Intensidad del Punto de Contacto en Resinas Clase II. Revisión Sistemática

RESUMEN: Factores como el tipo de resina compuesta y sistema de matrices son clave para lograr una adecuada intensidad del punto contacto, la cual puede determinar el éxito de una restauración clase II. Con el objetivo de comparar la intensidad del punto de contacto obtenida en restauraciones de resina clase II, cuando se usan diferentes consistencias de resinas compuestas y sistemas de matrices en estudios in vitro, se realizó una revisión sistemática según la pauta PRISMA. Los estudios fueron seleccionados a través de una estrategia de búsqueda para cada base de datos electrónica (MEDLINE/ PubMed, Scopus, Web of Science y EBSCO host). En cada artículo seleccionado, se tabularon: autor/año, tamaño muestral, diente utilizado y preparación cavitaria, tipo de resina compuesta, tipo de sistema matriz e intensidad del punto de contacto (resultado medido en Newton). La calidad metodológica se analizó mediante una pauta modificada para estudios in vitro. De 90 artículos, un total de 5 artículos reunieron los criterios de selección y fueron incluidos. De estos cinco artículos, sól o dos artículos estudiaron la influencia de la consistencia de la resina compuesta y los sistemas de matrices en forma simultánea. El riesgo de sesgo para los estudios fue bajo para 1 artículo, medio para 2 y alto para los otros 2 artículos. No se obtiene la misma intensidad de punto de contacto entre diferentes consistencias de resina compuesta y distintos sistemas de matrices, ya que los mayores valores se obtuvieron al utilizar matrices seccionales combinadas con anillo de separación y resinas compuestas de mayor viscosidad.

ABSTRACT: Factors such as the type of composite resin and matrix system are key to achieving an adequate proximal contact tightness, which can determine the success of a class II restoration.To compare the proximal contact tightness obtained in class II resin restorations, when different consistencies of composite resins and matrix systems are used, on in vitro studies. The systematic review was carried out according to the PRISMA Statement guidelines. The studies were selected through a search strategy for each electronic database (MEDLINE/PubMed, Scopus, Web of Science and EBSCO host). In each selected article, the following were tabulated: author/year, sample size, tooth used and cavity preparation, type of composite resin, type of matrix system and proximal contact tightness (result measured in Newton). The methodological quality was analyzed using a modified guideline for in vitro studies. Of 90 articles, a total of 5 articles met the selection criteria and were included. Of these five articles, only two articles studied the influence of the consistency of the composite resin and the matrix systems simultaneously. One of the articles was a low risk of bias, two of medium and two of high. The same proximal contact tightness is not obtained between different consistencies of composite resin and different matrix systems, since the highest values were obtained when using sectional matrices combined with a separation ring and composite resins of higher viscosity.

Restabelecimento de ponto de contato em dentes com coroas totais posteriores: relato de caso / Reestablishment of contact point on teeth with posterior crowns: case report

A presença do ponto de contato é essencial para manter a saúde das estruturas periodontais, além de evitar inclinações dentárias e desgastes, conservando, assim, uma oclusão ideal. Objetivo: apresentar um relato de caso clínico com restabelecimento dos pontos de contato de forma conservadora, por meio da ortodontia e da dentística restauradora, em dentes com coroas totais. Relato de caso: paciente do gênero feminino, 69 anos de idade, compareceu à clínica odontológica da universidade com queixa de impacção alimentar e desconforto na região superior posterior direita da arcada. Foi observada clinicamente ausência do ponto de contato entre os dentes 15, 16 e 17, optando-se pelo tratamento multidisciplinar envolvendo a ortodontia e a dentística restauradora. Para isso, foram utilizados bráquetes no segundo pré-molar e no primeiro molar superior direito (dentes 15 e 16, respectivamente), e botões ortodônticos nas faces palatinas desses, e do segundo molar superior (dente 17), unidos por elástico corrente tamanho médio. Quando obtidos os pontos de contato, foi realizada a restauração do primeiro pré-molar direito (dente 17) com resina composta. Considerações finais: o uso de elásticos corrente e botões ortodônticos foi satisfatório para a obtenção de pontos de contato entre os dentes.(AU)

