Photoelastic Stress Analysis of Different Attachment Systems on Implant-Retained and Conventional Palatal Obturator Prostheses

Background: Considering that an increasing number of patients are victims of mutilator surgical resections, these studies are important for treatment success of rehabilitation of patients presenting oronasal communication.Purpose: The aim of this study was to assess the stress distribution through photoelasticity in palatal obturator prostheses with different attachment systems for implants.Methods: Two photoelastic models were obtained from an experimental maxillary model presenting an oronasal communication. One model was fabricated without implant, and the other with 2 implants 10 mm in length inserted in the left crest. Four colorless palatal obturator prostheses were fabricated. One prosthesis presented no attachment system, whereas the remaining prostheses were adapted to 3 attachment systems. The assembly was positioned in a circular polariscope for application of axial load.Results: The results were based on photographic records of stress in the photoelastic model submitted to loading. The records revealed higher stress concentration on the bar-clip system followed by the O'ring/bar-clip and O'ring systems, respectively. A homogeneous stress distribution was observed on the photoelastic model with the mucous-supported prosthesis.Conclusions: The attachment systems generated different characteristics of stress distribution that was concentrated surrounding the implants. The bar-clip system exhibited the highest stress concentration on the alveolar crest.

Upper Lip Prosthesis Retained to a Palatal Obturator

In cases of total or partial maxillectomies, the prosthetic rehabilitation is an effective alternative to minimize the sequelae left by surgical resection. The present study reports a clinical case of a 52-year-old patient who underwent partial maxillectomy, with upper lip involvement. The oronasal communication, resultant from surgical resection, did not allow the patient to return to her normal social life. Besides, the upper lip partial resection damaged her face's aesthetics. The proposed treatment was the confection of an upper lip prosthesis retained by a palatal obturator. The prosthesis insertion restored the patient's facial aesthetics, contributing not only to function, but also to psychosocial adaptation.

Obturator for Rehabilitation of Cleft Palate With Implant-Supported Retention System

Objective: Surgical reconstruction and prosthetic obturation are alternatives for the treatment of cleft in the soft palate.Design: The present case reports the rehabilitation of a patient presenting cleft palate with obturator prosthesis associated with implant-supported retention system.Conclusions: The use of ball attachment system improved speech, masticatory efficiency, swallowing, and social behavior of the patient.

Photoelastic Analysis of Implant-Retained and Conventional Obturator Prostheses With Different Attachment Systems and Soft Relining

Complete and partial loss of maxillary bone may jeopardize oral physiology and generate complications as oral-sinus-nasal communication. Palatal obturator prostheses are a treatment alternative for rehabilitation of these patients. The aim of this study was to assess stress distribution, through photoelasticity, on palatal obturator prostheses associated with different attachment systems (o'ring, bar clip, and o'ring/bar clip) of implants and submitted to relining. Two photoelastic models were fabricated according to an experimental maxillary model with oral-sinus-nasal communication. One model did not present implants, whereas the other included 2 implants with 13.0 mm in length in the left ridge. Four colorless maxillary obturator prostheses were fabricated and relined with soft silicone. One of these prostheses presented no attachment system, whereas the remaining prostheses included attachment systems adapted to the implants. The assembly (model/attachment system/prosthesis) was positioned in a circular polariscope during loading with 100 N at 10 mm/s. The results were based on observation during the experiment and photographic records of stress on the photoelastic model. The bar clip system exhibited the highest stress concentration followed by o'ring/bar clip and o'ring systems. The attachment systems presented different stress distribution with greater concentration surrounding the implants and homogenous stress distribution on the photoelastic model without implants. The highest concentration of fringes occurred, in ascending order, with o'ring, o'ring/bar clip, and bar clip systems.

Photoelastic analysis to compare implant-retained and conventional obturator dentures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Stress analysis in oral obturator prostheses: Imaging photoelastic

Maxillary defects resulting from cancer, trauma, and congenital malformation affect the chewing efficiency and retention of dentures in these patients. The use of implant-retained palatal obturator dentures has improved the self-esteem and quality of life of several subjects. We evaluate the stress distribution of implant-retained palatal obturator dentures with different attachment systems by using the photoelastic analysis images. Two photoelastic models of the maxilla with oral-sinus-nasal communication were fabricated. One model received three implants on the left side of the alveolar ridge (incisive, canine, and first molar regions) and the other did not receive implants. Afterwards, a conventional palatal obturator denture (control) and two implant-retained palatal obturator dentures with different attachment systems (O-ring; bar-clip) were constructed. Models were placed in a circular polariscope and a 100-N axial load was applied in three different regions (incisive, canine, and first molar regions) by using a universal testing machine. The results were photographed and analyzed qualitatively using a software (Adobe Photoshop). The bar-clip system exhibited the highest stress concentration followed by the O-ring system and conventional denture (control). Images generated by the photoelastic method help in the oral rehabilitator planning. © 2013 SPIE.

