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.

Three-dimensional evaluation of mandibular width after mandibular asymmetric setback surgery using sagittal split ramus osteotomy.

Objective: The study aimed to evaluate the changes in mandibular width after sagittal split ramus osteotomy (SSRO) in patients with mandibular asymmetric prognathism using cone-beam computed tomography (CBCT). Methods: Seventy patients who underwent SSRO for mandibular setback surgery were included in two groups, symmetric (n = 35) and asymmetric (n = 35), which were divided according to the differences in their right and left setback amounts. The mandibular width was evaluated three-dimensionally using CBCT images taken immediately before surgery (T1), 3 days after surgery (T2), and 6 months after surgery (T3). Repeated measures analysis of variance was applied to verify the differences in mandibular width statistically. Results: Both groups showed a significant increase in the mandibular width at T2, followed by a significant decrease at T3. No significant difference was observed between T1 and T3 in any of the measurements. No significant differences were found between the two groups (p > 0.05). Conclusions: After mandibular asymmetric setback surgery using SSRO, the mandibular width increased immediately but returned to its original width 6 months after surgery.

Three-dimensional evaluation of the pharyngeal airway space in patients with anterior open bite.

Objective: : This study aimed to three-dimensionally evaluate the pharyngeal airway space (PAS) of patients with anterior open bite (AOB) by using cone-beam computed tomography (CBCT) and compare the findings with those obtained in individuals with normal occlusion. Methods: : The open bite group (OBG, n = 25) consisted of patients with an anterior overbite of -3 mm or less, while the control group (n = 25) consisted of age- and sex-matched individuals with an anterior overbite of 1-3 mm, Angle Class I malocclusion (1° ≤ point A-nasion-point B angle ≤ 4°), and a normodivergent profile (22° ≤ Frankfort mandibular plane angle ≤ 28°). After the CBCT data were reconstructed into a three-dimensional image, the PAS was segmented into four parts, and the volume of each part was measured. Pharyngeal airway length (PAL) and the area and transverse width of the part showing minimal constriction were also measured. Pearson's correlation analysis was used to evaluate the correlation between changes in the PAS and the amount of anterior overbite. Results: : The OBG showed a significantly narrower airway space in the nasopharyngeal, hypopharyngeal, and total airway volumes. The OBG also showed a significantly smaller area and transverse width of the part with minimal constriction. The OBG showed a significantly longer PAL, but there was no correlation between the amount of anterior overbite and the changes in PAS. Conclusions: : The PAS was associated with AOB. Patients with AOB had a narrower PAS and a smaller part showing minimal constriction.

Effects of different distalization directions and methods on maxillary total distalization with clear aligners: a finite element study.

OBJECTIVES: To analyze the effects of maxillary tooth distalization by clear aligner (CA) treatment with variations in the angular direction of the distalization force, presence of attachments, and force-application method used. MATERIALS AND METHODS: A finite element model containing alveolar bone, dentition, and periodontal ligament was constructed. Analytical model groups were as follows: (1) distalization with buttons (without attachments), (2) buttons on canines (with attachments), (3) precision cuts on the canines (without attachments), and (4) precision cuts on the canines (with attachments). A distalization force of 1.5 N was applied to the button or precision cut at -30°, -20°, -10°, 0°, 10°, 20°, and 30° to the occlusal plane. RESULTS: As the direction of force approached +30°, the dentition inclined posteriorly. The posterior movement pattern was significantly influenced by the presence of an attachment and the direction of force, rather than the area where the force was applied. Distal inclination was dramatically reduced with attachments. A disengagement or deformation of the CA may reduce the distalization efficiency of the dentition or move the dentition in an inappropriate direction. CONCLUSIONS: Attachments for efficient distalization by the CA are necessary. The use of miniscrews in the direction of force parallel to the occlusal plane is more advantageous than the use of Class II elastics. Due to CA deformation, distalization with the button on the canines can be more effective for distal movement of the maxillary dentition.

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.

Unilateral condylar hyperplasia treated with simultaneous 2-jaw orthognathic surgery and posterior segmental osteotomy.

A 25-year-old woman presented with left condylar hyperplasia, canting-type facial asymmetry, mandibular prognathism, and arch width discrepancy. Bone scintigraphy confirmed the inactive status of the condyle, and the temporomandibular joint functioned within the normal range; thus, orthognathic surgery without condylectomy was performed. To correct facial asymmetry successfully through orthognathic surgery, sufficient dentoalveolar decompensation must be achieved in the presurgical orthodontic phase. In cases of canting-type facial asymmetry, teeth on the nondeviated side are extruded as dentoalveolar compensation. Therefore, vertical decompensation is required for intrusion of the extruded teeth. A miniscrew and resin build-ups were used for the intrusion of teeth, and posterior segmental osteotomy was simultaneously performed with orthognathic surgery for further intrusion. The canting-type facial asymmetry was notably corrected through successful vertical decompensation and close cooperation between orthodontists and maxillofacial surgeons. After 2 years of retention, the treatment results remained stable.

