3D evaluation of palatal rugae for human identification using digital study models

A Systematic Review of the Use of Intraoral Scanning for Human Identification Based on Palatal Morphology

A common application for intraoral scanners is the digitization of the morphology of teeth and palatal rugae. Palatal scans are most commonly required to fabricate complete dentures and immediate transitional dentures and serve as a reference point for assessing orthodontic results. However, they are also frequently included by accident, even though the main purpose of intraoral scanning is to reconstruct dentition using computer-aided manufacturing (CAM). The literature shows that the identification of disaster victims has frequently involved palatal rugae impressions. As the skull provides sound insulation, the rugae are resistant to heat, chemicals, and stress. Antemortem data might be difficult to find during a forensic inquiry, particularly in disaster victim identification cases. In contrast with DNA and fingerprints, there is a greater likelihood of having a dental record that contains palatal scans. With specialized software, the scans can be exported as open stereolithography (STL) files. Considering that a full case consumes up to about 100 MB of hard drive space, long-term storage should not be an issue compared to a plaster model. Additionally, dentists widely use online databases to exchange data for smile design, implant registration, and orthodontic purposes. This will produce a digital database that grows quickly and is readily usable for forensic investigations. The uniqueness of forensic features is frequently challenged; however, palatal morphology's unique trait could make it possible as it is characteristic of individuals as well as the most distinguishing factor. This review will highlight how rugae, palatal morphology, mirroring, superimposition, and geometrics can serve in forensic identification.

Clinical comparative study on the accuracy of palatal rugae in models obtained by different impression materials and intraoral scanning

OBJECTIVE

Palatal rugae are frequently used in the evaluation of tooth movement after treatment in orthodontics and as a stable region in superimposition. It is important to note that the impression method and material used to record the rugae region affect the accuracy of the impression. The aim of this study is to compare the accuracy of palatal rugae, in three-dimensional (3D) by employing both conventional and digital impression methods.

MATERIALS AND METHODS

In this study, 22 patients (12 females, 10 males) mean age of 13.5 ± 1.7 years old were selected with complete permanent dentition. Three different impressions were taken from the maxillae of the patients: conventional impression using silicone rubber impression material, conventional impression using alginate impression material, and optical impression using an intraoral scanner. The impressions' digital data were analyzed by the GOM Inspect (Version 2018, Braunschweig, Germany), a 3D analysis software. The Root Mean Square (RMS) values of the total ruga region were evaluated in this software. The data were statistically analyzed using the Jamovi program. The Kruskal-Wallis test and Mann-Whitney U test were performed due to the non-normal distribution of the data.

RESULTS

There is no statistically significant difference between the comparison points of the right and left rugae's medial and lateral points and total rugae regions' RMS values. Although there was no statistically significant difference, the total RMS values of alginate and digital scan measurements showed closer results than the RMS values of silicone and digital scan measurements.

CONCLUSION

The study found that there was no statistically significant difference in the total RMS values of the ruga region between traditional and digital impression methods.

CLINICAL RELEVANCE

The treatment period in orthodontics is long. Different impression materials and methods can be used for diagnostic, mid-treatment, and final impressions. For superimpositions and treatment and post-treatment palatal ruga evaluations, traditional and digital impression methods are clinically acceptable and can be used as alternatives to each other.

Comparative 3D study of dental arches in children with microcephaly associated with congenital Zika syndrome, orofacial cleft, and without craniofacial anomalies

INTRODUCTION

The dentist participates in the treatment protocol for craniofacial anomalies in individuals from the first months of life.

OBJECTIVE

to compare in a retrospective cohort study the morphometry of the edentulous palate of children microcephaly associated with congenital Zika syndrome (CZS), unilateral complete cleft lip and alveolus (UCL), and without craniofacial anomalies.

METHODS

Forty-five digitized dental molds composed the sample divided into three groups: CZS; UCL; and without craniofacial anomalies (control group). The following measurements were evaluated: intercanine and intertuberosity distances; dental arch length, area, volume, and mismatch superimposition. Parametric and non-parametric tests were applied (α = 5%).

