Replication of Known Dental Characteristics in Porcine Skin: Emerging Technologies for the Imaging Specialist

This study demonstrates that it is sometimes possible to replicate patterns of human teeth in pig skin and determine scientifically that a given injury pattern (bite mark) correlates with the dentitions of a very small proportion of a population dataset, e.g., 5 percent or even 1 percent. The authors recommend building on the template of this research with a sufficiently large database of samples that reflects the diverse world population. They also envision the development of a sophisticated imaging software application that enables forensic examiners to insert parameters for measurement, as well as additional methods of applying force to produce bite marks for research. The authors further advise that this project is applied science for injury pattern analysis and is only foundational research that should not be cited in testimony and judicial procedures. It supplements but does not contradict current guidelines of the American Board of Forensic Odontology regarding bite mark analysis and comparisons. A much larger population database must be developed. The project’s methodology is described in detail, accompanied by 11 tables and 41 figures

A tooth preparation technique in fixed prosthodontics for students and neophyte dentists

The aim of this study was to evaluate a novel technique of tooth preparation in fixed prosthodontics suitable for dental students and neophyte dentists.MATERIALS AND METHODS: Twenty-four dental students of the sixth-year class were recruited to verify the predicibility of this technique. Each student prepared two mandibular second premolars on a typodont for a dental crown with a 90° shoulder finishing line. One tooth was prepared using standard procedures taught in the prosthodontic dental course; the other tooth was prepared with the new technique. Three Professors of Prosthodontics of the same University evaluated the result on the basis of 10 criteria. RESULTS: A statistically significant difference between the two techniques was found in 8 out of 10 criteria. The new technique showed higher values (p<0.05) in 7 criteria, while the conventional technique had better results in just 1 criterion. Moreover, the total sum of values was higher for the new technique (total 41.2±3.98, p<0.05) compared to the conventional technique (total 38.12±5.18, p<0.05). CONCLUSIONS: This study showed that the results were less dependent on manual abilities and personal experience with the novel technique. It could helps dental students and neophyte dentists in their learning curve

Evaluation of Die Trim Morphology Made by CAD-CAM Technology

Statement of problem The die contour can affect the emergence profile of prosthetic restorations. However, little information is available regarding the congruency between a stereolithographic (SLA) die and its corresponding natural tooth. Purpose The purpose of this vitro study was to evaluate the shapes of SLA die in comparison with the subgingival contour of a prepared tooth to be restored with a ceramic crown. Material and methods Twenty extracted human teeth, 10 incisors, and 10 molars, were disinfected and mounted in a typodont model. The teeth were prepared for a ceramic restoration. Definitive impressions were made using an intraoral scanner from which 20 SLA casts with removable dies were fabricated. The removable dies and corresponding human teeth were digitized using a 3-dimensional desktop scanner and evaluated with computer-aided design software. The subgingival morphology with regard to angle, length, and volume at the buccolingual and mesiodistal surfaces and at zones A, B, C, and D were compared. Data were first analyzed with repeated measures analysis of variance (ANOVA), using locations (buccolingual and mesiodistal), zones (A, B, C, and D), and model type (SLA and Natural) as within-subject factors and tooth type (molar and incisor) as the between-subject factor. Post hoc analyses were performed to investigate the difference between natural teeth and corresponding SLA models, depending upon the interaction effect from the repeated measures ANOVA (α=.05). Results For angle analysis, the incisor group demonstrated a significant difference between the natural tooth and SLA die on the buccolingual surfaces (PPPPPP Conclusions For the comparison of angles, SLA dies did not replicate the subgingival contour of natural teeth on the buccolingual surfaces of the incisal groups. For the comparison of length and volume, SLA dies were more concave and did not replicate the subgingival contour of natural teeth in the incisal and molar groups

Comparison of The Kois Dento-Facial Analyzer System with an Earbow for Mounting a Maxillary Cast

Statement of problem: The Kois Dento-Facial Analyzer System (KDFA) is used by clinicians to mount maxillary casts and evaluate and treat patients. Limited information is available for understanding whether the KDFA should be considered as an alternative to an earbow. Purpose: The purpose of this study was to evaluate maxillary casts mounted using the KDFA with casts mounted using Panadent\u27s Pana-Mount Facebow (PMF). Both articulation methods were compared against a lateral cephalometric radiograph. Material and methods: Fifteen dried human skulls were used. Lateral cephalometric radiographs and 2 maxillary impressions were made of each skull. One cast from each skull was mounted on an articulator by means of the KDFA and the other by using the PMF. A standardized photograph of each articulation was made, and the distance from the articular center to the incisal edge position and the occlusal plane angle were measured. The distance from condylar center to the incisal edge and the occlusal plane angle were measured from cephalometric radiographs. Finally, the 3-dimensional position of each articulation was determined with a Panadent CPI-III. A randomized complete block design analysis of variance (RCBD) and post hoc tests (Tukey-Kramer HSD) (α=.05) were used to evaluate the occlusal plane angle and axis-central incisor distance. A paired 2-sample t test for means (α=.05) was used to compare the X, Y, and Z distance at the right and left condyle. Results: The KDFA and PMF mounted the maxillary cast in a position that was not statistically different from the skull when comparing the occlusal plane angle (P=.165). Both the KDFA and the PMF located the maxillary central incisor edge position in a significantly different position compared with the skull (P=.001) but were not significantly different from each other. The 3-dimensional location of the maxillary casts varied at the condyles by approximately 9 to 10.3 mm. Conclusion: The KDFA mounted the maxillary cast in a position that was not statistically different from the PMF when comparing the incisal edge position and the occlusal plane angle. Both the KDFA and the PMF located the maxillary incisal edge position in a significantly different position compared with the anatomic position on dried human skulls

