Effects of ferrule and diameter of parallel cast post and core on fracture resistance / Efeitos da férula e diâmetro de núcleos metálicos paralelos na resistência a fratura

Objective: The aim of this study was to evaluate the effects of using different diameters of parallel cast posts with, or without ferrule, on the overall fracture resistance of Cast Post and Core (CPC). Material and Methods: Forty (40) endodontically treated human maxillary central incisors were divided into four groups (n=10): [F1] 1.0 mm diameter post with ferrule; [NF1] 1.0 mm diameter cast post without ferrule; [F1.5] 1.5 mm diameter cast post with ferrule; [NF1.5] 1.5 mm diameter post without ferrule. For all teeth, the post space (9.0 mm, in depth) was prepared using ParaPostTM drill. CPC using base metal alloy were fabricated and were cemented using resin modified glass ionomer (RMGI) cement along with the Porcelain Fused to Metal (PFM) crowns. A universal testing machine (Instron) was used to apply horizontal force perpendicular to the long axis of the tooth at the center of lingual surface, until catastrophic failure. Data was submitted to two-way ANOVA and Scheffé tests (P<0.05). Results: Both post diameter and ferrule statistically affected the maximum load at fracture (P=0.004 and P=0.013, respectively). The highest mean values were observed for samples with ferrule and wider post size (490N), while the lowest were observed for samples without ferrule and narrower post size (254N). There was no relationship between the presence of a ferrule and post size (P=0.937). Conclusion: For endodontically treated teeth with no ferrule, a wider-diameter cast post increased fracture resistance of a CPC and PFM crown procedure. (AU)

Objetivo: O objetivo do presente estudo foi avaliar os efeitos de diferentes diâmetros de núcleos metálicos paralelos (com ou sem férula) na resistência a fratura do procedimento restaurador. Material e Métodos: Quarenta (40) incisivos centrais superiores humanos foram tratados endodonticamente e divididos em quarto grupos (n=10): [F1] Diâmetro de 1.0 mm, com férula; [NF1] Diâmetro de 1.0 mm, sem férula; [F1.5] Diâmetro de 1.5 mm, com férula; [NF1.5] Diâmetro de 1.5 mm, sem férula. Para todos os dentes, o espaço foi preparado para o núcleo (9.0 mm, em comprimento) utilizando brocas do ParaPostTM. Os núcleos metálicos e as coroas metalocerâmicas fabricadas foram cimentados utilizando-se cimento de ionômero de vidro modificado por resina. Uma máquina de ensaios universal (Instron) foi utilizada para aplicar uma força horizontal perpendicular ao longo eixo do dente, no centro da face lingual, até falha catastrófica. Os dados foram analisados através de análise de variância de dois fatores e teste de Scheffé (p<0.05). Resultados: O diâmetro do núcleo e a presença (ou ausência) de férula afteram estatiscamente a resistência máxima a fratura do procedimento (P=0.004 e P=0.013, respectivamente). Os maiores valores foram observados para amostras com férula e de maior diâmetro (490N), enquanto os menores valores foram observados para amostras sem férula e de menor diâmetro (254N). Conclusão: Para dentes tratados endodondicamente, com férula, um núcleo de maior diâmetro aumentou a resistência a fratura de procedimentos restauradores envolvendo coroas metalocerâmicas cimentadas sobre núcleos metálicos fundidos. (AU)

Successful Management of Early Peri-Implant Infection and Bone Loss Using a Multidisciplinary Treatment Approach.

INTRODUCTION: Peri-implant infections can occur any time postloading. Although management of peri-implant infections has been described extensively in the literature, no consensus exists on the best approach to its treatment. Infections and bone loss can also occur around implants prior to loading, leading to early implant loss. Little has been reported on the management of peri-implant infections occurring prior to loading. This report describes the identification as well as the surgical and restorative management of infection and bone loss around a preloaded dental implant. CASE PRESENTATION: A 52-year-old systemically healthy, non-smoking white female had severe inflammation with bleeding on probing and bone loss around implant #28 (Universal Numbering System) 7 weeks after placement and augmentation with autogenous and deproteinized bovine bone and a resorbable collagen membrane (RCM). Surgical exposure revealed a deep bony crater around the entire implant. The implant was cleaned for 4 to 5 minutes with a tetracycline and saline slurry. Guided bone regeneration was performed with demineralized freeze-dried bone allograft and an RCM. Azithromycin, ibuprofen 800 mg three times daily, and 0.12% chlorhexidine gluconate rinse were given post-surgery. Postoperative healing was uneventful. Nearly complete bone fill was noted at 1 year of observation when implants were permanently restored. A combination of screw- and cement-retained restorations were placed. Tissues remained healthy 5.5 years postloading with maximum 3-mm probing depth and no changes in bone levels. CONCLUSIONS: This case shows that it is possible to arrest early peri-implant infection, regenerate bone, and maintain health over 5.5 years postloading. Early detection and multidisciplinary care resulted in long-term success.

Maximising the potential of part-time clinical teachers.

