapse. CONCLUSIONS: The volume and morphology of the 6-month postoperative changes in PAS were stable at 6 years for patients who had undergone maxillary advancement and mandibular setback.

Effect of different sizes of bioactive glass-coated mesoporous silica nanoparticles on dentinal tubule occlusion and mineralization.

OBJECTIVES: To synthesize two different sizes of bioactive glass-coated mesoporous silica nanoparticles (BGN@MSNs) and to investigate their effects on dentinal tubule occlusion and remineralization. MATERIALS AND METHODS: Two different sizes of mesoporous silica nanoparticles (MSNs) were synthesized using the Stöber method (368A, 1840A) and coated with bioactive glass nanoparticles (BGNs) using a modified quick alkali-mediated sol-gel method (368B, 1840B). Sensitive tooth disc models were prepared and divided into six groups and the following treatments were applied: group 1-no treatment, group 2-bioglass, group 3-368A, group 4-368B, group 5-1840A, and group 6-1840B. Then, five discs were selected from each group and soaked in 6 wt% citric acid to test acid resistance. Dentinal tubule occlusion and occlusion ratio were observed using field-emission scanning electron microscopy. In vitro mineralization tests using simulated body fluid solution were performed to evaluate the remineralization effect of the treatment. RESULTS: All samples effectively occluded the dentinal tubule and formed a membrane-like layer. After acid treatment, 1840B (group 6) exhibited the highest rate of dentinal tubule occlusion. Remineralization was observed in 368B and 1840B, and 1840B exhibited the fastest remineralization. CONCLUSIONS: Dentinal tubule remineralization induced by the BGN@MSN biocomposite can be used to stabilize long-term prognosis in dentin hypersensitivity. The 1840B induced the most efficient remineralization, and its smaller size and larger surface area were effective for remineralization. CLINICAL RELEVANCE: The BGN@MSN biocomposite with its smaller size and larger surface area was more effective for remineralization and dentinal tubule sealing.

Association between the FGFR1 rs13317 single nucleotide polymorphism and orbitale-nasion depth based on cephalometric images.

The fibroblast growth factor receptor 1 (FGFR1) gene plays an important role in craniofacial morphogenesis. In our previous study, an association between FGFR1 single nucleotide polymorphisms (SNPs) and craniofacial morphology was demonstrated in Japanese and Korean subjects. The present study aimed to evaluate the relationship between a common FGFR1 SNP (rs13317) with craniofacial morphology, increasing the number of measurements and examining Egyptian subjects (n = 191) in addition to the Japanese (n = 211) and Korean (n = 226) subjects. Genotyping for rs13317 was performed using the TaqMan assay, and its associations with 81 craniofacial measurements derived from lateral and posteroanterior cephalograms were analyzed by multiple regression analysis controlling sex and facial size. The results from each of the populations were then statistically combined. In the Egyptian subjects, rs13317 was significantly associated with the nasion-orbitale depth (P = 0.00040), and a suggestive association was also observed in the Japanese (P = 0.037) and Korean subjects (P = 0.045). The combined analysis revealed that only the nasion-orbitale depth showed a significant association (P = 0.000062) and that several measurements showed a suggestive association. Our results strongly indicate that rs13317 is associated with a smaller depth between the nasion and orbitale, representing a relative protrusion of the cheekbones and retrusion of the nasal root. A similar characteristic is also observed in individuals with Pfeiffer syndrome, which is caused by a dysfunctional FGFR1 mutation.

Common polymorphisms in WNT10A affect tooth morphology as well as hair shape.

Hair and teeth are appendages of ectodermal origin, and there are common molecular backgrounds involved in their formation. To date, it has been revealed that a non-synonymous polymorphism in EDAR has effects on the morphological variation in both hair and teeth. Previous association studies have confirmed that single-nucleotide polymorphisms (SNPs) in/near THADA, FRAS1, WNT10A, NAF1 and FGFR2 are associated with hair morphology. In this study, we thus examined whether these SNPs are also associated with dental characteristics. We measured metric dental traits including crown size and also evaluated non-metric dental traits using plaster casts obtained from subjects (272 Japanese and 226 Koreans). DNA samples were prepared from the subjects and genotyped for the hair morphology-associated SNPs. We observed a significant association of crown size with an SNP in WNT10A (rs7349332), but not with SNPs in other genes. Therefore, we further examined four SNPs within and around WNT10A, among which rs10177996 had the strongest association with dental traits. World distribution of the derived allele in rs10177996, which is associated with larger teeth, showed that Eurasians have a higher allele frequency than Africans. Together with previous studies on hair morphology, this study demonstrated that common variations in WNT10A have pleiotropic effects on the morphology of ectodermal appendages.

Preliminary Study to Determine the Reference Plane of Patients With a Unilateral Cleft Lip and Palate.