Rehabilitation of maxillary cleft with hybrid obturator prosthesis

The hybrid obturator prosthesis aims to provide a sense of well-being to the patient, offering improvements in speech, chewing, and swallowing. Thus, the retention and stabilization of the prosthesis become decisive factors for the success of the rehabilitation treatment. The objective of this study was to describe the treatment of a 70-year-old man with a congenital maxillary cleft performed through aesthetic and functional prosthetic rehabilitation with hybrid obturator prosthesis. In this study, the fabricated prosthesis achieved its purpose by providing adequate functional and aesthetic conditions to the patient, promoting the reduction of airspace through the sealing of the oronasal communication, with consequent improvement in the quality of life. Copyright © 2013 by Mutaz B. Habal, MD.

Stress analysis in oral obturator prostheses over parallel and tilted implants: photoelastic imaging

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Stress analysis in oral obturator prostheses, part II: photoelastic imaging

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Obturator prostheses versus free tissue transfers: a systematic review of the optimal approach to improving the quality of life for patients with maxillary defects

Patient perspectives on the treatment options for maxillary defects, which include free tissue transfers or obturator prostheses, may help eliminate current uncertainty as to the best choice of treatment plan. The purpose of this systematic review was to evaluate the quality of life (QoL) of patients with maxillary defects who had undergone restoration with obturator prostheses and/or free tissue transfers. A systematic search of Medline/PubMed and Web of Science databases for articles published before April 2015 was performed by 2 independent reviewers. A manual search of articles published from January 2005 to March 2015 was also conducted. Studies published in English that evaluated the QoL in patients with head and neck cancers were included. The Cohen kappa method was used to calculate inter-reviewer agreement. Ten studies were included. The University of Washington Head and Neck Questionnaire (UW-QOL) was most commonly used to measure QoL. The majority of maxillary defects were Class IIa-b. Two studies reported that the global QoL for patients with obturator prostheses is equivalent to or even better than that of other chronic disease populations. One study revealed no significant difference in QoL when the 2 treatment options were compared. The limited data indicate that the QoL of patients treated with obturator prostheses and that of patients free of tumors is similar. Well-designed clinical studies are necessary to draw definitive conclusions about how obturator prostheses compare with free tissue transfers in terms of affecting patient QoL.

Magnet-retained facial prosthesis combined with maxillary obturator

Prosthetic rehabilitation of the midfacial defects has always perplexed prosthodontists. These defects lead to functional and esthetic deficiencies. The purpose of this clinical case report was the presentation of the prosthetic rehabilitation of an extraoral-intraoral defect using two-piece prosthesis magnetically connected. This prosthesis has dramatically improved the patient’s speech, mastication, swallowing, and esthetic.

FINITE ELEMENT ANALYSIS OF MAXILLARY BONE STRESS CAUSED BY ARAMANY CLASS IV OBTURATOR PROSTHESES

Statement of problem. The retention of an Aramany Class IV removable partial dental prosthesis can be compromised by a lack of support. The biomechanics of this obturator prosthesis result in an unusual stress distribution on the residual maxillary bone. Purpose. This study evaluated the biomechanics of an Aramany Class IV obturator prosthesis with finite element analysis and a digital 3-dimensional (3-D) model developed from a computed tomography scan; bone stress was evaluated according to the load placed on the prosthesis. Material and methods. A 3-D model of an Aramany Class IV maxillary resection and prosthesis was constructed. This model was used to develop a finite element mesh. A 120 N load was applied to the occlusal and incisal platforms corresponding to the prosthetic teeth. Qualitative analysis was based on the scale of maximum principal stress; values obtained through quantitative analysis were expressed in MPa. Results. Under posterior load, tensile and compressive stresses were observed; the tensile stress was greater than the compressive stress, regardless of the bone region, and the greatest compressive stress was observed on the anterior palate near the midline. Under an anterior load, tensile stress was observed in all of the evaluated bone regions; the tensile stress was greater than the compressive stress, regardless of the bone region. Conclusions. The Aramany Class IV obturator prosthesis tended to rotate toward the surgical resection when subjected to posterior or anterior loads. The amount of tensile and compressive stress caused by the Aramany Class IV obturator prosthesis did not exceed the physiological limits of the maxillary bone tissue. (J Prosthet Dent 2012;107:336-342)

Radiological anatomy of the obturator nerve and its articular branches: basis to develop a method of radiofrequency denervation for hip joint pain

