Correlation of "K" plane to occlusal plane and three different ala-tragal lines in dentulous subjects with different skeletal forms: A cephalometric study.

Aim: Orientation of the occlusal plane is an important clinical procedure for complete denture fabrication. An attempt had been made to reconstruct the occlusal plane using a different reference plane. The aim of this study was to find the correlation of the "K" plane to the occlusal plane and to assess the angular deviation between the K-plane to the occlusal plane (KO) with different skeletal forms. Settings and Design: An in vivo observational study was conducted on dentulous subjects having Class I dental occlusion with different skeletal forms undergoing orthodontic treatment. Materials and Methods: The study was conducted on 54 subjects aged 18-30 years. Metallic balls (3 mm in diameter) were attached to the desired landmarks, and a lateral cephalogram was taken for each subject. Cephalometric analysis was done using the Dolphin Imaging software, and the values obtained were recorded and subjected to statistical analysis. Statistical Analysis Used: The values obtained were recorded and subjected to statistical analysis using simple descriptive analysis, Shapiro-Wilk test, Mann-Whitney U-test, and Pearson's correlation. Results: A positive correlation was found between KO with a mean angular deviation of 8.59° ± 3.05°. The angle was found to be steeper in skeletal Class II subjects. Conclusions: Clinical application of the K-plane to use as a reference plane to orient the posterior occlusal plane can enhance the treatment outcome for a removable prosthesis. The results of this study provide a theoretical foundation for the practical restoration of the occlusal plane in different skeletal forms.

Evaluation of the marginal fit of full contoured zirconia, lithium disilicate and metal crowns fabricated using CAD-CAM: An in vitro study.

Introduction: The marginal fit of any dental restoration is vital to its long-term success. Lack of adequate fit is potentially detrimental to both the tooth and the supporting periodontal tissues. The purpose of this study was to evaluate the marginal fit of monolithic zirconia, monolithic lithium disilicate and monolithic metal crowns and compare the three groups. Methods: The study was conducted by fabricating ten samples for each group, total of 30 samples. A premolar stainless steel die was used to standardize the preparation. PVS putty material was used to make impressions of the model and was poured using type IV die stone. The samples were all fabricated using CAD-CAM. The marginal gap was measured by SEM, and the results were analysed using SPSS software. Results: The mean marginal gap of zirconia, metal and lithium disilicate crowns was 79.49 µm, 46.83 µm and 70.79 µm, respectively. Discussion: The metal group showed the lowest marginal gap among the groups. This difference in marginal fit is due to the sintering process where the organic binders in soft metal burn out and the metallic powder particles are being sintered (caked) without creating a fused phase. Clinical Significance: Marginal fit plays a very important role in the long-term success of a crown. Discrepancy in marginal fit results in food and plaque accumulation causing caries and periodontal breakdown, eventuating the failure of the restoration. A perfect marginal fit would enhance the longevity of any indirect restoration. Knowledge about which indirect restoration has the best marginal fit is critical.

Influence of Aerated Drink, Mouthwash, and Simulated Gastric Acid on the Surface Roughness of Dental Ceramics: A Comparative In Vitro Study.

BACKGROUND: Dental ceramics are known for their natural appearance and their durable chemical and optical properties, and their uses mainly reflect their excellent aesthetic properties, biocompatibility and resistance to wear. In addition, dental ceramics are considered to be chemically inert restorative material with large differences in the chemical compositions and microstructures. Although ceramics exhibit excellent physical properties and biocompatibility, the oral environment presents a series of external factors that affect its physical and mechanical properties in its long term function. AIMS AND OBJECTIVES: The aim of this study is to compare and evaluate the surface roughness of 2 dental ceramics (Noritake® & IPS Emax ceram) before and after exposure to an aerated drink, a mouthwash and simulated vomit solution with distilled water. MATERIALS AND METHODS: 128 ceramic discs were made, 16 for each of the 4 groups of 2 ceramics to be tested. It was fabricated in the form of discs of diameter 10 mm × 2 mm thickness. The test specimens were calibrated by grinding, using a medium grit diamond bur. Both the above specimens were divided into 4 groups of 16 each. They were then subjected to test solutions. Each specimen in a group was immersed in the following solutions: Coca-Cola, chlorhexidine mouthwash, simulated vomit solution and distilled water. RESULTS: The results analyzed statistically using one way ANOVA (analysis of variance), paired t test and independent t test. CONCLUSION: Within the limitations of this study, it was concluded that the surface roughness of the evaluated ceramics increased upon exposure to Coca-Cola, chlorhexidine mouthwash and simulated vomit solution. Simulated vomit solution caused the maximum change in surface roughness followed by coca cola and then chlorhexidine mouthwash. No changes were observed after immersion in distilled water. Noritake® showed slightly more resistance to change in surface profile when compared to IPS e.max.

