Radix molaris is a hidden truth of mandibular first permanent molars: A descriptive- analytic study using cone beam computed tomography.

BACKGROUND: Cone-beam computed tomography (CBCT) could be more beneficial in clinical situations that involve the determination of root canal morphology. AIM: The aim of the study was to ascertain the prevalence of radix molaris (paramolaris-RP and entomolaris-RE) in a subpopulation of Saudi Arabia using CBCT. METHOD: A total of 700 CBCT scans of mandibular permanent first molars were included in this study. All CBCT scans were interpreted by two trained dentists and an endodontist. Mandibular permanent first molars with fully developed roots and closed apices were only included. Computed Tomography scans were obtained from the dental college record. The anatomic characteristics which were checked included: the prevalence of radix molaris in both RE and RP and the prevalence of radix molaris according to the patient's gender and age. All CBCT images were processed and reconstructed using OnDemand3DTM imaging software. RESULTS: Of the 700 patients included, 651 (93.0%) did not have radix molaris, 46 (6.6%) had radix entomolaris and 3 (0.4%) had radix paramolaris in the study group. There was no statistically significant difference between the genders and age in the incidence of RE and RP (P-value < 0.05). CONCLUSION: The study showed that RE prevalence is more compared to RP in the first lower molars in the population studied. It is important to identify extra roots and associated canals to perform successful root canal treatment and avoid failure.

Dimensional Stability of Light-Activated Urethane Dimethacrylate Denture Base Resins.

An accurate and dimensionally stable trial denture base is required for a successful denture. The aim of this in vitro study was to assess the dimensional stability of a light-activated urethane dimethacrylate (UDMA) visible light cure (VLC) denture base with three fabrication techniques and different curing cycles. Forty-five VLC denture base samples were divided evenly into three groups. Group A used a conventional fabrication technique with a curing cycle of 5 min. Group B used a modified fabrication technique with two 4-min curing cycles. Group C used a multi-step fabrication technique with three curing cycles (4 min, plus 4 min, plus 2 min). The samples were sectioned and observed under a stereomicroscope to measure the discrepancy between the sample and the master cast. The mean dimensional discrepancy (mm) at the molar region at mid-palate, after 24 h in Group A, B and C was 0.790 mm, 0.741 mm and 0.379 mm, respectively; at the right ridge crest, it was 0.567, 0.408 and 0.185, while at the left ridge crest it was 0.475, 0.331 and 0.125, respectively. Statistical analysis showed significantly different dimensional discrepancies among the groups at all three sites; right ridge crest (F = 93.54, p < 0.001), left ridge crest (F = 105.96, p < 0.001) and mid-palate (F = 125.53, p < 0.001). Within the limitations of this laboratory study, it can be concluded that the denture base using a multi-step fabrication technique with three curing cycles provides better adaptation than the conventional technique. The significance of the study is that clinicians should consider performing denture base fabrication using a multi-step technique to enhance adaptation and hence the stability of the dentures for patients.

Retentive Forces and Deformation of Fitting Surface in RPD Clasp Made of Polyether-Ether-Ketone (PEEK).

BACKGROUND: Polyetheretherketone (PEEK) has provided the option to fabricate RPDs with aesthetics unlike metal RPDs, but little attention has been paid to its suitability, especially towards the retentive forces and deformation of the clasp. This study aimed to examine the retentive forces and the fitting surface (inner surface) deformation of clasps made from PEEK and compare it with cobalt-chromium (Co-Cr) clasp. METHODS: Forty-two circumferential clasps (14 Co-Cr and 28 PEEK) were fabricated and divided into two groups with clasp undercuts (0.25 mm and 0.5 mm) with thicknesses of 1 mm and 1.5 mm. Each was examined for retentive forces after cycle test on its abutment for 360 cycles. Initial and final retentive forces were recorded. The fitting surface deformation was determined using 3-Matic research analysis software. RESULTS: The results revealed that highest mean initial retentive force was of Co-Cr clasps with 0.50 mm undercut 22.26 N (±10.15 N), and the lowest was the 1 mm PEEK clasps with 0.25 mm undercut 3.35 N (±0.72 N) and highest mean final retentive force was the Co-Cr clasps with 0.50 mm undercut 21.40 N (±9.66 N), and the lowest was the 1 mm PEEK clasps with 0.25 mm undercut 2.71 N (±0.47 N). PEEK clasps had a lower retentive force than Co-Cr clasps with 0.50 undercut. PEEK clasps (1.5 mm) at 0.25 mm undercut had the least deformation (35.3 µm). PEEK showed significantly less deformation (p ≤ 0.014) than Co-Cr. CONCLUSION: The deformation of PEEK clasps fitting surface was lower than Co-Cr clasps and retentive forces were close to the Co-Cr clasps, suggesting the use of PEEK as an aesthetic clasp option for RPD framework.

