Precision Attachments for Aesthetics and Function: A Case Report Dentistry Section

ABSTRACT Successful restoration of the dentition requires plenty of contem porary and conventional treatment techniques and planning and attachment retained partial dentures are one such kind of treatment modality in prosthodontics. Limited space for extracoronal attachments is a serious gap in the design and the fabrication of a precision attachment Removable Partial Denture (RPD). A custom semi-precision attachment with a partial denture offers strength and improved aesthetics in cases with minimal space. This article presents a method of fabrication of semi-precision attachment to eliminate metal display and enhance aestheticity. CASe RepoRT A 38-year-old female was presented to the Department of Prosthodontics, with a failing dentition. Examination revealed that some of the teeth required conservative and endodontic treatment. There was reduced vertical facial height due to loss of mandibular posterior teeth. She was diagnosed for full-mouth rehabilitation. According to the Kennedy's Classification System and Applegate's rules, the maxillary partially edentulous arch was classified as Class III and the mandibular arch as Class I [Table/ Patient was advised to wear the interim removable prosthesis with an increased vertical dimension for 1 month, to determine the appropriate vertical dimension. Restorative and endodontic treatment procedures were initiated. Post and core was customised for the grossly mutilated maxillary anterior teeth. Single metal ceramic crowns and a cast partial denture were planned for the maxillary and mandibular arches. The RPD for the mandibular was desi gned and fabricated in the conventional manner. While designing the maxillary partial denture, it was seen that a clasp would have to be placed on the right central incisor. Since the clasp would appear unaesthetic, a custom precision attachment (CPA) was fabricated on the right central incisor to make it more aesthetic and pleasing without compromising on the principles. Technique • Preliminary impressions were made and the casts mounted on a semi-adjustable articulator with the pre-established vertical dimension. • The diagnostic wax-up was completed and the RPD designed. A-P palatal strap major connector was designed for maxillary and lingual bar for the mandibular arch, respectively. • A putty matrix of the completed diagnostic wax-up was made to evaluate of the existing space for the extracoronal attachment. • Maxillary teeth were prepared and full contour wax-up made. The wax-up was separated carefully, where the use of an attachment was required. • The patrix was added to the distal surface of the anterior abutment wax-up on the master cast (central incisor). • The dental surveyor was used to maintain parallelism with the collateral side and the additional guide plane surfaces. [ • The crowns were fabricated and veneered. • A pick-up impression of fixed components was made and poured to obtain the cast. • The patrix was positioned on the cast and parallelism was obtained with the milling tool attached to the surveyor

Measurements of Small-Scale Propellers Operating in the Vortex Ring State

The behavior of small-scale propellers operating in vertical descent and through the vortex ring state (VRS) was measured. In particular, a total of 26 propellers with varying diameters (9 to 11 in) were tested in the UIUC 2.8 x 4 ft wind tunnel at low Reynolds numbers to measure the propeller thrust over a range of advance ratios from -0.8 to 0. Also, time histories of the measured thrust for different propellers were recorded to characterize the unsteady thrust fluctuations for advance ratios through the vortex ring state. The effects of propeller geometry, e.g. pitch and planform effects, on the thrust characteristics of these propellers in the VRS are discussed. The motivation of this research is to understand better, the phenomenon of VRS observed in helicopter rotors in descent

A Comparative Evaluation of Stress Distribution at the Implant Abutment Interface between Platforms Switched Morse Taper and Pseudo Platform Switched Internal Hex Connection Implant - A 3D Finite Element Analysis