Hearing Assessment of Dental Personnel: A Cross-sectional Exploratory Study.

AIM: Dental professionals are prone to have hearing impairment due to prolonged exposure of noise in dental college. The aim of the study was to assess the hearing ability of dental personnel working in Yenepoya Deemed to be University, Mangaluru, Karnataka, India. MATERIALS AND METHODS: A cross-sectional exploratory study was conducted on 60 subjects (30 male and 30 female). Audiometric analysis was carried out using pure-tone audiometry (PTA) and otoacoustic emission test (OAE). STATISTICAL ANALYSIS: Data were calculated and analyzed using two-way analysis of variance and Tukey's honestly significant difference test. RESULTS: No statistically significant difference was observed between hearing loss and its association with age, gender, working experience, mean daily working time, and specialization. PTA results showed a statistically significant hearing loss in the left ear, showing a dip at frequency of 4000 Hz among working experience group of 11-15 years and at 6000 Hz for 21-25 years. Also, a statistically significant hearing loss was observed in the left ear at 6000 and 8000 Hz for the age-group of 51-55 years. OAE results were consistent with PTA findings. CONCLUSION: Dentists and dental personnel are at a higher risk of noise-induced hearing loss. As the working experience increases, the threshold shift is seen to shift from 4000 to 6000 Hz, which is indicative of sensorineural hearing loss due to noise-induced dental environment.

A Novel Design Modification to Improve Flexural Strength of Zirconia Framework: A Comparative Experimental In Vitro Study.

AIM: Zirconia-based restoration is successfully replacing metal ceramic restorations in posterior areas. Although higher mechanical properties of zirconia, their use in compromised situation is questionable. Hence, there is a need to modify the design which to strengthen the framework. The aim of this in vitro study was to evaluate the influence of lingual collar design on the flexural strength of CAD/CAM-fabricated posterior three-unit zirconia framework. MATERIALS AND METHODS: A mandibular metallic stainless steel master mold is designed for a three-unit fixed partial denture framework. All CAD-milled 20 samples are divided into two groups based on the design. Group A--with collar (10 samples) and Group B--without collar (10 samples), tested using universal testing machine to calculate the mean fracture load and flexural strength. STATISTICAL ANALYSIS USED: Descriptive statistics and independent sample t test were used to find the difference between the groups, and simple linear regression was used to find the relationship between load and displacement between the groups. RESULTS: The result of the mean flexural strength for Group A was 11328.06 ± 3770MPa and for Group B was 7633.95 ± 3196MPa; the mean fracture strength observed for Group A was 1274.04 ± 424MPa and for Group B was 858.80 ± 359MPa. A statistically significant difference was observed in flexural strength between Groups A and B (P < 0.05). CONCLUSION: Zirconia framework with connector dimension of 7 mm2 with lingual collar design can be successfully incorporated in compromised situation where an ideal connector dimension of 9 mm2 cannot be placed.

Comparison of the Bond Strength of Composite Resin to Zirconia and Composite Resin to Polyether Ether Ketone: An In Vitro Study.

AIM: The aim of the study was to compare the shear bond strength of composite resin bonded to polyether ether ketone (PEEK) and zirconia, and also to evaluate the effect of thermocycling on the shear bond strength. MATERIALS AND METHODS: A total of 22 zirconia (Group 1) and 22 PEEK (Group 2) specimens (disks of 10 mm in diameter and 10 mm in thickness) were machine milled using computer-aided design (CAD)/computer-aided manufacturing (CAM) from commercially available zirconia and PEEK. These specimens were air abraded with 110-µm aluminum oxide. Following which these two groups were subdivided into four groups, that is, Group 1A: 11 zirconia specimens before thermocycling, Group 1B: 11 zirconia specimens after thermocycling, Group 2A: 11 PEEK specimens before thermocycling, and Group 2B: 11 PEEK specimens after thermocycling. These four groups of specimens were embedded in an acrylic block, and bonding agent was applied over the upper surfaces of the disks of each of these specimens. Composite resin was then cured, and then Group 1B and group 2B were thermocycled under a standard temperature. The bond strength of the specimen was tested using universal testing machine. RESULT: The result showed that there was no significant difference in shear bond strength between the groups, although higher shear bond strength was observed in the PEEK group. CONCLUSION: Shear bond strength of PEEK is similar to zirconia. The results suggest that the pretreatment method and primers used were effective in improving the bonding of resin cements to zirconia ceramic and the bonding properties of the veneering resin to the PEEK surface.

