No abstract

Finite Element Analysis or Finite Element Method is based on the principle of dividing a structure into a finite number of small elements. It is a sophisticated engineering tool, which has been used extensively in design optimization and structural analysis first originated in the aerospace industry to study stress in complex airframe structures. This method is a way of getting a numerical solution to a specific problem, used to analyze stresses and strains in complex mechanical systems. It enables the mathematical conversion and analysis of mechanical properties of a geometric object with wide range of applications in dental and oral health science. It is useful for specifying predominantly the mechanical aspects of biomaterials and human tissues that cannot be measured in vivo. It has various advantages, can be compared with studies on real models, and the tests are repeatable, with accuracy and without ethical concerns.

Background The actual burden of dental caries prevalence varies with the caries assessment tool used. Therefore, the present study evaluated the caries diagnostic potentials of Decayed, Missing and Filled Teeth (DMFT); International Caries Detection and Assessment System (ICDAS) II and Caries Assessment Spectrum and Treatment (CAST) indices in estimating the caries prevalence rate of first permanent molar (FPM) in Saudi male children aged 7–9 years. Methods This descriptive, cross-sectional study included 390 children by multistage stratified cluster sampling method in Al-Jouf Province, Saudi Arabia. The prevalence rates of FPM caries were determined by DMFT, ICDAS II and CAST indices at various diagnostic cut-off points. Intra- and inter-examiner reliability was determined. Results The prevalence rates of FPM caries determined by DMFT (decayed), ICDAS II (codes 1–6) and CAST (codes 3–7) were 64.4% (61.6–67.2), 71.5% (69.2–73.2) and 71.0% (68.7–73.3), respectively. The prevalence rates of FPM caries determined by ICDAS II at various diagnostic cut-offs were as follows: ‘sound’ (code ‘0’), 28.5% (26.3–30.8); ‘enamel caries’ (codes 1–3), 57.2% (54.7–59.7) and ‘dentinal caries’ (codes 4–6), 14.3% (12.6–16.1). Similarly, the prevalence rates estimated by CAST at different diagnostic cut-off points were: ‘healthy’ (scores 0–2), 28.1% (25.9–30.4); ‘premorbid’ (score 3, enamel carious), 56.5% (54.0–59.0); ‘morbid’ (scores 4–5, cavitated carious dentin), 7.9% (6.6–9.3); ‘severe morbidity’ (scores 6–7, pulp exposure/fistula/abscess), 6.6% (5.4–8.1) and ‘mortality’ (score 8, lost), 0.8% (0.4–1.4). Conclusion Enamel caries lesions were found in more than half of the FPMs investigated in the current study. CAST index is preferable because it detects the complete spectrum of caries. ICDAS II at codes 1–6 and CAST at codes 3–7 projected similar caries prevalence rates in FPMs.

Objective. To investigate the correlation of periodontal parameters and bite force in different stages of periodontitis after phase I periodontal therapy. Methods. Periodontal clinical parameters such as mobility, attachment loss, gingival recession, and percentage of bone remaining were recorded at the mandibular first molar region after phase I therapy in subjects categorized according to the stage of periodontitis. Corresponding bite force was recorded at the first mandibular molar region using a bite force device after phase I therapy. ANOVA test was used to assess the significant difference among different groups. Pearson correlation coefficient was used to assess the correlation between measured variables. Results. The ANOVA test represents that there is no statistical significant difference between the bite force in stage I, stage II, and stage III type of periodontitis. A strong positive correlation was found ( r = 0.537 ) between bite force and percentage of remaining alveolar bone support whereas negative correlation was observed in measured parameters such as mobility ( r = − 0.0181 ), attachment loss ( r = − 0.608 ), and gingival recession ( r = − 0.435 ). Conclusion. Among all periodontal clinical parameters, the percentage of remaining alveolar bone is the strong predictor of bite force and mobility; attachment loss and gingival recession cannot predict the bite force in the first molar region. Bite force is variable in different stages of periodontitis.

