Fabricating CAD/CAM Implant-Retained Mandibular Bar Overdentures: A Clinical and Technical Overview.

This report describes the clinical and technical aspects in the oral rehabilitation of an edentulous patient with knife-edge ridge at the mandibular anterior edentulous region, using implant-retained overdentures. The application of computer-aided design and computer-aided manufacturing (CAD/CAM) in the fabrication of the overdenture framework simplifies the laboratory process of the implant prostheses. The Nobel Procera CAD/CAM System was utilised to produce a lightweight titanium overdenture bar with locator attachments.

In Vitro Three-Dimensional Accuracy of Digital Implant Impressions: The Effect of Implant Angulation.

Purpose: To compare the three-dimensional (3D) accuracy of conventional impressions (CIs) with digital scans (DSs) using an intraoral scanner (IOS) with intraoral scan bodies (SBs) and varying buccolingual interimplant angulations. A secondary aim was to measure the SB machining tolerance and height with and without application of torque.

Materials And Methods: Three master models (MMs) with two implants simulating an implant-supported three-unit fixed partial denture for bone-level implants were used.

Reliability, failure probability, and strength of resin-based materials for CAD/CAM restorations.

Objective:: This study investigated the Weibull parameters and 5% fracture probability of direct, indirect composites, and CAD/CAM composites.

Material And Methods:: Discshaped (12 mm diameter x 1 mm thick) specimens were prepared for a direct composite [Z100 (ZO), 3M-ESPE], an indirect laboratory composite [Ceramage (CM), Shofu], and two CAD/CAM composites [Lava Ultimate (LU), 3M ESPE; Vita Enamic (VE), Vita Zahnfabrik] restorations (n=30 for each group). The specimens were polished, stored in distilled water for 24 hours at 37°C.

Three-Dimensional Accuracy of Digital Implant Impressions: Effects of Different Scanners and Implant Level.

Purpose: To compare the three-dimensional (3D) accuracy of conventional direct implant impressions with digital implant impressions from three intraoral scanners, as well as different implant levels-bone level (BL) and tissue level (TL).

Materials And Methods: Two-implant master models were used to simulate a threeunit implant-supported fixed dental prosthesis. Conventional test models were made with direct impression copings and polyether impressions.

Three-dimensional accuracy of a digitally coded healing abutment implant impression system.

Purpose: This study examined the three-dimensional (3D) accuracy of the Encode Impression System (EN) in transferring the locations of two implants from master models to test models and compared this to the direct impression (DI) technique. The effect of interimplant angulation on the 3D accuracy of both impression techniques was also evaluated.

Materials And Methods: Seven sectional polymethyl methacrylate mandibular arch master models were fabricated with implants in the first premolar and first molar positions.

Three-dimensional accuracy of plastic transfer impression copings for three implant systems.

Purpose: The purpose of this study was to compare the three-dimensional accuracy of indirect plastic impression copings and direct implant-level impression copings from three implant systems (Nobel Biocare [NB], Biomet 3i [3i], and Straumann [STR]) at three interimplant buccolingual angulations (0, 8, and 15 degrees).

Materials And Methods: Two-implant master models were used to simulate a three-unit implant fixed partial denture. Test models were made from Impregum impressions using direct implant-level impression copings (DR).

Three-dimensional repositioning accuracy of semiadjustable articulator cast mounting systems.

Statement Of Problem: In spite of its importance in prosthesis precision and quality, the 3-dimensional repositioning accuracy of cast mounting systems has not been reported in detail.

Purpose: The purpose of this study was to quantify the 3-dimensional repositioning accuracy of 6 selected cast mounting systems. Five magnetic mounting systems were compared with a conventional screw-on system.

Load fatigue performance of conical implant-abutment connections.

Purpose: Conical implant-abutment connections for platform switching have been recently introduced in implant systems. This study investigated the load fatigue performance of three conical abutment systems and their corresponding titanium and zirconia abutments.

