Influence of metal sleeves in the accuracy of dental implant placement using guided implant surgery

The fabrication of implant surgical guides through stereolithographic 3D printing has become a staple in dental implant guided surgery over the last couple decades. These surgical guides have typically utilized metal sleeves to assist in guidance of the drills during osteotome preparation. The metal sleeves can be costly and potentially cause deviations if improperly placed during post-processing of the guide. This research explored a novel method for the utilization of sleeve-free surgical guides by comparing the dimensional and angulational deviations between the implant guides with and without a metal sleeve. To achieve this goal, two separate aims were pursued. Our first aim analyzed the implant deviation differences created by a single guide with a metal sleeve and one guide without. Ten implants were placed in ten dental models per each type of surgical guide and the deviations were measured in the mesial, apical, cervical, and angulational dimensions. The second aim of this study was to analyze any angulational and positional differences produced when the sample size of the surgical guides was increased for the two different groups to produce a guide to cast ratio of 1:1. This was achieved by analyzing the same two surgical guide designs and dimensional parameters but increasing the number of surgical guides produced to yield one guide per dental model with a total of 10 pairs of guide-cast per group. The results provided no significant difference in implant deviations between the guides with and without a metal sleeve except for the mesial dimension in the second aim. This study concluded that the surgical guide without a metal sleeve demonstrates similar accuracy and precision to the surgical guide with a metal sleeve. Thus, metal sleeves may not be required for accurate implant placement

Metric Sexual Dimorphism in Permanent Canines

The degree of sexual dimorphism of permanent human canines in cervical buccolingual and mesiodistal diameters was investigated through discriminant analyses. Measurements were recorded in 254 canines from 85 individuals in four populations and sex was estimated with multifactorial morphological methods. Age was similar assessed in order to rule it out as a factor. Tooth and body size were controlled for in three of the populations (56 individuals) by the greatest buccolingual diameter of the right first molar of the corresponding jaw and the coronal diameter of the right femoral head, respectively. Age and tooth and body size were statistically insignificant factor2s (p > 0.05). Inter-observer error varied from 0.04 to 0.17 mm or 0.7-3.0% and was largely insignificant. Student’s t-tests found jaw was significant (p0.05) so measurements for both sides were averaged to increase the sample size. Sexual dimorphism was statistically insignificant for all four diameters individually or grouped with the exception of mandibular buccolingual width. Accuracy values ranged from 49-73% which, adjusted for a generous error margin from sexing techniques, became 39-58%. These results indicate that the landmarks, assemblages, or both do not exhibit significant sexual dimorphism. Future work should consider similar populations with different landmarks and/or the same landmarks on a different assemblage, preferably one of known sex

Odontometric Sex Estimation Using a Modern Forensic Skeletal Collection

Forensic anthropologists are responsible for estimating the biological profile—the age, sex, population affinity, and stature—of unknown deceased individuals. Many methods used for estimating the biological profile are sex-specific, which implicates sex estimation as one of the most important components of the biological profile. Historically, the skull and postcranial elements have been heavily utilized for morphological and metric sex estimation methods, whereas odontometric methods have been overlooked and underutilized. Odontometric data has proven to be a worthwhile avenue for the estimation of sex in several population-based studies (Acharya et al., 2011; Adams & Pilloud, 2019; Angadi et al., 2013; Cardoso, 2008; Harris & Foster, 2015; Joseph et al., 2013; Kazzazi & Kranioti, 2018; Pilloud & Scott, 2020; Prabhu & Acharya, 2009; Zorba et al., 2012). Due to population-based variation found within the dentition, the creation of population-based methods is encouraged. Using odontometric data from a modern forensic sample, this research uses linear discriminant function analysis to provide another route in which forensic anthropologists can estimate sex. Measurements of the maximum crown and cervical mesiodistal and buccolingual dimensions were used in this study, which has highlighted the benefits of including cervical dimensions into odontometric investigations. Linear models provided in this research produce 71.11% to 89.99% overall correct allocation rates utilizing various teeth, specific sets of teeth, and individual teeth. Within this sample, the mandibular canine is the most sexually dimorphic tooth. When isolated, the mandibular third premolar was the most effective tooth for sex estimation with a correct allocation rate of 82.22%. When possible, odontometric data should be utilized in forensic casework to aide in the estimation of sex for unknown individuals, especially if other skeletal elements are unavailable. Advisor: William R. Belche

Biodistance analysis of cemetery structure, social status, and postmarital residence in medieval Poland

