Dental 3D Research Articles

Evaluation of Chemical Mechanical Polishing-Based Surface Modification on 3D Dental Implants Compared to Alternative Methods

Chemical mechanical polishing (CMP) has been introduced in previous studies as a synergistic technique to modify the surface chemistry and topography of titanium-based implants to control their biocompatibility. In this study, the effectiveness of CMP implementation on titanium-based implant surface modification was compared to machined implants, such as baseline and etching and biphasic calcium phosphate (BCP) particle-based sand blasting treatments, in terms of the surface chemical and mechanical performance. Initially, a lab-scale 3D CMP technique was developed and optimized on commercial dental implant samples. The mechanical competitiveness of the dental implants treated with the selected methods was examined with the Vickers microhardness test as well as pull-out force and removal torque force measurements. Furthermore, the surface structures were quantified through evaluation of the arithmetic mean roughness parameter (Ra). Subsequently, the surface chemistry changes on the treated implants were studied as wettability by contact angle measurement, and surface passivation was evaluated through electrochemical methods. In each evaluation, the CMP treated samples were observed to perform equal or better than the baseline machined implants as well as the current method of choice, the BCP treatment. The ability to control the surface topography and chemistry simultaneously by the use of CMP technique is believed to be the motivation for its adaptation for the modification of implant surfaces in the near future.

Fast 3D reconstruction of dental cast model based on structured light

To quickly obtain accurate 3D data of dental cast model, this paper proposes a 3D reconstruction method for dental cast model based on structured light. This method combines the structured light with the motor turntable to obtain a group of 3D data for the dental cast model from multiple angles, and automatically registers the dental 3D data from multiple angles through the ball calibration of turntable. Compared with the real data of the dental cast model, the maximum error of the 3D reconstruction results in this paper is 0.115 mm. The reconstruction time of this process is about 130 s. The experimental results show that the method has high precision and high scanning speed for the 3D reconstruction of the dental cast model.

Mandibular radiomorphometry using cone beam computed tomography for predicting osteoporosis in postmenopausal women

Purpose: This study evaluated the potential use of the computed tomography indices (CTI) on cone beam CT (CBCT) images for an assessment of the bone mineral density (BMD) in postmenopausal osteoporotic women. Materials and Methods: Ninety postmenopausal women were enrolled as the subjects. The BMD of the lumbar vertebrae, femur and forearm were calculated by dual energy X-ray absorptiometry (DXA) using a DXA scanner. The CBCT images were obtained from the bilateral mental foramen region using a Kodak TM 9500 Cone Beam 3D Dental CT system. The axial, sagittal, and coronal images were reconstructed from the block images using Carestream TM software. The radiomorphometric indices were computed tomography mandibular index superior (CTI(S)), computed tomography mandibular index inferior (CTI(I)), and computed tomography cortical index (CTCI), and computed tomography mental index (CTMI: inferior cortical width). The relationship between the CT measurements and BMDs were assessed and the intra-observer agreement was determined. Results: The results of CBCT indices showed a significant difference among the three studied groups for CTI scores. The mean values of CTMI and CTCI showed higher values in control than in osteopenic and osteoporotic groups and the differences were highly significant (p < 0.001) among the three studied groups. The current study revealed that, mandibular indices on CBCT may help in predicting and detecting osteoporosis.

Job sizing and sequencing in additive manufacturing to control process deterioration

The term Additive Manufacturing (AM) describes a set of novel manufacturing technologies in which successive layers of matter are formed to create an object, e.g., three-dimensional (3D) printing. These technologies have several major advantages that have led to their rapidly increasing involvement in mass production. However, due to their unique properties they are subject to deterioration, which is expressed in the aging of different components followed by random maintenance requirements. Additionally, they are all preemptive-repeat; namely, if a failure occurs during the printing of an object, then its printing will have to recommence from the start as the work is resumed. This article addresses the problem of sequencing an AM process while referring to its relevant properties. It also addresses a more complicated environment in which the work may arrive over time. We adopt a stochastic preemptive-repeat scheduling model, generalize it to incorporate the process age, and develop the formalization of two main measures of a given schedule: the expected completion time, i.e., the time duration required to complete the printing of all jobs, and the total expected flow time, i.e., the expected time a job spends in the system. Our formalization enables the determination of a schedule that minimizes these measures. In particular, we formulate and solve a constrained continuous optimization problem to determine the optimal size of the designed jobs to be printed. This challenge, which relates to the unique flexibility of these technologies, currently hinders the practice of dental 3D printing manufacturing lines.

