Novel genes linked to Class II Division 1 malocclusion with mandibular micrognathism.

INTRODUCTION: Mandibular micrognathism (MM) is an underdeveloped mandible resulting from complex interactions between genetic and environmental factors. Prior research focused mainly on the genetic determinants of mandibular retrognathism, not necessarily reflecting micrognathism, thus supporting the need to study MM. This study aimed to explore the inheritance pattern and identify the candidate genes involved in the development and familial transmission of MM. METHODS: Diagnosing probands with MM was based on clinical and lateral cephalometric data. The pedigrees were drawn for 11 identified families, 5 of whom accepted to undergo detailed data and biospecimen collection. These families included 15 MM and 13 non-MM subjects over 2-3 generations. The procedure involved the withdrawal of 5 mL of blood. Genomic DNA was isolated from blood cells to investigate protein-coding regions via whole exome sequencing. Standardized filtering steps were employed, and candidate genes were identified. RESULTS: Most of the pedigrees suggested a Mendelian inheritance pattern and segregated in an autosomal-dominant manner. One of the families, which also underwent biospecimen, displayed an X-linked inheritance pattern of the trait. Genetic screening disclosed 8 potentially novel genes (GLUD2, ADGRG4, ARSH, TGIF1, FGFR3, ZNF181, INTS7, and WNT6). None of the recognized exonic regions were previously reported. CONCLUSIONS: Eight novel genes were identified in association with MM in the largest number of families reported to date. The genes were X-linked in 1 family, a finding previously not observed in mandibular genetics.

Semantic Segmentation of Maxillary Teeth and Palatal Rugae in Two-Dimensional Images.

The superimposition of sequential radiographs of the head is commonly used to determine the amount and direction of orthodontic tooth movement. A harmless method includes the timely unlimited superimposition on the relatively stable palatal rugae, but the method is performed manually and, if automated, relies on the best fit of surfaces, not only rugal structures. In the first step, motion estimation requires segmenting and detecting the location of teeth and rugae at any time during the orthodontic intervention. Aim: to develop a process of tooth segmentation that eliminates all manual steps to achieve an autonomous system of assessment of the dentition. Methods: A dataset of 797 occlusal views from photographs of teeth was created. The photographs were manually semantically segmented and labeled. Machine learning methods were applied to identify a robust deep network architecture able to semantically segment teeth in unseen photographs. Using well-defined metrics such as accuracy, precision, and the average mean intersection over union (mIoU), four network architectures were tested: MobileUnet, AdapNet, DenseNet, and SegNet. The robustness of the trained network was additionally tested on a set of 47 image pairs of patients before and after orthodontic treatment. Results: SegNet was the most accurate network, producing 95.19% accuracy and an average mIoU value of 86.66% for the main sample and 86.2% for pre- and post-treatment images. Conclusions: Four architectural tests were developed for automated individual teeth segmentation and detection in two-dimensional photos that required no post-processing. Accuracy and robustness were best achieved with SegNet. Further research should focus on clinical applications and 3D system development.

Three-dimensional surgical management of a patient with Pruzansky I hemifacial microsomia and severe facial asymmetry: A 4-year follow-up.

Treatment of hemifacial microsomia is challenging and often requires multiple interventions to restore function and facial esthetics. In this article, the combined orthodontic-surgical treatment of a young patient exhibiting Pruzansky I hemifacial microsomia is reported. The patient was aged 15 years, but his bone age was determined to be 18 years. His facial asymmetry was severe, with the nose and a retrusive chin deviated to the left side and a canted smile. The presurgical phase was aimed at centering the mandibular midline to the center of the chin through the distal movement of the mandibular left buccal dentition. The surgery was planned with 3-dimensional computer-aided surgical simulation and included a LeFort I and unilateral sagittal split osteotomies combined with a genioplasty. This report illustrates the therapeutic stages and a 4-year follow-up of a unique and complex orthognathic surgical approach, chosen among other alternatives and leading to improved function and appearance and stable results.

Potential and limitations of orthodontic biomechanics: recognizing the gaps between knowledge and practice.

The perennial goals of efficient biomechanics are to obtain more controlled and faster movement and using more discrete appliances. The most recent technological advances have buttressed these goals. Temporary anchorage devices have revolutionized orthodontic practice and loom as a solid cornerstone of orthodontic science, along with the use of light forces, facilitated by "smart" archwires for optimal tooth movement. Accelerated tooth movement with decortication has been successful because of decreasing the resistance of cortical bone but micro-osteoperforation has not matched the same results. Clear aligners and preprogrammed regular or lingual appliances reflect the importance of three-dimensional technology in appliance design based on treatment outcome. These mechanical developments have inched the science closer to the traditional goals, but advances lack regarding their enhancement by biomaterials in a system where the physical stimulus is exerted on the teeth but the expression of tooth displacement is through the biological processes within the surrounding tissues. In this article, present tenets, applications, and advances are explored along with the gaps between knowledge and practice and the possibilities to bridge them. Anchorage control remains the major widely used development but slower is the development of faster noninvasive treatment.

Three novel genes tied to mandibular prognathism in eastern Mediterranean families.