Aim: The purpose of the study was to evaluate and compare the stress distribution at the implant abutment interface in a platform switched Morse taper and pseudo platform switched internal hex connection implant system under simulated load using a 3D finite element analysis. Materials and Method: In the study ANKYLOS which is a Morse taper platform switching implant system (Group A) and XiVE having an internal hex connection which forms a pseudo platform switched implant system (Group B) were used. The geometric properties of implant systems were modeled using 3D finite element analysis. The masticatory forces of 200 N, 500 N and 1000 N were applied axially to both the implant systems with the abutment screw tightening torque of 110 Nm2, 320 Nm2 and 550 Nm2. Von Mises stress distribution pattern was analyzed considering the objectives of the study. In order to interpret the result, the data generated by finite element analysis (FEA) were statistically analyzed. Results: There was better stress distribution for Group B at the neck of implant as compared to Group A but on screw Group A showed more decrease in force concentration and therefore better stress distribution. Conclusion: Stress concentration on connecting screw of pseudo platform switch implant was more and may lead to fracture or loosing of screw than platform switched Morse taper implant

Effect of Topical Fluoride on Surface of Cast Titanium and Nickel-Chromium: An In Vitro Study

Objectives: The aim of this in-vitro study was to evaluate the effect of topical fluoride on surface of cast titanium and nickel-chromium. Materials and Methods: Thirty-nine rectangular specimens of titanium (grade 2) and 39 rectangular specimens of nickel-chromium were cast in equal dimensions and divided into three groups of 13 samples each. Group one specimens of titanium and nickel-chromium were placed in 2% neutral sodium fluoride (NaF) solution for 16 minutes. Group two specimens of titanium and nickel-chromium were immersed in 1.23% acidulated phosphate fluoride (APF) gel for eight minutes. Group three specimens of titanium and nickel-chromium were immersed in distilled water for 16 minutes. The surface roughness of the specimens was evaluated and the data were analyzed using two-way ANOVA and post-hoc comparison test with the level of significance set at 5% (P< 0.05). The surface of the specimens was further analyzed using a scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Results: Group two titanium specimens showed a statistically significant increase in surface roughness (P0.05). Qualitative SEM and EDS analyses further revealed the surface corrosion of titanium (group two) and localized mild corrosive pitting of nickel-chromium specimens (group two). Conclusion: Topical fluoride with acidic pH affects the surface roughness of titanium and to a certain extent, nickel-chromium. Neutral NaF solutions cause no significant change in corrosion resistance of titanium or nickel-chromium

A novel and easy technique for restoring grossly decayed mandibular molar with a modified cast-post

The article addresses the difficulty of restoring a grossly carious molar tooth, where very little tooth structure is left after caries excavation. When enough sound tooth structure is missing for satisfying the ferrule effect, a clinician can follow this technique and easily restore such teeth. A step by step procedure, including instrumentation and materials and a new impression technique, is described in detail, with clinical photographs. This technique results in the fabrication of a robust and extremely retentive post and core on which to place fixed prosthodontic restorations. A 2 and half year study showed that the tooth well in function with no signs of any problem. The author has restored around many decayed molars using this technique. Over a period of three years, no failure was reported. With an increasing demand on the dentist for restoring a structurally compromised teeth, this technique provides the patients with a robust prosthodontic solution

A comparative evaluation of intraoral and extraoral digital impressions: An in vivo study