RESULTS

CZS group showed the smallest means of intercanine distance and area than those of the other groups (p = .001 and p = .010, respectively). The dental arch length was greater in the CZS group than in the control group (p = .020). The evaluation of the mismatch superimposition showed that the CZS group had the lowest means of maximum distance and root mean square than that of the UCL group (p = .025 and p = .005, respectively).

CONCLUSION

CZS participants tended to palatal narrowing, while UCL individuals had parameters similar to those of the control group, despite the alveolus defect.

Reproducibility of the digital palate in forensic investigations, a two-year retrospective cohort study of twins

OBJECTIVES

The palatal scans of the same individuals were compared after two years to assess forensic reproducibility. The effect of orthodontic treatment, the comparison area and the digitization approach were investigated.

METHODS

The palate was scanned in 20 pairs of monozygotic twins by an intraoral scanner (IOS) three times to assess repeatability. They were rescanned two years later by two different IOSs. An elastic impression and a plaster model were also made and scanned by a laboratory scanner (indirect digitization). Mean absolute distance between scans was compared after best-fit alignment. Scans from the two sessions were compared to evaluate the combined effect of aging, orthodontic treatment and different digitization methods (forensic reproducibility). Additionally, the scans of different digitization methods from the second session were compared (technical reproducibility). The between-siblings difference was compared in the two sessions to evaluate the effect of aging on palatal morphology.

RESULTS

The anterior palatal area showed significantly better repeatability and forensic reproducibility than the whole palate (p<0.001), but orthodontic treatment had no effect. Indirect digitization produced lower forensic and technical reproducibility than IOSs. For IOSs, repeatability (22 µm) was significantly (p<0.001) better than either forensic (75-77 µm) or technical reproducibility (37 µm). No significant changes were observed from the first to the second session in the between-sibling comparison. The closest between-sibling value (239 µm) considerably exceeded the highest forensic reproducibility value (141 µm).

CONCLUSIONS

Reproducibility is acceptable between the different IOSs, even two years apart, but is poor between IOS and indirect digitization. The anterior palate is relatively stable in young adults.

CLINICAL SIGNIFICANCE

Intraoral scanning of the anterior palatal area has superior reproducibility, regardless of the IOS brand. Therefore, the IOS method could be suitable for identifying humans through anterior palatal morphology. However, the digitization of elastic impressions or plaster models had low reproducibility, preventing their application for forensic purposes.

3D intraoral scan and diagnostic plaster model under General Data Protection Regulation - Legal protection

No legal subsumption of dental impressions, plaster models and intraoral scanning has been attempted yet. It should be examined to what extent the General Data Protection Regulation (GDPR) applies to them. The aim of this study is to legally classify 3D intraoral scans and plaster models prepared on the basis of alginate impressions within the context of personal data safety and determination of legal protection applicable to their use. The authors set the deliberations concerning legal protection of plaster models and 3D intraoral scans in the light of recently published articles regarding palatal rugae pattern stability, thus enabling accurate personal identification regardless of age or dental treatment. The deliberations concerning legal protection will be based on the analysis of the international legal acts, in particular GDPR. The intraoral scan constitutes biometric data, because it is information about a natural person - a patient is identifiable on the basis of elements defining physical identity. The plaster model itself does not constitute personal data. However, both of them constitutes medical documentation. The biometric data must be processed in a manner compliant with the GDPR provisions. The GDPR shapes only aims which should be attained. When creating a data safety system, ISO or NIST standards may help to ensure the proper level of protection against possible liability resulting from breaches in the scope of personal data processing.

Characteristic changes of the palatal rugae following orthodontic treatment

Background

Because of the individuality of the palatal rugae, they are applicable for human identification purposes the same as the fingerprints. Therefore, it is important to assess the effect of different factors on rugae characteristics. We assessed the characteristic changes of the palatal rugae following extraction and expansion during orthodontic treatments. Before and after orthodontic treatment dental casts of 30 patients were scanned by 3Shape Trios 3D intraoral scanner, and superimposed in Geomagic X 2018 software. Displacement of 13 reference points was analyzed in three dimensions. The length of the palatal rugae was also measured. SPSS version 22.0 was applied for data analysis, using independent t test, sample t test, and chi-square test.

