Effectiveness of commercially available denture adhesives on retention of mandibular complete denture in resorbed mandibular ridge: an in vitro study / Efectividad de los adhesivos disponibles comercialmente sobre la retención de prótesis removibles completas mandibulares en el reborde mandibular reabsorbido: un estudio in vitro

Background: Denture adhesives are alternatives used to improve retention, stability, comfort and satisfaction in patients with complete dentures. Evidence on the effectiveness of denture adhesives on resorbed mandibular ridges is scarce. Among the many commercially available denture adhesives, the ideal material for the severely resorbed mandibular ridge remains in dispute. Objective: The aim of this study was to evaluate the effectiveness of different quantities of four commercially available denture adhesives on the retention of mandibular complete dentures in severely resorbed ridges. Materials and Methods: A resorbed edentulous mandibular ridge model was manufactured in acrylic resin. A denture base was made and three loops were attached to it. Four commercially available denture adhesives (Fixodent, Perlie White, Fiftydent and Polident) were tested in amounts of 0.2 g, 0.4 g, 0.6 g, 0.8 g and 1.0 g. The acrylic resin model was evenly moistened with 1 ml of water and a weighted amount of adhesive material was applied to the denture base. The universal testing machine engaged the loops fixed on the denture base and applied the vertical displacement force. The maximum vertical displacement force values were recorded for each denture adhesive material at different amounts. Statistical calculation was performed using Kruskal Wallis with Bonferroni post hoc correction. Results: Statistically significant differences were observed in the mean values of the vertical displacement force for adhesive amounts of 0.2 g, 0.4 g, 0.6 g and 1.0 g (p<0.05) between the four adhesive materials tested. Statistically significant differences were observed when four denture adhesives were compared to each other in different amounts (p<0.05). Statistically significant differences were observed between different amounts for each of four denture adhesives (p<0.05). Conclusions: Among the four materials tested, Polident showed greater effectiveness at 0.6 g and 0.8 g, Fittydent at 0.6 g, 0.8 g and 1 g, Fixodent at 0.4 g and 0.6 g and Perlie White at 1 g and 0.8g quantity to resist vertical displacement. forces on the severely resorbed mandibular crest. Using an appropriate amount of denture adhesive allows for proper retention of the denture; Replacement of this adhesive is necessary once a day.

Introducción: Los adhesivos para prótesis dentales son alternativas utilizadas para mejorar la retención, la estabilidad, la comodidad y la satisfacción en los pacientes con prótesis completas. La evidencia sobre la efectividad de los adhesivos para prótesis dentales en los rebordes mandibulares reabsorbidos es escasa. Entre los muchos adhesivos para prótesis dentales disponibles comercialmente, sigue estando en disputa cuál es el material ideal para el reborde mandibular severamente reabsorbido. Objetivo: El objetivo de este estudio fue evaluar la efectividad de diferentes cantidades de cuatro adhesivos para prótesis dentales disponibles comercialmente sobre la retención de prótesis dentales completas mandibulares en reborde mandibular reabsorbido severamente. Materiales y Métodos: Se fabricó un modelo de reborde mandibular edéntulo reabsorbido en resina acrílica. Se hizo una base para la prótesis y se le colocaron tres bucles. Se probaron cuatro adhesivos para dentaduras postizas disponibles comercialmente (Fixodent, Perlie White, Fiftydent y Polident) en cantidades de 0,2 g, 0,4 g, 0,6 g, 0,8 g y 1,0 g. El modelo de resina acrílica se humedeció uniformemente con 1 ml de agua y se aplicó la cantidad correspondiente de material adhesivo sobre la base de la dentadura. La máquina de prueba universal enganchó los bucles fijados en la base de la dentadura postiza y aplicó la fuerza de desplazamiento vertical. Se registraron los valores máximos de fuerza de desplazamiento vertical para cada material adhesivo para dentaduras postizas en diferentes cantidades. El cálculo estadístico se realizó utilizando Kruskal Wallis con corrección post hoc de Bonferroni. Resultado: Se observaron diferencias estadísticamente significativas en los valores medios de la fuerza de desplazamiento vertical para cantidades de 0,2 g, 0,4 g, 0,6 g y 1,0 g (p<0,05) entre los cuatro materiales adhesivos para prótesis dentales probados. Se observaron diferencias estadísticamente significativas cuando se compararon cuatro adhesivos para prótesis dentales entre sí en diferentes cantidades (p<0,05). Se observaron diferencias estadísticamente significativas entre diferentes cantidades en los cuatro adhesivos para prótesis (p<0,05). Conclusión: De los cuatro materiales probados, Polident mostró mayor efectividad a 0,6 g y 0,8 g, Fittydent a 0,6 g, 0,8 g y 1 g, Fixodent a 0,4 g y 0,6 g y Perlie White a 1 g y 0,8 g para resistir fuerzas de desplazamiento vertical en la cresta mandibular severamente reabsorbida. El uso de una cantidad adecuada de adhesivo para dentaduras postizas permite una retención adecuada de la dentadura postiza; El reemplazo de este adhesivo es necesario una vez al día.