Materials And Methods: Regular-diameter implants of the Ankylos (AK), PrimaConnex (PC), and Straumann (ST) systems were tested with their corresponding titanium (Ti) and zirconia (Zr) abutments tightened to the recommended torque (n = 5 implant-abutment assemblies per group).

Evaluation of the marginal fit of a zirconia ceramic computer-aided machined (CAM) crown system.

Statement Of Problem: The marginal fit of crowns is a concern for clinicians, and there is no conclusive evidence of any one margin configuration yielding better results than others in terms of marginal fit.

Purpose: The purpose of this study was to evaluate the marginal fit with respect to gap and overhang of Y-TZP (yttria-stabilized tetragonal zirconia polycrystals) ceramic crowns and compare them with lithium disilicate pressable and complete metal crowns. The influence of margin configuration on the marginal fit was also evaluated.

Critical bending moment of four implant-abutment interface designs.

Purpose: Critical bending moment (CBM), defined as the bending moment at which the external nonaxial load applied overcomes screw joint preload and causes loss of contact between the mating surfaces of the implant screw joint components, was measured for four different implants and their single-tooth replacement abutments.

Materials And Methods: CBM at the implant-abutment screw joint for four implant-abutment test groups was measured in vitro at 80%, 100%, and 120% of the manufacturers' recommended torque levels. Regular-platform implants with their corresponding single-tooth abutments were used.

Load fatigue performance of implant-ceramic abutment combinations.

Purpose: The mechanical properties and functional load performance of implant restorations coupled with metal abutments have been studied widely. However, the fatigue performance of the newly introduced ceramic implant abutments has not been reported. This study investigated the load fatigue performance of four implant systems and their corresponding zirconia ceramic abutments at the manufacturers' recommended torque levels.

Influence of osseointegration degree and pattern on resonance frequency in the assessment of dental implant stability using finite element analysis.

Purpose: Resonance frequency analysis (RFA) has been widely used to predict dental implant stability by assessing conditions surrounding the implant. The aim of this study was to investigate the influence of osseointegration degree and pattern on the resonance frequency of implant-bone structure by means of finite element analysis (FEA).

Materials And Methods: A basic FEA model was created to represent a titanium implant in a portion of the maxillary bone at the left first premolar region.

Load fatigue performance of four implant-abutment interface designs: effect of torque level and implant system.

Purpose: Biomechanical load-fatigue performance data on single-tooth implant systems with different implant-abutment interface designs is lacking in the literature. This study evaluated the load fatigue performance of 4 implant-abutment interface designs (Brånemark-CeraOne; 3i Osseotite-STA abutment; Replace Select-Easy abutment; and Lifecore Stage-1-COC abutment system). The number of load cycles to fatigue failure of 4 implant-abutment designs was tested with a custom rotational load fatigue machine.

Load fatigue performance of a single-tooth implant abutment system: effect of diameter.

Purpose: This study investigated the load fatigue performance of narrow-, regular-, and wide-diameter CeraOne (Nobel Biocare) single-tooth implants and abutments.

Materials And Methods: Five samples of each implant-abutment combination in 3 different widths were tested at 3 applied screw torque levels (recommended torque, recommended torque +20%, and recommended torque -20%). A rotational load fatigue machine was used to apply a 21-N load, at an angle of 45 degrees to the long axis of the specimens.

Load-fatigue performance of gold crowns luted with resin cements.

Statement Of Problem: Resin cements have gained popularity over the past few years because of their improved physical properties. There is a need to test these cements under fatigue loading, as there is growing recognition that fatigue testing is more clinically relevant than traditional monotonic static tests.

Purpose: This study investigated the load-fatigue performance of complete gold crowns cemented with 4 types of resin cement.

Risk perception and impact of Severe Acute Respiratory Syndrome (SARS) on work and personal lives of healthcare workers in Singapore: what can we learn?