Enhanced antimicrobial and remineralizing properties of self-adhesive orthodontic resin containing mesoporous bioactive glass and zwitterionic material.

Abstract Background/purpose: Self-adhesive resins (SARs) do not require additional restorative adhesives and provide adequate adhesion to mineralized dental structures by shortening the bonding time in clinics where moisture control and isolation are difficult. The aim of this study was to evaluate the mechanical and biological properties of SARs containing mesoporous bioactive glass nanoparticles (MBNs) and 2-methacryloyloxyethyl phosphorylcholine (MPC) and to determine their antibacterial and remineralization effects. Materials and methods: MBNs and MPC were added to SARs to improve their physical properties and remineralization ability. The experimental resins assessed in this study were SARs mixed with 3%MPC, 5%MPC, 1%MBN+3%MPC, or 3%MBN+3%MPC. The shear bond strength, microhardness, adhesive remnant index, ion dissolution, degree of conversion, and antibacterial properties of the SARs were evaluated. To assess the remineralization properties, micro-computed tomography analysis was performed after pH cycling. Results: Increasing the MBN content in SAR resulted in higher microhardness compared to the control SAR. The shear bond strength decreased in the SAR+5%MPC group and increased in the SAR+1%MBN+3%MPC and SAR+3%MBN+5%MPC groups. Conclusion: Our findings suggest that SARs containing MBNs and MPC have antibacterial and remineralization effects on the enamel.

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.

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.

Effects of Zn-Doped Mesoporous Bioactive Glass Nanoparticles in Etch-and-Rinse Adhesive on the Microtensile Bond Strength.

The purpose of this study was to assess the effects in the dentin bond strength of dental adhesives (DAs) and biological effects using zinc (Zn)-doped mesoporous bioactive glass nanoparticles (MBN-Zn). Synthesized MBN and MBN-Zn were characterized by scanning electron microscopy (SEM), X-ray diffraction and the Brunauer, Emmett and Teller (BET) method. The matrix metalloproteinases (MMP) inhibition effects of DA-MBN and DA-MBN-Zn were analyzed. The microtensile bond strength (MTBS) test was conducted before and after thermocycling to investigate the effects of MBN and MBN-Zn on the MTBS of DAs. The biological properties of DA-MBN and DA-MBN-Zn were analyzed with human dental pulp stem cells (hDPSCs). Compared with the DA, only the DA-1.0% MBN and DA-1.0% MBN-Zn exhibited a statistically significant decrease in MMP activity. The MTBS values after thermocycling were significantly increased in DA-1.0% MBN and DA-1.0% MBN-Zn compared with the DA (p < 0.05). It was confirmed via the MTT assay that there was no cytotoxicity for hDPSCs at 50% extract. In addition, significant increases in the alkaline phosphatase activity and Alizarin Red S staining were observed only in DA-1.0%MBN-Zn. These data suggest the 1.0% MBN and 1.0% MBN-Zn enhance the remineralization capability of DAs and stabilize the long-term MTBS of DAs by inhibiting MMPs.

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.

The Effect of Mesoporous Bioactive Glass Nanoparticles/Graphene Oxide Composites on the Differentiation and Mineralization of Human Dental Pulp Stem Cells.

The purpose of this study was to investigate the effects of mesoporous bioactive glass nanoparticle (MBN)/graphene oxide (GO) composites on the mineralization ability and differentiation potential of human dental pulp stem cells (hDPSCs). MBN/GO composites were synthesized using the sol-gel method and colloidal processing to enhance the bioactivity and mechanical properties of MBN. Characterization using FESEM, XRD, FTIR, and Raman spectrometry showed that the composites were successfully synthesized. hDPSCs were then cultured directly on the MBN/GO (40:1 and 20:1) composites in vitro. MBN/GO promoted the proliferation and alkaline phosphatase (ALP) activity of hDPSCs. In addition, qRT-PCR showed that MBN/GO regulated the mRNA levels of odontogenic markers (dentin sialophosphoprotein (DSPP), dentine matrix protein 1 (DMP-1), ALP, matrix extracellular phosphoglycoprotein (MEPE), bone morphogenetic protein 2 (BMP-2), and runt-related transcription factor 2 (RUNX-2)). The mRNA levels of DSPP and DMP-1, two odontogenesis-specific markers, were considerably upregulated in hDPSCs in response to growth on the MBN/GO composites. Western blot analysis revealed similar results. Alizarin red S staining was subsequently performed to further investigate MBN/GO-induced mineralization of hDPSCs. It was revealed that MBN/GO composites promote odontogenic differentiation via the Wnt/ß-catenin signaling pathway. Collectively, the results of the present study suggest that MBN/GO composites may promote the differentiation of hDPSCs into odontoblast-like cells, and potentially induce dentin formation.