Maxillary reservoir denture to overcome radiation-induced xerostomia - Light at the end of the tunnel.

Xerostomia is a subjective symptom of dry mouth. It can occur as a part of the systemic disease, drug-induced side effect, or following therapeutic radiation therapy to the head-and-neck region. The primary complication faced by these xerostomic patients is the difficulty in retention of removable dentures. It is important to recognize that the prosthodontic management of these patients requires special attention and care. In an attempt to overcome the presence of xerostomia, several techniques of introducing reservoirs into the dentures containing salivary substitutes have been proposed. This case report presents a simplified approach for the construction of a reservoir in the maxillary denture, specifically in patients where other treatment modalities have failed. This technique provided excellent lubrication to oral tissues, hygienic for the patient, and utilized routine denture base material.

Comparison of the retention of conventional dentures after the use of common adhesive brands on poor denture foundations: an in vitro study / Comparación de la retención de dentaduras convencionales con el uso de marcas comerciales de adhesivos en procesos alveolares deficientes: un estudio in vitro

There is no information about the possible impact in denture retention after the use of common denture adhesives (DAs) when poor denture foundations (PDF) are present. Moreover, there is a lack of information about which current formulation provides greater retention and for how long. Twelve models from edentulous patients with different ridge shape and border height were used and complete dentures were manufactured. Four different formulation brands of DAs were tested after 10 minutes and three, six, nine, and 12 hours of DA application using a universal testing machine. The Fittydent® and Fixodent® adhesives had the highest retention at 12 hours. The PDF group increased on average its retention by 400 %. However, the group presented lower retention compared to the good denture foundation group. In conclusion, DAs significantly increased denture retention. The PDF group were the most benefited with the application of DAs. The Fixodent® paste had the highest retention.

No existe información acerca del posible impacto en la retención de dentaduras después del uso de adhesivos dentales comunes (DAs) cuando existen rebordes alveolares deficientes (PDF). Más aun, existe una falta de información acerca de cuál formula actual provee mayor retención y por cuanto tiempo. Doce modelos de pacientes edentulos con diferentes formas y alturas en sus rebordes alveolares fueron usados, y dentaduras completas les fueron realizadas. Cuatro diferentes fórmulas y marcas de DAs fueron evaluadas después de 10 minutos, tres, seis, nueve y 12 horas de que se aplicó el DA usando una maquina universal de pruebas. Los adhesivos Fittydent® y Fixodent® presentaron la retención más alta a las 12 horas. El grupo con PDF incrementó su retención hasta en un 400 %. Sin embargo, el grupo presentó menor retención cuando se comparó con el grupo que posee adecuados procesos alveolares. Los DAs incrementaron significativamente la retención de las dentaduras. El grupo PDF fue el más beneficiado con la aplicación de DAs. La pasta Fixodent® provee la más alta retención.

Immediate Vacuum Formed Overdenture for a Pediatric Patient with Ectodermal Dysplasia.

Restoring the dental and facial esthetics in a growing patient with ectodermal dysplasia (ED) is fundamental to improve psychosocial issues, esthetics, and function. The purpose of this clinical report was to present a simple, fast, and cost-effective technique to re-establish a pleasant smile of an eight-year-old male patient with hypohydrotic ED. A vacuum-formed overdenture prosthesis is described, which is recommended as an immediate interim restorative treatment in the maxillary arch with excellent stability and retention.

