Crown Contour Research Articles

Creation of Methods for Automated Determination of Forest Parameters Based on Data from UAVS

The article presents a scientific study on the use of aerial photographs obtained by unmanned aerial vehicle (UAV), for the automated collection of data on forest resources in the taiga forests of the European North of Russia. On the example of the trial plot, a technique is described for automated allocation of crown contours, calculation of the trunk diameter and timber stock in the forest area. The methodology used morphological methods for processing digital images, geographic information tools for representing and processing spatial information, as well as the results of statistical observations of leading scientists in the field of forestry. The results have been verified in the field in several plots. The technique is applicable to automate the process of thematic interpretation of orthorectified aerial photographs with a spatial resolution of five to ten centimeters per pixel. The experiments presented in the article were carried out on images of forests in the north of the European part of Russia. The research results are used for regular automated updating of information on forest resources.

Comparative Experimental Studies on Four Stroke Four Cylinder Diesel fuelled Base Line Engine and Low Heat Rejection Engine

The depletion of conventional fuel source at a fast rate and increasing of environment pollution motivated extensive research in energy efficient engine design. In the present work, experimental investigations were carried out on a four-stroke four-cylinder dieselfuelled Base Line Engine (BLE) by conducting a normal load test and measuring the required Brake Thermal Efficiency (BThE) and Specific Fuel Consumption (SFC) in a 100 HP dyno facility. A six-gas Analyser was used for the measurement of Unburnt
 Hydrocarbons (UBHC), Carbon monoxide (CO), Carbon dioxide (CO2), free Oxygen (O2), Nitrogen oxides (NOx), Sulphur oxides (SOx) and a smoke meter was used to measure smoke opacity. Low Heat Rejection (LHR) engine was realized by coating the crown of the aluminium alloy piston with the most popular Thermal Barrier Coating (TBC) material, namely 8%Yttria Partially Stabilized Zirconia (8YPSZ), after coating qualification on research pistons, specifically fabricated to retain the piston material specification, and the geometry of the crown contour. A normal load test was conducted on LHR engine to evaluate the performance as well as to determine the concentration of pollutants. A ~30% improvement in BThE and ~35% improvement in SFC was exhibited by the LHR engine at all loads studied (7 to 64%). While UBHC level showed an increase, the CO, CO2 and O2 contents as revealed in the emission test showed a mixed response (high and low) for an LHR engine. Compared with BLE, NOx and smoke level in LHR engine emission showed an increasing trend with the load. On comparing BLE and LHR engine test results, value addition to the BLE in terms of reduced fuel consumption and pollutants was observed.

Extraction of Information on Trees outside Forests Based on Very High Spatial Resolution Remote Sensing Images

The sparse Ulmus pumila L. woodland in the Otingdag Sandy Land of China is indispensable in maintaining the ecosystem stability of the desertified grasslands. Many studies of this region have focused on community structure and analysis of species composition, but without consideration of spatial distribution. Based on a combination of spectral and multiscale spatial variation features, we present a method for automated extraction of information on the U. pumila trees of the Otingdag Sandy Land using very high spatial resolution remote sensing imagery. In this method, feature images were constructed using fused 1-m spatial resolution GF-2 images through analysis of the characteristics of the natural geographical environment and the spatial distribution of the U. pumila trees. Then, a multiscale Laplace transform was performed on the feature images to generate multiscale Laplacian feature spaces. Next, local maxima and minima were obtained by iteration over the multiscale feature spaces. Finally, repeated values were removed and vector data (point data) were generated for automatic extraction of the spatial distribution and crown contours of the U. pumila trees. Results showed that the proposed method could overcome the lack of universality common to image classification methods. Validation indicated the accuracy of information extracted from U. pumila test data reached 82.7%. Further analysis determined the parameter values of the algorithm applicable to the study area. Extraction accuracy was improved considerably with a gradual increase of the Sigma parameter; however, the probability of missing data also increased markedly after the parameter reached a certain level. Therefore, we recommend the Sigma value of the algorithm be set to 90 (±5). The proposed method could provide a reference for information extraction, spatial distribution mapping, and forest protection in relation to the U. pumila woodland of the Otingdag Sandy Land, which could also support improved ecological protection across much of northern China.