Immediate effects of mandibular posterior displacement on the pharyngeal airway space: A preliminary study.

OBJECTIVE: This study aimed to evaluate the immediate effects of mandibular posterior displacement on the pharyngeal airway space (PAS) by using cephalometric evaluations and to investigate how the surrounding structures are schematically involved. METHODS: In this retrospective study, 38 subjects with functional Class III malocclusion and two lateral cephalograms were selected. The first lateral cephalogram was taken with the mandible in the habitual occlusal position, and the second in anterior edge-to-edge bite. Paired t-test was used to analyze changes in the PAS, hyoid bone, tongue, and soft palate, followed by mandibular posterior displacement. Pearson's correlation analysis was used to determine the relationship between the amount of mandibular posterior displacement and other variables. RESULTS: A statistically significant decrease was observed in the PAS following mandibular posterior displacement. Along with mandibular posterior displacement, the tongue decreased in length (p < 0.001) and increased in height (p < 0.05), while the soft palate increased in length, decreased in thickness, and was posteriorly displaced (p < 0.001). The hyoid bone was also posteriorly displaced (p < 0.05). There was no correlation between the amount of mandibular posterior displacement and the measured variables. CONCLUSIONS: The PAS showed a statistically significant decrease following mandibular posterior displacement, which was a consequence of retraction of the surrounding structures. However, there were individual variances between the amount of mandibular posterior displacement and the measured variables.

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.

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.

Root proximity of miniscrews at a variety of maxillary and mandibular buccal sites: Reliability of panoramic radiography.

OBJECTIVES: To assess the root proximity and the insertion angles of miniscrews after miniscrew placement at a variety of maxillary and mandibular buccal sites using cone-beam computed tomography (CBCT) and to determine the differences in root proximity between CBCT and panoramic radiography (PR). MATERIALS AND METHODS: This retrospective study included 50 patients (mean age, 22.0 ± 4.5 years) who underwent postoperative CBCT and PR after miniscrew placements for intermaxillary fixation in orthognathic surgery. Twelve miniscrews were placed in the buccal bone of each patient: at sites between the central incisor and lateral incisor (SII), sites between the canine and first premolar (SCP), and sites between the second premolar and first molar (SPM) on the right and left sides of the mandible and maxilla. The insertion angles were measured on CBCT, and the root proximity was assessed on CBCT and PR. RESULTS: The mean vertical placement angles ranged from 84.27° to 95.12°, and the mean horizontal placement angles ranged from 90.93° to 101.1°. The rates of no contact between the root and the miniscrew were 68.0% in the SII, 50.5% in the SCP, and 57.8% in the SPM, which were significantly different (P = .000). The total concordance rate between PR and CBCT was 41.3%. CONCLUSIONS: Clinicians should use extreme caution during placement of miniscrews in the SCP. There are limitations on the use of PR for evaluating the root proximity of miniscrews.

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.

Interferon regulatory factor 6 variants affect nasolabial morphology in East Asian populations.

OBJECTIVE: The interferon regulatory factor 6 gene (IRF6) is one of the most conspicuous genes among a large number of candidate risk genes for non-syndromic cleft lip with or without cleft palate, which is considered to be a multifactorial defect. Variants of IRF6 are also suggested to affect normal craniofacial variations, especially in the area of the nose and the upper lip. In the present study, we used lateral cephalograms to establish the relationship between IRF6 and sagittal nasolabial morphology in healthy East Asian subjects. DESIGN: Genomic DNA was extracted from 215 Japanese and 226 Korean individuals, and genotyped for five IRF6 single nucleotide polymorphisms (SNPs): rs17389541, rs642961, rs2013162, rs2235371, and rs7802. These SNPs were tested by multiple regression analyses for their association with craniofacial measurements obtained from lateral cephalometrics. RESULTS: We detected a significant association between the derived variants, rs2013162 and rs2235371 and the distances between a facial bone plane indicated by distance from Nasion and Point A (NA plane) to soft tissue landmarks; the Subalare (NA-Sbal) and the Subnasale (NA-Sn) in the sagittal plane. CONCLUSION: Our results indicate that IRF6 variants play an important role in the normal range of variation in nasolabial soft-tissue morphology.

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.