Results

The alterations in the mean palatal rugae length were significant in the first right and third right ridges after extraction, and right and left second ridges after expansion treatment (P < 0.05). Changes in coordinates in the X, Y, and Z axes were significant at 8 points on the rugae after extraction, and 5 points after expansion treatment (P < 0.05). The changes in the sum of means of displacements were significant at all 13 points after extraction and expansion treatments (P < 0.05).

Conclusions

The palatal rugae do not remain stable during expansion and extraction orthodontic treatments. Some changes occurred in length, and the most medial and most lateral points on each ridge were displaced. The length of the incisive papilla did not change during treatment; thus, it can serve as a stable landmark. If we consider palatal rugae as an individual landmark, we can refer the patients after orthodontic treatment for scanning of their palatal rugae to document their post treatment pattern; but it should be noted that treatment relapse may change it again.

Is Palatal Rugae Pattern a Reliable Tool for Personal Identification following Orthodontic Treatment? A Systematic Review and Meta-Analysis

Background: To qualitatively and quantitatively review the reliability of palatal rugae as a tool for personal identification following orthodontic treatment. Methods: Cross-sectional retrospective studies assessing the accuracy of matching palatal rugae pattern pre- and post-orthodontic treatment were identified from PubMed and SCOPUS databases. The title and abstract of the articles identified in the search were screened for potential duplicates and relevancy to the topic of interest. The full text of the articles selected in the screening was analyzed using the inclusion and exclusion criteria. Quantitative analysis of the studies representing coherent data in terms of age and treatment choice was performed using RevMan software. Results: Out of 64 screened articles, only 18 articles fulfilled the eligibility criteria and were included in the systematic review. Out of these 18 articles, only 3 studies had data compatible with the quantitative analysis. Significant changes were noted in lateral first rugae in transverse bilateral direction (p = 0.02) and between second and third lateral rugae of the left side in the anteroposterior direction (p = 0.04). Despite the dimensional changes, observers in most studies were able to accurately (>90%) match the palatal rugae pre- and post-orthodontic treatment through visual observation. Conclusion: The accuracy of the visual matching, despite the significant dimensional changes, indicates that morphology could have potentially been the major matching factor. Thus, a combination of dimensional and morphological evaluation of the palatal rugae could potentially increase the accuracy of personal identification.

The effect of piezocision vs no piezocision on maxillary extraction space closure: A split-mouth, randomized controlled clinical trial

INTRODUCTION

The aim of this 2-arm-parallel, split-mouth trial was to investigate the effects of piezocision compared with no piezocision on maxillary canine distalization and to evaluate patient perceptions on the surgical procedure.

METHODS

Twenty-two participants requiring extractions of maxillary first premolars were recruited from the Department of Orthodontics (Sydney Dental Hospital) waiting list. After leveling and alignment, a minimum of 3 mm space was required for canine retraction. Piezocision cuts distal to the canines were 4 mm long and 3 mm deep into the buccal cortical plate. The canine retraction was initiated on both sides immediately after surgery, with coil springs delivering 150 g of force per side. Random assignment of piezocision or control intervention on the patient's right side was performed (www.randomisation.com) for the random number generation, and allocation concealment was accomplished with opaque, sealed envelopes. Patients were assessed every 6 weeks for coil activation and alginate impressions over 18 weeks. The primary outcome was the amount of tooth movement in mm. Secondary outcomes were canine rotation, anchorage loss measured on scanned dental models, and patient pain levels and perception on piezocision using visual analog scale questionnaires. Blinding was feasible for the dental model measurements.

RESULTS

Twenty patients completed the trial. The treatment × time interaction showed no statistically or clinically significant differences in maxillary extraction space closure (b = -0.02; 95% confidence interval [CI], -0.29 to 0.25; P = 0.89) canine rotation (b = -1.45; 95% CI, -4 to 1.09; P = 0.26) and anchorage loss (b = -0.02; 95% CI, -0.38 to 0.34; P = 0.92). All patients except for one had minimal pain associated with the piezocision surgery but found the procedure tolerable and would recommend it. No harm occurred during the trial.

CONCLUSIONS

Piezocision-assisted maxillary canine distalization was similar to distalization with conventional orthodontics with patients tolerating the procedure.