INTRODUCTION: Mandibular prognathism (MP) is subject to major polygenic influence and segregates within families in autosomal dominance with variable expressivity and incomplete penetrance. We aimed to identify the inheritance pattern and genes and loci involved in the development of MP in Mediterranean families and to evaluate the dentoskeletal characteristics of affected individuals. METHODS: Fifty-one eastern Mediterranean families with individuals affected by MP were identified. Data and biospecimens were collected from 14 of the families, including clinical examination, lateral cephalography (on subjects with Class III malocclusion), and 5 mL blood drawn from consenting affected and nonaffected relatives. Next-generation sequencing (NGS) was performed on 8 families (7 Lebanese, 1 Lebanese/Syrian), including large numbers of affected individuals over many generations and severe conditions, with the use of whole-exome sequencing. RESULTS: Most pedigrees suggested autosomal-dominant inheritance with an equal number of affected male and female individuals. Affected individuals had macrognathic and prognathic mandibles with dentoalveolar compensation. Genetic screening did not correspond with previously reported MP-linked genes, but yielded 3 novel genes (C1orf167, NBPF8, NBPF9) on chromosome 1 potentially responsible for mandibular development and macrognathism. CONCLUSIONS: In this first genetic study with the use of NGS on the largest reported number of families with MP, novel genes (C1orf167, NBPF8, NBPF9) were associated with familial MP in the eastern Mediterranean population.

Association Between Facial Length and Width and Fundamental Frequency.

OBJECTIVE: This study aimed to evaluate the association between facial width and length and fundamental frequency (F0) and habitual frequency. STUDY DESIGN: Prospective cross-sectional study. SUBJECTS: A total of 50 subjects (35 females;15 males) were included in this study. METHODS: Lateral and posteroanterior cephalometric measurements included: facial height (N-Me); widths of the maxilla (J-J), mandible (AG-AG), and face (Zyg-Zyg); ratios J-J to AG-AG, N-Me to Zyg-Zyg, and lower face to total face heights. All subjects underwent acoustic analysis using Visi-Pitch IV. Sample was stratified according to age and gender. RESULTS: In the total group (mean age: 14.19±6.49 years; range 6-35 years), a significantly moderate negative correlation existed between Zyg-Zyg, J-J, and AG-AG, and F0 and habitual pitch. Similarly, N-Me moderately correlated with habitual pitch. In males, there was a significant moderate negative correlation between Zyg-Zyg and J-J, and habitual pitch, and between J-J and F0 (-0.571;p=0.026). In females, a significant moderate correlation existed between Zyg-Zyg and AG-AG, and habitual pitch, and between AG-AG and F0 (-0.347;p=0.041). In the prepubertal group (n=25), a negative moderate correlation occurred between J-J and AG-AG, N-Me and habitual frequency, and between J-J and F0 (-0.407;p=0.043). In the postpubertal group, there was a significant moderate correlation only between AG-AG and F0 (-0.403;p=0.046). CONCLUSION: Facial length correlates significantly with habitual frequency, and facial width correlates significantly with both F0 and habitual pitch. A larger sample of adult subjects is needed to substantiate this conclusion.

Effect of Rapid Maxillary Expansion on Voice.

OBJECTIVE: The purpose of this investigation is to evaluate the effect of rapid maxillary expansion (RME) on the fundamental frequency (F0) and formant frequencies F1-F4. STUDY DESIGN: Cross-sectional study. MATERIALS AND METHODS: A total of 14 consecutive patients between the ages of 9.6 years and 15 years with a constricted maxilla undergoing RME were included in this study. Measurements were made before (T1) and after treatment (T2). These included maxillary arch length, depth, width, and perimeter in addition to F0, habitual pitch, and formants F1, F2, F3, and F4 for the vowels /ɑ/, /i/, /o/, and /u/. RESULTS: There was a significant difference in the mean of F1/ɑ/ and F2/ɑ/ before and after treatment (P value of 0.04 and 0.013, respectively). It is worth noting that F1/ɑ/ decreased in 11 and F2/ɑ/ decreased in 10 of the 14 subjects. CONCLUSION: The application of RME in the treatment of maxillary constriction leads to a significant lowering of the first and second formants for the vowel /ɑ/ in most subjects. Subjects undergoing rapid maxillary application should be aware of the potential change in voice quality especially in case of professional voice users.

Correlation Between the Position of the Hyoid Bone on Lateral Cephalographs and Formant Frequencies.

OBJECTIVES: The objective of this study is to examine the F1, F2, F3, and F4 during sustained vowels /ɑ/, /i/, /o/, /u/. STUDY DESIGN: Prospective cross-sectional study. METHODS: Fifty-two consecutive patients aged between 9 years and 38 years were invited to participate in this study. Linear measurements included linear vertical distance from the hyoid bone to the sella turcica (H-S); linear vertical distance from the hyoid bone to the posterior nasal spine (H-PNS); linear measure from the hyoid bone to the most anterior point of the cervical vertebra C3 (H-C3); and linear vertical distance from the hyoid bone to the mandibular plane (H-MP). RESULTS: The results showed a moderate and statistically significant correlation between the average fundamental frequency for the vowel /ɑ/ and H-C3, H-S, and H-PNS and another moderate negative correlation between F3 and F4, and the vertical position of the hyoid bone H-C3 and H-S. For the vowel /i/, there was a moderate negative correlation between F1, F3, and F4 and H-S and also a moderate negative correlation between F3 and F4 and H-C3. For the vowel /o/, there was a moderate negative correlation between F4 and H-S and H-PNS. For the vowel /u/, only F4 correlated significantly with H-S. CONCLUSION: There is a moderate correlation between the high formants, mostly F4, and the cephalo-caudal position of the hyoid bone.