Técnica de impresión para rebordes móviles. Parte 1: maxilar / Impression technique of movable fibrous ridge. Part 1: maxilla

RESUMEN: El reborde móvil maxilar producido por reabsorción ósea extrema compromete la estabilidad de la prótesis total, por lo que debe ser registrado en reposo. Se describe una nueva técnica de impresión mucoestática simple y rápida que, junto al esquema oclusal y ordenamiento dentario planificados, optimiza la retención protésica. Se discuten sus resultados y se comparan con otras técnicas de impresión.

ABSTRACT: The movable fibrous ridge caused by extreme maxillary bone resorption compromises the stability of complete dentures, so it must be registered passively. A new, simple and quick mucostatic impression technique along with the occlusal scheme and dental planning system optimizes prosthetic retention. Results are discussed and compared with various impression techniques.

An Alternative Prosthetic Approach for Rehabilitation of Two Edentulous Maxillectomy Patients: Clinical Report.

Obturator prosthesis is a common treatment method for maxillectomy patients for maintaining their oronasal separation and resuming their social lives. After tumor resection, the remaining anatomical structures have a significant effect on prosthesis retention. The present study describes the rehabilitation of two maxillectomy patients after cancer surgery using a prosthesis consisting of a denture and a special retentive obturator that is positioned in the anatomical undercuts of the nasal cavity. These patients have undergone total and subtotal maxillectomy surgery after the diagnosis of squamous cell carcinoma. The systemic and local health status of the total maxillectomy patient was not suitable for zygomatic implant surgery. Only one osseointegrated dental implant was placed into the left maxillary tuberosity area in the subtotal maxillectomy patient. In addition, the quality, vertical height, and horizontal width of the remaining bone structures in the maxilla limited the use of osseointegrated dental implants. Mechanical prosthesis retention was provided using a multiunit retentive mechanism composed of an orthodontic forsus fatigue resistant device (OFFRD), two Herbst appliances, and an acrylic piece associated with healthy keratinized mucosa. The OFFRD could easily apply a consistent force and push the acrylic pieces toward the retentive undercut under the control of the two Herbst appliances. Two OFFRD units in different directions were designed for the total maxillectomy patient, while only one OFFRD unit was placed on the opposite side of the osseointegrated implant in the subtotal maxillectomy patient. A sufficient retention was obtained for both patients. The patients were satisfied, and no major complications were observed in periodic controls.

Interference factors regarding the path of insertion of rotational-path removable partial dentures.

BACKGROUND: The aims of this study were to evaluate the effect of the location of the rotational center and the morphology of teeth resulting in interference with the rotational path of insertion and to estimate when an interference test should be performed. METHODS: A total of 400 dental radiograms of maxillary and mandibular first and second molars (100 for each position) were selected. The radiograms were used to hand-sketch the outlines on tracing paper. Then, an interference test was simulated using calipers. Mesial long occlusal rest seats with three different lengths were designed. A curve-simulated rotational path was drawn on the tracing paper showing the outline of a molar. If the curve was intersected by the mesial outline, interference was occurred. A total of 1200 tests were performed. RESULTS: A significant number of interference cases (18.5%, N = 400) occurred when the rotational center was placed at the most distal margin of the occlusal surface. The interference was reduced (2.75%, N = 400) but still present at the distal fourth of the occlusal surface. At the distal one-third of the occlusal surface, interference did not occur (0%, N = 400). There was a significant difference between the results of the three rotational centers (p < 0.0001). CONCLUSIONS: The interference test was not required for a rotational center at the distal third to half of the occlusal surface. However, if the length of the long occlusal rest extends beyond the distal third, an interference test is recommended before final impression.

Use of Mini-anchors and Rehabilitation with 0° Cusp Angle Teeth Complete Denture in Recurrent Condylar Dislocation: Technical Adequacy and Procedure.