First 3D Dental Topographic Analysis of the Enamel-Dentine Junction in Non-Primate Euarchontans: Contribution of the Enamel-Dentine Junction to Molar Morphology

Molar morphology plays a key role in the systematics and behavioral interpretation of fossil taxa, so understanding the developmental patterns that shape occlusal morphology in modern taxa is of central importance to informing analysis of the fossil record. The shape of the outer enamel surface (OES) of a tooth is largely the result of the forming and folding of the inner enamel epithelium, which is preserved in fully formed teeth as the enamel-dentine junction (EDJ). Previous research on living primates has shown that the degree of correlation between the EDJ and OES can be used to inform our understanding of developmental patterns because lower correlations imply that later developmental events modify the template provided by the EDJ more extensively. Here, we use three topographic metrics to investigate the degree of correlation between the EDJ and OES across living euarchontans by analyzing treeshrews and dermopterans in addition to primates. We found that all living euarchontans show a high degree of topographical correlation, whereas non-primates, especially basally divergent taxa such as Ptilocercus lowii, show the highest degree of correlation between these two surfaces. Our results indicate, that while it is the earlier stages of dental development that have the most influence on overall crown morphology in euarchontans generally, among primates, anthropoids have a lower degree of correlation, implying a greater emphasis on later phases of dental development. This provides insight relevant to interpreting the evolutionary context of the diversity of dental form observed within Euarchonta.

Beyond the Map: Enamel Distribution Characterized from 3D Dental Topography.

Enamel thickness is highly susceptible to natural selection because thick enamel may prevent tooth failure. Consequently, it has been suggested that primates consuming stress-limited food on a regular basis would have thick-enameled molars in comparison to primates consuming soft food. Furthermore, the spatial distribution of enamel over a single tooth crown is not homogeneous, and thick enamel is expected to be more unevenly distributed in durophagous primates. Still, a proper methodology to quantitatively characterize enamel 3D distribution and test this hypothesis is yet to be developed. Unworn to slightly worn upper second molars belonging to 32 species of anthropoid primates and corresponding to a wide range of diets were digitized using high resolution microcomputed tomography. In addition, their durophagous ability was scored from existing literature. 3D average and relative enamel thickness were computed based on the volumetric reconstruction of the enamel cap. Geometric estimates of their average and relative enamel-dentine distance were also computed using 3D dental topography. Both methods gave different estimations of average and relative enamel thickness. This study also introduces pachymetric profiles, a method inspired from traditional topography to graphically characterize thick enamel distribution. Pachymetric profiles and topographic maps of enamel-dentine distance are combined to assess the evenness of thick enamel distribution. Both pachymetric profiles and topographic maps indicate that thick enamel is not significantly more unevenly distributed in durophagous species, except in Cercopithecidae. In this family, durophagous species such as mangabeys are characterized by an uneven thick enamel and high pachymetric profile slopes at the average enamel thickness, whereas non-durophagous species such as colobine monkeys are not. These results indicate that the distribution of thick enamel follows different patterns across anthropoids. Primates might have developed different durophagous strategies to answer the selective pressure exerted by stress-limited food.

Three-dimensional evaluation of mandibular anterior dental crowding in digital dental casts.

ABSTRACTIntroduction: Digital dental models provide a more accurate and comprehensive assessment of orthodontic cases. Although this technique is quite promising, there are few three-dimensional measurements methods described in the literature. Objective: The aim of this study was to propose a method for assessing the degree of mandibular anterior dental crowding in the three planes of space, using digital dental models. Methods: Thirty dental casts were selected and scanned by Maestro 3D Dental Scanner and imported by Geomagic Qualify 2013 software. The degree of crowding was calculated by two examiners, based on the Little’s Irregularity Index, by means of the definition of axial, coronal and sagittal planes for each model. Intraexaminer analysis was performed with Dahlberg’s Formula (DF) and Intraclass Correlation Coefficients (ICC), and interexaminer analysis was performed with ICC and paired t-test. Results: The ICC showed an excellent agreement (p < 0.05) for all measurements, except for the intraexaminer and interexaminer in the Z-axis, in which it was found a moderate agreement. The DF showed a satisfactory accuracy with all measurements showing less than 1 mm difference. The paired t-test showed statistical difference between the examiners in two measurements, although it was clinical irrelevant. Conclusion: When comparing the three planes of space, the Z-axis showed the greatest variation in landmarks placement; however, overall, the present method seems precise and reproducible.

