Effect of different dental implant drilling template designs on heat generation during osteotomy - an in vitro study.

OBJECTIVES: This in vitro study examined the effect of different implant drilling template designs on heat generation during osteotomy and on cooling fluid distribution. MATERIAL AND METHODS: Five different template designs were investigated in a standardized setup against a control group and a negative control group: Occlusal-splint-design (OSD), OSD-covering, OSD-lateral opening, Bar design, and Orientation template. Pilot and one consecutive drill were run at 800 rpm with external irrigation and 2-kg load. Thermocouples recorded temperature changes at depths of 3, 6, and 9 mm in a bovine rib model. In the second experimental setup, the drill channel of one rib sample was perforated, and the irrigation volume passing through the drill channel was collected separately over time. RESULTS: Following mean temperature rises occurred [in °C]: control, 4.9; negative control, 12; OSD, 5.6; OSD-covering, 4.7; OSD-lateral opening, 3.8; Bar design, 5.1; and Orientation template, 4.9. The highest temperature increases were found at a drilling depth of 6 mm (p < .006). The 2.2-mm drill resulted in a significantly higher temperature rise than the 2.8-mm drill (p < .001). The mean volume (ml/min) of irrigation through the drill channel was Control group-flow, 28.5; OSD, 4.1; OSD-covering, 2; OSD-lateral opening; 5.8; bar design, 4; and Orientation template, 24.1. CONCLUSION: Within the limitations, it was shown that fully guided drilling templates reduce the amount of cooling liquid at the point of osteotomy. The template design had an influence on the effective volume of the cooling liquid. However, this did not seem to increase the intraosseous temperature significantly.

Three-dimensional surface scanning methods in osteology: A topographical and geometric morphometric comparison.

OBJECTIVES: Three-dimensional (3D) data collected by structured light scanners, photogrammetry, and computed tomography (CT) scans are increasingly combined in joint analyses, even though the scanning techniques and reconstruction software differ considerably. The aim of the present study was to compare the quality and accuracy of surface models and landmark data obtained from modern clinical CT scanning, 3D structured light scanner, photogrammetry, and MicroScribe digitizer. MATERIAL AND METHODS: We tested 13 different photogrammetric software tools and compared surface models obtained by different methods for four articulated human pelves in a topographical analysis. We also measured a set of 219 landmarks and semilandmarks twice on every surface as well as directly on the dry bones with a MicroScribe digitizer. RESULTS: Only one photogrammetric software package yielded surface models of the complete pelves that could be used for further analysis. Despite the complex pelvic anatomy, all three methods (CT scanning, 3D structured light scanning, photogrammetry) yielded similar surface representations with average deviations among the surface models between 100 and 200 µm. A geometric morphometric analysis of the measured landmarks showed that the different scanning methods yielded similar shape variables, but data acquisition via MicroScribe digitizer was most prone to error. DISCUSSION: We demonstrated that three-dimensional models obtained by different methods can be combined in a single analysis. Photogrammetry proved to be a cheap, quick, and accurate method to generate 3D surface models at useful resolutions, but photogrammetry software packages differ enormously in quality.

The association of parturition scars and pelvic shape: A geometric morphometric study.

OBJECTIVES: Pelvic features, mostly known as parturition scars, have been extensively studied in the last decades and are frequently investigated in archaeological and forensic contexts. It is still unclear, however, whether they really relate to pregnancy and birth, or whether these features are caused by other biomechanical factors. Because the length and difficulty of labor correlates with the form of the birth canal, we studied the association between the expression of pelvic features and pelvic shape using geometric morphometrics. MATERIALS AND METHODS: We scored the expression of the preauricular sulcus, margo auricularis groove, sacral preauricular extension, dorsal and ventral pubic pitting for 54 individuals from a 19th century collection and 19 individuals from the Bronze Age cemetery of Hainburg-Teichtal, Austria. Based on photogrammetric surface models, pelvic shape was captured by 331 landmarks and semilandmarks. The multivariate association between pelvic features and pelvic shape was explored by partial least squares analysis. RESULTS: Within the female subsample, we detected a significant association of a constrained birth canal with a strong expression of the preauricular sulcus, the margo auricularis groove, and a retroverted position of the acetabulum. No significant association was found among males. DISCUSSION: This suggests that difficult or prolonged labor may indeed cause more strongly expressed pelvic features, presumably because of increased strain of the pelvic ligaments during birth. Furthermore, the retroversion of the acetabulum, which is known to cause sacroiliac joint dysfunction, changes the strain on pelvic ligaments and can thus also result in the development of pronounced pelvic features.

