Importance in the occurrence rate of shortest buccal bone marrow distance (<1 mm) for sagittal split ramus osteotomy.

BACKGROUND/PURPOSE: The neurosensory disturbance is a common complication following sagittal split ramus osteotomy (SSRO) whereas the shortest buccal bone marrow (SBM) is an important risk factor. The present study aimed to investigate the relationship between the occurrence rates of SBM among three skeletal patterns. METHODS: The cone-beam computed tomography (CBCT) images of 90 participants were divided into skeletal Class I, II, and III. There were six horizontal planes separated apart by a 2 mm interval; it started with plane 0 (original intact mandibular canal) to plane 5 which was 10 mm below. The data of SBM were divided into two groups (SBM ≥ 1 mm and SBM < 1 mm). With an SBM value < 1 mm, we defined a high occurrence rate of postoperative neurosensory abnormality or unfavorable split. RESULTS: The Class III patients had the smallest SBM value (1.31-1.75 mm) whereas the Class II patients had the largest SBM value (1.57-2.09 mm). For the Class III patients, the highest and lowest occurrence rates of SBM were 56.5% and 43.5% respectively. For the Class II patients, the highest and lowest occurrence rates of SBM were 37.1% and 17.7% respectively. The patients with Class III malocclusion had higher occurrence rates of SBM than the patients with Class II malocclusion. CONCLUSION: Class III had a significantly higher occurrence of probability (SBM < 1 mm) than Class II. Therefore, patients with Class III were more likely to experience postoperative neurosensory abnormalities and unfavorable split than patients with Class II.

Recognizing the peak bone mass (age 30) as a cutoff point to achieve the success of orthodontic implants.

The aim of present study was to investigate the critical risk factor (age 30: peak bone mass) to evaluate the success of orthodontic implants. A total of 426 orthodontic implants were placed in 270 patients as orthodontic anchorages. Data were analyzed according to patient's characteristics, location of placement, implant categories, and orthodontic force. The young patients were the age ≤ 30 years and the older patients were the age > 30 years. Statistical analysis was performed and a p value < 0.05 was considered to indicate statistical significance. The Chi-square or Fisher exact test was used depending on sample sizes. The null hypothesis was no statistically significant correlation between age ≤ 30 years and age > 30 years. The overall success rate (with and without predrill) was 89.2%. The success rate of orthodontic implants was significantly larger in younger patients (89.9%) than in older patients (76.1%). Recognizing age-related factor in the success rates, older patient (> 30 years) were significant lower than young patients (≤ 30 years) in the gender (female and male), malocclusion (Class II), facial pattern (ortho and hyperdivergent), location (infrazygomatic crest), jaw (maxilla), side (right), material (titanium and stainless), length (9 mm and 10 mm), diameter (2 mm), load (< 3 weeks), and force (intrusion). Therefore, the null hypothesis was rejected. Age 30 is a cutoff point to achieve the success of orthodontic implants. The success rates of older patients (age > 30 years) were significant lower than young patients (age ≤ 30 years), especially in female.

Increased tumor distribution and expression of histidine-rich plasmid polyplexes.

BACKGROUND: Selecting nonviral carriers for in vivo gene delivery is often dependent on determining the optimal carriers from transfection assays in vitro. The rationale behind this in vitro strategy is to cast a net sufficiently wide to identify the few effective carriers of plasmids for in vivo studies. Nevertheless, many effective in vivo carriers may be overlooked by this strategy because of the marked differences between in vitro and in vivo assays. METHODS: After solid-phase synthesis of linear and branched histidine/lysine (HK) peptides, the two peptide carriers were compared for their ability to transfect MDA-MB-435 tumor cells in vitro and then in vivo. RESULTS: By contrast to their transfection activity in vitro, the linear H2K carrier of plasmids was far more effective in vivo compared to the branch H2K4b. Surprisingly, negatively-charged polyplexes formed by the linear H2K peptide gave higher transfection in vivo than did those with a positive surface charge. To examine the distribution of plasmid expression within the tumor from H2K polyplexes, we found widespread expression by immunohistochemical staining. With a fluorescent tdTomato expressing-plasmid, we confirmed a pervasive distribution and gene expression within the tumor mediated by the H2K polyplex. CONCLUSIONS: Although mechanisms underlying the efficiency of gene expression are probably multifactorial, unpacking of the H2K polyplex within the tumor appears to have a significant role. Further development of these H2K polyplexes represents an attractive approach for plasmid-based therapies of cancer.