Influence of cervical crown contour on marginal bone loss around platform‐switched bone‐level implants

Background Preservation of peri-implant bone and maintaining healthy soft tissues are important for long-term implant success. However, this success can be influenced by prosthetic aspects. It is recommended that implant suprastructures should be designed in a way that oral hygiene measures can be performed, plaque accumulation is prevented and implants are accessible for probing. Studies on how to design the crown contour in order to prevent influence on the marginal bone level remain unknown. Aim/Hypothesis The aim of the present cohort study was to evaluate the influence of the cervical crown contour on marginal bone loss and soft tissue health around platform-switched, bone-level implants in the posterior region. Material and Methods A dataset was used from two previous studies. This dataset included clinical parameters and standardized peri-apical radiographs taken at 1 month and 5 years after final crown placement. A new measurement method (using Image J, National Institutes of Health, USA) was developed to analyse geometric values of the cervical crown contour. Emergence angles were measured at 1, 2 and 3 mm, parallel to the implant axis, above the implant shoulder (see Figure 1). The distance from the most outside point of the implant neck to the level of bone-to-implant contact was measured at both the mesial and distal aspect of the implant to determine marginal bone loss (using DicomWorks® software). A Pearson correlation coefficient was calculated. Clinical evaluation of the peri-implant soft tissue was performed at 1 month (baseline, T0) and 5 years (T60) after placement of the final implant crown. The sulcus bleeding index, the gingival mucosal index and the probing pocket depth were clinically recorded. Results A total of 64 patients with 67 posteriorly placed implants met the inclusion criteria. At 1, 2 and 3 mm above the implant shoulder, mean emergence angles at the mesial implant sites were 0.5 ± 2.8, 12.8 ± 12.8 and 18.0 ± 11.3 degrees, respectively. At the distal sites corresponding values were 2.8 ± 8.3, 16.2 ± 16.6 and 18.7 ± 13.8 degrees. Mean marginal bone loss between 1 month and 5 years after restoration placement was 0.14 ± 0.34 mm at the mesial and 0.26 ± 0.47 mm at the distal aspect of the implants. The clinical parameters at the 5-year evaluation generally indicated healthy peri-implant soft tissues. In 67.2% of the implants no bleeding was recorded as measured by the sulcus-bleeding index. The gingival index indicated healthy soft tissue in 97% of the implants 89.5% of the implants showed no probing pockets depth deeper than 5 mm. No correlation between peri-implant bone loss, soft tissue health and cervical crown contour could be found. Conclusion and Clinical Implications No correlation appears to exist between the cervical crown contour and peri-implant marginal bone loss and soft tissue health around bone-level, platform-switched implants at least when emergence angles do not exceed 20 degrees in the first 3 mm from the implant shoulder. Clinicians should therefore pay attention to a steep slope implant crown design.

Algorithm for the boundary detection of dental crowns for 3D dental model segmentation

This paper presents the segmentation algorithm on the 3D digital dental model for separating individual dental crown using fuzzy multi criteria analysis and Visualization Toolkit (VTK). The aim is to apply the algorithm in the 3D aligner development software package. The digital dental model is produced by 3D scanner in STL format and dental crown contour is calculated based two control points defined by user. Fussy multi criteria analysis with pairwise comparison of the mesh points aims to select a points subset that define the boundary between the dental crown and the jawbone. VTK provides ease of use computer graphics algorithms and visualisation tools. The result has shown that the proposed approach can successfully separate dental crown on the 3D digital dental model.

Влияние густоты древостоя на формирование кроны и рост по диаметру сосны обыкновенной (Pinus sylvestris L.)