Comparison of Microleakage in Nanocomposite and Amalgam as a Crown Foundation Material Luted with Different Luting Cements under CAD-CAM Milled Metal Crowns: An In Vitro Microscopic Study.

Microleakage is a persistent problem despite advancement in materials and techniques in fixed prosthodontics. This leads to the importance of sound crown foundation material and luting agents used to maintain the marginal seal. The literature is deficient with studies, comparing microleakage under various crown foundation materials and luting agents, especially with CAD-CAM (computer-aided design and computer-aided manufacturing) metal crowns. This study was aimed to compare microleakage in a nanocomposite/dentinal bonding agent and amalgam/cavity varnish as crown foundation materials luted with two different luting cements: resin-reinforced glass ionomer cement and self-adhesive resin cement, under both dry and contaminated conditions. A hundred intact, caries-free human molars were prepared to receive crown foundation material and extra coronal restorations. Amalgams with cavity varnish and nanocomposites with dentinal bonding agent in both ideal and contaminated conditions were used as crown foundation materials. After restoration, each sample was cemented with a CAD-CAM milled metal crown using two different luting agents-resin-reinforced glass ionomer cement and self-adhesive resin cements both in ideal and contaminated conditions. Cementation was followed by thermocycling of samples, immersion in erythrosine B dye, embedding in clear auto polymerizing acrylic resin and sectioning to evaluate microleakage using stereomicroscope. The mean microleakage between different luting cements on the experimental side of the facial surface was 137.64 µm and 211.01 µm for resin-reinforced GIC and for self-adhesive resin cement was 119.78 µm and 150.42 µm, under ideal and contaminated condition, respectively. There was a significant difference in mean micro-leakage between different crown foundation material and cement groups used in the study. The composites and amalgam, both when used as crown foundation material and luted with use of technically advanced CAD-CAM metal crown with self-adhesive resin cement (in both ideal or contaminated condition), showed less microleakage than in resin-reinforced glass ionomer cement. Overall, the self-adhesive resin cement showed comparatively reduced microleakage in all combinations with different crown foundations. Thus, this combination can be used in daily clinical practice to provide better protection from further decay.

Computerized occlusal forces analysis in complete dentures fabricated by additive and subtractive techniques.

BACKGROUND: Fabrication of complete dentures by computer-aided designing and computer-aided manufacturing (CAD-CAM) techniques are now common. Subtractive and Additive are the two principal CAD-CAM techniques used for this purpose. However, studies that evaluated the occlusal forces by CDs manufactured by these techniques are lacking. OBJECTIVES: To compare the occlusal forces in complete dentures fabricated by additive, subtractive and conventional techniques with different occlusal schemes, using computerized occlusal force analysis system [Tech-Scan III (T-Scan III)]. METHODS: Three groups (Gr) were made on the basis of techniques of fabrication of CDs: Conventional CDs (CCD), Subtractive CDs (SCD), and Additive CDs (ACD). Each group CDs were further divided into three sub groups based on occlusion schemes: bilateral balanced occlusion (BBO), lingualized occlusion (LO) and mono plane occlusion (MO). A total of 45 CDs were made: 15 in each group with 5 CDs of each occlusal scheme. For all samples, occlusal force analysis (percentage of occlusal force applied on the right and left sides of the arch, centralization of forces and percentage of maximum occlusal force) was done using computerized occlusal analysis system: T-Scan III. Univariate regression analysis and logistic regression analysis were used to find the effects of the technique of fabrication and occlusion scheme over the occlusal forces (p< 0.05). RESULTS: The intergroup comparison revealed statistically significant differences (p< 0.01) in right-left side force difference, maximum bite force in CDs fabricated by various techniques and with different occlusion schemes. Though the effect of occlusion scheme was more than the technique of fabrication (according to effect size estimation). The maximum force difference between right-left side was observed in combination of CCD technique and MO scheme (36.88 ± 2.82 N). Furthermore, the maximum bite force was observed for SCD technique (89.14 ± 6.08 N) and LO scheme (92.17 ± 3.22 N). In comparison to ACD, the chances of centre of force out of ellipse was 2.53 time more in CCS and 0.75 times less in SCD techniques and in comparison to MO, the chances of out of ellipse was 0.298 times less in BBO and 0.396 times less in LO schemes, though these chances were not statistically significant (p> 0.05). CONCLUSIONS: The digital CDs fabricated by subtractive technique were proved to be superior to additive technique in terms of occlusal force analysis on tested parameters. However, further research is needed on patients to determine the exact superiority of one technique over the other.