Introduction: Healthcare workers (HCWs) were at the frontline during the battle against Severe Acute Respiratory Syndrome (SARS). Understanding their fears and anxieties may hold lessons for handling future outbreaks, including acts of bioterrorism.

Method: We measured risk perception and impact on personal and work life of 15,025 HCWs from 9 major healthcare institutions during the SARS epidemic in Singapore using a self-administered questionnaire and Impact of Events Scale and analyzed the results with bivariate and multivariate statistics.

Relationships between depression/somatization and self-reports of pain and disability.

Aims: To examine the relationship between depression and somatization and pain during muscle and joint palpation as well as limitations related to mandibular functioning (LRMF) in patients with temporomandibular disorders.

Methods: The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) data for Axes I and II for 196 consecutive patients (56 men and 140 women) with a history of facial pain were obtained. The mean age of the predominantly Chinese patient population (83.

Critical bending moment of implant-abutment screw joint interfaces: effect of torque levels and implant diameter.

Purpose: Critical bending moment (CBM), the moment at which the external nonaxial load applied overcomes screw joint preload and causes loss of contact between the mating surfaces of the implant screw joint components, was measured with 2 types of implants and 2 types of abutments.

Materials And Methods: Using 4 test groups of 5 implant-abutment pairs, CBM at the implant-abutment screw joint was measured at 25%, 50%, 75%, and 100% of the manufacturer's recommended torque levels. Regular Platform (RP) Nobel Biocare implants (3.

Depressive symptoms in Asian TMD patients and their association with non-specific physical symptoms reporting.

Background: The expression of depression in Asian temporomandibular disorder (TMD) patients may differ from that of their Caucasian counterparts. This study examined the prevalence of depressive symptoms and their association with non-specific physical symptoms (NPSs) reporting in Asian patients.

Methods: Two hundred and fifty-five Asian TMD patients (68 males; 187 females) with a mean age of 33.

Prevalence of temporomandibular disorder subtypes, psychologic distress, and psychosocial dysfunction in Asian patients.

Aims: To use the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) to investigate the physical diagnoses, psychologic distress, and psychosocial dysfunction in Asian TMD patients. The RDC/TMD Axis I and II findings were compared to those of Swedish and American TMD patients.

Methods: One hundred ninety-one patients (53 male and 138 female) referred to 2 institutionalized TMD clinics in Singapore were enrolled in the study.

Depression and somatization in patients with temporomandibular disorders.

Statement Of Problem: Psychological and behavioral traits may be important for the diagnosis and management of orofacial pain.

Purpose: This study compared the levels of depression and somatization in patients in single and multiple research diagnostic criteria for temporomandibular disorders (RDC/TMD) diagnostic groups.

Material And Methods: The RDC/TMD was established to allow standardization and replication of research into the most common forms of muscle- and joint-related research and is divided into 2 axes: axis I, clinical TMD, and axis II, pain-related disability and psychological status.

Multiple pains and psychosocial functioning/psychologic distress in TMD patients.

Purpose: This study assessed multiple pain conditions and their association with psychosocial functioning, psychologic distress, and somatization in patients with temporomandibular disorders (TMD) based on RDC/TMD Axis II findings. Nonspecific pain items examined included headaches, heart/chest pain, lower back pain, nausea/abdominal pain, and muscle pain.

Materials And Methods: In this study, 202 TMD patients (58 men and 144 women) referred to two TMD clinics participated.

The effect of 3 torque delivery systems on gold screw preload at the gold cylinder-abutment screw joint.

Purpose: This study measured the gold screw preload at the gold cylinder-abutment screw joint interface obtained by 3 torque delivery systems.

Materials And Methods: Using a precalibrated, strain-gauged standard abutment as the load cell, 3 torque delivery systems tested were shown to have significant differences in gold screw preload when a gold cylinder was attached.

Results: Mean preloads measured were 291.