Crown size determines tree’s life space formation, its growth and development. The research object was a middle-aged pine stand spatially included in the Krasnoyarsk island forest-steppe. The permanent trial plot of 0.15 ha size with over 300 trees was established in high-yield green moss pine forest. Each tree on the plot was mapped and assigned with an individual number; its diameter at breast height was measured. A large-scale survey of the trial plot with resolution of 25 cm was acquired using the unmanned aerial vehicle (UAV). The trial plot identification on the image and its matching with the land-based mapping data were performed in ArcMap. In this program crowns of all trees are outlined and areas of their projections are calculated using GIS-technology methods. The data analysis showed a close correlation between crown projection contours and areas and the field data. Dominance area (SОД) was used as an available resource valuation for a tree in the competition conditions in a forest stand. Dominance area is defined as an area, where each individual tree has dominating influence in space around it and obtains light and soil resource in assumption that this influence is directly proportional to sample size and inverse to squared distance to it. It was found that crowns of rare and medium density with projection area (Sкр) of 2…6 m2 are formed in case of a low dominance area (less than 6 m2). Crowns with SОД of 6…12 m2 have high density and projection area up to 10 m2 and length more than 40 % of tree height. The dynamics of tree radial increment after thinning at the age of 37 was studied depending on the dominance area increase. During 4 years after thinning, annual radial increment increases up to 2 times with increase of available resource. Regression analysis has shown strong correlation between crown projection area and dominance area with a correlation coefficient R = 0.84. Use of UAV is a promising, low-cost and effective technique of distance studying the tree stand structure. Office analysis of images allows to obtain crown projection area characteristics. These data can be used in improvement thinning and forming of even-aged pine stand canopy, which provide the maximum use of lightand soil resource and effective ecological forest functioning. For citation: Ivanov V.V., Borisov A.N., Petrenko A.E. Influence of Stand Density on Crown Formation and Growth along the Diameter of Scots Pine (Pinus sylvestris L.). Lesnoy Zhurnal [Forestry Journal], 2019, no. 3, pp. 9–16. DOI: 10.17238/issn0536-1036.2019.3.9 Funding: The research was carried out within the framework of fundamental scientific research programs of the Russian Academy of Sciences no. 0356-2016-0706. State Registration (TsITIS) no. АААА-А17-117101940014-9 “Theoretical Foundations for the Ecological and Resource Potential Conservation of Siberian Forests in the Conditions of Increasing Anthropogenic Pressure and Climatic Anomalies”. Acknowledgements: The authors are grateful to Rubtsov A.V. for the provided aerial photographic image of the forest site.

In-vitro analysis of maxillary first molars morphology using three dimensional Micro-CT imaging: considerations for restorative dentistry.

The aim of this study was to determine the differences between the positional relationship of the crown contour and the pulp chamber of left and right maxillary first molars, as well as their morphological characteristics by using micro-CT system with reconstruction from a volumetric rendering software. In total, 21 extracted maxillary first molars, including 11 left and 10 right teeth, were used. The positional relationship between the crown contour, pulp chamber and morphology of the teeth were investigated three-dimensionally by means of micro-CT imaging. Closest distance of mesio-buccal pulp horn to enamel surface in mm was calculated as 2.5±0.20 mm for right and 2.29±0.17 mm for left teeth. This difference was statistically significant (p=0.017). The means of closest distance of disto-buccal pulp horn to enamel surface were also significantly different between left and right teeth (p=0.001). The mean pulp volumes of right side and left side teeth were, respectively, 32.94±3.19 mm3 and 33.71±2.82 mm3 but this difference was not statistically significant. These results suggest that right and left maxillary first molars should be treated differently during preparation of cavities. Further studies must be done with larger samples as well as for other molar teeth in different populations to reveal the morphology of the molar for further considerations in restorative dentistry.

Optimization Technology of Roll Contours during Skin-Pass Rolling Process of Hot-Rolled Strip

The hot-rolled strip skin-pass mill is the important technological equipment of finishing process in the hot rolling plant, and its role is to apply a slight thickness reduction of approximately 1% - 4% to the finished products cooled to room temperature to repair flatness defects and improve the surface quality and mechanical properties. In this study, the initial flat roll contours were optimized to solve some problems such as the serious and non-uniform wear of work rolls and the poor shape control abilities of the strip. A three-dimensional rolls–strip coupling model of hot-rolled strip skin-pass mill was established using the nonlinear finite element software ABAQUS. The effects of the roll contours on the contact pressure between rolls and the control effect of bending forces were analyzed, and a variable contact-length backup roll (VCR) contour configured with a positive crown contour for work rolls was proposed. Compared with the initial flat roll contours, the average replacement cycle of work rolls for the optimized roll contours increased from 465.4 tons to 701.3 tons, the non-uniform wear amount was reduced by nearly 15%, and the adjustment ratio of the negative bending forces decreased from -100% to -40% by industrial experiments in the 1580 mm single-stand four-high hot-rolled strip skin-pass mill.

Prevention and Management of Cheek and/or Tongue Biting Related to Posterior Implant‐Supported Fixed Dental Prostheses (ISFDPs)

After the loss of several adjacent posterior teeth, bone resorption occurs that can lead to a marked occlusal discrepancy between arches. This discrepancy may originate from the more pronounced resorption at the facial portion of the alveolar bone crest, often resulting in a more palatal implant position. Therefore, establishing normal overbite and cusp-fossa relation may become difficult, namely causing inappropriate crown contours and emergence profiles. This manuscript describes a technique in which a different occlusal configuration is given to solve some problems that edge-to-edge occlusal configuration produces. For instance, patients may suffer from cheek and/or tongue biting after the delivery of a maxillary posterior implant-supported fixed dental prosthesis resulting in an edge-to-edge occlusal configuration. In instances of severe maxillary resorption in the posterior buccal zone, it is recommended to consider a distinct cross-bite occlusion and by this prevent the well-known discomfort and clinical signs associated with both an edge-to-edge interarch relationship or a so-called "stretched" transversal overbite.