Innovative method to assess maxillary arch morphology in oral cleft: 3d-3d superimposition technique

This study aimed to analyze the maxillary growth and development of children with oral clefts using the innovative method of 3D-3D superimposition technique. Children with unilateral complete cleft lip (UCL) and unilateral cleft lip and palate (UCLP) participated in the study. The impressions of the dental arches were executed 1 day before and 1 year after lip repair surgery. A 3D laser scanner digitized the dental models and the stereophotogrammetry system software analyzed the 3D-3D superimpositions in two groups of matches (same child, UCL and UCLP) and one group of mismatches (different individuals). The differences were evaluated by Root Mean Square (RMS) and expressed in millimeters (mm). Kruskal-Wallis test followed by post-hoc Dunn test and Mann-Whitney test were assessed to compare the groups (α=5%). RMS was 1.34 mm (± 0.37) in UCL group, 1.41 mm (± 0.32) in UCLP group, and 3.38 mm (± 1.28) in mismatches group. RMS was significantly greater in mismatches than in matches groups (p<0.0001). No statistically significant differences occurred between genders. The 3D-3D superimposition technique showed the maxillary development after lip repair surgery in the anterior region of the palate. Thus, it is suggested that the cleft amplitude and the palatal segments proportion influenced the morphological heterogeneity and, consequently, the development and maxillary growth of children with orofacial cleft.

3D Scanners in Orthodontics-Current Knowledge and Future Perspectives-A Systematic Review

Background: Nowadays the use of intraoral scanners has become a routine practice in orthodontics. It allows the introduction of many treatment innovations. One should consider to what extent intraoral scanners have influenced the everyday orthodontic practice and in what direction should the further research in this field be conducted. This study is aimed to systematically review and synthesize available controlled trials investigating the accuracy and efficacy of intraoral scanners for orthodontic purpose to provide clinically useful information and to direct further research in this field. Methods: A literature search of free text and MeSH terms was performed by using MedLine (PubMed), Scopus, Web of Science and Embase. The search engines were used to find studies on application of intraoral scanners in orthodontics (from 1950 to 30 September 2020). The following keywords were used: “intraoral scanners AND efficiency AND accuracy AND orthodontics”. Results: The number of potential identified articles was 71, including 61 from PubMed, two from Scopus, three from Web of Science and five from Embase. After removal of duplicates, 67 full-text articles were analyzed for inclusion criteria, 16 of them were selected and finally included in the qualitative synthesis. Conclusions: There are plenty of data available on accuracy and efficacy of different scanners. Scanners of the same generation from different manufacturers have almost identical accuracy. This is the reason why future similar research will not introduce much to the orthodontics. The challenge for the coming years is to find new applications of digital impressions in the orthodontic practice.

Application of intraoral scanner to identify monozygotic twins

BACKGROUND

DNA base identification is a proper and high specificity method. However, identification could be challenged in a situation where there is no database or the DNA sequence is almost identical, as in the case of monozygotic (MZ) twins. The aim of this study was to introduce a novel forensic method for distinguishing between almost identical MZ twins by means of an intraoral scanner using the 3D digital pattern of the human palate.

METHODS

The palatal area of 64 MZ twins and 33 same-sex dizygotic (DZ) twins (DZSS) and seven opposite-sex dizygotic twins (DZOS) were scanned three times with an intraoral scanner. From the scanned data, an STL file was created and exported into the GOM Inspect® inspection software. All scans within a twin pair were superimposed on each other. The average deviation between scans of the same subject (intra-subject deviation, ISD) and between scans of the two siblings within a twin pair (intra-twin deviation, ITD) was measured. One-sided tolerance interval covering 99% of the population with 99% confidence was calculated for the ISD (upper limit) and the ITD (lower limit).

RESULTS

The mean ISD of the palatal scan was 35.3 μm ± 0.78 μm. The calculated upper tolerance limit was 95 μm. The mean ITD of MZ twins (406 μm ± 15 μm) was significantly (p < 0.001) higher than the ISD, and it was significantly lower than the ITD of DZSS twins (594 μm ± 53 μm, p < 0.01) and the ITD of DZOS twins (853 μm ± 202 μm, p < 0.05).

CONCLUSION

The reproducibility of palatal intraoral scans proved to be excellent. The morphology of the palate shows differences between members of MZ twins despite their almost identical DNA, indicating that this method could be useful in forensic odontology.