The Medieval and Early Modern Period in Poland (AD 10th-18th c.) was characterized by a long-term sociopolitical transformation that drew culturally diverse immigrants across Europe and Asia. Historical, archaeological, and bioarchaeological evidence indicates an increase in craft specialization and interregional trade. Although extensive research has investigated these cultural changes, demographic and sociocultural bioarchaeological investigations are lacking. Based on this information, this study has two primary objectives: 1) investigate demographic changes that occurred through three regions of medieval Poland, and 2) investigate the social practices of a medieval community. Previous scholars have used cranial data to examine biological distance between pre-medieval, medieval, and post-medieval populations. However, the use of dental data and cranial data combined to investigate biocultural practices has been underutilized. Dental and cranial morphological and metric data were collected on adults of the Medieval Period site Stręgoborzyce 38, located in Małopolska Poland. These data were used to explore the biological diversity of Stręgoborzyce in comparison to other cemeteries in the regions of Mazovia and Silesia, the relatedness of Stręgoborzyce to other groups, the construction of kinship and social status as expressed through mortuary practices, and postmarital residence. Results indicate significant diversity at Stręgoborzyce in comparison to other medieval cemeteries. Biological distance analyses indicate Stręgoborzyce is phenotypically similar to contemporary populations in Mazovia and Małopolska; individuals from Stręgoborzyce are most similar to an Early Modern period cemetery in Silesia, indicating gene flow and contact between these three regions. There is limited biological patterning in mortuary practices with individuals in the same burial row. There is considerable homogeneity between locations and heterogeneity within locations. The differences suggest temporal variation. There is no evidence of correlation between indicators of social status (cultural) and biological similarity in the Stręgoborzyce 38 sample. These results indicate that the correlation between biological relatedness and social status was likely insignificant. Finally, the dental and skeletal morphological data suggest equal mobility. However, the skeletal metric data suggest slightly more male variability suggesting a matrilocal postmarital residence system at Stręgoborzyce 38. The results of this study contribute to the understanding of urbanization, institutionalization, and aggrandizement during the Medieval Period. This period is characterized by migration and associated gene flow. The lack of biologically patterned interment locations and biologically patterned grave goods indicate kinship and social status were complex. The findings of this dissertation have allowed for a discussion of social structure of a medieval cemetery. This research contributes to our understanding of how a medieval Polish population was organized

Dental metric standards for sex estimation in archaeological populations from Iran

Sex estimation of skeletal remains is one of the major components of forensic identification of unknown individuals. Teeth are a potential source of information on sex and are often recovered in archaeological or forensic contexts due to their post-mortem longevity. Currently there is limited data on dental sexual dimorphism of archaeological populations from Iran. This dissertation represents the first study to provide a dental sex estimation method for Iron Age populations. The current study was conducted on the skeletal remains of 143 adults from two Iron Age populations in close temporal and geographic proximity in the Solduz Valley (West Azerbaijan Province of Iran). 2D and 3D cervical mesiodistal and buccolingual and root volume measurements of maxillary and mandibular teeth were used to investigate the degree of sexual dimorphism in permanent dentition and to assess their applicability in sex estimation. In total 1327, 457, and 480 anterior and posterior teeth were used to collect 2D cervical, 3D cervical, and root volume measurements respectively. 2D cervical measurements were taken using Hillson-Fitzgerald dental calliper and 3D measurements were collected using CT images provided by Open Research Scan Archive (ORSA) - Penn Museum. 3D models of the teeth were created using manual segmentation in the Amira 6.01 software package. Since tooth density largely differs from crown to apex, root segmentation required two threshold levels: the segmentation of the root from the jaw and the segmentation of the crown from the root. Thresholds used for root segmentation were calculated using the half maximum height protocol of Spoor et al. (1993) for each skull, and thresholds used for crown segmentation were set visually for each tooth separately. Data was analysed using discriminant function analysis and posterior probabilities were calculated for all produced formulae where sex was previously assessed from morphological features of pelvis and skull. Bootstrapping was used to account for small sample sizes in the analysis. Statistical analysis was carried out using SPSS 23. The percentage of sexual dimorphism was also used to quantify the amount of sexual dimorphism in the sample. The results showed that incisors and canines were the most sexually dimorphic teeth, providing percentages of correct sex classification between 80% and 100% depending on the measurement used. Root volume measurement was shown to be the most sexually dimorphic variable providing an accuracy of over 90% in all functions. The present study provided the first dental metric standards for sex estimation using odontometric data in Iranian archaeological populations. Dental measurements, particularly root volume measurements, were found to be of value for sex assessment and the method presented here could be a useful tool for establishing accurate demographic data from skeletal remains of the Iron Age from Iran

Sex estimation method using cervical canine diameters: a validation study

Thesis (M.S.F.S.) PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.This thesis presents a validation study of the research by Hassett (2011). It examined the permanent canines’ cervical diameters using established measurement techniques set forth by Hillson et al. (2005) to determine sex in a known population of male and female adults and juveniles. The present study combined the Maxwell Collection, housed at University of New Mexico, and the Hamann-Todd Collection, housed at the Cleveland Museum of Natural History, as the known-sex sample. The sample included 642 permanent canines resulting in 862 measurements from 218 individuals. There were 120 males and 98 females between the ages of 12 and 98 years old. Of the 218 individuals, 148 were White, 62 were Black, 2 were Hispanic, 1 was Native American, and 5 were an unknown ancestry. The measurements used were the cervical mesiodistal diameter and the cervical buccolingual diameter of each upper and lower, right and left canine. The author hypothesized that research conducted on this known age skeletal collection sample would support Hassett (2011), who concluded that the cervical diameter of the canine is sexually dimorphic and can be used to predict sex accurately. In addition, it was predicted that there would not be a significant statistical difference between adult and juvenile permanent canine measurements. An intra-observer error test found that original and repeated measures were not statistically different from one another. Statistical analysis found that adults and juveniles did not have significantly different measurements, so the two samples were combined into one larger known-sex sample. The accuracy of all the functions for both sexes using the cervical diameter method is between 80.2% and 87.5%. The fourth function’s formula, which uses both diameters from one maxillary canine and one mandibular canine, had the best overall accuracy of 87.1%. The accuracy of all the functions for males was between 81.1% and 91.7% and for females the accuracy was between 74.8% and 89.7%. Analysis also indicated that no tooth nor measurement proved to be a better predictor of sex; therefore, any tooth and measurement can be used to estimate sex. The author believes that this validation will allow further research into the applicability of the permanent canine using cone-beam computed tomography to determine sex in juveniles whose permanent canines have not yet erupted. This determination is highly significant, given the dearth of usable techniques to sex juvenile human remains.2031-01-0