Morphometric analysis of the cranial base in Asians.

This study tested the hypothesis that developmental heterogeneity in cranial base morphology increases the prevalence of Class III malocclusion and mandibular prognathism in Asians. Thin-plate spline (TPS) graphical analysis of lateral cephalometric radiographs of the cranial base and the upper midface configuration were compared between a European-American group (24 females and 31 males) and four Asian ethnic groups (100 Chinese, 100 Japanese, 100 Korean and 100 Taiwanese; 50 females and 50 males per group) of young adults with clinically acceptable occlusion and facial profiles. Procrustes analysis was performed to identify statistically significant differences in each configuration of landmarks (P < 0.001). The TPS graphical analysis revealed that the greatest differences of Asians were the horizontal compression and vertical expansion in the anterior portion of the cranial base and upper midface region. The most posterior cranial base region also showed horizontal compression between the basion and Bolton point, with forward displacement of the articulare. Facial flatness and anterior displacement of the temporomandibular joint, resulting from a relative retrusion of the nasomaxillary complex and a relative forward position of the mandible were also noted. These features that tend to cause a prognathic mandible and/or retruded midface indicate a morphologic predisposition of Asian populations for Class III malocclusion.

Direct observation of dynamic mechanical regulation of DNA condensation by environmental stimuli.

Gene delivery is a promising way to treat hereditary diseases and cancer; however, there is little understanding of DNA:carrier complex mechanical properties, which may be critical for the protection and release of nucleic acids. We applied optical tweezers to directly measure single-molecule mechanical properties of DNA condensed using 19-mer poly-L-lysine (PLL) or branched histidine-lysine (HK) peptides. Force-extension profiles indicate that both carriers condense DNA actively, showing force plateaus during stretching and relaxation cycles. As the environment such as carrier concentration, pH, and the presence of zinc ions changes, DNA:HK complexes showed dynamically regulated mechanical properties at multiple force levels. The fundamental knowledge from this study can be applied to design a mechanically tailored complex which may enhance transfection efficiency by controlling the stability of the complex temporally and spatially.

Comparison of the transverse cranial base dimension in different craniofacial skeletal relationships: A cone-beam computed tomography study.

Background/purpose: In comparing the cranial base's size, most cephalometric studies focused on the length and angle in the anteroposterior direction. However, investigating the anterior, middle, and posterior cranial base's transverse dimensions is challenging. This study aimed to investigate the transverse dimensions of the cranial base in different craniofacial skeletal patterns and sexes using cone-beam computed tomography (CBCT). Materials and methods: A total of 210 adults (105 males and 105 females), including three different skeletal relationships, were included in the study. The cranial base dimensions were measured on a three-dimensional image structure rendered by CBCT. Statistical methods included the Kappa statistic for analysis of consistency and reproducibility and the independent t-test for differences in cranial base dimensions between sexes. A general linear model (GLM) was used to compare the transverse size of the cranial base among skeletal Class I, II, and III groups. The Pearson correlation coefficient explored the correlation among the cranial base dimensions. Results: The cranial base dimensions did not differ significantly between skeletal Class I, II, and III. The more prominent cranial base size was found in males than females, except for the crista galli length (CGL) and cribriform ethmoid plate width (CEPW). The cranial base dimensions did not differ significantly between different skeletal relationships. Most dimensions have significant correlations in the middle and the posterior cranial base. Conclusion: The cranial base's transverse dimensions in Taiwanese adults show no significant differences between craniofacial skeletal relationships. In the middle and posterior cranial base, transverse measurements reveal significant sexual dimorphism.

Investigating the postoperative soft tissue changes in different vertical facial divergent patients with mandibular prognathism.