OBJECTIVE: The objective of this study was to determine the three-dimensional midsagittal reference planes for unilateral cleft lip and palate (UCLP) patients that can be easily applied in a clinical setting. DESIGN: This was a retrospective analysis. PATIENTS: There were 35 UCLP patients (25 men, 10 women; 28.1 ± 6.9 years old) in this study. METHODS: With landmark's three-dimensional coordinates obtained from cone-beam computed tomography, the symmetric midsagittal reference planes were calculated by applying the ordinary Procrustes superimposition method using the original and mirror images. Procrustes analysis was also used to find the closest landmarks to the calculated symmetric midsagittal reference plane and test its compatibility with the symmetrical midsagittal reference plane. MAIN OUTCOME MEASURE: The three nearest landmarks to the symmetric midsagittal reference plane were Opisthion, Basion, and Nasion. RESULTS: The averages of the sums of the squared Euclidean distance and squared Procrustes distance differences between the two configurations and shapes fabricated by the symmetrical and landmark-based midsagittal reference planes, respectively, were calculated as 1.836 ± 3.295 and 1.519 × 10-5 ± 2.351 × 10-5. CONCLUSION: It was confirmed that the midsagittal reference planes from these selected landmarks for UCLP patients were compatible with symmetric midsagittal reference planes from the Procrustes analysis and the asymmetric measurements.

Assessment of the root apex position of impacted maxillary canines on panoramic films.

INTRODUCTION: In this study, we aimed to analyze the root apex positions of impacted maxillary canines on panoramic radiographs according to their labiopalatal positions and to propose a new panoramic radiographic predictor of impacted maxillary canines. METHODS: Paired panoramic films and cone-beam computed tomography images of 104 patients with unilateral impacted maxillary canines were selected. The sector locations of the impacted canine root apices on the panoramic radiographs were compared with the labiopalatal positions of impacted maxillary canines on cone-beam computed tomography. Statistical correlations between panoramic and cone-beam computed tomography findings were examined with the chi-square test. RESULTS: A statistically significant association was observed between the sector locations of impacted canine root apices and the labiopalatal positions of the canines (P <0.001). The root apices of labially impacted canines were more frequently located in sector 2 (corresponding to the lateral incisor position), those of palatally impacted canines were more frequently located in sector 4 (corresponding to the first premolar), and those of midalveolus impacted canines were more frequently located in sector 3 (corresponding to the canine). CONCLUSIONS: On panoramic films, the root apices of palatally impacted canines tended toward the root apices of the maxillary first premolars, whereas those of labially impacted canines tended toward the root apices of the maxillary lateral incisors. Therefore, the sector locations of impacted canine root apices on panoramic radiographs could be used for the early prediction of maxillary canine impactions and determination of the labiopalatal positions of impacted canines.

How far is the root apex of a unilateral impacted canine from the root apices' arch form?

INTRODUCTION: The purpose of this study was to determine the arch form of the root apices of normally erupting teeth and then determine the differences in the location of the apex of impacted canines relative to normally erupting canines. In addition, we sought to determine whether the labiopalatal position of the impacted canines influences the position of the apices. METHODS: The study included 21 patients with unerupted canines that subsequently had a normal eruption, 21 patients with palatally impacted canines, 27 patients with labially impacted canines, and 17 patients with midalveolus impacted canines. Images were obtained using cone beam computed tomography, and the x, y, and z coordinates of the root apices were determined using Ondemand3D software (Cybermed Co., Seoul, Korea). Two-dimensional coordinates were converted from acquired 3-dimensional coordinates via projection on a palatal plane, and the Procrustes method was used to process the converted 2-dimensional coordinates and to draw the arch forms of the root apices. Finally, we measured the extent of root apex deviation from the arch forms of the root apices. RESULTS: Normally erupting canines showed that even though calcifications may be immature, their positions were aligned with a normal arch form. The root apices of the impacted canines were an average of 6.572 mm away from the root apices' arch form, whereas those of the contralateral nonimpacted canines were an average distance of 2.221 mm away, a statistically significant difference. The palatally impacted canines' root apices distribution tended toward the first premolar root apices. CONCLUSIONS: Incompletely calcified, unerupted teeth with a subsequent normal eruption showed a normal arch form of the root apices. The root apices of impacted canines were farther from the arch forms than were the nonimpacted canines. Also, the root apices of impacted canines in the palatal area showed distributions different from those of the other impacted canine groups.

Statistical shape analysis-based determination of optimal midsagittal reference plane for evaluation of facial asymmetry.