OBJECTIVE: A previous study of radiofrequency neurotomy of the articular branches of the obturator nerve for hip joint pain produced modest results. Based on an anatomical and radiological study, we sought to define a potentially more effective radiofrequency method. DESIGN: Ten cadavers were studied, four of them bilaterally. The obturator nerve and its articular branches were marked by wires. Their radiological relationship to the bone structures on fluoroscopy was imaged and analyzed. A magnetic resonance imaging (MRI) study was undertaken on 20 patients to determine the structures that would be encountered by the radiofrequency electrode during different possible percutaneous approaches. RESULTS: The articular branches of the obturator nerve vary in location over a wide area. The previously described method of denervating the hip joint did not take this variation into account. Moreover, it approached the nerves perpendicularly. Because optimal coagulation requires electrodes to lie parallel to the nerves, a perpendicular approach probably produced only a minimal lesion. In addition, MRI demonstrated that a perpendicular approach is likely to puncture femoral vessels. Vessel puncture can be avoided if an oblique pass is used. Such an approach minimizes the angle between the target nerves and the electrode, and increases the likelihood of the nerve being captured by the lesion made. Multiple lesions need to be made in order to accommodate the variability in location of the articular nerves. CONCLUSIONS: The method that we described has the potential to produce complete and reliable nerve coagulation. Moreover, it minimizes the risk of penetrating the great vessels. The efficacy of this approach should be tested in clinical trials.

Mid-urethral slings for treatment of stress urinary incontinence : long- and mid-term follow-up

Urinary incontinence is a common problem, affecting one third of the women at least at some time during their lives. The prevalence of urinary incontinence increases with advancing age, and the everyday impact of incontinence on women and on health services is enormous. Urinary incontinence is usually divided into three different subtypes, of which stress urinary incontinence (SUI) is the most common. Surgical treatment is often needed to cure SUI, and modern mid-urethral sling procedures give the possibility to cure this condition with a low risk of adverse events, a problem often associated with the so-called traditional incontinence operations. Life expectancy among women in Western countries has grown beyond 80 years of age. Long-term efficacy of treatment options for urinary incontinence therefore becomes an important issue in a world with limited eco-nomic resources. The purpose of the present study was to prospectively evaluate the long-term efficacy and safety of the first minimally invasive mid-urethral tape procedure, the Tension-free Vaginal Tape (TVT) procedure. The long-term (5-year) follow-up results of the TVT procedure as a repeat operation af-ter an unsuccessful mid-urethral tape operation were studied and the reasons for failure of the first operation were analyzed. Another purpose was to compare the original TVT procedure with a newer modification, the Tension-free Vaginal Tape Obturator (TVT-O) procedure within a multi-centre, randomized context in order to find out possible differences between these procedures re-garding efficacy and complications and the effects on symptoms of urgency. The first study of the present thesis is a prospective, Nordic, three-centre follow-up study of 90 women suffering from SUI, who were treated by means of the TVT procedure. The mean follow-up time was more than eleven years, and the study is the first to be published in connection with more than ten years of follow-up. The second study is a retrospective analysis of 26 women who were treated with a repeat TVT procedure after an unsuccessful primary mid-urethral tape procedure. The third and fourth studies concern 273 women in seven centres in Finland who were ran-domly assigned to the TVT and TVT-O procedures, the 3-year follow-up results of which are pre-sented in this thesis. After eleven years of follow-up, 90% of the women had a negative cough stress test result and a negative 24-h pad test result. The subjective cure rate measured as the women s global impression of cure was 77%, the rate of improvement 20%, and only 3% thought that the treatment had failed. No late-onset adverse effects were found. The repeat TVT procedure was successful in 75% of the cases when women who were cured and women who were significantly improved were included. The reasons for failure of the first operation could be separated into four different groups: tape material-related, operation technique-related, concomitant illness-related and a group with no identifiable reason. There were no intra-operative complications during the repeat operation. In the randomized trial comparing the TVT with the TVT-O procedure a cough stress test results were negative in 94.6% and 89.5% of the women in the two groups, respectively, after a 3-year follow-up period. There were no statistical differences in the cure rate or the rate of complications be-tween the two procedures. Symptoms of urgency were analyzed more closely and the main finding was that the prevalence of urgency symptoms decreased significantly after both mid-urethral sling procedures. The TVT operation was found to be an effective and safe procedure even after eleven years of follow-up. Long-term follow-up after a repeat TVT procedure revealed that the TVT procedure can well be considered after an unsuccessful mid-urethra tape procedure, because 75% of the patients showed significantly improvement of their incontinence. The TVT and TVT-O procedures showed no statistically significant differences in efficacy and rate of complications after three years of follow-up. In most cases these procedures alleviate preoperative symptoms of urgency and the risk of developing de novo urgency is low.