Assessment of the Stability of the Palatal Rugae in a 3D-3D Superimposition Technique Following Slow Maxillary Expansion (SME)

The Palatal Rugae are considered a useful human identification marker for both orthodontists and forensic personnel. The principal aim of the present study was to evaluate the stability of palatal rugae with a 3D-3D superimposition procedure following Slow Maxillary Expansion (SME), in order to assess whether they kept their uniqueness and validity for human identification, even after a specific dental treatment. For this purpose, a sample of 27 digital dental models - belonging to growing patients (13 males and 14 females), aged between 8.5 and 15 years, who underwent SME therapy - was retrospectively studied and compared with a control group of 27 untreated subjects - (13 males and 14 females). Digital dental models were obtained pre-treatment and at device removal; both were processed by means of an intraoral scanner. A superimposition procedure was thus performed to reach the minimum point-to-point distance between two models of palatal rugae. Intra- and inter-observer differences were statistically analyzed by paired Wilcoxon test and Intra-class Correlation coefficient (ICC), showing values larger than 0.93. There was no difference in Root-Mean-Square (RMS) values between untreated control subjects and subjects treated with Leaf Expander (p = 0.062). A RMS value of 0.43 was the threshold to distinguish the pooled group (“Untreated” and “Leaf”) from any mismatch. According to the obtained results, this study failed to reject the null hypothesis and presented no differences between the RMS values of the Test group and the RMS values of the untreated control group. This work highlighted the usefulness of 3D superimposition procedure for purposes of human identification, in subjects undergoing dental treatment. However, keeping in sight the forensic use of this technique as a helpful probation element in court, further studies should be performed to confirm these findings.

[Dental forensic identification of the user of a complete removable denture]

The identification of personality based on dental status of the remains of presumably Evgenii Sergeevich Botkin physician-in-ordinary of the family of the Nicholas II. We examined the scull #2 (presumably attributed to Tsar's family physician-in-ordinary E.S. Botkin) fragments of edentulous maxilla and mandible in particular, 2 stereolithographic resin models of full dentures belonged to Botkin E.S. We utilized the following examination methods: Visual evaluation (odontoscopy, morphoscopy) Anthropometric analysis (odontometric and morphometric) 3D digital scanning of the studied objects Manual and digital superimposition of their contours Digital scanning was performed with the use of optical scanner device Neway Scanway 2017 12 REV C and also with NobelProcera 2G scanner. Outline superimposition was performed with Nobel Procera Software v3.1, Exocad 2.2, Romexis ver. 4.5.1. CBCT of the objects was acquired on Planmeca Promax 3D Mid. Results of the current investigation prove the congruency and conformity of the dentures to the bony remains of the jaws and with high probability confirm the assumption of the appurtenance of the examined copy of the denture to the dentoalveolar system of the described scull #2 and the object itself - identified as the scull of the physician-in-ordinary to the last Russian Royal family Evgenii Sergeevich Botkin.

Forensic odontology in DVI: current practice and recent advances

Forensic odontology frequently plays a significant role in identification of the victims of multi-fatality disasters, but not in all. It depends on adequate dental remains surviving the disaster and on the availability of dental records to be successful. This paper describes current practice in the techniques of identification in forensic odontology and outlines recent advances that are moving into the mainstream.Key PointsForensic odontology plays a key role in mass disaster victim identification (DVI) when good-quality antemortem (AM) dental records are available.Images including radiographs, computerized tomography (CT) data and three-dimensional (3D) scan data are considered more reliable AM records than written dental charts and odontograms.Interpretation, transcription and comparison of dental datasets are complex processes that should be undertaken only by trained dental professionals.The future of forensic odontology DVI techniques is likely to include the use of 3D datasets for comparison.

Deviations in palatal region between indirect and direct digital models: an in vivo study

Background

Studies focusing on accuracy of intraoral digital models in the palatal region are scarce. The present study aimed to investigate the influence of different scanning sequences on palatal trueness and to assess deviation and distribution character of trueness in palate.

