Alex Mathews Muruppel

Background: Retention and resistance forms are the characteristics of a preparation that prevent castings from becoming uncemented, debonded, or cement failures, which are one of the top three reasons for the replacement of castings Aim: This study aims to discern an actually achieved degree of taper in a clinical situation, and the textbook recommended degree of taper. Furthermore, it also assessed how resistance and retention form correlate with the degree of taper of tooth preparation. Materials and Methods: Scanned digital images of 114 die preparations for all ceramic restorations (n = 114) were collected from a dental laboratory. All the images were also analyzed digi- tally using Adobe Photoshop® software to analyze the degree of taper (angle of convergence) of each preparation and then applied the Zuckerman’s circle, and the Lewis perpendicular methods were used to measure the resistance form. Results: For the current study, the overall average degree of taper was found to be 20.9° (range, 2–80°), which is more than what is recommended by most previous studies and also sharply greater than the textbook ideal of 3 to 6°. Mean degree of taper for maxillary was 17.56° (anterior—10.50°, posterior—23.7°), and for mandibular teeth, it was 25.22° (anterior—15°, posterior—28.45°). Out of the 64 analyzed images of maxillary teeth, 61 presented resistance form, while 3 were without it. Out of the 50 mandibular teeth analyzed, 38 possessed resistance form, whereas 12 were without. All the anterior teeth showed resistance form irrespective of the arch. Conclusion: The degree of taper showed a significant relation- ship with resistance and retention form, which was inversely proportional to each other. The recommended “degree of taper” is not always the clinically achievable as advocated in textbooks, as it is modified by various factors in the actual clinical situation. Clinical Significance: The study provides scientific background regarding the relationship between the degree of taper with resistance and retention form, and the relationship was found to be inversely proportional to each other. The recommended “degree of taper” is not always the clinically achievable as advocated in textbooks, and it is modified by various modifying or limiting factors in the actual clinical situation.

Background: Gingival hyperpigmentation is a major concern for a significant number of patients, as a relevant aesthetic or cosmetic need. Oral melanin pigmentation is considered to be multifactorial and could be related to physiological or even pathological reasons and can be the consequence of a variety of local or systemic factors. This pigmentation varies individually across races or age groups and is without any gender predilection. Evidence gleaned from literature is presented from case–control studies and from the authors’ own research work in prospective, split-mouth, double-blinded, clinical trials comparing treatment modalities in effecting depigmentation. Methods: A systematic review of published articles, using suitable assay criteria, was carried out to formulate a consensus on laser-assisted modalities. A total of 295 published sources were subject to critical analysis and resulted in six papers that were subject to data scrutiny. Additionally, evidence is presented on clinical protocols and treatment outcomes. Results: Analysis of randomized clinical studies identified the use of two laser wavelength groups—near infrared diode and erbium group of mid-infrared lasers. Several areas of analysis were examined, and inconsistent degrees of significance were obtained to establish which laser group was optimal and if they were any better than scalpel depigmentation. Conclusion: A definitive conclusion is wanting as studies with scientific and standardized protocols of evaluation are yet to provide a take on comparative assessments between different techniques of depigmentation.

This in vitro study was designed to evaluate and compare the effectiveness of a dentifrice containing 8% arginine and calcium carbonate, diode laser (810 nm) and the combined use of diode laser (810 nm) and the same dentifrice in occluding dentinal tubules. Forty sectioned dentine discs were observed in this study. The Samples were randomly divided into 4 groups. In group A, a dentifrice containing arginine and calcium carbonate was applied. In group B, the specimens were subjected to diode laser (810 nm) irradiation. In group C, the same dentifrice was applied and the specimens were subjected to diode laser (810 nm) treatment. Group D was left untreated and served as the control. The specimens were observed under the scanning electron microscope. Then the photomicrographs of each specimen were taken which were uploaded into Photoshop 7®, and the diameters of the dentinal tubules of each specimen were measured and the data were analyzed statistically. The overall comparison between different treatment modalities using one-way analysis of variance (ANOVA) and multiple comparisons of two modalities assessed using post hoc Tukey method revealed that there is a highly significant difference (p value = 0.0001) in the dentinal tubule diameter and rate of occlusion in different treatment modalities. The study concluded that all three treatment modalities caused significant occlusion of dentinal tubules. The combined use of desensitizing toothpaste and diode laser (810 nm) is the most effective, then comes the diode laser (810 nm) alone and finally the desensitizing toothpaste alone. This study suggests an effective treatment of dentinal hypersensitivity using diode laser and desensitizing toothpaste.

