An in vitro comparative evaluation between virtually planned implant positions on interactive implant software versus actual implant positions achieved using sterolithographic open guide system

Purpose: To evaluate and compare the positional and angular accuracy of virtual implant positions planned on cone-beam computed tomography and final implant positions achieved using a universal open guide system. Materials and Methods: A dual scan of a partially edentulous jaw model along with prosthesis was done, and virtual implant planning was performed. Three implant positions in relation to 35, 36, and 37 were simulated (Group A). In total, 24 implants were placed in eight replaceable bone blocks (Group B) in the same region on the model using an open stereolithographic template. The linear positions and angulation of the placed implants were determined using Vision Measuring Machine. Deviations between virtually planned and surgically placed implants were analyzed in terms of linear and angular measurements. Data were analyzed with the independent-sample t-test with differences P ≤ 0.05 being considered statistically significant. Results: The linear distance (mean ± standard deviation [SD]) in mesiodistal direction between implants in relation to 35 and 36, 36 and 37, 35 and 37 in Group A was 8.79 ± 0 mm, 8.71 ± 0 mm, and 17.50 ± 0 mm, respectively, and in Group B was 7.70 ± 0.58 mm, 8.11 ± 0.30 mm, and 15.80 ± 0.48 mm. All these above values were found to be statistically significant (P ≤ 0.05). The linear distance (mean ± SD) in the vertical direction (mesial) for implants placed in the region of 35, 36, 37 for Group A was 1.51 ± 0 mm, 1.51 ± 0 mm, and 2.47 ± 0 mm, respectively, and for Group B was 1.37 ± 0.32 mm, 1.65 ± 0.48 mm, and 1.79 ± 0.36 mm, respectively. The linear distance (mean ± SD) in the vertical direction (distal) for implants placed in the region of 35, 36, 37 for Group A was 3.37 ± 0 mm, 1.51 ± 0 mm, and 1.51 ± 0 mm, respectively, and for Group B was 1.86 ± 0.48 mm (P ≤ 0.05), 1.56 ± 0.23 mm, and 1.29 ± 0.39 mm (P ≤ 0.05), respectively. The angular deviation (perpendicularity) values for virtually planned implants (Group A) were 90.00° ± 0° and for implants placed in the region of 35, 36, and 37 (Group B) were 84.52° ± 5.4°, 83.57° ± 1.52°, and 80.41° ± 2.37°, respectively, which are highly significant (P ≤ 0.05). Conclusions: The stereolithographic universal open guide used in the study may be considered accurate for placement of implants in mesiodistal position and also in terms of perpendicularity but not in the vertical position. Stereolithographic open guide may be recommended for more accurate implant position, especially for the placement of multiple implants.

Evaluation of the marginal fit of metal copings fabricated on three different marginal designs using conventional and accelerated casting techniques: An in vitro study.

Introduction: Abundant resources and techniques have been used for complete coverage crown fabrication. Conventional investing and casting procedures for phosphate-bonded investments require a 2- to 4-h procedure before completion. Accelerated casting techniques have been used, but may not result in castings with matching marginal accuracy. Aims and Objectives: The study measured the marginal gap and determined the clinical acceptability of single cast copings invested in a phosphate-bonded investment with the use of conventional and accelerated methods. Materials and Methods: One hundred and twenty cast coping samples were fabricated using conventional and accelerated methods, with three finish lines: Chamfer, shoulder and shoulder with bevel. Sixty copings were prepared with each technique. Each coping was examined with a stereomicroscope at four predetermined sites and measurements of marginal gaps were documented for each. Statistical Analysis: A master chart was prepared for all the data and was analyzed using Statistical Package for the Social Sciences version. Evidence of marginal gap was then evaluated by t-test. Analysis of variance and Post-hoc analysis were used to compare two groups as well as to make comparisons between three subgroups . Results: Measurements recorded showed no statistically significant difference between conventional and accelerated groups. Conclusion: Among the three marginal designs studied, shoulder with bevel showed the best marginal fit with conventional as well as accelerated casting techniques. Accelerated casting technique could be a vital alternative to the time-consuming conventional casting technique. The marginal fit between the two casting techniques showed no statistical difference.

