A Promising Potential of Brown Algae Sargassum polycystum as Irreversible Hydrocolloid Impression Material

This study aimed to investigate the potential use of brown algae Sargassum polycystum as irreversible hydrocolloid (alginate) impression material. Potassium alginate extracted from Sargassum polycystum was prepared in three different compositions (14%, 15%, and 16%) and mixed with other standard components to form an alginate impression material. Prior to that, the purity of potassium alginate was quantified with Fourier Transform Infrared Spectroscopy (FTIR) analysis. As a control material, the alginate impression material from a commercially available product was used. All alginate impression materials were then applied to a die stone model. Dimensional accuracy was measured by calculating the mesiodistal width of incisors in the generated dental cast using a digital caliper 0.01 accuracy (five replications). In addition, to evaluate the dimensional stability, the impression results were poured at four different periods (immediately, 5 min, 10 min, and 15 min). An independent t-test was performed to compare the measurement results with p < 0.05 considered significant. Analytical results confirm that the impression material containing 15% potassium alginate gives the best dimensional accuracy similar to control (p > 0.05). Meanwhile, the optimal dimensional stability was produced in the impression material containing 16% potassium alginate. Our study suggested that brown algae Sargassum polycystum has a promising potential to be used as an alginate impression material in clinical application.

Influence of Different Wax Hardening Agents on Surface Roughness of Refractory Cast Investment Materials

Background: Phosphate-bonded investments produce a refractory cast model with rough surface and undesirable properties. Dental Surface hardening agents are then applied to refractory investment materials to enhance its properties. Purpose: compare and evaluate the effects of different dental cast hardening agents (Bees wax, Carnauba wax, and Ceresin wax) on surface roughness of refractory model investment material. Approach: 30 specimens were constructed from commercially available phosphate bonded investment material. Specimens were subjected to a roughness test before dipping in handing agents, then divided into three groups according to the type of wax in which they were dipped. (10 specimens for each type). Surface roughness test was done by a profilometer where three readings were taken for all the specimens' surfaces randomly. The mean was then extracted for the roughness values before and after dipping in waxes. Results: the mean and standard deviation were tabulated and statistically analyzed using students T- test. The roughness values were decreased after the specimens were dipped in waxes (P value < 0.001 HS highly significant). Conclusion: The dipping process with hardening agents has significantly improved the surface roughness of the specimens' investment materials.

Evaluation of Relationship between Mesiodistal Width of Permanent Canines and Premolars with Permanent Lower First Molars and Incisors for Space Analysis

Introduction: One of the simplest methods to predict mesiodistal width of permanent canines and premolars is using Tanaka and Johnston’s prediction formula; however, dental size varies according to race. The study aimed to examine the relationship between incisors mesiodistal width and mandibular first molar’s with mesiodistal width of maxillary and mandibular canines and premolars and to determine the reliability of Tanaka and Johnston prediction formula. Materials & Methods: In the present cross-sectional study, 200 pairs of a dental cast of 12-25 years old were selected and the greatest mesiodistal width of canines and premolars crown in each jaw and incisors and mandibular first molars were measured with a digital caliper with 0.01 resolution. Data were analyzed using regression analysis, t-test (p value < 0.05). Results: There was a significant statistical difference between actual width and Tanaka and Johnston prediction formula in the group under study (p value < 0.001). Moreover, a new linear equation for the prediction of mesiodistal width of maxillary and mandibular canines and premolars based on mesiodistal width of lower incisors and mandibular first molars was developed using regression analysis. Conclusion: In statistical terms, Tanaka and Johnston’s prediction formula is not applicable for the population under study because maxillary estimated measures were a little high and mandibular estimated measures were a little low.

