Repositório RCAAP

Mestre em Odontologia

The clinical success of dental implants has as important factor the way the mechanical stress is transferred from the implant the surrounding bone tissue. This transference and its magnitude may be related to the material of the screwed the prosthesis to the implants, risking the longevity of osseointegration. This study has as proposal to determinate the stress distribution of the region of implants, to compare the energy level to obtained when they are interconnected by bar constructed metallic alloy or in acrylic resin activated chemically, using the photoelastic method. For that it was constructed two photoelastic models with to implant positioned and united by bars in metal and acrylic resin activated chemically. The load of 2 kgf was applied in the center of bars (A point), on the implant B and in one extremity of point C, distance 10,0 mm of implant. The reading of distribution and location of stress was made from photographs that register the images after the applied loads. The results show, qualitatively, that when the load was applied in A point, it was distributed symmetrical along them and the high stress concentration occurred in the distal portion of implants; when applied over the implant (B point), it was noted an increase of stress levels; loads applied in one extremity (C point), distance 10,0 mm of implant center, produced the highest stress level, showing more solicitation of implant in the side that the load is applied, generation distortion in the geometry producing more level of energy, being that the distortion of resin bars more that metal bars. The consequence is: for situations of one extremity (cantilever), where the biggest values are found, the distortions generate high stress levels in the first lines and to the long one of the line next to the apex to the implant and no depends of the type of bar, but the point application of the load.

The bond strength may be influenced by the different composition and manipulation of the adhesive systems, the dentin structure and the method of evaluation. After exposure of the occlusal dentin surface 160 third human molars were divided in 2 groups (n=80) for the micropush-out (&#956;PBS) and microshear (&#956;SBS) bond strength tests. For the &#956;PBS, 4 groups (n=20) were obtained and a tapered cavity (2,5x1,5x1,0mm) was prepared on the dentin surface and restored with composite resin after treatment using different adhesive systems: Adper Single Bond, Adper Scotchbond MP, Prompt-L-Pop, AdheSE. After water storage for 24 hours, from 10 teeth per group, 1 oclusal slice (1,5 ±0,3mm) was obtained from each tooth, and the restoration submitted to vertical load. The other 10 teeth were storage for 12 months and then submitted to the same procedure. For the &#956;SBS another 80 teeth were divided into 4 groups (n=20), the dentin surface was treated using the same adhesive systems and composite resin cylinders (1x1mm) were constructed and polymerized in a single increment onto the bonding area. Ten specimens were tested after 24 hours and 10 after 12 months of water storage. The null hypotheses were that (1) the composition and manipulation of the adhesive systems, (2) the water storage and (3) the method of evaluation might influence the bond strength of direct composite resin restorations. Results of ANOVA did not show significant difference for the storage time factor (p=.6343), but there was difference between the methods (p<.0001), with higher values for the &#956;PBS test, and among the adhesive systems (p<.0001). The Adper Scotchbond and AdheSE systems presented higher bond strength values. Adhesive x method (p=.0002) and adhesive x method x time (p=.0037) interactions were significant, with different behaviors from adhesive systems within the method and time of evaluation. Conclusions were that the storage time might be not sufficient to result in alterations and that adhesive systems composition and manipulation might influence the bond strength. The &#956;PBS test, presented the higher bond values with lower coefficient of variation, indicating more consistence than the &#956;SBS test, besides of reproduce more faithfully clinical conditions.

The biomechanic limitations of the dental implants have been widely studied and one of the attempts presented by the companies was the change the shape of the abutment/implant junction, with the aim to improve the stress distribution. Therefore, the proposal of this study was to load obliquely three junctions presented commercially as more efficient than the conventional external hexagonal junction, for substitution of teeth that will receive this type of loading, verifying the hypothesis that one presents better stress distribution that the others. The analyzed junctions had been: external hexagonal (Lifecore type), internal hexagonal (Frialit type) and internal taper (Ankylos type). The technique of photoelasticity in two-dimensional plane stress was used to analyze the state of stress generated in 21 points next to the implants of each group (n=4), submitted to oblique loading. The value of the area under the graph of shear stress of the 21 points of each analyzed model was submitted to the statistical test of Kruskal-Wallis (p<0,05) showing no statistically significant difference between the groups (p = 0,058). It can be concluded that all the evaluated junctions had presented similar behavior under oblique loading, being the three junctions capable to substitute teeth that receive this type of loading.