A Study to Assess the Bond Strength of Acrylic Teeth With Different Retentive Features.

BACKGROUND AND AIM: Flexible denture base has been gaining attention as a denture base material because of its toxicological safety, comfort, and enhanced aesthetics. Debonding of acrylic teeth from the flexible denture base material has posed a great problem to the clinician and patient. This study aimed at comparing the bond strength between flexible denture base with acrylic teeth having different mechanical modifications. MATERIALS AND METHODS: Forty mandibular molar teeth (Combination Acry Rock, Badia Polesine (Ro), Italy) were used in four groups for mechanical modifications on the ridge lap area. The groups were group 1 (no mechanical modifications), group 2 (round groove 2 mm in diameter and 2 mm deep on the ridge lap surface), group 3 (horizontal slot 2 mm deep, 2 mm wide, and 4 mm long prepared on the ridge lap surface of the teeth), and group 4 (T-shaped groove 2 mm deep, 2 mm wide, and length of 4 mm mesiodistally and 2 mm buccolingually prepared with a straight fissure bur). The acrylic teeth were attached to a wax block of dimension 1.2 cm × 1.2 cm × 2.5 cm. These were flasked and dewaxed, followed by injection molding with Valplast flexible denture base material. The bond strength was assessed by attaching the specimens to universal testing machine tested under a tensile load at a cross-head speed of 1 mm/min till it fractured. Data obtained were statistically evaluated by one-way analysis of variance and post hoc test. RESULTS: There was significant increase in mean bond strength after various mechanical modifications. Group with T-shaped diatoric hole showed greatest bond strength value compared to other groups. CONCLUSION: Incorporating mechanical retentive features with increased surface area and undercut can improve the bonding of acrylic teeth to flexible denture base.

Influence of Different Zirconia Coping Designs on the Fracture Resistance of All-Ceramic Crowns: An In Vitro Study.

BACKGROUND AND AIM: Increased demand for metal-free restorations in posterior areas has increased the focus on zirconia restorations because of its advantages in excellent mechanical properties, patient comfort, and acceptance. Although all-ceramic crowns have better biocompatibility and esthetic properties, there are some clinical reasons for the fracture of the veneer or the core materials in the posterior region. This study aims at comparing the influence of zirconia coping designs on the fracture resistance of all-ceramic crowns. MATERIALS AND METHODS: A total of 32 zirconia copings (n = 8 for each group) were designed and fabricated based on the marginal collar height of zirconia coping. The groups were the following: Group 1: 0.0 mm zirconia coping; Group 2: 0.5 mm collar; Group 3: 1.0 mm collar; and Group 4: 1.5 mm collar. All these zirconia copings were veneered with porcelain. Master die with cemented ceramic-layered zirconia copings was tested using Universal testing machine. Data obtained were statistically evaluated by one-way analysis of variance and post hoc test. RESULTS: There was statistically significant difference between the groups with P < 0.001. Group 4 has the highest strength (3318.89 ± 395.67) followed by Group 3 (2910.0 ± 219.22), then Group 1 (2320.02 ± 547.36) that is the control group and the least strength with Group 2 (2286.59 ± 496.66). CONCLUSION: On the basis of the results obtained from this study, it can be concluded that, the more the height of the zirconia collar, the higher the fracture strength of the all-ceramic crowns. Thus ceramic-layered zirconia coping design with 1.5 mm marginal collar height is recommended for functional long life, at least in the posterior higher load-bearing areas with lesser esthetic demands.

Evaluation of Fracture Resistance and Color Stability of Crowns Obtained by Layering Composite Over Zirconia and Polyetheretherketone Copings Before and After Thermocycling to Simulate Oral Environment: An In Vitro Study.