Objectives: To assess the association amongst oral hygiene practices, untreated dental caries (UDC) and clinical consequences of UDC in pre-and primary school children aged 3-5 and 6-7 years.Materials and methods: A total of 250 subjects were recruited. The demographic and oral hygiene data were collected using a closed-ended questionnaire. The UDC was measured using the 'd/D' component of the decayed, missing, filled teeth (dmft/ DMFT) index, and its clinical consequences were recorded using the 'p/P' component of the pulpal involvement, ulceration, fistula and abscess (pufa/PUFA) index. The data were analyzed by multiple logistic regression.Results: Overall, 94.2% and 56.5% of the participants had one or more UDC and pulp involvement (p ≥ 1), respectively in 3-5-year-old age group. In the 6-7-yearage group the prevalence of UDC was 26.7% and the pulp involvement was 11.6%.Children who brushed with their fingers were 4.7 times more likely to have UDC (crude odds ratio [COR] = 4.71; 95% CI: 1.21-18.40). Twice-daily brushing resulted in a 39% (p = 0.732) lower likelihood of having UDC compared with once-daily brushing (COR = 0.61; 95% CI: 0.04, 10.09). Children with irregular brushing frequency were 3.2 times more likely to have pulpal involvement (COR = 3.21; 95%

Aim: To digitally evaluate the marginal adaptation of different types of all-ceramic crowns on two different marginal configurations such as Shoulder and Chamfer of the prepared teeth. Methods:The marginal fit of the crown specimens on the model of the prepared teeth were assessed using the dual scan replica technique. Two plastic teeth were prepared; one having a Shoulder finishing line (A), while the other with a Chamfer finish line (B). Three types of different all-ceramic crowns, layered zirconia, monolithic zirconia, and pressed lithium disilicate, were fabricated for each prepared tooth (A) and (B). Measurements for assessing the marginal discrepancy were done on four designated points on the mesial, distal, buccal, and palatal surface of the superimposed image. Results:The average marginal gap was the largest in the layered zirconia group, followed by monolithic zirconia, while pressed lithium disilicate crowns showed the least marginal gaps. Crowns with Chamfer finish lines were better fitting (less marginal gap) than the shoulder finish lines across all the groups.Conclusions: Chamfer finish lines produced better fitting restorations, and heatpressed lithium disilicate crowns showed better adaptation at the margins than both layered zirconia and monolithic zirconia.

To evaluate the better method of implant insertion into the osteotomy site in compromised quality bone for attaining optimal primary stability and thereby achieving the osseointegration for the ultimate success of implant. A total of 32 specimens (wood blocks) simulating D4 bone, were categorized into two groups. The osteotomy site was prepared as per the protocol and implants were placed till the level of the block. The insertion torque was quantified using digital Kratos torque meter. While the implants were inserted and abutments placed by hand ratcheting in the first group; they were motor-driven in the second group. Later pullout test was carried out in universal testing machine and results were analyzed using IBM SPSS Statistics for Windows Software, version 22 (IBM Corp., Armonk, NY, USA). The mean pull out force values obtained in implants placed by hand driven method were 624.375 N while the force values for implants inserted by motor-driven was 692.625 N. There was a statistically significant difference between hand and motor driven implant into the osteotomy site (p<0.05) between the groups. Of the different methods of implant insertion evaluated in this study, motor-driven imply to have a better primary stability indicating better integration with the bone to become a successful implant.

One of the commonest treatment options for replacing missing teeth is a root-form implant. Clinically, the key mechanical factor in achieving success is primary stability. This ex vivo study aims to evaluate whether osseodensification method will achieve good primary stability or the conventional drilling protocol. MethodsFresh iliac bone of the sheep was selected similar to D3 and D4 bone densities. A total of 22 osteotomy sites were prepared in the bone sample, of which 11 were prepared by osseodensification method (test group) and other 11 by conventional undersized drilling (control group). Primary stability was measured using insertion torque (IT), resonance frequency analysis (RFA), and reverse torque values (RTVs) by measuring implant stability quotient (ISQ). The recorded data were statistically analyzed using Statistical Package for the Social Sciences (SPSS) Version 22.0. The differences between groups were compared using the Mann-Whitney U test and independent t-test. The Pearson correlation coefficient test was performed to measure the linear relationship between two variables. The statistical significance level was established at p<0.05. ResultsWhen the correlation among IT, RTV, and ISQ was measured, a statistically significant correlation between IT and RTV (p=0.001) and between IT and ISQ (p=0.0001) was observed. A statistically significant (p=0.014) correlation between RTV and ISQ was also found. ConclusionOsteotomy prepared by osseodensification method showed higher IT, RTV, and ISQ values than the conventional undersized group.