The methods of fixation of the facial prostheses, it has been developing for larger comfort and safety, improving the quality and the patients' life. Consulting the information informs on the theme, there was the coincidence of subjects studied in some of these goods, having, also the disagreement possibility in their conclusions. The objective of this study was to evaluate the fixation methods (implants extra orals and stickers) of facial prosthesis in patient of cancer, through a systematic review (Meta analysis). Searches were accomplished by rehearsals controlled randomized of studies about fixation of facial prosthesis in patient of cancer through stickers and implants facial in bases of bibliographical data. It was located 259 summaries that were read and selected by two examiners, according to eligibility criteria and quality. The clinical endings of fixation mechanic's methods and anatomical, it was not possible to accomplish methanalysis. For the studies whose fixation method was adhesive and facial implants, it took place methanalysis eleven goods, selected were considered eligible and presenting quality for the study, involving 787 patient that do use of facial prosthesis. The methanalysis shows evidences of the beneficial effects of the use of implants extra orals for retention of the facial prostheses. The good effectiveness of the fixation methods is evidenced by implants extra orals, but for cases where no there is a good selection of the bone type and all is not possible the placement of implants the stickers is an alternative to keep the prostheses facial.

The use of fixed partial dentures in rehabilitations of edentulous jaw with implants is a well documented fact, although controversies still exists about splinting or not prosthetic crowns in these conditions. Thus, the aim of this study was to analyze the effect of prosthetic crowns detachment of a fixed partial denture with surface and punctual contacts by means of stress gradient evaluation determined by the technique of plane transmission photoelasticity. Three photoelastic models were created with 3 contiguous implants corresponding to posterior jaw aligned in straight line, varying the contact between the crowns (contact point = PC; contact surface = SC; splinted = ES). Three loading types were applied: a = axial in group (30 N); b = lateral with a 40º angle (10.8 N) over the implant corresponding to the first molar; c = central axial (9.8 N) over the implant corresponding to the second premolar. Thirty images were obtained of each loading type in each group (n = 270) in the circular polariscope. Fringe orders and maximum shear stress (&#964;) values were obtained by the program Fringes by means of photoelastic analysis of 27 points of each image and right away of 12 points in bone crest region. It was carried out the t-Student test with p<0.05 and the calculation of the graphics area. The majority of the points presented statistically different (p<0.05) in different groups. The ES group presented minimum stress values in all loadings. The SC group showed more homogeneous stress distribution around the implants in all loadings and minimum stress values in the bone crest region when compared to the PC group. Within the limitations of this study, the ES group presented better results, followed by the SC group.

In cases of upper edentulous patients with atroffic maxilla, the zigomatic implant is one of the techniques used for rehabilitation with implanted fixed prosthesis. The screw s loosening is one of the main problems related to this type of prosthesis. The aim of this work was to evaluate the golden and abutments screws loosening in fixed prosthesis over two conventional implants and two zigomatic implants before and after fatigue test. Five samples with external hexagonal junctions (HE) and five with internal conical junctions (CM) had been used. Each specimen with two anterior conventional implants and two distal zigomatic implants. The respective abutments had been installed on the implants and metallic structures of screwed fixed prosthesis had been casted. The specimens had been submitted to four fatigue protocols with different load levels in cantilever and different number of cycles. Untorque values of retaining and abutment screws had been verified before and after each cyclic loading with a digital torquemeter. The prosthetic screws had had reduction in the untorques values when compared with the iniitial torques, but there was no difference between the two interfaces in study. The untorque values of the HE abutments screws after all cycles, had a reduction in 51,56% of the cases. 60,6% f these in zigomatic implants and 39,4% in conventional implants. The screws of the CM abutments had untorque loss in 39,58% of the cases. 21,05% had ocurred in zigomatic implants and 78,95% in conventional implants. The variation of junction type does not interfere in the untorque of retention screws of the prosthesis. The mechanical behavior was different when comparing CM and HE abutment screws. In the HE specimens the torque loss was greater in the zigomatic implants whereas in the CM specimens, the absolute untorque values of the zigomatic implants increased after the fatigue test.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Given the importance of the wisdom tooth in the area of Oral and Maxillofacial Surgery, the aim of this study was to assess the various characteristics and classifications of these teeth by means of clinical and radiographic exams. For this purpose, information was collected from all the patients attended by graduation course at the Unidade de Clínica Odontoestomatológica Integrada (UCOEI) III and IV, and at the surgery clinics of VI Curso de Especialização em Cirurgia e Traumatologia Buco-Maxilo-Facial (CECTBMF) of the School of Dentistry of the Federal University of Uberlândia (FOUFU), who were submitted to the extraction of wisdom teeth during the period from June to December, 2006. Information was collected with reference to the patients, these teeth and the surgical procedures. The results indicated that among the 290 patients comprising the sample, 63.79% were women, 93.79% resident in Uberlândia, 53.10% were referred by the Pronto Socorro Odontológico (PSO) of the Federal University of Uberlândia (UFU) and the mean age was 25 years and 3 months. Periapical radiography was used in 63.1% of the patients, with 854 wisdom teeth being documented: 816 were indicated for extraction and 563 extracted (385 in the graduation course and 178 in the specialization course). The main indication for extraction was inclusion/impaction/retention (66.54%). In the graduation course, 1.37 teeth/procedure were extracted, in a mean time of 1 hour and 10 minutes (51 minutes per tooth) and 2.11 teeth in the specialization course, with a mean duration of 59 minutes (28 minutes per tooth).