Biological Interfaces in Prosthetic Dentistry: A Review

The interaction between periodontology and restorative dentistry plays an important role in many aspects including the location of restorative margins, crown contours and response of all gingival tissues to restorative preparations. Most of the clinicians are aware of this inter-relationship, but the dilemma remains concerning specific concepts such as biologic width (BW), its maintenance and applications of crown lengthening in cases of BW violation.

Fabrication of capsule-like inflatable woven fabric used for tunnel plugs

Considering safe and continuous operation of the subway tunnel, apart from the conventional drainage system, the entrances or exits of tunnels generally are designed to install special devices to block the influx of either floods due to sudden storms or harmful gases caused by terrorist attack. Traditional devices include metal plates or sandbags. In recent years, researchers have invented textile-based capsule-like inflatable device to replace the traditional devices because the new one can be flexibly located in the tunnel, capable of blocking fluids completely, light-weight and low cost. However, the fabrication of capsule-like textile structure has been seldom discussed in the literature. The capsule-like textile structure is either created by fabric weaving followed by sewing for the capsule form, which may result in unevenness of stress distribution due to existence of seams in the structure, or produced by expensive and specially designed weaving equipment. This paper is to explore two different fabrications of capsule-like textile structure for the purpose that the device is evenly structured and can be produced in one step with conventional weaving loom. The techniques of fabrication with trapezoid-formed reed as well as the application of double-layered structure have been investigated. The contour of spherical crown of capsule-like structure is well in line with calculated values.

Esthetic Evaluation of Implant-Supported Single Crowns: The Implant Restoration Esthetic Index and Patient Perception.

To test the validity and reliability of a newly developed Implant Restoration Esthetic Index (IREI) and to compare esthetic outcomes reported by patients and professionals. Ten graduate students and 10 prosthodontists assessed esthetic outcomes of 27 single-tooth implants with the IREI. Six peri-implant soft tissue parameters were measured using visual analog scales: mesial papilla presence, distal papilla presence, gingival trigone, soft tissue curvature, alveolar process deficiency, and soft tissue color and texture, as well as the six crown parameters: crown contour, crown position, crown labial convexity, crown characterization, crown color and translucency, and abutment visibility. The validity was tested based on Pearson's correlation. The internal consistency reliability was analyzed by Cronbach's alpha. Interclass correlation coefficients (ICC) were calculated to express the test-retest reliability and the inter-rater reliability. The correlations between patient and professional evaluations were analyzed by Pearson's correlation. The IREI demonstrated significant correlation (p < 0.05) to the pink esthetic score and white esthetic score (PES/WES). The internal consistency reliability showed a Cronbach's Alpha of 0.830. The test-retest reliability was excellent in both the graduate student group and the prosthodontist group, with ICCs of 0.961 and 0.952, respectively (p < 0.05). The inter-rater reliability was acceptable, with ICCs of 0.649 and 0.667, respectively (p < 0.05). Low correlation coefficients were found between patient and professional evaluations. The results of this study indicated that the IREI was considered a valid and reliable index involving sufficient parameters for professional esthetic evaluation of single-tooth implant restorations. The patient-reported esthetic outcomes had poor or no significant correlation to professional-reported outcomes.

The Effect of Coded Healing Abutments on Treatment Duration and Clinical Outcome: A Randomized Controlled Clinical Trial Comparing Encode and Conventional Impression Protocols.

To compare the Encode impression protocol (Biomet 3i) with the conventional impression protocol in terms of treatment duration, clinical accuracy, and outcome up to the first postplacement review of single-implant crowns. A total of 45 implants were included in this study. The implants were randomly allocated to the Encode group (23 implants) or the conventional group (22 implants). At the time of surgery, all implants received two-piece Encode healing abutments. The implants were restored 3 months after insertion. In the conventional protocol, open-tray implant-level impressions were taken and the implants were restored with prefabricated abutments and porcelain-fused-to-metal (PFM) crowns. For the implants in the Encode group, closed-tray impressions of the healing abutments were taken. The generated casts were sent to the Biomet 3i scanning/milling center for custom abutment manufacturing on which PFM crowns were fabricated. Treatment duration (laboratory and clinical), clinical accuracy of occlusal and proximal contacts, and outcome (esthetics, patient satisfaction, and crown contour) were evaluated with the aid of a series of questionnaires. The Encode protocol required significantly less laboratory time (18 minutes) than the conventional protocol for adjustment of the abutments. The impression pour time, time for the laboratory to return the crown, time for crown insertion at the final appointment, and total clinical time for crown insertion did not differ significantly between the two protocols. Likewise, clinical accuracy, esthetics, and patient satisfaction were similar for the two protocols. The two protocols were clinically comparable. The Encode protocol is advantageous in reducing the laboratory time before crown fabrication.