Clinical analysis of CAD-CAM milled and printed complete dentures using computerized occlusal force analyser.

BACKGROUND: Digital complete dentures (CDs) by computer-aided designing and computer-aided manufacturing (CAD-CAM) techniques (milling and three-dimensional (3-D) printing) have been evaluated clinically and provided satisfactory results. But clinical studies assessing occlusal forces by digital dentures are lacking. OBJECTIVES: To compare the occlusal force parameters in complete dentures (CDs) fabricated by milling, 3-D printing and conventional techniques having 3 commonly used occlusal schemes, using computerized occlusal force analysis system (Tech-Scan III- T-Scan III). METHODS: A total of 45 CDs were fabricated for 5 patients. Nine sets of CDs were made for each patient and were divided into 3 groups: Conventional CDs (CCD), Milled CDs (MCD), and 3-D printed CDs (3-DP CD). The CDs in each group were further divided into 3 sub-groups based on occlusion schemes - bilateral balanced (BBO), lingualized (LO) and mono plane (MP). Occlusal force analysis [percentage (%) of occlusal force applied on the right and left sides of the arch difference between them, centralization of forces and % of maximum occlusal/bite force] was done using computerized occlusal analysis system (T-Scan III) at the time of denture insertion. Univariate regression analysis and logistic regression analysis were performed (p< 0.05). RESULTS: The intergroup comparison of force distribution on right and left side in CDs fabricated by various techniques showed insignificant differences (p> 0.05) but statistically significant differences (p< 0.01) were found in right-left side force difference, maximum bite force % and centralization of forces. The maximum force difference on right and left side was observed CCD with MO (37.48 ± 1.03 N) and maximum occlusal-bite force % was observed for 3-DPCD with LO (95.40 ± 1.30 N). In comparison to 3-DP CD, the chances of centre of force out of ellipse (centralization of forces) was 3.36 and 2.15 times more in CCD and MCD techniques made CDs respectively. CONCLUSIONS: The occlusal parameters in CDs were affected by the fabrication techniques and occlusal schemes of CDs. The digital CDs retain adjusted occlusal schemes better and 3-DP CDs with BBO and LO occlusal schemes provided centralization of forces, better distribution and high maximum occlusal force % respectively.

The Tooth Size Discrepancy among Orthodontic Patients and Normal Occlusion Individuals from Saudi Arabia: A Three-Dimensional Scan Analysis of Diagnostic Casts.