Methods

Overall, 35 participants accepted three types of procedures to acquire upper digital models. Indirect models digitalised from plaster models were considered as the reference. Two direct digital models were acquired using TRIOS 3 POD intraoral scanners, namely Groups Tr1 and Tr2, wherein intraoral scanning differed in terms of palatal scanning sequences. Based on a modified dental-level superimposition method, 3D measurements of trueness in palate and palatal vault region (PVR) for palatal stable regional superimposition in Groups Tr1 and Tr2, respectively, were performed. Absolute deviations were measured for trueness, while signed deviations were analysed for shape distortion. Colour-coded maps were used for quantitative analysis of deviation distribution pattern. Paired t test was used to analyse differences in palatal trueness between different scanning sequences. One-way repeated-measures analysis of variance and Bonferroni test were used to compare trueness measurements among different superimposition methods. Intraclass correlation coefficient (ICC) was used to verify reproducibility of the proposed method.

Results

Palatal trueness in Group Tr1 (118.59 ± 37.67 μm) was slightly less accurate than that (108.25 ± 33.83 μm) in Group Tr2 (p = 0.012 < 0.05). Trueness of PVR in Groups Tr1 (127.35 ± 54.11 μm) and Tr2 (118.17 ± 49.52 μm) did not differ significantly (p = 0.149). Moreover, no significant difference was noted in distortion of the palatal region and PVR in Groups Tr1 and Tr2 (p = 0.582 and 0.615, respectively). A similar pattern of palatal trueness was noted in a majority of participants (22/35). For 3D palatal trueness measurement, there were different applications for different superimposition methods. ICC for the proposed method was > 0.90.

Conclusions

Scanning sequences can affect palatal trueness. Palatal scanning should be initiated at the palatal side of the posterior teeth where the initial scan begins. For 3D PVR superimposition, distal boundary of the selected region should be adjusted mesially whilst referring to intraoral digital models.

Trial registration

The trial has been registered (registration No: R000039467, Trial ID: UMIN000034617, date of registration: 2018/10/24‘retrospectively registered’).

Reliability of palatal rugoscopy for sexual dimorphism in forensic dentistry: A systematic literature review and meta-analysis

OBJECTIVE

This study aimed to assess the validity of palatal rugoscopy for sexual dimorphism in the casework routine of forensic dentistry.

DESIGN

A systematic literature reviews was established following the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) and Cochrane guidelines. Six electronic databases were searched as the primary source of information. "Grey literature" was included to avoid selection and publication bias. As a secondary source of information, the reference lists of the eligible studies were also consulted to increase the search spectrum. Methodological quality and risk of bias were assessed with Joanna Briggs Institute Critical Appraisal Tools for Systematic Reviews. Statistic tests, namely the meta-analysis of diagnostic accuracy, Cochran Q test, and I2 test, were performed to verify the heterogeneity between the eligible studies.

RESULTS

The systematic search resulted in 263 studies, out of each 8 fulfilled the inclusion criteria. An additional eligible article was included after the search in reference lists. From the 9 studies that underwent qualitative data extraction, six were selected for quantitative analysis. The meta-analysis of grouped sex estimates showed sensitivity and specificity rates of 89% and 83%, respectively. The Area Under the Curve reached 0.93. High heterogeneity and important methodological limitations were detected among the studies.

CONCLUSION

Palatal rugoscopy seems to have discriminant power for sexual dimorphism. However, the limitations found specifically in each study and the strong heterogeneity across studies suggest that palatal rugoscopy lacks evidence-based confirmation for reliable application as a sole tool for sexual dimorphism in practice.

Application of 3D models of palatal rugae to personal identification: hints at identification from 3D-3D superimposition techniques

Palatal rugae are known in literature as individualizing anatomical structures with a strong potential for personal identification. However, a 3D assessment of their uniqueness has not yet been performed. The present study aims at verifying the uniqueness of 3D models of the palate. Twenty-six subjects were recruited among the orthodontic patients of a private dental office; from every patient, at least two dental casts were taken in different time periods, for a total of 62 casts. Dental casts were digitized by a 3D laser scanner (iSeries, Dental Wings©, Montreal, Canada). The palatal area was identified, and a series of 250 superimpositions was then performed automatically through VAM©software in order to reach the minimum point-to point distance between two models. In 36 matches the models belonged to the same individual, whereas in 214 mismatches they came from different subjects. The RMS (root mean square) of point-to-point distances was then calculated by 3D software. Possible statistically significant differences were assessed through Mann-Whitney test (p < 0.05). Results showed a statistically significant difference in RMS mean point-to-point distance between matches (mean 0.26 mm; SD 0.12) and mismatches (mean 1.30; SD 0.44) (p < 0.0001).All matches reached an RMS value below 0.50 mm. This study first provided an assessment of uniqueness of palatal rugae, based on their anatomical 3D conformations, with consequent applications to personal identification.