The presence of the proximal contact is essential to maintain the periodontal structures health, besides preventing diseases and wastes, thus preserving an ideal occlusion. Aim: the aim of this article is to present a clinical case report with restoration of the proximal contact in a conservative way, through orthodontics and restorative dentistry, in teeth with total crowns. Case report: a 69-year-old female patient attended the university dental clinic with complaint of food impaction and discomfort in the upper right posterior region of the arcade. It was clinically observed absence of the point of contact between the teeth 15, 16 and 17 and opted for the multidisciplinary treatment involving orthodontics and restorative dentistry. For this, brackets were used in the second premolar and first maxillary right molar (teeth 15 and 16, respectively), and orthodontic buttons on the palatal surfaces of the same, and on the second upper molar (tooth 17), joined by the current elastic medium size. When the proximal contact was obtained, the first right premolar restoration was performed with a composite resin. Final considerations: the use of current elastics and orthodontic buttons were satisfactory for obtaining proximal contact between these teeth.(AU)

Evaluation of adjacent tooth displacement in the posterior implant restoration with proximal contact loss by superimposition of digital models

PURPOSE: This study was conducted to investigate patterns of adjacent tooth displacement in the posterior implant with interproximal contact loss (ICL) by 3-D digital superimposition method. MATERIALS AND METHODS: Posterior partially edentulous patients, restored with implant fixed partial prostheses before 2011 and suffered from food impaction of ICL between 2009 and 2011, were included. Two dental casts, at the time of delivery and at the time of food impaction in a same patient, was converted into 3-D digital models through scanning and superimposition was performed to assess chronologic changes of the dentition. Directions of tooth displacement were evaluated and the amount of ICL was calculated. Correlations between the amount of ICL and elapsed time, or between the amount of ICL and age after function, were assessed at a significance level of P.05). CONCLUSION: Natural teeth showed various directional movements to result in occlusal change in the arch. The 3-D superimposition of chronologic digital models was a helpful method to analyze the changes of dentition and individual tooth displacement adjacent to implant restoration.

Clinical evaluation of differences in proximal contact strength of various fixed dental prosthesis materials

The study compared the proximal contact strength (CS) of different fixed dental prosthesis (FDP) materials. Materials and Methods: Thirty volunteers participated in this study with definitive inclusion and exclusion criteria. Participants were divided into full metal, zirconia, and metal ceramic groups. The CS between the natural teeth and the maxillary posterior quadrant FDP was measured with force gauge. The data were evaluated with one-way analysis of variance test, and Tukey's honest significant difference post hoc was done to compare the mean values. Paired samples t-test was used to compare the mean values between pre- and postoperative CS. Results: The postoperative CS observed in the full metal group in premolar was 0.320 ± 0.1092 N and in second molar was 0.385 ± 0.1130 N. CS obtained with zirconia FDP in both premolar (0.679 ± 0.0927 N) and molar (0.770 ± 0.0960 N) was highest among all groups. The results were statistically significant (P < 0.001). Conclusion: Postoperative CS was greater in zirconia when compared with metal and metal ceramic FDP. Clinical Relevance: FDP materials had acceptable CS. Zirconia is preferable for optimal CS.

