Polishing is taken up as an alternative to reglazing after adjustments of glazed ceramic prosthesis. An in vitro study was carried out to evaluate three different ceramic polishing systems and their combinations to identify a method that would achieve surface smoothness superior to the glazed surface. 77 glazed feldspathic porcelain disc surfaces, of diameter 12.5 mm and thickness 2 mm were constituted into seven groups of 11 specimen surfaces each. The glazed surfaces in the first group served as control (C). They were not subjected to deglazing or polishing. The remaining 66 surfaces underwent deglazing. The deglazed surfaces in the second group (D) were retained as such and did not undergo polishing. The deglazed surfaces in the third group (Wh), were polished using a polishing wheel (CeraMaster). In the fourth group (K), an adjustment kit (Porcelain Adjustment kit) was used for polishing the deglazed surfaces. The fifth group (Wx) was polished with diamond particle-impregnated wax (Dura-Polish Dia). In all these three groups, polishing was done for 40 s. The deglazed surfaces of the sixth group (WhWx) were polished initially with polishing wheel for 40 s and then with diamond particle-impregnated wax for 40 s. In the seventh group (KWx), the deglazed surfaces were polished with an adjustment kit (Porcelain Adjustment kit) for 40 s followed by diamond particle-impregnated wax (Dura-Polish Dia) for 40 s. In the sixth and seventh groups, the total polishing time was 80 s each. From each group, one specimen was set aside for scanning electron microscopy (SEM). The remaining ten specimens in each group underwent colorimetry and profilometry. Colorimeter (Minolta CR-200b ChromaMeter; Minolta, Osaka, Japan) was used to measure parameters according to CIE L*a*b* colour system and colour difference (ΔE) between control and other groups were calculated. Profilometer (Talysurf CLI 2000) was used to measure the surface roughness (Ra). The data were statistically analysed by one way ANOVA and Tukey HSD tests. The colour differences were well within the acceptable range of 3.3 units in groups subjected to polishing. Polishing with porcelain adjustment kit alone, diamond particle-impregnated wax alone or polishing wheel followed by diamond wax created surfaces with smoothness comparable to the glazed surfaces. The group polished by adjustment kit followed by diamond particle-impregnated wax showed surface roughness significantly less than the glazed surfaces. The SEM observations were corroboratory. It can be concluded that polishing with porcelain adjustment kit followed by diamond particle-impregnated wax, created surfaces significantly smoother than the glazed specimens with no significant negative effect on colour and thus can be a technique superior to glazing.

Aim: To systematically review the reported techniques, for evaluating the risk and difficulty encountered in the management of fractured abutment screw in accordance with the location of fracture, and to develop a logical sequence in managing an implant abutment screw fracture. Settings and Design: Systematic review following PRISMA guidelines. Materials and Methods: A systematic search of the PubMed/MEDLINE database for articles published between January 2000 and March 2020 was performed by 2 independent reviewers. Case reports and case series that described the management of fractured implant abutment screw were included. Published articles were qualitatively analyzed employing CARE guidelines and were classified according to the location of screw fracture with respect to implant platform, risk of damage to the implant, and intervention for managing the fractured screw. Statistical Analysis Used: Qualitative analyisis. Results: A total of 28 articles were included in the review. Two of them explained the management of screw fracture at or above the implant platform and required only mild approach with low risk while the others explained the management of screw fracture below the level of implant platform. Among them, 6 were considered mild approach with low risk, 13 moderate approach with moderate risk, and 8 of them severe approach with high risk. Conclusion: Irrespective of the technique, any attempt to retrieve abutment screw fragment poses some risk to the implant which is varying from mild to severe. As the location of fracture is more gingival to the implant platform, difficulty of retrieval as well as risk to the implant increases. The proposed decisionmaking tree will be a useful tool in helping clinicians to manage abutment screw fracture.

No abstract

Physiologic rest position of the mandible is an important parameter to be considered in the fabrication of a complete denture as well as in a case of full mouth rehabilitation. Violation of the rest position would lead to detrimental effects on the facial musculature and the temporomandibular joint. This article reviews the various concepts pertaining to the rest position of mandible and its clinical implication.

Aims and objectives: To determine and compare the retention of different esthetic post systems within the root canal, i.e., zirconium dioxide ceramic post (Zr post) (Cosmopost Ivoclar Vivadent) and glass fiber-reinforced composite post (FRC post) (Twin Luscent Anchor, Dentatus, USA), and the effect of increase in diameter and different surface treatments on the retentivity of these posts. Materials and methods: A total number of 24 prefabricated endodontic posts, including 18 Zr post and six glass FRC post, were used for the study. Two diameters of Zr post, i.e., 1.4 and 1.7 mm, and two diameters of FRC post, 1.3 and 1.6 mm, were used. The Zr posts were divided into three main groups and subjected to three different surface treatments. The first group (group I) served as the control group and was given no surface treatment; instead, it was used as obtained from the manufacturer. The second group (group II) was given a surface treatment of airborne particle abrasion using 110 µm alumina particles. The third group (group III) was ground evenly with a coarse grit diamond bur mounted on a high-speed handpiece. The fourth group (group IV) constituted the FRC post and this group of posts was not given any surface treatment. Thus, the total sample size was fixed as 24 with 6 each to groups I, II, III, and IV. In each of these four groups, three posts each will be with 1.4 and 1.7 mm diameter, respectively. These samples were tested for retentivity, in an Instron universal testing machine. Results: One-way analysis of variance (ANOVA), small sample Student's t-test, and Pearson correlation coefficient were the statistical tools employed to analyze the observations. The glass FRC post group IV were reported to have the greatest retentivity, followed by group II. When airborne particle abrasion with 110 µm alumina on the Zr posts significantly improved its retention, and were related in a linear fashion, the surface roughening with coarse diamond bur on Zr post failed to do so. Both groups I and III did not show any increase in retentivity with an increase in the diameter. Group IV showed an increase in retentivity when the diameter of the posts was increased. Conclusion: Clinical implications of the study are that in highly demanding situations of esthetics and fracture, the zirconium dioxide ceramic post after airborne particle abrasion with 110 µm alumina is a promising restoration, provided the individual is not a bruxer or engaged in sports where there is a risk of tooth fracture. Even though zirconia post showed better fracture resistance than glass fiber-reinforced posts, the cost factor, retention, and its free availability make the glass FRC posts a promising endodontic restoration for badly damaged teeth.