3D RECONSTRUCTION AND SLM SURVEY FOR DENTAL IMPLANTS

This research studies an integrated dental 3D reconstruction scanning method which combines impression model scanning, intraoral camera scanning and CT scanning. In the dental integrated scanning, tooth root data is acquired from CT DICOM data and 3D reconstruction is processed by Mimics®software developed from Materialise. The tooth crown and the tooth bridge 3D data are obtained by scanning the tooth impression model or scanning with an intraoral scanner. Also, it surveys that the dental prosthesis are fabricated with traditional methods and printed with Select Laser Melting (SLM) technology. In the research, it presents that SLM additive manufacturing (AM) method can fabricate customized dental prosthesis with high dimensional accuracy.

Dental Students’ Attitude towards Problem-Based Learning before and after Implementing 3D Electronic Dental Models

Dental Students’ Attitude towards Problem-Based Learning before and after Implementing 3D Electronic Dental Models

가속노화 효과에 의한 치과용 3D 프린터 출력물의 변형도 평가

가속노화 효과에 의한 치과용 3D 프린터 출력물의 변형도 평가

Is a Basic Erosive Wear Examination (BEWE) reliable for recording erosive tooth wear on 3D models?

ObjectivesTo assess the reliability of the BEWE index on 3D models and to compare 3D-assessed erosive tooth wear scores with clinically detected scores. MethodsIn total, 1964 members of the Northern Finland Birth Cohort 1966 participated in a standardized clinical dental examination including the Basic Erosive Wear Examination (BEWE) and dental 3D modelling at the age of 45–46 years. Of those examined, 586 were randomly selected for this study. 3D models were assessed using the same BEWE criteria as in the clinical examination. Calculated kappa values as well as the prevalence and severity of erosive wear according to the clinical examination and 3D models were compared. Re-examinations were performed to calculate intra- and inter-method and −examiner agreements. ResultsThe BEWE index on 3D models was reproducible; the mean intra- and inter-examiner agreement were 0.89 and 0.87, respectively, for sextant level, and 0.64 and 1, respectively, for BEWE sum scores. Erosive tooth wear was recorded as more severe in 3D models than in the clinical examination, and inter-method agreement was 0.41 for severe erosive wear (BEWE sum>8). The biggest inter-method differences were found in upper posterior sextants. ConclusionsThe BEWE index is reliable for recording erosive tooth wear on 3D models. 3D models seem to be especially sensitive in detecting initial erosive wear. Additionally, it seems that erosive wear may be underscored in the upper posterior sextants when assessed clinically. Due to the nature of 3D models, the assessment of erosive wear clinically and on 3D models may not be entirely comparable. Clinical significance3D models can serve as an additional tool to detect and document erosive wear, especially during the early stages of the condition and in assessing the progression of wear. When scoring erosive wear clinically, care must be taken especially when assessing upper posterior sextants.

Evaluation of sleep bruxism with a novel designed occlusal splint

PurposeThis report presents our evaluation system that assesses sleep bruxism. The characteristics and fabrication process of our novel designed splint, and the analysis process of our system are presented. MethodsThe subjects were 17 volunteers. The splint was fabricated with a self-curing resin compounded with an amino-acid powder for easy wear on the semi-adjustable articulator, and adjusted for a full-balanced occlusion. An impression of the splint, located on the cast, was taken before and after it was worn. The analytical casts were made and scanned via a dental 3D scanner. The datasets were superimposed using two kinds of regions of interest (palate and occlusal surface). The differences between the two datasets were quantitatively presented with pseudo-color mapping. The maximum differences in coronal and apical directions were calculated on the selected area in the occlusal surface when the occlusal surface was used as a region of interest for registration. The relationship between the EMG activities and the change of occlusal surface of the splint were investigated. ResultsIn all subjects, deformation and wear facets on the splint were observed. The differences in the apical direction, which indicate wear depth, were correlated with the maximum muscle activity during sleep (p=0.036). ConclusionFrom our results, it is suggested that we are not able to eliminate the influence of parafunction for the prosthesis only by designing the surface of occlusal splint using the semi-adjustable articulator. Our splint may have the potential to detect specific facets due to parafunctions as nocturnal bruxism.