AIM: To report a case of association between the surgical treatment of temporomandibular dysfunction and rehabilitation with denture total prosthesis (TP) using nonanatomic teeth (cusp 0°) in patients with anterior recurrent dislocation of the temporo-mandibular joint (TMJ) and persistent uncontrolled mandibular movement, showing a technical adaptation and conduct. INTRODUCTION: There are several treatment approaches available for dislocation of the TMJ. The use of condylar mini-anchors for recurrent TMJ dislocation is a valid option and should be considered since it does not alter the joint anatomy. In edentulous patients undergoing TMJ surgical procedures, prosthetic rehabilitation can be seen as a means of treatment preservation. CASE REPORT: A 73-year-old female patient attended the oral and maxillofacial surgery clinic presenting with joint instability, ligament laxity, and chronic recurrent TMJ dislocations. She had already been through three previous unsuccessful surgical procedures. A treatment plan was done based on the installation of a mini-anchor in the patient's TMJ through the preauricular surgical access. Dislocations were then resolved, but the lack of mandibular control even to a lesser extent after surgery precluded the use of prosthetics even at rest. Thus, it was planned to manufacture two conventional TPs with 0° cusp angle teeth, a clinical protocol shortened to three sessions in an attempt to improve the stability of the prosthesis. CONCLUSION: The use of an individual mini-anchor is simple and effective, and the use of artificial teeth is well suited to the case. CLINICAL SIGNIFICANCE: A multidisciplinary intervention (surgery/ prosthesis) is of utmost importance for the resolution and preservation of the treatment of these complex cases.

Influence of Inner Circular Sealing Area Impression Method on the Retention of Complete Dentures

The aims of the present study were to describe an impression method of "inner circular sealing area" and to evaluate the effect of the method on retention, aesthetics and comfort of complete dentures, which lack labial base for patients with maxillary protrusions. Three patients were subjected to the experiment, and two sets of complete maxillary dentures were made for each patient; the first set was made without labial base via an inner circular sealing area method (experimental group) and the second had an intact base that was made with conventional methods (control group). Retention force tests were implemented with a tensile strength assessment device to assess the retention and a visual analogue scale (VAS) was used to evaluate the comfort between the two groups. Results showed larger retention force, better aesthetics and more comfort in the experimental group. The improved two-step impression method formed an inner circular sealing area that prevented damage to the peripheral border seal effect of the denture caused by incomplete bases and obtained better denture retention.

O objetivo deste caso foi descrever um método de impressão por "área de selamento circular interno" e avaliar o efeito deste método na retenção, estética e conforto de próteses totais sem base labial para pacientes com protrusão maxilar. Três pacientes foram objeto desta experiência e foram feitas duas próteses maxilares completas para cada um deles; a primeira foi elaborada sem base labial pelo método de área de selamento circular interno (grupo experimental) e a outra teve uma base feita pelo método convencional (grupo controle). Foram realizados testes de retenção com estudo de tensão para avaliar a retenção e para avaliação do conforto dos dois grupos, foi empregada a escala analógica visual (EAV). Os resultados demonstraram que o grupo experimental apresentou força de retenção maior, estética melhor e mais conforto. O método modificado de impressão em duas etapas formou uma área de selamento circular interno que evitou danos ao selamento periférico causados por bases incompletas e obteve melhor retenção da prótese.

Oral crest lengthening for increasing removable denture retention by means of CO2 laser.

The loss of teeth and their replacement by artificial denture is associated with many problems. The denture needs a certain amount of ridge height to give it retention and a long-term function. Crest lengthening procedures are performed to provide a better anatomic environment and to create proper supporting structures for more stability and retention of the denture. The purpose of our study is to describe and evaluate the effectiveness of CO2 laser-assisted surgery in patients treated for crest lengthening (vestibular deepening). There have been various surgical techniques described in order to restore alveolar ridge height by pushing muscles attaching of the jaws. Most of these techniques cause postoperative complications such as edemas, hemorrhage, pain, infection, slow healing, and rebound to initial position. Our clinical study describes the treatment planning and clinical steps for the crest lengthening with the use of CO2 laser beam (6-15 Watts in noncontact, energy density range: 84.92-212.31 J/cm(2), focus, and continuous mode with a focal point diameter of 0.3 mm). At the end of each surgery, dentures were temporarily relined with a soft material. Patients were asked to mandatorily wear their relined denture for a minimum of 4-6 weeks and to remove it for hygienic purposes. At the end of each surgery, the deepest length of the vestibule was measured by the operator. No sutures were made and bloodless wounds healed in second intention without grafts. Results pointed out the efficiency of the procedure using CO2 laser. At 8 weeks of post-op, the mean of crest lengthening was stable without rebound. Only a loss of 15% was noticed. To conclude, the use of CO2 laser is an effective option for crest lengthening.