Quantification of dental macrowear using 3D occlusal surface topographic measurements in deciduous and permanent molars of children.

OBJECTIVES: Childhood paleodietary reconstruction via dental macrowear analysis is limited in part by available methods to measure dental macrowear. We describe a method to quantify dental macrowear progression (in both deciduous and permanent molars) using a handheld intraoral scanner and two 3D occlusal topographic measurements. We assess the agreement of our macrowear proxies with an established qualitative wear scoring system and their relationship to age. MATERIAL AND METHODS: We scanned 92 well-preserved dentitions of immature individuals from the medieval cemetery of St. Pölten in Lower Austria using an intraoral scanner. Two measurements were made on the resulting mesh files-the relative flat surface area in % of the occlusal surface (RFSA%) and the mesial interior slope angle. We estimated the technical error of measurement (TEM). Comparisons were made with the macrowear scoring system-tooth wear index. RESULTS: We found that TEM for both measurements was between 1 and 3%, except the interobserver TEM of RFSA% which was above 5%. Both quantitative measurements generally agree with the established qualitative scores and correlate with age; however, RFSA% does not reliably indicate the progression of macrowear for teeth after dentine exposure occurs. DISCUSSION: The proposed 3D topographic measurements can be made reliably, and within a certain range of wear provide good quantitative proxies of the progression of dental macrowear. Such measurements constitute a promising approach for improving dental macrowear analysis in contexts such as childhood paleodietary reconstruction, which benefit from additional precision in wear rate estimation and present less dentine exposure.

Lateral angle: A landmark-based method for the sex estimation in human cremated remains and application to an Austrian prehistoric sample.

OBJECTIVES: Estimating the sex of cremated human remains is difficult. The petrous bone frequently survives the cremation due to its density. Wahl observed the lateral angle to be sexually dimorphic in the 1980s. Previous studies showed various cut-off points to separate females from males, which are hardly replicable and difficult to apply. We want to test the Wahl method and compare it to a new landmark-based version. MATERIALS AND METHODS: In this study, we measured the lateral angle of 35 cremated petrous bones from late bronze age Austria using micro-CT scans. Technical errors of measurement were calculated for two different methods to intersect the internal acoustic meatus virtually in the midline (manual or landmark-based intersection). Furthermore, sex was estimated based on morphological features and metric measurements. This information was used in logistic regression modeling to define a cut-off point in our sample. RESULTS: The technical errors of measurement suggested that a landmark-based method was more precise in comparison to a manual intersection which was much more intuitive. Inter- and intra-observer errors were low which improved reliability. The logistic regression model produced good results in our sample (p = 0.02, R2 = 0.38, accuracy = 0.8). The mean lateral angle was similar to studies which focused on prehistoric cremated petrous bones. DISCUSSION: The proposed landmark-based method was precise, quick, and could be easily applied, even by unexperienced researchers. The size of the lateral angle seemed to be population-specific but also dependent on the method applied. We recommend to use the proposed landmark-based method which is more precise.

More than urns: A multi-method pipeline for analyzing cremation burials.