Identifying missing people: the contribution of forensic dentistry and DNA

Abstract Introduction Human identification is considered one of the major steps concerning missing people. The Forensic Anthropology Sector of Legal Medical Institutes identifies corpses. Forensic dentistry and DNA tests stand out among the existing standard tests. Objective This article aimed to evaluate human identification effectiveness through forensic dental examination performed in the forensic anthropology sector in a Forensic Medical Institute, comparing them with DNA analyses. Methodology This is a cross-sectional study using secondary data available in the department´s database, from 2008 to 2014, concerning identification procedures using forensic dentistry and DNA techniques. Result The analysis of the examinations eligible to this study (241) showed that DNA analysis was the method used for identification in 79.3% of the cases and forensic dental examinations were used in 20.7% of the cases. As for the type of biological material used during these examinations, unidentified corpses corresponded to 131 cases (53.9%), skeleton structures corresponded to 109 cases (44.9%) and there were 3 cases of body segments (1.2%). When analyzing the time spent to complete the tests, dental examinations were faster than DNA tests. The time spent for forensic dental examination does not depend on the type of dental documentation evaluated. Conclusion The analysis of the results in this study showed that human identification through forensic dentistry is effective, rapid and less costly, contributing to greater agility in solving issues related to locating missing people.

Assessment of different techniques for 3D superimposition of serial digital maxillary dental casts on palatal structures

Serial 3-dimensional dental model superimposition provides a risk-free, detailed evaluation of morphological alterations on a patient’s mouth. Here, we evaluated accuracy and precision of five palatal areas, used for superimposition of maxillary 3D digital dental casts. Sixteen pre- and post-orthodontic treatment dental casts of growing patients (median time lapse: 15.1 months) were superimposed on each palatal area using the iterative closest point algorithm. Area A (medial 2/3 of the third rugae and a small area dorsal to them) was considered the gold standard, due to high anatomical stability. Areas B, C, and D added a distal extension along the midpalatal raphe, an anterior extension to the second rugae, and the remaining palatal surface, respectively. Area E was similar to A, located more posteriorly. Non parametric multivariate models showed minimal or no effect on accuracy and precision by operator, time point, or software settings. However, the choice of superimposition area resulted in statistically significant differences in accuracy and clinically significant differences in detected tooth movement (95% limits of agreement exceeding 1 mm and 3°). Superimposition on area A provided accurate, reproducible, and precise results. Outcomes were comparable for area B, but deteriorated when alternative areas were used.

Dentoalveolar and arch dimension changes in patients treated with miniplate-anchored maxillary protraction

INTRODUCTION

The aim of this study was to evaluate dentoalveolar and arch dimension changes in 2 miniplate-anchored maxillary protraction protocols in relation to an untreated control group using 3-dimensional digital models.

METHODS

Thirty growing Class III subjects with maxillary deficiency in the late mixed or early permanent dentition phase were randomly divided into 3 groups. In group 1 (n = 10), patients were treated with skeletally anchored facemasks anchored with miniplates placed at the zygomatic buttress. In group 2 (n = 10), patients were treated with Class III elastics extending from infrazygomatic miniplates in the maxilla to symphyseal miniplates in the mandible. Group 3 (n = 10) was an untreated control group. The decision to discontinue orthopedic treatment was made when the patients had 3 to 4 mm of positive anterior overjet. Pretreatment, posttreatment, and observation 3-dimensional digital models were analyzed, superimposed, 3 dimensionally mapped, and sectioned.

RESULTS

In this study, there were no significant changes in maxillary arch depth and maxillary or mandibular intermolar width before and after maxillary protraction or after the observation period in the control group. The mandibular arch depth decreased by a small but statistically significant amount only in groups 1 and 3. Superimposition of the pretreatment and posttreatment or observation maxillary 3-dimensional digital models showed minimal clinically significant dentoalveolar changes.