Background/purpose: The extent of three-dimensional soft tissue changes in patients with varied facial skeletal patterns following mandibular setback surgery remains unclear. In this study, we aimed to investigate the postoperative changes in soft tissue chin thickness among mandibular prognathism patients, focusing on those presenting different divergence patterns, such as hyperdivergent and normodivergent patients. Materials and methods: Cone-beam computed tomography images were obtained from 56 skeletal Class III patients who underwent only mandibular setback. Based on vertical craniofacial skeletal relationship, patients were divided into normodivergent group (27°37°) group. The three-dimensional displacements of Infradentale (Id), B point (B), and Pogonion (Pog), the soft tissue thickness of Id-Li (Labrale inferius), B-B' (soft tissue B point), and Pog-Pog' (soft tissue Pog point) were measured. Factors influencing the change in soft tissue thickness were investigated. Results: Preoperative B-B' and Pog-Pog' thickness were significantly thinner in the hyperdivergent group than normodivergent group. Postoperative changes in B-B' and Pog-Pog' thickness were significantly larger in the hyperdivergent group than normodivergent group. A significant correlation was found between soft tissue thickness change (B-B' and Pog-Pog') and the preoperative soft tissue thickness and superior movement (B and Pog). Conclusion: Hyperdivergent patients with skeletal class III have thinner preoperative soft tissue thickness (B-B' and Pog-Pog') than normodivergent patients in the preoperation. Postoperative changes in B-B' and Pog-Pog' thickness were significantly larger in the hyperdivergent group than normodivergent group. Postoperative superior movement of B and Pog correlated with postoperative change of soft tissue thickness.

Surface-modified HK:siRNA nanoplexes with enhanced pharmacokinetics and tumor growth inhibition.

We characterized in this study the pharmacokinetics and antitumor efficacy of histidine-lysine (HK):siRNA nanoplexes modified with PEG and a cyclic RGD (cRGD) ligand targeting αvß3 and αvß5 integrins. With noninvasive imaging, systemically administered surface-modified HK:siRNA nanoplexes showed nearly 4-fold greater blood levels, 40% higher accumulation in tumor tissue, and 60% lower luciferase activity than unmodified HK:siRNA nanoplexes. We then determined whether the surface-modified HK:siRNA nanoplex carrier was more effective in reducing MDA-MB-435 tumor growth with an siRNA targeting Raf-1. Repeated systemic administration of the selected surface modified HK:siRNA nanoplexes targeting Raf-1 showed 35% greater inhibition of tumor growth than unmodified HK:siRNA nanoplexes and 60% greater inhibition of tumor growth than untreated mice. The improved blood pharmacokinetic results and tumor localization observed with the integrin-targeting surface modification of HK:siRNA nanoplexes correlated with greater tumor growth inhibition. This investigation reveals that through control of targeting ligand surface display in association with a steric PEG layer, modified HK: siRNA nanoplexes show promise to advance RNAi therapeutics in oncology and potentially other critical diseases.

Buffering capacity and size of siRNA polyplexes influence cytokine levels.

Induction of cytokines by small interfering RNA (siRNA) polyplexes has been a significant concern of researchers attempting to minimize the toxicity of this promising therapy. Although cationic carriers of siRNA are known to increase cytokine levels, few systematic studies have been done to determine what properties of the carrier are important to modulate cytokines. Because branched histidine-lysine (HK) peptides are effective carriers of siRNA and their sequence can be readily modified, we selected this class of carrier to determine which sequences of the peptide were important for cytokine induction. With the use of peripheral blood mononuclear cells (PBMCs), the HK peptide with a higher number of histidines (H3K(+H)4b) in complex with siRNA induced lower levels of cytokines compared with other HK (e.g., H2K4b, H3K4b, H3K(+N)4b) siRNA nanoplexes. Notably, these peptides' siRNA polyplexes showed a similar pattern of cytokine induction when injected intravenously in a mouse model, i.e., the HK with higher content of histidines induced cytokines the least. As indicated by the pH-sensitive dye within acidic endosomes, the greater pH-buffering capacity of H3K(+H)4b compared with other HK peptides may explain why cytokine levels were reduced. In addition to buffering capacity, the size of HK polyplexes markedly influenced cytokine production.