Accuracy of Integration of Dental Cast and Cephalograms Compared with Cone-Beam Computed Tomography: A Comparative Study

Background: This study proposes a method that integrates maxillary dental cast and cephalograms and evaluates its accuracy compared with cone-beam computed tomography (CBCT) scans. Methods: The study sample comprised 20 adult patients with records of dental casts, cephalograms, and craniofacial CBCT scans. The maxillary dental cast was integrated with lateral and frontal cephalograms based on best-fit registration of palatal and dental outline curves from dental cast with cephalogram tracings. Linear measurement was conducted to assess the intra- and inter-examiner reproducibility of the proposed intergration method using intraclass correlation coefficients; linear and angular measurements were conducted to assess its accuracy with CBCT scans as a standard reference. Paired t test, one sample t test, and mean ± standard deviation of the absolute value of difference were used to compare the integrated images and CBCT.Results: The integration method showed good intra- and inter-examiner reproducibility (intraclass correlation coefficients >0.98). The differences in linear and angular measurements between the integrated images and CBCT were not statistically significant but with a large deviation. When absolute value of difference was computed, the linear distance error was 0.51 ± 0.34 mm, the tooth point coordinate errors in X, Y and Z axis were 0.22 ± 0.22, 0.38 ± 0.32 and 0.21 ± 0.21mm respectively; the angular error in pitch, roll and yaw of the dental cast was 0.82 ± 0.51, 0.92 ± 0.59 and 0.80 ± 0.41 degree respectively. Conclusions: The proposed method for integration of dental cast and cephalograms showed good reproducibility and acceptable accuracy compared with CBCT. It could be helpful for researchers to study three-dimensional tooth growth changes using the existing craniofacial growth data especially cephalograms.

Evaluation of Growth and Development of Adolescents’ Dental Arch Asymmetry with Normal Occlusion Using Three-Dimensional Digital Models

Objective. The purpose of this study was to observe the dental arch asymmetry in 12-year-olds with normal occlusion during the early permanent dentition stage. Methods. Ninety-two 12-year-old students (46 males and 46 females) who had normal occlusion during early permanent dentition were selected from a junior high school in Tangshan, China. Once per year for three consecutive years, a dental cast was obtained from each subject, and the cast was scanned with a 3D digital scanner (R700 3D). The median palatal plane (MPP) and transverse palatal plane (TPP) were used as the reference plane for the transverse and anteroposterior measurements, respectively. Results. Most of the dental arch asymmetry indicators decreased with age, but these differences were not statistically significant. The values of the midincisal edge of the upper central incisors (U1), midincisal edge of the upper lateral incisors (U2), upper canine cusp tip (U3), upper first premolar buccal cusp tip (U4), upper second premolar buccal cusp tip (U5), upper first molar mesiobuccal cusp tip (U6MB), and upper first molar distobuccal cusp tip (U6DB) to the TPP were 0.019 mm, 0.279 mm, 0.017 mm, 0.016 mm, 0.016 mm, 0.027 mm, and 0.200 mm, respectively; these values were larger in males than in females ( P < 0.05 ). The values of 2–5, 6MB, and 6DB-TPP were 0.154 mm, 0.102 mm, 0.119 mm, 0.259 mm, 0.206 mm, and 0.123 mm, respectively, larger in the mandibular than in the maxillary dental arch ( P < 0.05 ). The values of the midincisal edge of the lower central incisors (L1), midincisal edge of the lower lateral incisors (L2), lower canine cusp tip (L3), lower first premolar buccal cusp tip (L4), lower second premolar buccal cusp tip (L5), lower first molar mesiobuccal cusp tip (L6MB), and lower first molar distobuccal cusp tip (L6DB) to the MPP were 0.399 mm, 0.197 mm, 0.258 mm, 0.248 mm, 0.214 mm, 0.575 mm, and 0.531 mm, respectively, larger than L1-5, L6MB, and L6DB-TPP ( P < 0.05 ). Conclusion. The asymmetry of the dental arch in 12-to-15-year-olds with normal occlusion did not change significantly with age. The anteroposterior asymmetry of the maxillary dental arch is larger in males than in females. With the exception of the central incisor, the anteroposterior asymmetry of the mandibular dental arch is larger than that of the maxillary dental arch. The transverse asymmetry of the mandibular dental arch is larger than the anteroposterior asymmetry.

Association of Morphological Characteristics of Palatal Rugae Pattern with Dental Malocclusion in Himachal Population

Introduction: Palatal rugae used for the evaluation of dental movements and as a landmark in the superimposition of dental cast for orthodontic purpose as it is a stable point. So, the aims and objectives of our study is to investigate the association of morphological characteristics of palatal rugae with dental malocclusion in Himachali population. Materials and methods: 90 subjects divided into three groups (n=30 each) on the basis of Angle’s classification. Palatal rugae were marked on dental casts and evaluated for length, pattern and orientation. Obtained measurements were then statistically analysed. Conclusion: Primary palatal rugae’s length was found more in Class II followed by Class III and Class I malocclusion. Among the pattern of the primary palatal rugae, curved pattern were more evident on both right and left sides of all malocclusion groups. Horizontal directed orientation is more predominant on the right side and posteriorly directed on the left side of the first primary palatine rugae. Keywords: Rugae, Malocclusion, orientation pattern, length, morphology.