Comparison of two different matrix band systems in restoring two surface cavities in posterior teeth done by senior undergraduate students at Qassim University, Saudi Arabia: A randomized controlled clinical trial

Dental students commonly face the problem of overhanging proximal margins and unsatisfactory proximal contact points (PCPs) while restoring Class II cavities in posterior teeth. Various matrix band systems are used in dental clinics to avoid such problems. Aims: The aim of this study is to compare the effects of two matrix band systems, circumferential matrix system and sectional matrix system on the PCPs and contours when restoring Class II cavities in posterior teeth. Settings and Design: This was a randomized controlled clinical trial done at College of Dentistry, Qassim University, Saudi Arabia. Subjects and Methods: Total 1200 Class II cavities in teeth were selected for this study. Treatment was done by senior undergraduate students. Cavities were randomly divided into two groups. Group 1: Total 600 cavities were restored using circumferential band system. Group 2: Total 600 cavities were restored using sectional band system. Teeth were restored either with the composite or the amalgam restoration. Contact points were evaluated. The presence or absence of proximal overhangs was assessed. Overhanging margins were categorized as positive overhangs, negative overhangs, and absent overhangs. Statistical Analysis Used: To identify the relationship between matrix band systems and other factors, Chi-square tests (χ2-tests) and Z-tests were used. Pearson correlation coefficient was computed and logistic regression analysis was carried out to assess variables that can affect proximal margins and contact points of final restorations. Results: All optimum contacts 389 (100%) were found in restorations done using sectional band system. A highly significant association was found between open contact points and negative overhanging margins with the use of circumferential matrix band system (P < 0.00). Conclusion: Sectional matrix band system has been found superior to circumferential matrix band system.

The effects of two different patterns on the precision of zirconia all-ceramic crowns / 口腔疾病防治

Objective@#The objective of this study was to compare the early clinical effects of zirconia all⁃ceramic crowns using two different impression methods. Zirconia ceramic crowns were produced using digital models based on either a silicone rubber impression perfusion model in vitro or a 3D mouth scanner.@*Methods @#A total of 50 patients with a planned restoration of the first permanent molar with zirconia all⁃ceramic crowns after root canal therapy were se⁃ lected and randomly divided into two groups: a digital impression by intraoral 3D scanning group and a digital impres⁃ sion by extraoral scanning after silicone rubber impression group. Zirconia all⁃ceramic crowns were created by CAD/ CAM in both groups. Marginal adaptation, proximal contact, and occlusal contact were compared between groups. @*Results@#There was no significant difference between the two groups in marginal adaptation (P > 0.05). For proximal con⁃ tact and occlusal contact, no significant differences regarding the number of cases for the criteria of level A and level B were found between two groups (P > 0.05), while the misfit value in level B was smaller in the first group than in the second group (P < 0.05). @*Conclusion@#Zirconia all⁃ceramic crowns with intraoral 3D scanning show excellent early clinical performance.

Intrusion phenomenon of natural tooth bounded by implant-prostheses: a clinical report / 대한치과보철학회지

In case of implant-tooth connected prosthesis, a natural tooth tends to intrude. There are several mechanisms that explain an intrusion phenomenon. So it is reco mmended not to connect an implant with a natural tooth. A 68-year-old female had upper left 2nd premolar and 2nd molar extracted and underwent implant surgery on the missing area. We made an implant prosthesis and treated upper left 1st molar with a gold crown. 2.5 year later, the patient complained about loose proximal contact and food impaction between upper left 1st molar and 2nd molar. Mesial side of upper left 2nd molar implant prosthesis was soldered so that proximal contact became tight again. But after 7 months, about 2 mm intrusion of upper left 1st molar occurred, and the patient felt periodontally originated pain on intruded upper left 1st molar. After the gold crown on upper left 1st molar was removed, extrusion occurred and pain was relived.