Orthodontic treatment for a mandibular prognathic girl of short stature under growth hormone therapy.

This report presents a case of a 12-year-old girl with maxillary deficiency, mandibular prognathism, and facial asymmetry, undergoing growth hormone (GH) therapy due to idiopathic short stature. Children of short stature with or without GH deficiency have a deviating craniofacial morphology with overall smaller dimensions; facial retrognathism, especially mandibular retrognathism; and increased facial convexity. However, a complete opposite craniofacial pattern was presented in our case of a skeletal Class III girl with idiopathic short stature. The orthodontic treatment goal was to inhibit or change the direction of mandibular growth and stimulate the maxillary growth of the girl during a course of GH therapy. Maxillary protraction and mandibular retraction were achieved using occipitomental anchorage (OMA) orthopedic appliance in the first stage of treatment. In the second stage, the patient was treated with a fixed orthodontic appliance using a modified multiple-loop edgewise archwire technique of asymmetric mechanics and an active retainer of vertical chin-cup. The treatment led to an acceptable facial profile and obvious facial asymmetry improvement. Class I dental occlusion and coincident dental midline were also achieved. A 3½-year follow-up of the girl at age 18 showed a stable result of the orthodontic and dentofacial orthopedic treatment. Our case shows that the OMA orthopedic appliance of maxillary protraction combined with mandibular retraction is effective for correcting skeletal Class III malocclusion with midface deficiency and mandibular prognathism in growing children with idiopathic short stature undergoing GH therapy.

Correlation between facial asymmetry of skeletal class III jaw relationship and morphology of the temporomandibular joint: A cone beam computed tomography study.

Background/purpose: Facial asymmetry is a common dentofacial deformity especially in skeletal Class III jaw relation. The purpose of this study was to evaluate the condylefossa relationship of Taiwanese people in skeletal Class III jaw relation with or without facial asymmetry by CBCT image. Materials and methods: CBCT images were collected from Kaohsiung Medical University Hospital and then divided into symmetric Class III group (Menton [Mn] deviation â‰¦ 4 mm) and asymmetric Class III group (Menton [Mn] deviation > 4 mm). Maxilla deviation, upper and lower dental midline deviation, joint space, condylar axial angle and condylar volume was measured. Independent t test was used for comparison between groups, and paired t test was applied for comparison between both condyles within each group. The Pearson correlation coefficient was used to analyze the correlation between skeletal midline deviations and joint morphology. Results: No significant difference was found in joint space between groups or between sides within each group, but we can find a significant difference in axial condylar angle easurement which was greater on the non-deviation side of condyle. Significant lesser condylar volume was also found on the deviation side in asymmetric group. There had a significant positive correlation between Mn point deviation, geometric center difference and condylar volume ratio. Conclusion: These results demonstrated that in the side with greater mandibular growth potential, the axis rotation in axial plane would be greater. In the side with lesser mandibular growth potential, the total condyle volume would be lesser, even though with large variation.

Condylar and ramus volume in asymmetric and symmetric skeletal class III malocclusion: A cone-beam computed tomography study.

Background/purpose: Among the craniofacial structures, the mandible is the only bony structure with movable joints. Each part (including condyle process, coronoid process, and ramus) of mandible would interaction with the muscles and proceed different osteogenesis progress. The objective of this study was to evaluate the mandibles with symmetric and asymmetric skeletal Class III jaw relations by quantifying differences in the condyle process, coronoid process and ramus on CBCT (Cone-beam computer tomography) images. Our hypothesis was that CBCT would reveal no voluminal differences between deviated and non-deviated mandibular segments in asymmetric skeletal Class III. Materials and methods: CBCT imagines were collected from dental department, KMUH and then divided into symmetric Class III group (Menton deviation < 4mm) and asymmetric Class III group (Menton deviation≧4mm). The mandibular structure would be segmented to ramus, condylar and coronoid process. Each volume was measured. Independent t test was used for comparison between groups, and paired t test was applied for comparison between both segmented parts within each group. Results: Significant differences between deviation and non-deviation sides in the asymmetric group were found in condylar and ramus segments for volumetric quantitative measurements. There has no significant difference in ramus parts between groups. Significant greater condylar volume was found in non-deviation side of asymmetric group. Conclusion: The results demonstrated that in the side with greater mandible growth potential, the condylar and the ramus volume would be greater as well. CBCT is a useful and accurate modality for quantification and evaluation of mandibular asymmetry.