Influence of bone condition on implant placement accuracy with computer-guided surgery

Background The impact of the jaw bone condition, such as bone quantity and quality in the implant placement site, affecting the accuracy of implant placement with computer-guided surgery (CGS) remains unclear. Therefore, this study aimed to evaluate the influence of bone condition, i.e., bone density, bone width, and cortical bone thickness at the crestal bone on the accuracy of implant placement with CGS. Methods A total of 47 tissue-level implants from 25 patients placed in the posterior mandibular area were studied. Implant placement position was planned on the simulation software, Simplant® Pro 16, by superimposing preoperative computed tomography images with stereolithography data of diagnostic wax-up on the dental cast. Implant placement surgery was performed using the surgical guide plate to reflect the planned implant position. The post-surgical dental cast was scanned to determine the position of the placed implant. Linear and vertical deviations between planned and placed implants were calculated. Deviations at both platform and apical of the implant were measured in the bucco-lingual and mesio-distal directions. Intra- and inter-observer variabilities were calculated to ensure measurement reliability. Multiple linear regression analysis was employed to investigate the effect of the bone condition, such as density, width, and cortical bone thickness at the implant site area, on the accuracy of implant placement (α = 0.05). Result Intra- and inter-observer variabilities of these measurements showed excellent agreement (intra class correlation coefficient ± 0.90). Bone condition significantly influenced the accuracy of implant placement using CGS (p < 0.05). Both bone density and width were found to be significant predictors. Conclusions Low bone density and/or narrow bucco-lingual width near the alveolar bone crest in the implant placement site might be a risk factor influencing the accuracy of implant placement with CGS.

Comparative Evaluation of Digitization of Diagnostic Dental Cast (Plaster) Models Using Different Scanning Technologies

Rapidly developing digital dental technologies have substantially simplified the documentation of plaster dental models. The large variety of available scanners with varying degrees of accuracy and cost, however, makes the purchase decision difficult. This study assessed the digitization accuracy of a cone-beam computed tomography (CBCT) and an intraoral scanner (IOS), as compared to a desktop optical scanner (OS). Ten plaster dental models were digitized three times (n = 30) with each scanner. The generated STL files were cross-compared, and the RMS values were calculated. Conclusions were drawn about the accuracy with respect to precision and trueness levels. The precision of the CBCT scanner was similar to the desktop OS reference, which both had a median deviation of 0.04 mm. The IOS had statistically significantly higher deviation compared to the reference OS, with a median deviation of 0.18 mm. The trueness values of the CBCT was also better than that of IOS—median differences of 0.14 and 0.17 mm, respectively. We conclude that the tested CBCT scanner is a highly accurate and user-friendly scanner for model digitization, and therefore a valuable alternative to the OS. The tested IOS was generally of lower accuracy, but it can still be used for plaster dental model digitization.

Recyclability of Dental Gypsum via Calcination

Nowadays, either keeping or throwing out the final product of dental cast is the most common thing to do. The waste from dentistry can be considered toxic if not handled specifically and separately to other waste. Hence, the recycling process can reduce its effect and the waste of dental casts. It can also reduce the cost of producing new high-grade dental gypsum. This paper studies the behavior of before-after recycle and heat treatment to several grades of dental gypsum that will be used as impression material or dies. As it is designed to be an impression material that will undergo heat treatment, Simultaneous Thermogravimetry and Differential Scanning Calorimetry (TGA-DSC) will be applied to understand the Phase Transformation to its mass change and the behavior to a temperature difference. The result will be validated using an experimental approach. X-ray Diffraction (XRD) and Scanning Electron Microscope will also be done to identify the crystalline phases and the surface microstructure, and it will be validated using an experimental approach as well. A range of gaps between parameter values is expected between the fresh/new dental gypsum and the recycled one. However, it is expected some similar values between the heat-treated and the fresh/new dental gypsum.