Reproducibility and speed of landmarking process in cephalometric analysis using two input devices: mouse-driven cursor versus pen

To define if the new portable appliances, like smartphone, iPad, small laptop and tablet can be used in cephalometric tracing without dropping out the validity of any measurement. METHODS:We investigated and compared the reproducibility and the speed of landmarks identification process on lateral X-rays in two input devices: a mouse-driven cursor and a pen used as input means in mobile devices. One expert located 22 landmarks on 15 lateral X-rays in a repeated measure design two times, at time T1 and T2, after at least one month. The Intraclass Correlation coefficient was used to evaluate the reproducibility for each landmark tracing and the agreement between the value derived from both input devices. Also, the mean errors in measurements, the standard deviation and the Friedman Test significans (P < 0.05) between both input were statistically evaluated. RESULTS:All landmarks had a high agreement and the Friedman Test indicated statistically significant differences (P<0.05) for the identification of Na, Po, Pt, PNS, Ba, Pg, Gn, UIE, UIA, APOcc and PPOcc landmarks. CONCLUSIONS:Even if the mouse input give higher agreement for landmark tracing the differences are really minimal and they can be ignored in private practice. We suggest the adequacy of pen input in clinical setting

Is There a Relationship between the Axis Orbital Plane and the Inclination of the Maxillary Central Incisors: An in vivo Study

The purpose of this investigation was to evaluate if a relationship exists between the maxillary central incisors and the axis orbital plane determined by the SAM® anatomic face-bow. The study evaluated the angle formed by the incisal half (IA) and the cervical half (CA) of the tooth to the axis orbital plane and if there is a difference in angles with respect to gender. A relationship was determined to exist if the mean CA and IA angles where within 1 Standard Deviation (SD) of ±5° for each angle. An anatomical face-bow (SAM Präzisionstechnik , Munchen) was used to locate arbitrary transverse mandibular axis on fifteen males and fifteen females. Photos of cast models were taken in the sagittal view of each subject mounted in the SAM III articulator. The JPEG images were imported into an imaging-editing program (Photoshop CS6, Adobe Inc, San Jose CA) where a line was drawn representing the axis orbitale plane. Two more lines were drawn representing the incisal and cervical half of the maxillary central incisors producing the incisal angle (IA) and the cervical angle (CA). A statistical analysis of the CA and IA angles was performed using statistical software (SPSS 19.0; SPSS Inc., Chicago IL). A non-parametric t-test (Mann-Whitney U) was used to indicate significant differences between the genders (p<0.05). The mean cervical angles (CA) for males was 104.2°± 4.9 and for females 96.8°± 4.6. The mean incisal angles (IA) for males was 75.8°± 7.6 and for females was 68.2°± 6.6. There is a statistically significant difference (P≤0.001) between genders for both angles tested. The results and data analyzed suggest a relationship between the mean cervical angle (CA) and the axis orbital plane for males (104.2) and females (96.8). There was no relationship shown between the mean incisal angle (IA) and the axis orbital plane for either gender

Permanent Maxillary and Mandibular Incisors

The permanent incisors are the front teeth that erupt between 6 and 8 years of age. They are eight in number, four upper and four lower, two centrals and two laterals. They have sharp biting surfaces designed for shearing and cutting of food materials into small chewable pieces. They are the teeth most visible to the others during eating, smiling and talking, and thus, they have high aesthetic value for the individuals. The unique characteristics, arch position, function, development and chronological age of each tooth will be highlighted. In addition, the different aspects with their geometric outlines, outlines and surface anatomy of these teeth will be described. A brief explanation about the pulp cavity, tooth socket and normal occlusion for each tooth will be included

Porcelain veneers - preparation design: A retrospective review

This paper discusses the preparation of tooth design for porcelain veneers. It follows the literature more than three decades back in the past. From the very beginning, porcelain veneers were placed to no/minimally prepared tooth substance, showing different problems in clinical use. Later, the technique of etching the porcelain and controlling the reduction of tooth structure, presented the great steps forward in porcelain veneers accepting. A special accent concerning the preparative design was placed on variations of incisal edge preparation - the problem, which is still present in current practice. Additionally, the paper emphasizes the extremely demanding protocols in making the porcelain veneers as well as their expanded clinical indications