Reabilitação oral com prótese total através do emprego da técnica da zona neutra / Oral rehabilitation with complete dentures using neutral zone technique

A prótese total é um dispositivo mecânico destinado a substituir todos os dentes do arco dental e a parte gengival ausente, a fim de restituir a função, a estética e a saúde dos órgãos mastigatórios. Uma das técnicas de confecção de próteses totais visa localizar, dentro da área chapeável, a posição anteriormente ocupada pelos dentes naturais, chamada de “zona neutra”, em que as forças linguais são neutralizadas pelas forças dos lábios e bochechas. Uma vez que essas forças são desenvolvidas através da contração muscular durante as diversas funções orais, elas variam em magnitude nos diferentes indivíduos. A técnica consiste, basicamente, na colocação de um material de moldagem sobre uma base, normalmente de acrílico, sendo o conjunto levado à cavidade oral do paciente, que deverá realizar movimentos de deglutição e sucção visando uma moldagem da musculatura durante as funções orais. Esta técnica possui uma importante indicação na reabilitação de desdentados completos, principalmente quando se observa uma atrofia significativa do rebordo mandibular, culminando em instabilidade protética. Entretanto, quer seja pelas controvérsias existentes em relação à técnica ou pelo próprio desconhecimento dos profissionais quanto à sua realização, esta técnica permanece pouco utilizada na rotina diária. Desta forma, o objetivo deste estudo foi elaborar uma revisão da literatura sobre a técnica da zona neutra e sua utilização em reabilitações orais

Complete denture is a mechanical device developed to replace all the teeth of the dental arch and the missing gingival portion, in order to restore function, aesthetics and health of the masticatory organs. One of the techniques of complete denture treatment aims at locating within the basal area the position previously occupied by natural teeth, called “neutral zone”, in which tongue forces are neutralized by the forces of the lips and cheeks. Since these forces are developed by muscle contraction during the various oral functions, they vary in magnitude among different individuals. The technique consists of placing the impression material on a base plate, usually made of acrylic, and inserting it into patient’s oral cavity, while the patient performs suction and swallowing movements seeking for an impression of the musculature during oral functions. This technique has an important indication in the rehabilitation of complete edentulous, mainly when there is a significant atrophy of the mandibular ridge, culminating in prosthetic instability. However, due to the controversies regarding this technique or to the lack of knowledge about its performance, this technique is still rarely used in daily routine. Thus, the aim of this study was to present a literature review on the use of the neutral zone technique in oral rehabilitations

Short-term objective and subjective evaluation of small-diameter implants used to support and retain mandibular prosthesis.

BACKGROUND: The introduction of small-diameter implants has provided dentists the means of providing edentulous and partially edentulous patients with immediate functioning transitional prostheses while definitive restorations are being fabricated. The successful use of these small-diameter implants for temporary stabilization of prostheses has led many clinicians to explore the option of using them as a definitive alternative, especially as the technique requires minimal time and also is economical for the patients. To date, there has been no study with multiple patients looking at both the subjective and objective outcomes of these small-diameter implants. MATERIALS AND METHODS: Twenty-seven edentulous patients were enrolled in this study, seven of them were smokers. One-hundred and eight small-diameter (2.0 mm, MDL) implants were surgically placed in 24 edentulous mandibles. All implants were immediately loaded. The patients filled out a screening questionnaire and four subsequent questionnaires to test their satisfaction with the altered prosthesis at 6, 12, 18 and 24 months. The survival of the implants was also noted. RESULTS: Smokers had an implant survival of 79%. Non-smokers had an implant survival of 100%. The results of the questionnaire indicated an overall satisfaction with the implant-supported prosthesis.