Aim: This in vitro study evaluated the resistance form of die preparations for all ceramic restorations and, thereby, explored the concept of effective taper and its correlation between the ideal in theory and actual in the clinical situation by analyzing the digital images of the die preparations. Materials and methods: Scanned digital images of 114 die preparations for all ceramic restorations (n = 114) were collected from a dental laboratory. All the images were also analyzed digitally using Adobe Photoshop^® software to analyze the degree of taper (angle of convergence) of each preparation and then applied the Zuckerman's circle, and the Lewis perpendicular methods were used to measure the resistance form. Results: For the current study, the overall average degree of taper was found to be 20.9° (range, 2—80°), which is more than what is recommended by most previous studies and also sharply greater than the textbook ideal of 3 to 6°. Mean degree of taper for maxillary was 17.56° (anterior—10.50°, posterior—23.7°), and for mandibular teeth, it was 25.22° (anterior—15°, posterior—28.45°). Out of the 64 analyzed images of maxillary teeth, 61 presented resistance form, while 3 were without it. Out of the 50 mandibular teeth analyzed, 38 possessed resistance form, whereas 12 were without. All the anterior teeth showed resistance form irrespective of the arch. Conclusion: The degree of taper showed a significant relationship with resistance and retention form, which was inversely proportional to each other. The recommended “degree of taper” is not always the clinically achievable as advocated in textbooks, as it is modified by various factors in the actual clinical situation. Clinical significance: The study provides scientific background regarding the relationship between the degree of taper with resistance and retention form, and the relationship was found to be inversely proportional to each other. The recommended “degree of taper” is not always the clinically achievable as advocated in textbooks, and it is modified by various modifying or limiting factors in the actual clinical situation. How to cite this article: Muruppel AM, Thomas J, Saratchandran S, Nair D, Gladstone S, Rajeev MM. Assessment of Retention and Resistance Form of Tooth Preparations for All Ceramic Restorations using Digital Imaging Technique. J Contemp Dent Pract 2018;19(2):143-149.

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This review article first delves into the intricacies and basic mechanisms of photobiomodulation as proven by scientific research. This paper intends to give insights into studies correlating photobiomodulation in the sphere of osseointegration and bone regeneration, which are as yet evidence based in peer reviewed literature. The assimilated and collated matter is from five electronic databases (MEDLINE, EMBASE, PubMed, CINAHL, and Cochrane Database of Randomised Clinical Trials) and is a studious inquiry into both clinical and laboratory studies. The search criteria used keywords of “Photobiomodulation,” “Biostimulation,” and “low level laser therapy (LLLT)” in association with the term “Osseointegration.” The search was based on whether the studies hinged on the use of photobiomodulation or LLLT in the in vivo or in vitro effects on implant integration, bone healing around implants, cell culture on implant material, and the dosage and time of therapy. The search yielded 42 studies out of which 37 met the criteria for selection. Excluded studies differed from the primary objective of applying low level laser therapy to effect a biologic modulation on the body's own healing and reparative mechanisms. This review conclusively demonstrates the effectiveness of treatment protocols of photobiomodulation for osseointegration, specifically toward biostimulatory effects on cells and their interactions with implant surfaces and substantiates evidence of a bimodal or biphasic response of dosage and energy levels.