Proximal Contact Repair of Complex Amalgam Restorations.

The carving of a complex amalgam restoration may occasionally result in light proximal contact with the adjacent tooth. The purpose of this study was to investigate the strength of complex amalgam restorations repaired with a proximal slot amalgam preparation. Extracted human third molars of similar coronal size were sectioned 1 mm apical to the height of the contour using a saw and were randomly distributed into 9 groups of 10 teeth each. One pin was placed at each line angle of the flattened dentinal tooth surface. A metal matrix band was placed and an admixed alloy was condensed and carved to create a full crown contour but with a flat occlusal surface. A proximal slot was prepared with or without a retention groove and repaired using a single-composition spherical amalgam 15 minutes, 24 hours, one week, or six months after the initial crown condensation. The specimens were stored for 24 hours in 37°C water before fracture at the marginal ridge using a round-ended blade in a universal testing machine. The control group was not repaired. The mean maximum force in newtons and standard deviation were determined per group. Data were analyzed with a 2-way analysis of variance as well as Tukey and Dunnett tests (α=0.05). Significant differences were found between groups based on type of slot preparation (p=0.017) but not on time (p=0.327), with no significant interaction (p=0.152). No significant difference in the strength of the marginal ridge was found between any repair group and the unrepaired control group (p>0.076). The proximal repair strength of a complex amalgam restoration was not significantly different from an unrepaired amalgam crown. Placing a retention groove in the proximal slot preparation resulted in significantly greater fracture strength than a slot with no retention grooves. Time of repair had no significant effect on the strength of the repair.

Crown Segmentation From Computed Tomography Images With Metal Artifacts

Tooth segmentation from dental computed tomography (CT) images with metal artifacts is challenging as metal artifacts make some of the crown boundaries unrecognizable. This letter proposes a semiautomatic method for crown segmentation from CT images with metal artifacts. A user manually selects a starting slice and initializes this slice. Then crown contours are segmented automatically from volumetric CT images slice by slice. In the segmentation of each slice, the Radon transform is used to extract a line to separate neighboring crowns into independent ones. A statistical shape prior-based level set model is then applied to segment each crown from the mesial or distal side of the line. The proposed method was tested on 15 set of volumetric images. Experimental results validated that it is effective to extract crown contours from CT images with metal artifacts.

クラウンカントゥア，フィニッシュラインの設定とブラックトライアングルの処理（インプラント治療を含む）

クラウンカントゥア，フィニッシュラインの設定とブラックトライアングルの処理（インプラント治療を含む）

Knowledge, attitude, and practice of dental professionals regarding the effect and management of food impaction associated with fixed partial denture prostheses: A survey.

Objective:This survey was undertaken to assess dentist's opinion regarding the occurrence and pattern of food impaction in relation to fixed partial denture (FPD) prostheses, its commonly observed consequences, factors contributing to it, and its management.Methods:A descriptive survey was conducted on a sample size of 150 dental practitioners. The pro forma consisted of informed consent, demographic information, and questionnaire. The results were tallied and quantitative analysis was performed to obtain the descriptive statistics for the data using SPSS version 20.Results and Interpretation:All the study respondents had come across patients who complained of food impaction in relation to FPD. The most common consequences of food impaction were proximal caries of the adjacent teeth and interdental bone loss. Majority of the dentists considered faulty FPD design with improper contact relation, improper crown contour, poor margin adaptation, and faulty pontic design as the most likely reason for food impaction. Repeating the FPD with emphasis on prescribing and reinforcing the use of proper interdental aids was considered as the ideal treatment option. It was also observed that about half of the dentists always communicated inadequate information of the FPD prostheses that needed replacement to the dental laboratory technician for the successive bridge. Most of the times, prosthodontists were consulted to rectify the problem of food impaction resulting from faulty FPD prostheses. However, it is obvious that it is easier and more prudent to prevent rather than treat food impaction. This study gives an overview of some of the common errors in designing the FPD prostheses which often lead to food impaction and measures to be taken to overcome them.Conclusion:It may be concluded as all the dentists participating in the survey agreed that food impaction is one of the common complaint among FPD Patients. Proximal caries and interdental bone loss were the prevalent outcomes of food impaction. Faulty FPD design was allegedly attributed as the reason for food impaction. Prosthodontists were routinely consulted to resolve the dilemma of food impaction. However, it is rational to prevent food impaction rather than to tackle the sequel later.