Wear of double crown systems: electroplated vs. casted female part

OBJECTIVES: The wear of telescopic crowns is a common problem often reducing the patient's satisfaction with the denture and resulting in a renewal of the denture. The study aims to compare the wear behavior of conical crowns using electroplated copings (group E ) with standard telescopic crowns with cast female parts (group C). MATERIAL AND METHODS: 10 conical crowns were milled for each group of a cast gold alloy. The specimen of group E had a conicity of 2º. The cast secondary crowns of group C had a 0º design. The electroplated coping was established by direct electroforming. An apparatus accomplishing 10,000 wear cycles performed the wear test. The retentive forces and the correlating distance during insertion and separation were measured. The wear test was separated in a start phase, an initial wear phase and the long term wear period. The retention force value and the force-distance integral of the first 0.33 mm of each cycle were calculated. RESULTS: The retentive forces were significantly higher for group E and the integrals were significantly lower for this group except the integral at cycle 10,000. The changes of retention force and integral did not differ significantly between both groups in all phases. The change of the integrals as well as the integral at the particular cycles showed higher interquartile distances for group C. CONCLUSIONS: Within the limitations of this study the tested conical crowns showed clinically acceptable retentive properties. The values reached a range comparable to retentive elements tested in recent literature. The values of group C showed higher ranges. The force measured for group E was significantly higher than for group C but the integrals showed an opposite tendency. The results indicate that an exclusive analysis of the force is not sufficient as the integral is not equivalent to the force although it describes the retentive property of the system in a better way than the force over a distance is described. Both systems seem to be suitable for clinical practice.

Use of the multi-cup denture for a severely resorbed maxilla: a clinical report.

Obtaining a satisfactory outcome for a patient with a severely resorbed maxilla can be extremely challenging. This clinical report describes the treatment of a patient with a history of multiple implant failures in the maxilla. A conventional upper complete denture had poor retention and so did not fulfil the patient's needs. Further surgery was not considered appropriate. A new upper complete denture was made with a fitting surface covered in multiple suction cups to attempt to improve the retention without surgery and resulted in a pleasing outcome for both the patient and authors.

Flabby ridge correction using an auxiliary technique with connective tissue graft.

A common finding in patients with edentulous maxilla and partially dentate mandible is mainly the presence of flabbiness in the anterior edentulous alveolar ridge that can compromise the retention and stability of a denture. Thus, this case report presents the correction of a flabby ridge, using an auxiliary technique combining surgical excision and autogenous connective tissue grafting. The technique improved the quality of the osteomucosal support of the alveolar ridge and increased the vestibule deepness, whose result increased the success rate of the new conventional total prosthesis.

Frecuencia de las retenciones dentarias en radiografías panorámicas: presentación de un estudio en 1000 pacientes / Frequency in deductions dental panaramic radiographs: presentation of a study in 1000 patients

La retención dentaria es una anomalía en la que una vez llegada la época normal de erupción, permanecen los dientes en el interior de los maxilares manteniendo la integridad de su saco pericoronario, pudiendo producir en su intento de erupción accidentes patológicos de variado aspecto e intensidad. Una de las causas se debe a que los maxilares de la especie humana son de menor tamaño que los de nuestros antecesores, y de esta manera no es posible alinear armónicamente los 32 dientes. La radiografía panorámica es de gran utilidad para diagnosticar esta lesión, sin manifestación clínica en algunos casos. Sobre una muestra de 1000 pacientes, desde los 6 hasta los 92 años, se diagnosticaron 334 retenidos; 180 en mujeres y 154 en varones. Las retenciones dentarias halladas fueron: 131 correspondieron a terceros molares inferiores, 70 derechos y 61 izquierdos; 107 correspondieron a los terceros superiores, 58 derechos y 49 izquierdos. Caninos permanentes 52: 43 superiores, y 9 inferiores. Premolares: 28, 20 inferiores y 8 superiores. El análisis de varianza nos indicó que hay diferencias significativas entre edades analizados por décadas pero no se halló diferencias entre sexos.

An impacted tooth is a dental anomaly in which a dental piece remains enclosed into the jaw after the normal eruption age is reached, despite it usually keeps the physiology of the pericoronal sac; but it is known to cause some pathological accidents of varying kind and intensity during the tooth's attempt of eruption. One of the reasons for this anomaly is probably the fact that the jaws of the human species are smaller in size than those of our ancestors, so it is almost impossible for the 32 teeth to be aligned in a harmoniously way. The panoramic radiography is very helpful to diagnose this abnormality, which in many instances may occur with no clinical manifestations. 1000 radiographs, taken from 6- to 92-year-old patients, a total of 334 impacted teeth were found, 180 female and 154 in male; their distributions were as follows: 131 lower third molars, 70 right and 61 left; 107 were upper third molars, 58 right and 49 left; 52 permanent canines were found, 43 upper and 9 lower; 28 premolars, 20 lower and 8 upper.The variance analysis indicated that theres`s a significate difference between the analized ages per decades, but there were no differences found between sexs.