BACKGROUND: A problem faced by health professions education throughout the world is a lack of full-time clinical teachers. This is particularly serious in dentistry and nursing, but is increasingly also true in medicine. To make up for this shortfall there is a growing reliance on part-time clinical teachers. CONTEXT: Part-time clinical teachers are essential for the education of students. However, compared with their full-time counterparts, the part-time teachers are often not adequately prepared for their roles as educators within the context of the clinical curriculum. They might not be trained in the latest educational practices, and may be unprepared for the time needed to excel as teachers and mentors. IMPLICATIONS: As part-time teachers take on more responsibility, it is important that they take part in orientation and training sessions to assist them in developing the skills they need to succeed. This will require a significant commitment from the institution as well as the part-time teacher, but is critical for maintaining the academic quality of the clinical training programmes. This also represents an untapped area for research into how to ensure the success of part-time clinical teachers.

Retrieval of a stripped abutment screw: a clinical report.

Mechanical complications, such as loosening or damaging of the prosthetic components of an osseointegrated implant, may occur. Stripping of the implant abutment screw head can be a serious problem which can render an implant unusable. This report describes a clinical situation involving a patient who presented with a fractured screw-retained interim crown. Upon further examination, it was determined that the abutment screw head was stripped. There was limited access and visibility in this situation since the implant was a bone-level implant. The procedure used for the removal of the stripped abutment screw head is described in detail in this clinical report.

Eleven-year report on a predoctoral implant dentistry program.

PURPOSE: An elective program on implant dentistry was started in the summer of 1994 at the University of Detroit Mercy School of Dentistry (UDM). The program provides comprehensive didactic and clinical training in implant dentistry to a select group of senior dental students. This study describes the program and clinical results of the first 11 years of the elective program in implant dentistry at UDM. MATERIALS AND METHODS: The program is 1 year long and is offered to a group of 10 senior students out of a class of 72. In addition to a one-semester lecture course offered to all dental students, students in the elective program participate in a one-semester seminar which includes literature review and "hands-on" surgical and prosthodontic components. Patients are assigned during the summer term to students who work in pairs. Students actively participate in diagnosis and treatment planning, assist in surgery, and accomplish the prosthodontic procedures. Prosthodontic services include single-tooth restorations, multiple-unit fixed restorations, overdentures, and full-arch fixed prostheses. A retrospective analysis of the patients treated in the first 11 years of the program was conducted. RESULTS: During the first 11 years of the program, 159 implants were placed in 70 patients. There were a total of 10 failed implants in seven patients (failure rate 6.3%): eight implants prior to loading and two following loading. Minor complications included gold screw loosening, gold screw fracture, porcelain fracture, and soft tissue inflammation, which occurred in less than 5% of the patients. CONCLUSIONS: The rates of implant failure and complications in the first 11 years of the elective implant program at UDM appear to be within an acceptable range when compared to other educational programs and studies reported in the dental literature.

Repair of fractured framework: scanning electron microscopy and energy dispersive X-ray spectroscopy.

Fractured metal prostheses can be analyzed for possible causes of failure using scanning electron microscopy (SEM). In this study, fractography is used to determine the cause of the failure and whether repair is practical. Energy-dispersive x-ray spectroscopy (EDS) is used to determine composition of the fractured prosthesis so that a repair process can be recommended. The technique is presented for the repair of a titanium framework for an implant-supported overdenture based on the analysis data.

Evaluation of surface finish and polish of eight provisional restorative materials using acrylic bur and abrasive disk with and without pumice.

This study evaluated the effects of two finishing techniques and pumice polishing on the surface roughness of eight different provisional materials. Provisional materials included polymethylmethacrylate-based Alike, Snap, Trim and Jetand composite-based provisional materials Temphase, Protemp 3 Garant, Luxatemp and Integrity. Baseline surface roughness was measured by a profilometer, then the provisional materials were finished using extra fine acrylic burs or medium abrasive disks. The surface roughness of each sample was measured following finishing using a profilometer as previously stated. Each surface was then polished with pumice and the surface roughness was measured again. The data were analyzed using repeated measures of ANOVA and Bonferroni pairwise comparisons (alpha = 0.05). The results indicated that with composite provisional materials, the unfinished surfaces are smoother than with bur or abrasive-disk finished surfaces. Pumice application did not smooth the surface finish for all materials. The different types of provisional materials required different finishing techniques to produce the smoothest finishes.

Implant dentistry in predoctoral education: the elective approach.

In response to interest by dental students and patient needs, an elective program in implant dentistry was started at the University of Detroit Mercy School of Dentistry (UDM) in the summer of 1994. The 1-year program is offered to a group of 10 senior students out of a class of 72. Implant treatment is provided to selected edentulous and partially edentulous patients. Predoctoral students participate in diagnosis and treatment planning, assist in surgical placement, and perform the prosthodontic procedures. A survey was sent to 160 UDM graduates, and 90 responded. Out of the 90 respondents, 35% had participated in the elective implant program and 65% had not. A Pearson correlation matrix was used to analyze their responses. A stronger positive correlation with offering and restoring implants was seen in graduates who had completed the elective program in implant dentistry.

One-step implant index verification and maxillomandibular relationship.

Before definitive fabrication of an implant-supported prosthesis, the accurate positioning of the fixtures or abutment replicas on the working master cast must be verified. In addition, the implant master cast must be accurately mounted against the opposing cast. The purpose of this paper is to demonstrate a technique that combines the verification index and a maxillomandibular relationship into one step, with an accurate technique to record the relationship.