Changes in Facial Profile after Modified Anterior Maxillary Subapical Osteotomy.

(1) Background: This study explored the effects of modified anterior maxillary subapical osteotomy (AMSO) on facial profile changes in patients with bimaxillary protrusion. (2) Methods: Cephalograms of patients were collected preoperatively and over 2 months postoperatively. The following landmarks were recorded: pronasale (Prn), subnasale (Sn), labrale superius (Ls), anterior nasal spine (ANS), and incisor superius (Is). The following distances and angles were measured: ANS-Prn, ANS-Sn, ANS-Ls, Is-Sn, Is-Ls, SNA angle, and nasolabial (NLA) angle. (3) Results: Is and ANS were significantly retracted by 7.3 and 2.3 mm, respectively. Soft tissue landmarks (Prn, Sn, and Ls) were significantly retracted (1.2, 1.6, 4.4 mm, respectively). Postoperative changes in soft/hard tissue ratios were 0.54, 0.72, 0.31, and 0.60 for Prn/ANS, Sn/ANS, ANS/Is, and Ls/Is, respectively. The NLA angle was increased significantly by 7.1°. (4) Conclusions: The horizontal soft/hard tissue ratios of Sn/Is, ANS/Is, and Ls/Is were 0.22, 0.31, and 0.60, respectively. The NLA angle was increased significantly by 7.1°. The modified AMSO provides an increased blood supply, allows for direct vision, and results in fewer complications than other AMSO methods.

Craniofacial skeletal dysplasia of opposite-sex dizygotic twins.

Craniofacial skeletal dysplasia can lead to different skeletal malocclusions. Both environmental factors and heredity contribute to the formation of malocclusions. There are strong familial tendencies in the development of Angle's Class II and III malocclusions. Cases such as opposite-typed (Class II and III) malocclusions with skeletal and dentoalveolar discordance in siblings or dizygotic (DZ) twins have seldom been reported. We describe the rare case of a pair of opposite-sex DZ twins with completely different skeletal malocclusions, and discuss the clinical considerations for treatment. The patients were twins aged 13 years and 4 months. The girl had mandibular prognathism and a Class III dentoskeletal relationship, whereas the boy had skeletal Class II with mandibular retrusion. Several morphological traits have been implicated with hormonal effect. However, there was no evidence of whether the masculinization effect had any impact on jaw size in the female fetus or whether this effect lasted into adolescence. We suggest that, although DZ twins share the same growth environment, genetic or other unknown extrinsic factors can result in discordance of characteristics of the craniofacial skeleton, dentition, and occlusion.

Treatment of adult Class III malocclusions with orthodontic therapy or orthognathic surgery: receiver operating characteristic analysis.

INTRODUCTION: The aim of this study was to distinguish between orthodontic patients with skeletal Class III malocclusions requiring surgery and those not requiring surgery by conducting a receiver operating characteristic analysis of cephalometric variables. METHODS: We used lateral cephalometric radiographs of 80 subjects (40 nonsurgical and 40 surgical patients) with Class III malocclusions and obtain 25 cephalometric measurements using computerized cephalometry. Of these, 14 measurements showed statistically significant differences between the 2 groups. Receiver operating characteristic analysis was used to determine the ability of the 14 cephalometric measurements in distinguishing between the 2 groups. Six statistically validated and clinically relevant measurements were used to obtain the optimum discriminant effectiveness. RESULTS: For a Class III malocclusion patient with any 4 of these 6 measurement criteria, the sensitivity was 88% and the specificity was 90% in determining the need for surgical treatment: overjet, ≤-4.73 mm; Wits appraisal, ≤-11.18 mm; L1-MP angle, ≤80.8°; Mx/Mn ratio, ≤65.9%; overbite, ≤-0.18 mm; and gonial angle, ≥120.8°. CONCLUSIONS: We selected 6 cephalometric measurements as the minimum number of discriminators required to obtain the optimum discriminant effectiveness of diagnosis between surgical and nonsurgical treatment of skeletal Class III malocclusions.