BACKGROUND/PURPOSE: Tooth size discrepancy is one of the causative factors of malocclusion. This study aimed to establish the TDS among various malocclusion classes and normal occlusion subjects in a Southern Saudi population. MATERIALS AND METHODS: The study casts of orthodontic patients from Southern Saudi Arabia (mean age: 19.6 years ± 2.45; n = 120) were randomly selected and grouped into eight equal classes based on Angle's classification and gender. An additional 30 study casts, devoid of malocclusion, having excellent intercuspation and class I occlusion, were grouped into two controls (n = 15) based on gender. The study casts were three-dimensional scanned to measure mesiodistal widths of all the teeth. The calculated anterior ratios (AR) and overall ratio (OR) were statistically analyzed with analysis of variance and t-tests. RESULTS: There were no significant differences in "OR" and "AR" between the genders (P > 0.05) and among the malocclusion and control subgroups (P > 0.05). The mean "OR" (92.01 ± 0.18) and "AR" (78.60 ± 0.27) of the malocclusion group were significantly higher than that of Bolton's ratios (P > 0.05). The "AR" of the control group was significantly higher than Bolton's standards (P = 0.048). However, "OR" was no different (P = 0.105). Malocclusion patients displayed a discrepancy (±2 standard deviation) in "AR" of 22.5% and 'OR' of 6.7% from Bolton's mean (BM). Similarly, the control group displayed a discrepancy in "AR" of 20% and "OR" of 10% from BM. CONCLUSION: The mean "OR" and "AR" of the Southern Saudi population showed no sexual dimorphism and no significant difference among various malocclusion and control subgroups. The "AR" of the malocclusion and control subgroups did not comply with Bolton's standards.

Spectrophotometric Analysis of Dental Enamel Staining to Antiseptic and Dietary Agents: In Vitro Study.

RESULTS: The mouthwash containing titanium dioxide (TiO2) nanoparticles produced the greater enamel discoloration compared to that of chlorhexidine. Brushing had little effect on removal of stains induced by all mouthwashes except for dietary solutions (lemon with sodium bicarbonate and olive with laurel) and distilled water (control). CONCLUSION: The results from this study show that mouthwashes containing TiO2 nanoparticles and other antiseptic mouthwashes cause change in color of the teeth and lead to poor esthetic appearance when compared to dietary and control solutions. Thus, future in vivo studies have to be conducted to confirm these findings as in vitro studies may not provide a reliable simulation of the clinical situations.

Marginal and internal fit of provisional crowns fabricated using 3D printing technology.

BACKGROUND: Clinicians routinely provide provisional crowns following teeth preparation. Three-dimensional (3D) printing technology could be used over conventional methods for better fit as lack of adequate fit would result in plaque accumulation, micro-leakage, teeth sensitivity, caries and periodontal diseases. OBJECTIVE: The aim of the study was to evaluate the marginal and internal fit of provisional crowns fabricated using 3D printing technology and to compare it with that of compression molding and milling methods. METHODS: Ninety study models were fabricated by duplicating metal master models of the maxillary first premolar molar with three different finish line chamfer, rounded shoulder and rounded shoulder with bevel. On each study model, provisional crowns were fabricated using compression molding (Mo. group, n= 30 - by over impression technique), milling (Mi. group, n= 30 - by 5-axis dental milling machine), and 3D printing method (3D-P. group, n= 30 - by 3D printer). Marginal and internal fit of the samples were evaluated by measuring gap using a scanning electron microscope with a magnification of 27 ×, at 7 zones A-G on different finish line models. The data were statistically analysed using one-way analysis of variance (ANOVA) at the 0.05 significance level. The p-values were calculated using Dunnett's test. RESULTS: The marginal gap was minimal for the 3D-P. group for each finish line with lowest for rounded shoulder with bevel at zone A 30.6 ± 5.3 and at zone G 32.8 ± 5.4. In axial area, i.e. zones B and F, the minimum gap was noticed for the Mo. group and in Occlusal area (cusp and fossa), for zones C-E maximum gap was determined in Mi. group followed by Mo. and 3D-P. groups. CONCLUSIONS: 3D printed provisional crowns have better marginal and internal fit compared to milled and molded provisional crowns.