Burial rites of archaeological populations are frequently interpreted based on cremated remains of the human body and the urn they were deposited in. In comparison to inhumations, information about the deceased is much more limited and dependent on fragmentation, selection of body regions, taphonomic processes, and excavation techniques. So far, little attention has been paid to the context in which urns are buried. In this study, we combined archaeological techniques with anthropology, computed tomography, archaeobotany, zooarchaeology, geochemistry and isotopic approaches and conducted a detailed analysis on a case study of two Late Bronze Age urns from St. Pölten, Austria (c. 1430 and 1260 cal. BCE). The urns were recovered en-bloc and CT-scanned before the micro-excavation. Osteological and strontium isotope analysis revealed that the cremated remains comprised a young adult female and a child that died at the age of 10-12 years. Both individuals had been subject to physiological stress and were likely local. Animal bones burnt at different temperatures suggested different depositional pathways into the urn and pit as part of the pyre, food offerings, and unintentional settlement debris. Eight wild plant and five crop plant species appeared as part of the local landscape, as food offerings and fire accelerants. Sediment chemistry suggests that pyre remains were deposited around the urns during burial. Multi-element geochemistry, archaeobotany, and zooarchaeology provide insights into the Late Bronze Age environment, the process of cremation, the gathering of bones and final funerary deposition.

SafetyCrown: a patient-centered, fully digital concept for immediate implant restoration following the one-abutment/one-time concept-a pilot case series of a new treatment concept.

INTRODUCTION: The patient-centered SafetyCrown-workflow enables the immediate restoration of posterior missing teeth and short free-end situations following one-abutment/one-time within three visits and only one surgical approach. This prosthodontic rehabilitation aims to combine the advantages of cemented and screw-retained restorations. REPORT: The concept has been performed with 4 restorations in 3 patients and followed up for up to 1 year (mean: 11.2 months) without technical and/or biological complication. Visit 1: Intraoral optical impression, CBCT, and tooth shade selection. Virtual implant planning is performed, and a surgical guide is printed. After exporting the planned implant position, a tooth-colored abutment is fabricated from zirconia with a 1-mm supragingival cementation line, adhesively bonded to a titanium base. Visit 2: Fully navigated implant placement with insertion of the definitive abutment. Subsequently, optical impressions are prepared for A: immediate restoration using a PMMA crown without functional contacts; B: definitive crown fabricated from monolithic zirconia and individualized. The localization of the screw channel is marked using stain thus permitting precise screw channel access, if necessary. Visit 3: After osseointegration of the implant, the definitive crown is adhesively cemented supragingival. In a retrospective analysis of PROMs ('How stressful was the treatment process […]?' (0 = not stressful at all, 100 = very stressful), mean VAS score for SafetyCrown of 14 (SD 11.7) and 29.8 (SD 23.1) for standard procedure were present. CONCLUSION: The SafetyCrown offers a shortened, patient-oriented concept for implant-supported single-tooth reconstructions omitting second-stage surgery. Clinical performance and hypothesized prosthodontic benefits require confirmation via an RCT.

Age dependent changes in pelvic shape during adulthood.

The human pelvis has been reported to change in shape throughout adult lifetime, and also the expression of parturition scars, or "pelvic features", increases with age. However, little is known about the causes and timing of these changes. Here we investigate changes in pelvic shape and the expression of pelvic features by applying a comprehensive geometric morphometric approach to a modern sample of 167 adult individuals with known age, parity, and cause of death. Our results confirm that the pelvis changes in shape during adult life, but to a larger magnitude in females compared to males. Moreover, females showed three different phases of pelvic shape change, coinciding with the main period of reproduction (from 17 to about 37-40 years), the period after that but before menopause, and the postmenopausal period (after 50 years of age). Males exhibited two phases with relatively similar shape changes. The expression of parturition scars increased in females until about 40 years of age and stayed relatively constant thereafter. Only a very weak increase of feature expression was found in males. We hypothesize that changes of adult pelvic shape and feature expression result from a combination of hormone-mediated and mechanically induced bone remodeling. Estrogen-induced and pregnancy-related bone remodeling dominates in premenopausal women, whereas bone remodeling in response to mechanical factors may underlie pelvic shape changes in men and postmenopausal women. The continual widening of the birth canal during the reproductive period eases childbirth in a population, but it is unlikely that this remodeling pattern specifically evolved as an obstetric adaptation in the human lineage. The highly conserved endocrine system and estrogen-induced pelvic bone remodeling were already in place when the neonatal brain increased in the human lineage. But the regularity control of this conserved pathway may have been "fine-tuned" by selective forces in the human lineage.