Implant Insertion Torque Load Analysis for Mandible using CBCT Images

ABSTRACT Introduction Osteoporotic patients require particular attention to their implant site bone quality as an indication of prognosis and may require modified surgical technique Insertion Torque (IT). Aim It is the purpose of this study to test whether IT is significantly correlated with bone density or not, as assessed by the cone-beam computed tomography (CBCT) in a group of osteopenic and osteoporotic patients. Materials and methods A total of 30 patients were included in the study. The mandibular second premolar region was chosen as the site of investigation to prevent variability in surgical implant placement technique in different locations affecting bone mineral density (BMD). Partially, edentulous female patients between 51 and 60 years of age who were scheduled to receive implant placement were recruited for the study. CBCT (Master Series 3D Dental Imaging) was used for preoperative evaluation of the jaws for each patient. Materialise's Interactive Medical Image Control System (MIMICS) was used to process stacks of 2D images from CBCT. Finite element analysis were carried out on bone using Ansys software. Maximum displacement and maximum stress—strain patterns were compared in normal, osteoporotic, and osteopenic groups. Results The difference in mean bone density in all three groups were statistically significant (p &lt; 0.05) (Table 1). FEA at 32, 36, 40 N in all 3 groups was statistically significant. (Table 2). Conclusion Within the limitations of the study, the amount of stress—strain that exhibits at 40 N load in normal bone will be almost the same stress—strain given at 32 N load in osteoporotic bone. Normal IT load analysis exhibits more stress/strain in osteoporotic patients when compared with other groups, showing that IT must be achieved to an optimum level to avoid further complication and failures. How to cite this article Venkatakrishnan CJ, Bhuminathan S, Chandran CR. Implant Insertion Torque Load Analysis for Mandible using CBCT Images. World J Dent 2017;8(3):183-189.

Case Study on 3D Clear Aligner and e-Business Strategy of Dental Orthodontics Hospital

Along with Europe and the United States, transparent braces seem to become popular in Asia. Owing to advances in dental technology, 3D printing and scanning cannot be treated with conventional orthodontic technology and will replace traditional braces as the development of various technologies is expected to increase customer volume. In addition, due to higher economic growth of neighboring countries, interests in beauty are increasing and price is relatively cheap; many customers come from a country with high dental hospital treatment. Recently a domestic dental hospital dentist called See-Through Tech company has been established to make 3D digital transparent orthodontic appliances cheaper than other orthodontic devices and to treat patients with short treatment method of treatment.

Dental 3d level simulators in the study of local anesthesia

The purpose of the study was to develop a training protocol for local anesthesia in dental students. The study involved 90 2d year dental school students divided into 3 groups according to procedure training method: on skeletal preparations; by «Typodont» simulator and by combination of methods. Manipulation effectiveness criteria in skeletal preparations was penetrating the mandibular foramina by isolation of the corresponding region by latex scarf. In «Typodont» the effective injection was determined by light and sound signals. The results showed the necessity for combined approach as it gives an opportunity to identify mandible foramina by projecting on soft tissue marks with further skills developing on the simulator. When using the combined approach only 4 students successfully completed their task by initial injection while at the second attempt only 4 were not successful.

Accuracy of a three-dimensional dentition model digitized from an interocclusal record using a non-contact surface scanner.