Formants frequency and dispersion in relation to the length and projection of the upper and lower jaws.

OBJECTIVE: Investigate the association between formants frequencies and length and sagittal projection of the maxilla and mandible. STUDY DESIGN: Cross-sectional study. METHOD: A total of 47 consecutive patients were recruited. Craniofacial measures included; maxillary length (ANS-PNS), mandibular length (Co-Gn), relationship between maxilla and mandible in the sagittal plane (ANB), the sagittal projection of the maxilla (SNA), and mandible (SNB). Subjects were asked to phonate vowels /a/, /i/, /o/, and /u/. Measurements were made in real-time and formant frequencies across F1, F2, F3, and F4 were determined. RESULTS: There was a significant negative association between the length of the maxilla and F4 for all the vowels, and a significant negative association between the length of the mandible and F4 for vowels /o/ and /u/. The length of maxilla and mandible also negatively associated with F3 for vowels /a/, /i/, /o/, and vowels /i/, /o/, and /u/ respectively. For the first two formants, the negative association was less pronounced. CONCLUSION: There was a significant negative association between the formant frequencies F3, F4, and the length of the mandible and maxilla for vowels /a/, /i/, /o/, and /u/.

Correlation between the length and sagittal projection of the upper and lower jaw and the fundamental frequency.

OBJECTIVE: To report on the correlation between the length and projection of the upper and lower jaw and the fundamental frequency (F0). STUDY DESIGN: Prospective study. MATERIALS AND METHODS: A total of 45 healthy subjects were included in this study. The facial skeletal measurements included: SNA, SNB, ANB, angles that reflect the position of the maxilla and mandible in relation to the base of skull and to each others, length of mandible Co-Gn, and length of maxilla PNS-ANS. All subjects underwent acoustic analysis using VISI-PITCH IV. RESULTS: The means for F0 and habitual frequency were 220.75 + 40.01 Hz and 216.99 + 43.9 Hz, respectively. The means for SNA, SNB, and ANB were 80.753 ± 3.20, 77.409 ± 3.64, and 3.336 ± 2.57, respectively. The mean length of the mandible and maxilla were 104.28 + 7.94 and 50.29 + 3.94, respectively. In the total group, there was a moderate negative correlation between F0 and habitual frequency and the length of the mandible (r = -0.528 and -0.577, respectively). There was also a moderate negative correlation between F0 and habitual frequency and the length of the maxilla (r = -0.473 and -0.519, respectively). Similar findings were present after excluding the pubertal subjects. With respect to the other cephalometric measurements, the correlation was poor (r value < 0.3). CONCLUSIONS: There is a moderate negative correlation between the length of the upper and lower jaw and the average F0 and habitual frequency. The remaining facial sagittal projection parameters do not correlate with the average F0 and habitual frequency.

Correspondence between subjective and linear measurements of the palatal airway on lateral cephalometric radiographs.

OBJECTIVE: To evaluate the correlation between and significance of 2 methods of palatal airway assessment on lateral cephalographs. DESIGN: Diagnostic lateral cephalometric imaging study that took place from January 1, 2006, to December 31, 2007. SETTING: American University of Beirut Medical Center. PATIENTS: Children with chronic mouth breathing referred by a pediatric otolaryngologist for cephalometric evaluation by participating orthodontists. MAIN OUTCOME MEASURES: Two distances were measured on the digitized lateral cephalographs between the adenoid and soft palate: the shortest adenoid distance (SAD) and the most convex adenoid distance (CAD). The palatal airway was assessed on a grade-1 to grade-3 scale independently by the referring otolaryngologist and an orthodontist. RESULTS: A total of 200 children were included in the study (127 boys and 73 girls; mean age, 6 years; age range, 1.71-12.62 years). High correlations were observed between the airway ratings gathered by both examiners (r = 0.96) and between SAD and CAD (r = 0.92). Significant correlations were noted between the palatal airway grade and the SAD and CAD measurements (r = -0.73 and r = -0.79, respectively). Shortest adenoid distance measures of 2 mm or less corresponded mostly to grade 3 obstruction and were more prevalent in patients younger than 6 years. Age was inversely proportional to both the grade and SAD (P < .001). CONCLUSIONS: Both methods are reliable for assessment of airway obstruction by the adenoid. Because SAD and CAD are highly correlated, we recommend the use of SAD as a more readily identifiable distance on cephalometric radiographs. Removal of adenoids when SAD is less than 2 mm may be indicated because this condition reflects a severe airway obstruction associated with potential changes in dentofacial structure.