BACKGROUND: Most common material used for the fabrication of an implant restoration is full-ceramic crown or an all-ceramic crown. Frequent chipping of the ceramic under occlusal load has posed a great problem to the clinician and the patient. Composites have been layered over zirconia successfully in the recent past to overcome this problem. This study, thus, aimed to evaluate and compare the fracture resistance and color stability of crowns obtained by layering composite over zirconia and polyetheretherketone (PEEK) copings before and after thermocycling to simulate oral environment. MATERIALS AND METHODS: A total of 40 crowns (20 per group) were obtained by layering composite of A3 shade over computer-aided design/computer-aided milling milled zirconia and PEEK copings. Thermocycling of the 10 out of the 20 crowns was performed in a thermocycler (5000 cycles, in water temperature of 5°C and 55°C with dwell time of 30s), and then they were kept in hot and cold beverages for 24h each, to simulate oral environmental conditions. After thermocycling, the crowns were divided into four groups of 10 samples each: Group Z, ZT, P, and PT. Shade evaluation of all the crowns was performed using digital shade guide (VITA Easyshade® Advance; VITA Zahnfabrik, Bad Säckingen, Germany) and VITAPAN classical (VITA Zahnfabrik). Fracture strength was tested for all the crowns in a universal testing machine. Fracture strength in megapascal and the applied occlusal load in kilograms were recorded. Data obtained were statistically evaluated by one-way analysis of variance and post hoc test. RESULTS: The final shade of the crowns obtained by layering A3 shade composite in the groups Z was A3, ZT was B3, P was C3, and PT was D2. The value of mean fracture strength of crowns of groups Z was 1142.3MPa, ZT was 1034.57MPa, P was 2134.64MPa, and PT was 1765.01MPa. CONCLUSION: Thermocycling affected the shade of all the crowns. The mean fracture strength of the crowns having PEEK copings was significantly higher than that of zirconia copings. Thermocycling did not have a significant effect on the mean fracture strength.

Assessment of Periodontal Disease Among the Dental Prosthetic and Nonprosthetic Wearers in an Adult Rural Population in Mangalore Taluk, South India.

BACKGROUND: Oral health as an integral part of general health. Rural population neglect oral health as they lack awareness on oral diseases and also due to inadequate availability of dental services. There is a very high prevalence of chronic inflammatory periodontal disease in the rural Indian population, which is left untreated. Hence, this cross-sectional survey was taken up in the rural area of Mangalore taluk, Karnataka, India. MATERIALS AND METHODS: A cross-sectional survey was carried out on 1312 participants aged 18 years and older. The prevalence of periodontal disease among the dental prosthetic and nonprosthetic wearers was assessed. The World Health Organization format was used to record the periodontal status and loss of attachment. Data collected were analyzed using chi-square test. P < 0.05 was considered as significant. RESULT: Of the 1312 included subjects, 520 were males (39.6%) and 792 were females (60.3%). Periodontal status showed that calculus was found to be high among all age groups. When the prevalence of periodontal disease was assessed among the prosthetic wearers, it was found that subjects wearing removable partial denture showed increased prevalence of periodontal pocket depth and attachment loss irrespective of age group, gender, and educational qualification. CONCLUSION: Lack of awareness among the individuals regarding periodontal diseases has been associated with consistently higher prevalence of periodontal diseases and treatment needs. Demographical studies need to be carried out at regular intervals, thus helping in planning the treatment needs nationwide for better oral health care in rural population.

Median Nerve Injury following K-wire Fixation of Bennett's Fracture-Lessons Learned.

Bennett's fracture is a relatively common injury. The fracture is unstable due to the displacing forces acting on the distal fragment and very commonly treated by stabilization with Kirschner wires. This would seem a relatively safe procedure, and injury to the median nerve has never been reported. We present this unusual complication following one such procedure with the evaluation of a safe approach utilizing the relevant surgical and radiological anatomy.

Fatal pulmonary embolism following shoulder arthroplasty: a case report.

INTRODUCTION: Fatal pulmonary embolism following a shoulder joint replacement is a rare event. The exact prevalence of shoulder arthroplasties is not clear. Unlike hip and knee joint replacements where some form of thromboprophylaxis is routinely prescribed, no such guidelines and practice exist for shoulder replacements. Other case reports have confirmed fatal and non-fatal pulmonary embolisms following shoulder replacements, but particular risk factors were identifiable in those patients. CASE PRESENTATION: We report the case of a 73-year-old Caucasian woman with fatal pulmonary embolism secondary to a calf deep vein thrombosis following a shoulder joint replacement procedure. The patient was otherwise healthy; there were no other risk factors directly contributing to deep vein thrombosis and pulmonary embolism except for a body mass index of 34. Post-mortem examination confirmed that the patient had a thrombus in the calf and a pulmonary embolus. CONCLUSIONS: Fatal deep vein thrombosis and pulmonary embolism can occur following shoulder joint replacements in otherwise normal patients. A high degree of suspicion should therefore be maintained in susceptible individuals. Thromboprophylaxis needs careful consideration in shoulder replacements in susceptible individuals.