A histological comparison of non-human rib models suited for sharp force trauma analysis.

Cut marks provide essential knowledge to interpret which and how tools were used, both in archaeological and forensic context. Lots of studies focused on experimentally produced cut marks on animal models to develop methods for stabbing incidents. However, animal models are criticized to be morphologically different in comparison to human bones. This study analyzed the bone composition and experimentally obtained cut marks done on ribs from humans, pigs and goats. Methods included a qualitative description of differences between the species and a quantitative analysis of the cut mark proportions in histological thin sections and micro CT scans. The results indicated that especially the cortical bone of non-human ribs was different in comparison to human bone tissue as they were more robust and usually juvenile. Plexiform bone dominates and remodeled lamellar bone is rarely visible. The knife impact tends to create debris inside the cut mark and stress fractures along lamellae and cement lines perpendicular to the cut mark. Moreover, entheses of the intercostal muscles are always affected by the incision. Pig ribs were shown to be better suited as a model for sharp force trauma than goat ribs in comparison to humans. Though, plexiform bone and non-remodeled bone made it not quite ideal. We suggested to use bone material from animals used for breeding instead of meat production as they are slaughtered at higher ages.

Child murder in the Early Bronze Age: proteomic sex identification of a cold case from Schleinbach, Austria.

The identification of sex-specific peptides in human tooth enamel by nanoflow liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) represents a quantum leap for the study of childhood and social relations more generally. Determining sex-related differences in prehistoric child rearing and mortality has been hampered by the insufficient accuracy in determining the biological sex of juveniles. We conducted mass spectrometric analysis to identify sex-specific peptides in the dental enamel of a child from a settlement pit of the Early Bronze Age settlement of Schleinbach, Austria (c. 1950-1850 bc). Four perimortal impression fractures on the skull of a 5-6-year-old child indicate an intentional killing, with a co-buried loom weight as possible murder weapon. Proteomic analysis, conducted for the first time on prehistoric teeth in Austria, determined the child's sex as male. While we cannot conclusively determine whether the child was the victim of conflicts between village groups or was slain by members of his own community, we suggest that contextual evidence points to the latter. A possible trigger of violence was the follow-on effects of an uncontrolled middle ear infection revealed by an osteological analysis. The boy from Schleinbach highlights the potential for further investigation of gender-biased violence, infanticide and child murder based on the recently developed method of proteomic sex identification.

Effects of heat on cut mark characteristics.

Cut marks on bones provide crucial information about tools used and their mode of application, both in archaeological and forensic contexts. Despite a substantial amount of research on cut mark analysis and the influence of fire on bones (shrinkage, fracture pattern, recrystallisation), there is still a lack of knowledge in cut mark analysis on burnt remains. This study provides information about heat alteration of cut marks and whether consistent features can be observed that allow direct interpretation of the implemented tools used. In a controlled experiment, cut marks (n=25) were inflicted on pig ribs (n=7) with a kitchen knife and examined using micro-CT and digital microscopy. The methods were compared in terms of their efficacy in recording cut marks on native and heat-treated bones. Statistical analysis demonstrates that floor angles and the maximum slope height of cuts undergo significant alteration, whereas width, depth, floor radius, slope, and opening angle remain stable. Micro-CT and digital microscopy are both suitable methods for cut mark analysis. However, significant differences in measurements were detected between both methods, as micro-CT is less accurate due to the lower resolution. Moreover, stabbing led to micro-fissures surrounding the cuts, which might also influence the alteration of cut marks.