Photoelastic analysis of the distribution of stress in different systems of overdentures on osseous-integrated implants.

OBJECTIVE: The aim of this study was to evaluate the distribution of generated stress around implants and adjacent bone tissue using different implant-retained overdenture designs through photoelastic analysis. METHODS: Over an edentulous human mandible, achieved from a human model, 2 or 4 microunit analog abutments were embedded (Master; Conexao Systems Prosthodontics, São Paulo, Brazil), settled in the interforaminal region. Three models of photoelastic resin (Araltec Chemicals Ltda, Hunstman, Guarulhos, São Paulo, Brazil), with 2 or 4 incorporated implants and microunit abutments, were obtained from molds using silicone for duplication. Inclusion, finishing, and polishing procedures were applied on the frameworks. This study was based on 3 different mechanisms of implant-retained mandibular overdentures: O'ring (GI), bar-clip (GII) (both with 2 implants), and their association (GIII) (with 4 implants). After the adaptation of each overdenture system on the photoelastic models, 100-N alternate occlusal loads were applied on back-side and front-side regions. The photoelastic analysis was made with the aid of a plain polariscope linked to a digital camera, Sony Cybershot α100, which allowed visualization of the fringes and registration of images on digital photographs. RESULTS: The results demonstrated higher tension concentrated over the GIII, with a flat distribution of stress to the posterior ridge and overload on the posterior implants. GI showed the smaller stress level, and GII, intermediate level; there was distribution of stress to the posterior ridge in these 2 groups. CONCLUSION: The use of bar attachment proved to be a better alternative, because it showed a moderate level of tension with a more uniform stress distribution and possessed higher retention than did the ball system.

Evaluation of stress patterns produced by implant-retained overdentures and implant-retained fixed partial denture.

The purposes of this study were to photoelastically measure the biomechanical behavior of 4 implants retaining different cantilevered bar mandibular overdenture designs and to compare a fixed partial denture (FPD). A photoelastic model of a human edentulous mandible was fabricated, which contained 4 screw-type implants (3.75 × 10 mm) embedded in the parasymphyseal area. An FPD and 3 overdenture designs with the following attachments were evaluated: 3 plastic Hader clips, 1 Hader clip with 2 posterior resilient cap attachments, and 3 ball/O-ring attachments. Vertical occlusal forces of 100 N were applied between the central incisor and unilaterally to the right and left second premolars and second molars. Stresses that developed in the supporting structure were monitored photoelastically and recorded photographically. The results showed that the anterior loading, the overdenture with 3 plastic Hader clips, displayed the largest stress concentration at the medium implant. With premolar loading, the FPD and overdenture with 3 plastic Hader clips displayed the highest stresses to the ipsilateral terminal implant. With molar loading, the overdenture with 3 ball/O-ring attachments displayed the most uniform stress distribution in the posterior edentulous ridge, with less overloading in the terminal implant. It was concluded that vertical forces applied to the bar-clip overdenture and FPD created immediate stress patterns of greater magnitude and concentration on the ipsilateral implants, whereas the ball/O-ring attachments transferred minimal stress to the implants. The increased cantilever in the FPD caused the highest stresses to the terminal implant.

Prótese destacável com sistema “Swivel Loc” – relato de caso clínico / Detachable prosthesis with Swivel Loc system – a clinical case report

A reabilitação total maxilar com próteses implantossuportadas representa em algumas situações clínicas dificuldades quanto a estética, fonética, suporte labial e higienização. As próteses destacáveis implantossuportadas são uma opção de tratamento frente a essa situação, onde o uso de encaixes permite a conexão entre uma prótese removível e uma infraestrutura metálica, sendo estéticos e funcionalmente eficientes. O objetivo deste trabalho foi de apresentar por meio de um caso clínico a confecção de uma protese destacável do sistema “Swivel Loc” como alternativa de aperfeiçoar a previsibilidade dessas reabilitações

The total rehabilitation of maxilla with supported implant prostheses represent in some clinical difficulties regarding aesthetics, phonetics, lip support and hygiene. The detachable implant supported dentures are a treatment option when faced with this situation, the use of attachments allows a connection between a removable prosthesis and a metallic infrastructure, being aesthetic and functionally efficient. The aim of this work was present through a clinical case the making of a detachable prosthesis with Swivel Loc system as an alternative to improve the predictability of these rehabilitations