CONCLUSIONS

Miniplate-anchored maxillary protraction protocols can accomplish maxillary advancement by eliminating movements of teeth and dentoalveolar changes. No spontaneous improvement in transverse deficiency was detected after correction of the anteroposterior deficiency at this age. Consequently, patients with transverse maxillary deficiency should have rapid maxillary expansion before or during the miniplate-anchored protraction period to improve the transverse deficiency.

3D Evaluation of Palatal Rugae in Identical Twins

The study of identical twins can point out potential limitations in biometrics and forensic odontology. This case report presents three-dimensional (3D) palatal rugae analysis in monozygotic twins utilizing digital models obtained directly by scanning the maxillary dental arch with the iTero® intraoral digital scanner. The results show that the rugae patterns contain related but not identical features between the pair of identical twins. Dental study models taken on a regular basis for diagnosis and treatment planning in dentistry include the palatal rugae, which could be valuable to forensics in identical twin identification cases.

Evaluation of palatal rugae pattern in different sagittal skeletal relationship adolescent subjects

The purpose of this study was to evaluate the morphological structure of palatal rugae in Turkish orthodontic subjects with different sagittal skeletal malocclusions. Orthodontic dental casts of 105 patients (Class I [23 females, 12 males]; 35, Class II [18 females, 17 males]; and 35, Class III [14 females, 21 males] 10-22 years old) were analyzed for rugae patterns. Palatal rugae pattern and number, direction of rugae alignment, shape of incisive papilla were analyzed. Modified Thomas and Kotze classification was performed to analyze palatal rugae characteristics. The data were analyzed using the Kruskal-Wallis test. Wavy and curved types were the most common types of rugae pattern in all groups (Class I, Class II, Class III). As regards to the number of primary and secondary rugae on the left and right sides, there was no statistically significant difference among subjects with different skeletal malocclusions. Droplet-shaped incisive papilla was the most common form of incisive papillae among different skeletal malocclusion groups. The most common palatal rugae were direction type arranged in the horizontal direction. All rugae patterns were unique for each individual. The use of antemortem or postmortem palatal rugae records may facilitate identification of the suspects in forensic investigations by enabling facial reconstruction through skeletal malocclusions.

3D evaluation of palatal rugae for human identification using digital study models

Background:

While there is literature suggesting that the palatal rugae could be used for human identification, most of these studies use two-dimensional (2D) approach.

Aim:

The aims of this study were to evaluate palatal ruga patterns using three-dimensional (3D) digital models; compare the most clinically relevant digital model conversion techniques for identification of the palatal rugae; develop a protocol for overlay registration; determine changes in palatal ruga individual patterns through time; and investigate the efficiency and accuracy of 3D matching processes between different individuals’ patterns.

Material and Methods:

Five cross sections in the anteroposterior dimension and four cross sections in the transverse dimension were computed which generated 18 2D variables. In addition, 13 3D variables were defined: The posterior point of incisive papilla (IP), and the most medial and lateral end points of the palatal rugae (R1MR, R1ML, R1LR, R1LL, R2MR, R2ML, R2LR, R2LL, R3MR, R3ML, R3LR, and R3LL). The deviation magnitude for each variable was statistically analyzed in this study. Five different data sets with the same 31 landmarks were evaluated in this study.

Results:

The results demonstrated that 2D images and linear measurements in the anteroposterior and transverse dimensions were not sufficient for comparing different digital model conversion techniques using the palatal rugae. 3D digital models proved to be a highly effective tool in evaluating different palatal ruga patterns. The 3D landmarks showed no statistically significant mean differences over time or as a result of orthodontic treatment. No statistically significant mean differences were found between different digital model conversion techniques, that is, between OrthoCAD™ and Ortho Insight 3D™, and between Ortho Insight 3D™ and the iTero^® scans, when using 12 3D palatal rugae landmarks for comparison.

Conclusion:

Although 12 palatal 3D landmarks could be used for human identification, certain landmarks were especially important in the matching process and were arranged by strength and importance. Proposed values for 3D palatal landmarks were introduced that could be useful in biometrics and forensic odontology for the verification of human identity.