INTRODUCTION: The purpose of this study was to determine, by statistical shape analysis of original and mirrored skeletal landmarks, the optimal landmark-based midsagittal reference plane for evaluation of facial asymmetry. METHODS: The study sample comprised 69 patients with facial asymmetry (36 men, 33 women; mean age, 23.0 ± 4.1 years). All landmarks were obtained with cone-beam computed tomography using a 3-dimensional coordinate system. For identifying the landmark-based midsagittal reference plane, the 3 landmarks nearest to the symmetric midsagittal reference plane were selected by ordinary and generalized Procrustes analyses. To verify the 3-landmark-based midsagittal reference plane's compatibility with the symmetric midsagittal reference plane, asymmetry measurements were calculated and tested for each. RESULTS: The 3 nearest landmarks (nasion, anterior nasal spine, and posterior nasal spine) were selected for the 3-landmark-based midsagittal reference plane. The averages of the sums of the squared Euclidean distance and the squared Procrustes distance differences between the 2 configurations and shapes fabricated by the symmetric and landmark-based midsagittal reference planes, respectively, were calculated as 0.121 ± 0.241 mm and 1.69 × 10(-6) ± 3.25 × 10(-6). The testing results for the symmetric and landmark-based midsagittal reference planes were almost the same. CONCLUSION: The results indicated that a 3-dimensional midsagittal reference plane constructed of nasion, anterior nasal spine, and posterior nasal spine could be a valuable tool for the evaluation of patients with facial asymmetry.

Differences Among Deviations, Genders, and Observers in the Perception of Eye and Nose Asymmetry.

PURPOSE: This study investigated the degree and range of recognition of canting of the interpupillary line and deviation of the nose, which were regarded as "normal," "acceptable," and "needing surgical correction," according to different observer groups. MATERIALS AND METHODS: Four different groups (40 each for laypeople, dental students, general dentists, and orthodontists) rated 11 simulated asymmetric images with canted eyes and a deviated nose separately. The raters categorized each image as normal, socially "acceptable" and not requiring correction, or abnormal and would benefit from correction. Survival analysis was used to evaluate the scope of perception. RESULTS: The degree of recognition for eye-canting and nose deviation was 2.31 and 2.92, respectively. Eye-canting and nose deviation had lower degrees of recognition in the clockwise direction (2.13°) and on the left side (2.65°), respectively. Women showed a lower degree of the "upper limit of the acceptable range" for canted eyes, and men showed a lower "degree of recognition" and "upper limit of the acceptable range" for a deviated nose. Orthodontists showed a larger upper limit of the acceptable range for eye-canting (P < .001). CONCLUSIONS: The perceptions of asymmetry of canted eyes and deviated nose were affected by gender, direction of asymmetry, and observer groups.

Skeletal stability after maxillary posterior-superior movement for skeletal Class III deformities: pterygoid process fracture versus removal.

PURPOSE: To evaluate maxillary stability after Le Fort I osteotomy using posterosuperior movement after pterygoid process fracture or removal and mandibular setback surgery for skeletal Class III deformities. MATERIALS AND METHODS: A retrospective cohort study was performed of changes in 28 patients with skeletal Class III deformity using 3-dimensional (3D) measurement point coordinates obtained by cone-beam computed tomographic superimposition. The predictor variable was management of the pterygoid process (fracture vs removal). The outcome variables were changes in measurement points based on 3D coordinates obtained preoperatively, immediately postoperatively, and 6 months after surgery. Linear mixed-effects models were applied to evaluate postoperative stability. RESULTS: The 3D cephalometric outcome variables for 14 patients who had undergone pterygoid process fracture were compared with those for 14 patients who had undergone pterygoid process removal. The postoperative nasopalatine canal points moved superiorly 0.11 mm and inferiorly 0.06 mm in the fracture and removal groups, respectively. However, most of the postoperative relapse was within 1 mm. There were no differences in postoperative skeletal changes shown by the fracture and removal groups (P < .05). CONCLUSIONS: The results suggest that surgeons can achieve good skeletal stability in posterosuperior movement from Le Fort I osteotomy, regardless of whether the pterygoid process is fractured or removed.

Quantitative skeletal maturation estimation using cone-beam computed tomography-generated cervical vertebral images: a pilot study in 5- to 18-year-old Japanese children.