Utilização da fita de politetrafluoretileno como matriz em odontologia restauradora: relato de caso clínico / The use of the polytetrafluorethylene tape as matrix in operative dentistry: a clinical report

O objetivo deste relato de caso clínico é apresentar a utilização da fita de politetrafluoretileno (PTFE) para facilitar a técnica de reprodução anatômica durante a restauração de incisivos centrais superiores. Paciente do sexo feminino, 10 anos de idade, apresentou-se na Clínica de Dentística Operatória e Estética da Universidade Peruana Cayetano Heredia - UPCH, para a realização de restaurações nos dentes 21 e 11. Os dentes foram preparados, de acordo com as técnicas convencionais. Em seguida, os dentes adjacentes foram secos e recobertos com um pedaço de fita de PTFE. Os dentes foram, então, restaurados, utilizando-se uma resina composta de nanopartículas, por meio das técnicas da matriz de silicone e da técnica incremental. No final da restauração, a fita de PTFE foi removida e procederam-se o acabamento e o polimento das restaurações. Após o término da restauração, uma aparência estética e natural do dente fraturado foi conseguida, satisfazendo as expectativas funcionais e estéticas do paciente.

The aim of this case report is to present the use of PTFE tape to make easier the copy of anatomic details, during the restoration of maxillary central incisors. A 10-year-old girl attended the Dental Clinic of the Universidad Peruana Cayetano Heredia - UPCH with fracture in the teeth 21 and 11. The teeth were prepared, in according to conventional techniques. Next, the adjacent teeth were dry and covered with a piece of tape of PTFE. The teeth were restored using a composite resin of nanoparticles, through the techniques of the silicon matrix and composite stratification. When the restoration was finished, the tape of PTFE was removed and the finishing and polishing of the restorations were made. After the restoration, an aesthetic and natural appearance of toothfracture was achieved, satisfying the expectations and functions of the patient.

Evaluation of proximal contact strength by postural changes

STATEMENT OF PROBLEM: Proper proximal contact is important for maintaining and stabilizing the dental arch. However, the proximal contact strength (PCS) is not a constant value and can be affected by a variety of factors. PURPOSE: This study examined the influences of postural changes on the posterior PCS. MATERIAL AND METHODS: Twelve adults with a normal occlusion and had not undergone prosthetic treatment or proximal restoration were participated in this study. A metal strip was inserted into the proximal surface and removed at a constant velocity. The contact strength was measured in every contact point between canine to second molar in both arches. The PCSs were obtained initially in the upright position, secondly in the supine position and finally in the upright position again. All measurements were repeated after a 2 hour period. Statistical analysis was carried out using the Friedman test (P < .05). RESULTS: Generally, a decrease in PCS occurred when the posture was changed from the initial upright to supine position, while it increased when the posture was changed from the supine to upright position. A significant change was observed in all areas except for between the canine-first premolar in the maxilla and between the first molarsecond molar in the mandible areas. CONCLUSION: The posterior PCS, which dentists generally believe to be a static feature of occlusion, is affected significantly by posture.

Evaluation of tightness of proximal tooth contact in permanent dentition / 대한치과보철학회지

STATEMENT OF PROBLEM: Proximal contact plays an important role in the stability and maintenance of the integrity of the dental arches. However, it is difficult to evaluate quantitatively the tightness of proximal tooth contact (TPTC). PURPOSE: The aim of this study was to measure the TPTC in permanent dentition. MATERIAL AND METHODS: Ten young adult volunteers with healthy dentition participated in this experiment. The TPTC between the teeth of both the maxilla and the mandible was measured at rest state by a novel device which records the TPTC by pulling of a stainless steel strip (0.03 mm thick) using the electric motor. One-way ANOVA test was used to compare the values in all measured area. When a statistically significant difference was calculated, Bonferroni correction was applied. Independent samples t-test was used to compare the values in male and female. RESULTS: The lowest TPTC and the highest TPTC was measured between the lower central incisors (0.87 +/- 0.20 N), and between the lower left first molar and second molar (1.99 +/- 0.68 N), respectively. All TPTC per quadrant demonstrated a similar pattern of a continuous increased gradient in an anterior-posterior direction. There are no significant difference between the maxilla and mandible. CONCLUSION: The TPTC was measured quantitatively by a novel device and decreased progressively in a posterior-anterior direction.