Developmental association of palatal dimensions and palatal rugae characteristics in Angle´s classes I, II and III of malocclusion / Asociación de desarrollo de las dimensiones palatinas y las características de las rugas palatinas en las clases I, II y III de maloclusión de Angle

During development, bony changes in the palate are reflected in the palatal rugae. Therefore, we hypothesized that the palatal dimensions (PD) influence the shape and number of palatal rugae (PR). The objectives were to record the palatal rugae characteristics (PRC) and palatal dimensions (intercanine distance (ICD), intermolar distance (IMD), palatal height (PH) and palatal area (PA) in Classes I, II and III malocclusion patients and investigate their interrelationship, and statistically examine the possibility of predicting PRC with the PD. Four hundred eighty-one pre-orthodontic study casts of healthy patients with normal palate anatomy were grouped as Classes I, II and III and scanned using 3D cast scanner. The PRC, ICD, IMD, PH, and PA were recorded digitally using 3D enabled software. The data was statistically analyzed. A strong statistically significant difference was observed between PA and number of straight and wavy rugae. ICD and the number of straight rugae were also related. A weak correlation exists between malocclusion classes and PA. The remaining rugae characteristics did not exhibit any relation with palatal dimensions. PA is positively related to the number of straight rugae and negatively related to the number of wavy rugae. Bigger palates have more straight rugae and less number of wavy rugae. A weak correlation between PA and Angle's class I malocclusion exists. We also propose that PA has a developmental association with the number and shape of PR.

Durante el desarrollo, los cambios óseos en el paladar se reflejan en las rugas palatinas. Por lo tanto, planteamos la hipótesis de que las dimensiones palatinas influyen en la forma y el número de las rugas palatinas. Los objetivos fueron registrar las características de las rugas palatinas y las dimensiones palatales (distancia intercanina, distancia intermolar, altura palatina y área palatina) en pacientes con maloclusión de clases I, II y III e investigar su interrelación, y examinar estadísticamente la posibilidad de predecir las características de las rugas palatinas con las dimensiones palatinas. Cuatrocientos ochenta y un estudios pre-ortodónticos de pacientes sanos con anatomía normal del paladar se agruparon como Clases I, II y III y se escanearon con un escáner de emisión 3D. La distancia intercanina, distancia inter molar, altura palatina y área palatina se registraron digitalmente utilizando el software 3D. Los datos se analizaron estadísticamente. Se observó una diferencia estadísticamente significativa entre la altura palatina y el número de rugas rectas y onduladas. Se registró también la distancia intercanina y el número de rugas rectas. Existe una correlación débil entre las clases de maloclusión y la altura palatina. Las características restantes de las rugas palatinas no mostraron ninguna relación con las dimensiones palatinas. El área palatina está relacionada positivamente con el número de rugas rectas y negativamente relacionada con el número de rugas onduladas. Los paladares más grandes tienen más rugas rectas y menor cantidad de rugas onduladas. Existe una correlación débil entre el área palatina y la clase I de maloclusión de Angle. También proponemos que el área palatina tiene una asociación de desarrollo con el número y la forma de rugas palatinas.

Prevalence of malocclusion, its association with occlusal interferences and temporomandibular disorders among the Saudi sub-population.

AIMS: This Study was conducted to determine the incidence of malocclusion, occlusal interferences, temporomandibular Disorder (TMD) among the Saudi population and to evaluate the possible existence of an association between malocclusion, occlusal interferences and TMD. METHODS: 250 patients attending dental clinics in Abha city, Saudi Arabia for treatment was clinically examined for the degree of malocclusion. Patients were further evaluated for the presence of occlusal interferences and TMD. Data was evaluated by person's correlation and logistic regression to evaluate the association between malocclusion, occlusal interference and TMD. RESULTS: The results of the study indicate 42.8% of the evaluated subjects had a definitive degree of malocclusion. Among the occlusal interference observed, balancing side interferences were high (47.6%), followed by protrusive interferences (41.2%). The prevalence of TMD among the evaluated subjects was 41.6%, with mandibular deviation and joint sounds were most prevalent. Statistical Analysis (Pearson's correlation) showed the statistically significant correlation between malocclusion and centric slide (p-0.030), posterior missing teeth (p-000). The statistically significant correlation was observed between TMD and balanced side interferences (p-0.000), slide RCP-ICP (p-0.001), reduced occlusal contacts (0.033). Logistic regression analysis showed the strong association of TMD with anterior open bite, increased maxillary overjet, balanced side interferences, and centric slide. CONCLUSION: The prevailing malocclusion and TMD among studied population is significantly higher. The preventive dental treatment and community dental education need to be more emphasized.