A Quantitative Assessment of Zygomatic Projection for Ancestry Estimation.

Anterior zygomatic projection (ZP) is historically referenced as a useful trait in ancestry estimation, particularly when differentiating between Native Americans and U.S. Whites and Blacks. However, methods of assessing ZP vary, are susceptible to multiple interpretations, and have not been quantitatively validated. This study uses 228 3D surface scans of U.S. Whites, U.S. Blacks, and Native Americans to quantitatively test the ZP methods published by Rhine in 1990 (Skeletal attribution of race: methods for forensic anthropology, Albuquerque, NM, Maxwell Museum of Anthropology, 1990) and Bass in 1995 (Human osteology: a laboratory and field manual, Columbia, MO: Missouri Archaeological Society, 1995). Two ZP angles and two distances, representing method interpretations, were collected and analyzed via ANOVA and discriminant function analyses. Although significant ancestry differences were found across all variables, only the Bass inferior zygomatic distance successfully differentiated the pooled Native American group from pooled U.S. Whites/Blacks (73.7% correct). Arctic Native Americans, displaying the most projecting zygomas, are driving group differences. Significant overlap in measurement distributions were observed between groups in all variables, indicating limited forensic utility.

Preserving the Facial Nerve During Orbitozygomatic Craniotomy: Surgical Anatomy Assessment and Stepwise Illustration.

OBJECTIVE: Surgical safety and efficiency during an orbitozygomatic (OZ) osteotomy rely on thorough knowledge of the surgical anatomy of the facial nerve. Although the anatomy of the facial nerve and its relation to the pterional craniotomy are described, a thorough assessment of facial nerve preservation techniques during the OZ approach and its variations is lacking. We assessed the surgical anatomy of the facial nerve related to the OZ approach and provided a thorough stepwise description on how to preserve it. METHODS: The OZ approach was performed bilaterally in 15 cadaveric heads. The interfascial and subfascial techniques were performed to study their nuances in preserving the facial nerve. We compared the 2 techniques and provided a thorough description on how to preserve the facial nerve during each step of the OZ approach. RESULTS: At the zygomatic arch, the facial nerve was found between the galea and the superficial temporal fascia. A cut in the fascia at the posterior end of the zygomatic arch did not cross any facial nerve branches. The subfascial technique was simpler, more efficient, and provided more structural protection of the facial nerve branches than the interfascial technique. CONCLUSIONS: The frontal division of the facial nerve is related directly to dissection over the zygomatic bone and may be injured during fascial dissection or osteotomies. Both interfascial and subfascial techniques are feasible to use during the OZ craniotomy and provide ample exposure of the OZ unit. Regarding the preservation of the facial nerve branches, we favor the subfascial method.

New diagnostic tenet of the esthetic midface for clinical assessment of anterior malar projection.

OBJECTIVE: To determine whether a visual classification of anterior malar support using vector relationships is supported by cephalometric analysis. MATERIALS AND METHODS: Forty white subjects between the ages of 10 and 12 years, without craniofacial syndromes or previous orthodontic treatment, were equally divided into groups based on visual assessment of negative and positive vector relationships. Group A comprised 20 subjects (10 male, 10 female) exhibiting a positive vector relationship. Group B comprised 20 subjects (10 male, 10 female) displaying a negative vector relationship. Sella-nasion-orbitale (SNO) angulations were measured to evaluate the subjects' anteroposterior position of the malar eminence relative to the cranial base. Gender differences and significant differences in SNO measurements between groups A and B were assessed with Mann-Whitney U-tests. RESULTS: There was no statistically significant difference between genders. SNO angulations in the negative vector group were smaller than the positive vector controls by an average of 6.0 degrees, and the difference was highly significant (P < .0001). CONCLUSION: Compared with subjects exhibiting a positive vector relationship, individuals displaying a negative vector relationship had significantly reduced malar support. Anterior malar projection can be effectively classified through visual assessment of vector relationships.

Assessment of the reliability and repeatability of landmarks using 3-D cephalometric software.

The aim of this study was to analyze the reliability and repeatability of identification landmarks using 3-D cephalometric software. Ten orthognathic patients were selected for this study and underwent the following protocol: 1. radiographic evaluation (CBCT technique); 2. stone casts; 3. photos; and 4. 3-D cephalometric evaluation. Twenty-one hard tissue landmarks and 14 cephalometric measurements were taken three times (T1, T2, and T3) on each patient, with an interval of one week by two experts in orthodontics (A, B). Standard deviation and Pearson's correlation coefficient were calculated to evaluate intra- and inter-observer repeatability. The results showed a strong correlation for both intra- and inter-observer Pearson's correlation coefficient (>0.7). The current preliminary study showed that the reliability and repeatability of the identification landmarks were very high if the 3-D cephalometric landmarks are defined correctly in the three planes of the space. Further evaluation is necessary to better define the 3-D cephalometric system.

Assessment of the posteroanterior cephalograms of the parents of children with cleft lip and/or cleft palate in Latvia.

OBJECTIVE: To compare the craniofacial morphology of parents of children with cleft lip with or without palate (CL±P), children with isolate cleft palate (CP) and individuals without family history of orofacial clefting in Latvia. MATERIALS AND METHODS: Posteroanterior (PA) cephalograms were obtained from all participants: 37 couples of noncleft biological parents of children with nonsyndromic CL±P and 17 couples of noncleft biological parents of children with nonsyndromic CP (the parents groups were made dividing the parents after gender and children cleft type). The control groups consisted of 40 females and 42 males, who had no history of clefts in the family. A conventional cephalometric analysis was used to measure various measurements of facial widths. RESULTS: Statistically significant differences (decreased facial and biorbital width) were found between fathers of children with CP and males from the control group. Results showed asymmetry of zygomatic width (left side dominance) in all parents groups compared with the control groups. The asymmetry was detected in maxillary part (left side dominance) in CP children mothers and females and males control groups. CONCLUSION: Some statistical significant differences in the PA cephalometric measurements among parents groups of children with CL±P and CP, and control groups were found. However the differences among study groups and the control groups were small, often not larger than variations in the population.

Assessment of infrazygomatic bone depth for mini-screw insertion.

OBJECTIVE: To investigate the bone depth at the infrazygomatic crest with regard to orthodontic mini-screw insertion. MATERIAL AND METHODS: Twenty-nine adult human dry skulls were imaged using CBCT technology, slice data were generated and multiple measurements were undertaken at three sites associated with the infrazygomatic crest and five different measurement levels. The data were analyzed using intraclass correlation and repeated measures ANOVA. RESULTS: The greatest bone depth was available at, on average, 11.48+/-1.92 mm apical from the cemento-enamel junction of the maxillary first molar and decreased rapidly further apically. Maximum bone depth (7.05+/-3.7 mm) was present at the lowest measurement level. However, here, insufficient clearance to the molar roots was present. Both the measurement site and the level at which the measurements were conducted had a significant impact on bone depth. CONCLUSIONS: When inserting orthodontic mini-screws (6 mm or longer) into the infrazygomatic crest while staying clear of the molar roots perforation of the maxillary sinus or the nasal cavity can be expected, but bone depth varies considerably between individuals.