A photoelastic stress analysis of fixed partial dentures with bicon implants on mandibular posterior area / 대한치과보철학회지

STATEMENT OF PROBLEM: Several prosthetic options are available for the restoration of multiple adjacent implants. A passively fitting prosthesis has been considered a prerequisite for the success and maintenance of osseointegration. Passivity is a particular concern with multiple implants because of documented inaccuracies in the casting and soldering process. One way to avoid this problem is to restore the implants individually, however, the restorations of individual adjacent impants requires careful adjustment of interproximal contacts. PURPOSE: The purpose of this study was to compare the stress distribution pattern and amount surrounding Bicon implants with individual crowns and splinted restorations. MATERIAL AND METHOD: A photoelastic model of a human partially edentulous left mandible with 3 Bicon implants(4*1 mm) was fabricated. For non-splinted restorations, individual crowns were fabricated on 3 abutments (4.0*6.5 mm, 0 degree, 2.0 mm post, Bicon Inc., Boston, USA) After the units were cemented, 4 levels of interproximal contact tightness were evaluated: open, ideal (8 micrometershim stock drags without tearing), medium(40 micrometer), and heavy(80 micrometer). Splinted 3-unit fixed partial dentures were fabricated and cemented to the model. Changes in stress distribution under simulated non-loaded and loaded conditions(7.5, 15, 30 lb) were analyzed with a circular polaricope. RESULTS: 1. Stresses were distributed around the entire body of fin in Bicon implants. 2. Splinted restorations were useful for distribution of stress around implants especially with higher loads. 3. By increasing the contact tightness between the individually restored three implants, the stress increased in the coronal portion of implants. CONCLUSIONS: Ideal adjustment of the contact tightness was important to reduce the stresses around individually restored Bicon implants.

A photoelastic stress analysis of fixed partial dentures with endopore implants according to splinting, contact tightness, and crown length / 대한치과보철학회지

STATEMENT OF PROBLEM: A difficulty in achieving a passive-fitting prosthesis can be overcome by individual crown restoation of multiple implants. But individualized crown has another difficulty in control of contact tightness and stress distribution. PURPOSE: This in vitro study is to evaluate the stress distribution and the magnitude in the supporting tissues around Endopore implants with different crown lengths, interproximal contact tightness, and the splinting effects. MATERIAL & METHODS: Three Endopore implants(4.1*9 mm) were placed in the mandibular posterior edentulous area distal to the canine and photoelastic model was made with PL-2 resin(Measurements Group, Raleigh, USA). Restorations were fabricated in two crown lengths: 9, 13 mm. For non-splinted restorations, individual crowns were fabricated on three custom-milled titanium abutments. After the units were cemented, 4 levels of interproximal contact tightness were evaluated: open, ideal(8 micrometershim stock drags without tearing), medium(40 micrometer), and heavy(80 micrometer). For splinted restorations, 3-unit fixed partial dentures were fabricated. This study was examined under simulated non-loaded and loaded conditions(6.8 kg). Photoelastic stress analysis was carried out to measure the fringe order around the implant supporting structure. RESULTS: 1. When restorations were not splinted, the more interproximal contact tightness was increased among the three implants, the more stress was shown in the cervical region of each implant. When crown length was increased, stresses tended to increase in the apex of implants but there were little differences in stress fringes. 2. When nonsplinted restorations were loaded on the first or third implant, stresses were increased in the apex and cervical region of loaded implant. Regardless of interproximal contact tightness level, stresses were not distributed among the three implants. But with tighter interproximal contact, stresses were increased in the cervical region of loaded first or third implant. 3. When the nonsplinted restorations were not loaded, there were little stresses on the supporting structure of implants, but low level stresses were shown in the splinted restorations even after sectioning and soldering. 4. With splinted restorations, there were little differences in stresses between different crown lengths. When splinted restorations were loaded, stresses were increased slightly on the loaded implant, but relatively even stress distribution occurred among the three implants. CONCLUSIONS: Splinting the crowns of adjacent implants is recommended for Endopore implants under the overloading situation.