Unique Dental Morphology of Homo floresiensis and Its Evolutionary Implications.

Homo floresiensis is an extinct, diminutive hominin species discovered in the Late Pleistocene deposits of Liang Bua cave, Flores, eastern Indonesia. The nature and evolutionary origins of H. floresiensis’ unique physical characters have been intensively debated. Based on extensive comparisons using linear metric analyses, crown contour analyses, and other trait-by-trait morphological comparisons, we report here that the dental remains from multiple individuals indicate that H. floresiensis had primitive canine-premolar and advanced molar morphologies, a combination of dental traits unknown in any other hominin species. The primitive aspects are comparable to H. erectus from the Early Pleistocene, whereas some of the molar morphologies are more progressive even compared to those of modern humans. This evidence contradicts the earlier claim of an entirely modern human-like dental morphology of H. floresiensis, while at the same time does not support the hypothesis that H. floresiensis originated from a much older H. habilis or Australopithecus-like small-brained hominin species currently unknown in the Asian fossil record. These results are however consistent with the alternative hypothesis that H. floresiensis derived from an earlier Asian Homo erectus population and experienced substantial body and brain size dwarfism in an isolated insular setting. The dentition of H. floresiensis is not a simple, scaled-down version of earlier hominins.

Taxonomic Implications of Molar Morphology Variability in Capuchins

Tooth morphology has been widely used to infer taxonomic affinities. Both morphological and genetic analyses have revealed significant differences among capuchins, suggesting that two distinct monophyletic groups exist: the gracile capuchins (Cebus) and the robust capuchins (Sapajus). We developed a geometric morphometrics (GM) model to determine if the two groups also show distinct molar shapes and to explore the influence of size, phylogeny, and biogeography in shaping molar morphology. We characterized first and second molar crown shape variability in seven species representative of the two genera (Cebus albifrons, C. olivaceus, Sapajus apella, S. robustus, S. libidinosus, S. nigritus, and S. xanthosternos), using two-dimensional (2D) and three-dimensional (3D) GM. The results showed that 2D GM discriminated the two groups better than 3D GM, possibly because it accounted for cusp position and crown contour, but not cusp height, which may be a useful trait for inferring adaptive foraging ecology but presents a risk of homoplasy. In addition, the presence of a phylogenetic signal in the first molar shape (2D) is likely to reflect similarity to the ancestral condition and provides evidence of gradual evolution of molar robustness in the robust clade. We suggest that the shape of the first molar is informative about phylogenetic affinities, whereas the shape of the second molar is more informative about biogeographic variability. However, molar shape similarities may be affected by convergent evolution, as environmental factors in different biogeographical regions may have a significant effect on molar morphology, as seen in the closely related capuchins.

Dental Shape Variability in Cercopithecoid Primates: A Model for the Taxonomic Attribution of Macaques from Roman Archaeological Contexts

Morphometric variation of biological structures has been widely used to determine taxonomic affinities among taxa, and teeth are especially informative for both deep phylogenetic relationships and specific ecological signals. We report 2-dimensional geometric morphometrics (GM) analyses of occlusal crown surfaces of lower molars (M₁, n = 141; M₂, n = 158) of cercopithecoid primate species. A 12-landmark configuration, including cusp tips and 8 points of the molar crown contour, were used to evaluate patterns of variation in lower molar shape among cercopithecoid primates and to predict the taxonomic attribution of 2 archaeological macaques from Roman time periods. The results showed that the lower molar shape of cercopithecoid primates reflects taxonomic affinities, mostly at a subfamily level and close to a tribe level. Thus, the cusp positions and crown contour were important elements of the pattern related to interspecific variation. Additionally, the archaeological specimens, attributed to Macaca sylvanus based on osteological information, were classified using the GM molar shape variability of the cercopithecoid primates studied. The results suggest that their molar shape resembled both M. sylvanus and M. nemestrina, and species attribution varied depending on the comparative sample used.