Women and tobacco: A total misfit or mis-unfit.

Women smokers are likely to increase as a percentage of the total. If the percentage of women who smoke in developing countries rise to the levels of men smokers, there will be more than 500 million women smokers in the next generation. Because women who smoke die from the same tobacco-caused diseases as men, such an increase will have dramatic effects on women's health and on the health and incomes of their families. In addition, women smokers are also at risk for developing cancer of the reproductive organs and osteoporosis. A gender perspective contributes to a better understanding of the epidemiological trends, social marketing strategies, economic policies, and international actions relating to women and the tobacco epidemic.

Oxidation heat treatment affecting metal-ceramic bonding.

Aim of the Study: There is dearth of literature regarding the effects of oxidation heat treatment (OHT) as surface pretreatments on bond strength of base metal alloys and porcelain. Materials and Methods: Forty-five bar specimens of each two commercially available base metal alloys Mealloy and Wirorn-99 (were fabricated. Dimensions of each specimen were 15.0 × 2.0 × 0.5 mm (according to the ISO 6872-1984). According to the surface pretreatments the samples of the two groups were categorized into three subgroups: With OHT only, with sandblasting only (with Al 2 O 3 of 110 μm) and with OHT and sandblasting. Application of commercially available Duceram porcelain in thickness of 2.00 mm was applied over the surface of metal with the pretreatments. Samples were then placed under SEM for EDX examination to evaluate ionic changes that occurred at the metal-ceramic interface. Flexural bond strength of each sample was calculated under Universal Testing Machine. Results: The one-way ANOVA indicated no significant influence of either metal type (P=0.811) or any surface pretreatment (P=0.757) on the metal-ceramic bond strength. Conclusion: OHT resulted in the increase in amount of oxides at the metal-ceramic interface. However, neither metal type nor surface pretreatments affected bond strength.

A Clinical Study To Evaluate Tooth Contact Patterns And Correlation With Masticatory Efficiency in Dentulous Subjects.

A variety of functional tooth contact patterns exist in population of young adult patients.The purpose of the present study is to find the relationship between different lateral tooth contact patterns and dental morphology and their effect on masticatory efficiency. Forty young dentulous subjects were selected and their impression with irreversible hydrocolloid was made. Polyvinyl silicone bite registration paste was used to record lateral tooth contact patterns in functional range of mandibular movement. Overjet and overbite including mesiodistal relation of tooth recoded with cast secured in the intercuspal position and masticatory efficiency was determined by calorimetric method by using raw carrot. Among all subjects 15% having canine protection, 55% group function, and 30% balance occlusion. There is positive correlation between age and masticatory efficiency [r=+0.656, p<.01] and negative correlation between overjet and masticatory efficiency [r=-0.409, p<0.01]. In the present study Canine protection occlusion had significantly lower mean masticatory efficiency than group function and balanced occlusion group. This signifies that the masticatory efficiency is dependent on lateral tooth contact patterns.

Secondary bone grafting in cleft lip and palate with eruption of tooth into the graft: a case report.

Secondary bone grafting in cleft lip and palate patients is performed preferably before the eruption of permanent canine in order to provide adequate periodontal support for eruption and preservation of the teeth adjacent to the cleft. Presented here with is a case of unilateral cleft lip and palate, which was followed up from birth to 15 years of age. The role of an orthodontist in the team approach for management of such anomalies is described. Also discussed in detail is the entire range of treatment procedures the child underwent, especially the role of secondary bone grafting.

Dentofacial characteristics in Apert syndrome: a case report.

Apert's syndrome is a developmental malformation characterized by craniosynostosis, a cone shaped calvarium, midface hypoplasia, pharyngeal attenuation, ocular manifestations and syndactyly of the hands and feet. The prodromal characteristic for the typical craniofacial appearance is early craniosynostosis of the coronal suture, cranial base and an agenesis of the sagittal suture. These craniofacial characteristics predispose the patient to maxillary transverse and sagittal hypoplasia with concomitant dental crowding, a pseudo cleft palate and a skeletal and dental anterior open bite. A case of Apert syndrome is presented with special emphasis on craniofacial characteristics and multidisciplinary approach to treatment. The differences between Apert and Crouzon's syndrome are highlighted.