Evaluation of pharyngeal airway volume for different dentofacial skeletal patterns using cone-beam computed tomography.

BACKGROUND/PURPOSE: Understanding of the three-dimensional airway space in three skeletal patterns is important in orthodontic treatment. This study investigated differences between the volume of pharyngeal airway sections and the smallest cross-sectional area in three skeletal patterns by using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: The 90 patients were collected to measure total pharyngeal airway volume (TP), velopharyngeal airway volume (VP), glossopharyngeal airway volume (GP), oropharyngeal airway volume (OP), hypopharyngeal airway volume (HP), and the smallest cross-sectional areas (SCA) of the upper respiratory tract as well as other relevant anatomical structures. The mean values differences between classes were analyzed using ANOVA. Pearson's test was used to compare classes in terms of the correlations between different factors. RESULTS: Patients in skeletal classes I and III exhibited significantly higher SCA values (322.6 mm2and 344.5 mm2 respectively) than those in skeletal class II (240.8 mm2). Subjects from skeletal classes I and III exhibited significantly higher values of VP, HP, and OP than those in skeletal class II. Skeletal classes I and III exhibited significantly higher TP values (31190.1 mm3 and 30696.2 mm3, respectively) than those in skeletal class II (22386.0 mm3). Non-significant relationships were discovered between pharyngeal airway and skeletal pattern. Conversely, significant relationships were found between TP and gender, ANB, SNB, hyoid and pogonion positions. CONCLUSION: The skeletal class II has smaller airway volume than those in skeletal class I and III. The pharyngeal airway volumes could serve as a guide in differentiating the different skeletal classes in clinical settings.

Changes in Tongue Area, Pharyngeal Area, and Pharyngeal Airway Velocity after Correction of Mandibular Prognathism.

This study aimed to investigate the correlation between the amount of mandibular setback, and the related changes of the tongue area, pharyngeal area, and pharyngeal airflow velocity. Twenty-five patients treated for mandibular prognathism, and serial cephalograms were obtained (T1: preoperation, T2: more than one year postoperation). The postoperative area of the tongue, pharyngeal airway space, and pharyngeal airflow velocity were investigated. Statistical analysis was performed with the Student t-test and Pearson correlation. The amount of mandible setback was significant after surgery (12.8 mm; p < 0.001). The pharyngeal area was significantly reduced 115.5 mm2 (p = 0.046). There was a slight reduction of the tongue area (43.2 mm2; p = 0.305) and an increase of pharyngeal airflow velocity (0.3 m/s; p = 0.133). The Pearson correlation coefficient test showed no statistical significance among the amount of horizontal setback and vertical movement of the mandible, such as the reductions in the tongue area, the pharyngeal airway space, and the increase in pharyngeal airflow velocity. Larger amounts of mandibular setback caused a significant reduction of pharyngeal airway area, but without significant changes of the tongue area and pharyngeal airflow velocity.

Morphology of Sella Turcica and Bridging Prevalence Correlated with Sex and Craniofacial Skeletal Pattern in Eastern Asia Population: CBCT Study.

PURPOSE: Sella turcica bridging (STB) refers to a rare anatomical variation formed by the ossification of the ligament between the anterior and posterior clinoid processes. The presence of the STB was significantly correlated with craniofacial skeleton classification and a higher prevalence rate in skeletal Class III. The current study is aimed at investigating the dimensions of sella turcica and the prevalence of STB in different sexes and on the three craniofacial skeletal patterns using cone beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 159 adults (66 males and 93 females), including 3 different craniofacial skeletal patterns (skeletal Classes I, II, and III), were included in the study. The sella turcica dimensions and the prevalence of STB were calculated. An independent t-test and generalized linear model were used to compare the differences in the sella turcica dimensions and the skeletal relations. The Spearman rank correlation coefficient was used to analyze the correlations between sella turcica dimensions and skeletal relation. RESULTS: The sella length (SL) was 11.05 ± 1.80 mm for males and 10.77 ± 1.56 mm for females. The anterior clinoid distance (ACD) which was measured for the anterior width of sella turcica showed 25.83 ± 2.04 mm and 24.04 ± 2.28 mm for males and females, respectively (p < 0.0001). The overall percentage of complete bridging and partial bridging was 6.6% and 56.9%, respectively. Complete bridges were more common in males (males: 9.1%, females: 4.8%), and partial bridges were more frequent in females (males: 49.2%, females: 62.4%). Both sexes differed with respect to sella turcica dimensions. Moreover, males had a significantly larger ACD, posterior clinoid distance (PCD), and diameter of sella turcica (DST), on both sides, relative to females. CONCLUSION: The prevalence rate of complete STB in the Taiwanese population was 6.6%. Significant differences between sexes were found in sella turcica dimensions. The prevalence rates of STB as well as the sella turcica dimensions did not significantly differ between different craniofacial skeletal patterns (skeletal Classes I, II, and III).