Aim: The accuracy of a dental impression is determined by two factors: “trueness” and “precision.” The scanners used in dentistry are relatively new in market, and very few studies have compared the “precision” and “trueness” of intraoral scanner with the extraoral scanner. The aim of this study was to evaluate and compare accuracy of intraoral and extraoral digital impressions. Materials and Methods: Ten dentulous participants (male/female) aged 18–45 years with an asymptomatic endodontically treated mandibular first molars with adjacent teeth present were selected for this study. The prepared test tooth was measured using a digital Vernier caliper to obtain reference datasets. The tooth was then scanned using the intraoral scanner, and the extraoral scans were obtained using the casts made from the impressions. The datasets were divided into four groups and then statistically analyzed. The test tooth preparation was done, and dimples were made using a round diamond point on the bucco-occlusal, mesio-occlusal, disto-occlusal, and linguo-occlusal lines angles, and these were used to obtain reference datasets intraorally using a digital Vernier caliper. The test tooth was then scanned with the IO scanner (CS 3500, Carestream dental) thrice and also impressions were made using addition silicone impression material (3M™ ESPE) and dental casts were poured in Type IV dental stone (Kalrock-Kalabhai Karson India Pvt. Ltd., India) which were later scanned with the EO scanner (LAVA™ Scan ST Design system [3M™ ESPE]) thrice. The Datasets obtained from Intraoral and Extraoral scanner were exported to Dental Wings software and readings were obtained. Repeated measures ANOVA test was used to compare differences between the groups and independent t-test for comparison between the readings of intraoral and extraoral scanner. Least significant difference test was used for comparison between reference datasets with intraoral and extraoral scanner, respectively. A level of statistical significance of P < 0.05 was set. Results: The precision values ranged from 20.7 to 33.35 μm for intraoral scanner and 19.5 to 37 μm for extraoral scanner. The mean deviations for intraoral scanner were 19.6 μm mesiodistally (MD) and 16.4 μm buccolingually (BL) and 24.0 μm MD and 22.5 μm BL for extraoral scanner. The mean values of the intraoral scanner (413 μm) for trueness were closest to the actual measurements (459 μm) than the extraoral scanner (396 μm). Conclusion: The intraoral scanner showed higher “precision” and “trueness” values when compared with the extraoral scanner

All Zirconia: A New Material for Posteriors with Minimal Tooth Preparation

Background: Planning and executing the restorative rehabilitation of a decimated dentition is probably one of the most intellectually and technically demanding tasks being faced by a dentist. Full mouth rehabilitation involves restoring the dentate or a partially dentate mouth to provide an orderly pattern of occlusal contact and articulation that will optimize oral function, occlusal stability and esthetics. This case report demonstrates a full mouth rehabilitation of a patient for esthetically and functionally compromised dentition by a recently introduced ′metal-free′ restoration. The final prosthesis ensured a restoration resulting in predictable posterior disclusion and anterior guidance in harmony with the condylar path

Various prosthetic rehabilitation for mucormycosis

Mucormycosis is a form of fungal infection that is invasive and rapidly progressive, thereby including nose and paranasal sinuses of the head and neck region with high mortality and morbidity. Compromised immunity such as uncontrolled diabetes mellitus, Leukaemia, long-term use of steroids are the most common causes of the disease. Acute surgical resection is performed that involves the resectioning of the affected maxillofacial structures such as orbit, maxilla and / or nose in such conditions. Prosthodontic rehabilitation of these large maxillofacial defects is challenging. Lack of retention due to dislodging forces exerted by scarred post-surgical soft tissues, lack of bony base, missing structures of the posterior palatal seal area, multiple defect sites and compromised medical status due to comorbidities are the numerous problems are encountered during the rehabilitation of such defects. The basic principle of any prosthetic rehabilitation design includes the preservation of the remaining natural tissues along with retention, stability, support, and aesthetics. Fixed or Removable Prosthodontic rehabilitation can be performed depending on the available supporting structures. &nbsp

A Movable Finger Prosthesis

I cried that I had no rings, till I saw someone who had no fingers. Whether the traumatic loss of limbs or fingers is due to war, congenital malformations, systemic diseases (diabetes), industrial, domestic or vehicular accident, or amputation, it leaves the individual with a long-lasting emotional scar from the disfigurement. We as prosthodontists have the skillset to change a patient’s life by making a prosthesis that would enhance a patients’ physical and psychological well-being. Through time, emphasis has been made on replacing a lost digit for aesthetic purposes but function is equally important, if not more. Movement of a finger using the movement of the patient’s own hand may provide the patient with adequate movement to carry out his or her daily activities. In this age of digitalization, the use of impression materials is slowly but steadily reducing. The movable finger prosthesis described in this article eliminates the need for using any impression material as well as shows the use of 3D printing to make a functional prosthesis. &nbsp