For orthodontic treatment, it is important to assess the dental morphology, as well as the position and inclination of teeth. The aim of this article was to develop an efficient and accurate method for the three-dimensional (3D) imaging of the maxillary and mandibular dental morphology by measuring interocclusal records using an optical scanner. The occlusal and incisal morphology of participants was registered in the intercuspal position using a hydrophilic vinyl polysiloxane and digitized into 3D models using an optical scanner. Impressions were made of the maxilla and mandible in alginate materials in order to fabricate plaster models and created into 3D models using the optical scanner based on the principal triangulation method. The occlusal and incisal areas of the interocclusal records were retained. The buccal and lingual areas were added to these regions entirely by the 3D model of the plaster model. The accuracy of this method was evaluated for each tooth, with the dental cast 3D models used as controls. The 3D model created from the interocclusal record and the plaster model of the dental morphology was analysed in 3D software. The difference between the controls and the 3D models digitized from the interocclusal records was 0.068±0.048mm, demonstrating the accuracy of this method. The presence of severe crowding may compromise the ability to separate each tooth and digitize the dental morphology. The digitization method in this study provides sufficient accuracy to visualize the dental morphology, as well as the position and inclination of these teeth.

Development of High Speed and High Accuracy 3D Dental Intra Oral Scanner

3D digitization technology, commonly known as Intra oral scanning method is a modern approach than traditional impression methods in dentistry. Utilization of 3D digitization results in accurate mapping of oral cavity and eliminates number of procedures for making dental prosthesis. This paper unveils design of 3D dental oral scanner with software integration is proposed for high speed and accuracy. The main parts of the system are Intra-Oral Scanning (IOS) hardware, CPU and display monitor. The IOS hardware is designed using non-contact optical technologies based on the principle of confocal laser scanner microscopy results in high speed scanning. The light intensity is detected by photo-detection device, transforming the light signal into an electrical one which is recorded by a computer and can be reconstructed. The software is designed using merging of active triangulation method, surface reconstruction and Image processing tools, results in high accurate 3D image of oral cavity, which will be displayed on the monitor screen.

The effect of 4,4'-bis(N,N-diethylamino) benzophenone on the degree of conversion in liquid photopolymer for dental 3D printing.

PURPOSEThe purpose of this preliminary study was to investigate the effects of adding 4,4'-bis(N,N-diethylamino) benzophenone (DEABP) as a co-initiator to a binary photoinitiating system (camphorquinone-amine) to analyze on the degree of conversion (DC) of a light-cured resin for dental 3D printing.MATERIALS AND METHODSCylindrical specimens (N=60, n=30 per group, ø5 mm × 1 mm) were fabricated using bisphenol A glycerolate dimethacrylate (BisGMA) both with and without DEABP. The freshly mixed resins were exposed to light in a custom-made closed chamber with nine light-emitting diode lamps (wavelength: 405 nm; power: 840 mW/cm2) for polymerization at each incidence of light-irradiation at 10, 30, 60, 180, and 300 seconds, while five specimens at a time were evaluated at each given irradiation point. Fourier-transform infrared (FTIR) spectroscopy was used to measure the DC values of the resins. Two-way analysis of variance and the Duncan post hoc test were used to analyze statistically significant differences between the groups and given times (α=.05).RESULTSIn the DEABP-containing resin, the DC values were significantly higher at all points in time (P<.001), and also the initial polymerization velocity was faster than in the DEABP-free resin.CONCLUSIONThe addition of DEABP significantly enhanced the DC values and, thus, could potentially become an efficient photoinitiator when combined with a camphorquinone-amine system and may be utilized as a more advanced photopolymerization system for dental 3D printing.

Dental status and 3D reconstruction of the malocclusion of the famous singer Farinelli (1705–1782)

The famous castrato singer Carlo Broschi, better known as Farinelli (1705-1782), was exhumed by our research group in July 2006 to study his skeletal remains and reconstruct his osteobiography. He was castrated before puberty to preserve his high voice into adulthood. The osteological study has revealed several skeletal features probably related to the effects of castration (Hyperostosis frontalis interna, long limb bones, persistence of epiphyseal lines, osteoporosis) (Belcastro et al., 2011). Here we present the study of the teeth and maxilla-mandibular region using classic and tomographic morphological methods. Considering the subject's age and the period during which he lived, his oral health conditions were good. On the basis of the very pronounced anomalous vestibular buccal wear, a overbite visualized by 3D reconstruction, was hypothesized. This facial disharmony is of particular interest when considering Farinelli's extraordinary singing qualities and stage presence.

Dental status and 3D reconstruction of the malocclusion of the famous singer Farinelli (1705-1782)

Dental status and 3D reconstruction of the malocclusion of the famous singer Farinelli (1705-1782)