OBJECTIVES: The purpose of this study was to establish multivariable regression models for the estimation of skeletal maturation status in Japanese boys and girls using the cone-beam computed tomography (CBCT)-based cervical vertebral maturation (CVM) assessment method and hand-wrist radiography. MATERIALS AND METHODS: The analyzed sample consisted of hand-wrist radiographs and CBCT images from 47 boys and 57 girls. To quantitatively evaluate the correlation between the skeletal maturation status and measurement ratios, a CBCT-based CVM assessment method was applied to the second, third, and fourth cervical vertebrae. Pearson's correlation coefficient analysis and multivariable regression analysis were used to determine the ratios for each of the cervical vertebrae (p < 0.05). RESULTS: Four characteristic parameters ((OH2 + PH2)/W2, (OH2 + AH2)/W2, D2, AH3/W3), as independent variables, were used to build the multivariable regression models: for the Japanese boys, the skeletal maturation status according to the CBCT-based quantitative cervical vertebral maturation (QCVM) assessment was 5.90 + 99.11 × AH3/W3 - 14.88 × (OH2 + AH2)/W2 + 13.24 × D2; for the Japanese girls, it was 41.39 + 59.52 × AH3/W3 - 15.88 × (OH2 + PH2)/W2 + 10.93 × D2. CONCLUSIONS: The CBCT-generated CVM images proved very useful to the definition of the cervical vertebral body and the odontoid process. The newly developed CBCT-based QCVM assessment method showed a high correlation between the derived ratios from the second cervical vertebral body and odontoid process. CLINICAL RELEVANCE: There are high correlations between the skeletal maturation status and the ratios of the second cervical vertebra based on the remnant of dentocentral synchondrosis.

Stability of Le Fort I Osteotomy With Propeller Graft for Canting Correction in Facial Asymmetry.

The aim of this study was to evaluate the maxillary stability in patients who had undergone Le Fort I osteotomy with propeller graft and mandibular sagittal split ramus osteotomy for correction of maxillary asymmetry. This was a retrospective study on 15 facial asymmetry patients (7 men, 8 women: 22.2 years) requiring surgical correction at the preoperative (T0), immediately postoperative (T1) and 6 months after surgery (T2) stages. To evaluate the skeletal stability, computed tomography (CT) superimposition was used, and skeletal landmarks were measured and compared from the superimposed images according to an x, y, z coordinate system. The skeletal changes at each stage (ΔT1-T0 and ΔT2-T1) were compared by paired t-test (P<0.05). The obtained data on the skeletal changes immediately postoperatively to 6-month follow-up (ΔT2-T1) showed that the Le Fort I osteotomy with propeller graft had effected stable maxillary skeletal stability at the maxillary measurement points (posterior nasal spine (PNS ), nasopalatine canal, U3 crown tip, U3 root apex, and U6 furcation). These results suggested that in cases of facial asymmetry where the upper tooth exposure is proper and anterior-posterior movement of the maxilla is not much required, Le Fort I osteotomy with propeller graft is an effective method for stable canting correction.

Effect of occlusal vertical dimension changes on postsurgical skeletal changes in a surgery-first approach for skeletal Class III deformities.

INTRODUCTION: The purposes of this study were to investigate the relationship between occlusal vertical dimension (VD) changes and postsurgical skeletal changes in the surgery-first approach and to derive regression models for the final mandibular setback at B-point. METHODS: This retrospective study included 40 patients (16 men, 24 women; ages, 22.6 ± 4.0 years) who had undergone a bimaxillary surgery-first approach. Using cephalograms generated from cone-beam computed tomography representing the presurgical, postsurgical, and posttreatment stages, skeletal landmarks in the maxilla and mandible were investigated to derive multivariate linear regression-based prediction models. Additionally, a patient classification based on the VD was established and verified to generate regression models for the classified groups. RESULTS: For the nonincreased VD group, the surgical setback of B-point was its predictor for the final mandibular setback (R(2) at 92%). Meanwhile, the final mandibular setback of the increased VD group was predicted according to the surgical upward movement of pogonion, the postsurgical horizontal position of A-point, and the postsurgical vertical position of the coronoid process (R(2) at 94%). CONCLUSIONS: The results of this study support the clinical observation that the more increased the vertical occlusal dimension after surgery, the less predictable the position of B-point at the posttreatment stage.

A genome-wide association study of third molar agenesis in Japanese and Korean populations.

Tooth agenesis is the most common developmental anomaly of human dentition, occurring most often in the third molar (wisdom tooth). It is affected by genetic variation, so this study aimed to identify susceptibility genes associated with third molar agenesis. Examination of panoramic radiographs and medical history about third molar extraction were used to diagnose third molar agenesis. We then conducted a genome-wide association study of 149 cases with at least one-third molar agenesis and 338 controls from Japan and Korea using the Illumina HumanOmniExpress BeadChip. After rigorous quality-control filtering, approximately 550 000 single-nucleotide polymorphisms (SNPs) were analyzed in association tests with the status. We identified three SNPs showing evidence of association at P<1 × 10(-5) and 69 SNPs showing evidence of association at P<1 × 10(-4). SNP rs1469622, which maps to an intron of THSD7B (thrombospondin, type I, domain containing 7B) on chromosome 2, showed the strongest association (combined odds ratio=1.88, 95% confidence interval=1.43-2.47, P=7.5 × 10(-6)). The identified SNPs may be considered candidates for future replication studies in independent samples.