Differences in the Buccal Bone Marrow Distance of ≤0.8 mm in the Mandible of Patients Undergoing Sagittal Split Ramus Osteotomy among the Different Skeletal Patterns: A Retrospective Study.

This study investigated the relationship between the thickness of the ramus and skeletal patterns using cone-beam computed tomography (CBCT) for sagittal split ramus osteotomy. Ninety participants were categorized into three skeletal patterns (Class I, Class II, and Class III). The first vertical slice (slice 0) was observed in the intact mandibular canal, and then moved forward to 40 mm (slice 21) with a 2 mm interval. The thickness of buccal bone marrow (B value) was measured. A B value of ≤0.8 mm was considered to be the major risk factor causing the occurrence of postoperative lower lip paresthesia. There were 461 sides with a B value of ≤0.8 mm. There was a significant difference in the skeletal patterns [Class III (198 sides: 15.7%) > Class I (159 sides: 12.6%) > Class II (104 sides: 8.3%)]. Class II participants had significantly larger B values (2.14 to 3.76 mm) and a lower occurrence rate (≤0.8 mm) than those of Class III participants (1.5 to 3 mm) in front of the mandibular foramen (from 6 mm to 20 mm). Class III participants had significantly shorter buccal bone marrow distance and a higher occurrence rate of B values (≤0.8 mm) than Class II.

Importance in the Occurrence Distribution of Minimum Oropharyngeal Cross-Sectional Area in the Different Skeletal Patterns Using Cone-Beam Computed Tomography.

PURPOSE: Obstructive sleep apnea is a condition involving repetitive partial or complete collapse of the pharyngeal airway, especially in patient with mandibular hypoplasia. The present study investigated the differences between the volume of the oropharyngeal airway and the minimum axial area in three skeletal patterns through the use of cone-beam computed tomography (CBCT). MATERIALS AND METHODS: CBCT scans of 147 patients were collected to measure the upper oropharyngeal airway volume (UOV), lower oropharyngeal airway volume (LOV), upper oropharyngeal airway area (UOA), minimum upper oropharyngeal airway area (MUOA), lower oropharyngeal airway area (LOA), minimum lower oropharyngeal airway area (MLOA), anatomical structures (orbitale, Or; porion, Po; pogonion, Pog; hyoid, H; second cervical vertebra, C2; fourth cervical vertebra, C4), and relevant angles. Statistical analysis was performed using analysis of variance and Pearson's test. RESULTS: Compared with patients in Class II, those in Class III and Class I exhibited a significantly anterior position of H and Pog. The vertical positions of H and Pog revealed no significant difference between the three skeletal patterns. Patients in skeletal Class III exhibited significantly larger oropharyngeal area (UOA, MUOA, LOA, MLOA) and oropharyngeal airway (UOV and LOV) than those in skeletal Class II did. The horizontal position of Pog had a moderately significant correlation with UOA (r = 0.471) and MUOA (r = 0.455). CONCLUSION: Patients in skeletal Class II had significantly smaller oropharyngeal airway areas and volumes than those in Class III did. The minimum oropharyngeal cross-sectional area had a 67% probability of occurrence in the upper oropharyngeal airway among patients in Class I and Class II and a 50% probability of occurrence among patients in Class III.