Objective: The aim of this study was to analyze the data from 226 charts of patients assisted in the Dental traumatized patients assistance program Ambulatory reference of the School of Dentistry of the Federal University of Uberlândia, from March 2005 to March 2008. Material and Methods: Data were collected and classified into different tables in computer data management software (Microsoft Excel), by age of patients, gender, etiological factor, modality of trauma and number of teeth involved. Results: The total number of traumatized patients was 196, of these, 73 were women (37.3%) and 123 were men (62.7%). The patients presented 358 traumatized teeth, representing approximately 1.8 traumatized teeth per patient. Dental traumas occurred manly in the second decade of life (40%), and the main etiologic factor was characterized by falls (39.8%) Maxillary central incisors (89.6%) were more commonly affected than the mandible central incisors (10.4%). Conclusion: The dental injuries were more frequent in males, occurring mainly in the first and second decades of life. Falls were characterized as the primary etiologic factor. Coronal simple fractures were the most common lesion.

Differents drafts of tooth implant insert differents levels of tension in the surrounding bones. This can results in differents prognostics for the implants installed. This work considered by photoelasticity (resilience) of the circuit transmission the gradient of tensions produced in near pre-ordered of the implants when installed in photoelasticity matrix. Eight points were considered when no burden and thirteen points when submited to the axial burden of 0,30N, testing the hypothesis that the tension is the same at the differents implants. The implants used were Titamax TI Medular, Titamax TI Cortical, Titamax Cone Morse and Alvim TI (Neodent, Curitiba, Brazil). The value of the midle cutting tension between the analysed points of each group was submited to the variant analyse showing that has a suggestive statistic difference (p<0,05) between the unburden group. In this situation the Tukey test showed where the difference was. The results outpointed that between the tested implants, the one that produced more medium tension after the installation was the Alvim TI and the axial burden incidence did not result in significative difference at the medium tension produced for all the groups. This work objective was to estimate, in photoelasticity analyse, the tension produced by differents drafts of implants after their installation and after burden incidence, testing the hypothesis that the tension is the same in the differents kinds of implants.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The aim of this study was to evaluate the presence of calcium hydroxide residuals, associated to different vehicles, into the cervical, medial and apical radicular thirds, after the medication removal. Forty-five bovine incisors were transversally sectioned 18mm from the apex. The canals were biomechanically prepared and received an intra-canal medication. The samples were distributed in groups (n = 10): G1 Physiological Saline; G2 PA; G3 Polyethylene Glycol; G4 Polyethylene Glycol + Camphorated Paramonochlorophenol; and G5 no medication (n = 5, control). After 7 days, the medication was removed, under the mechanical action of the files associated to the physiological saline irrigation, until the irrigative solution s reflux became transparent. The roots were longitudinally sectioned, where initially, by means of a slot made in the long axis of the root, using a chisel and a hammer, it was possible to divide the root in two halves. At this moment, the proof bodies were photographed and the images digitalized, creating conditions for the calcium hydroxide residuals to be macroscopically quantized using the ImageTool® software. According to the statistic results, all the roots presented remains from the medication within the canals. There were found differences among the cervical, medium and apical thirds, when the current vehicle was the Physiological Saline.

The aim of this study was to make a comparative analysis of the conventional methods for obtaining oral radiographs with digital image processing to improve visualization of the peri-implant bone structure. For this purpose, ten patients of both sexes, aged between 27 and 56 years, with endosseous implant, after the time required for the osseointegration process and being clinically apt for prosthetic rehabilitation, were submitted to having two radiographs taken; one being a periapical radiograph of the parallelism in the implant area, and the other an orthopantomographic radiograph. A digital photographic camera was used to capture the images of the radiographs obtained in the implant area, in a standardized size, and these were processed digitally by the following techniques: transformation to gray tonalities, equalization of the histogram, inversion (negative), coloring (pseudo-coloring), texturization (high-relief) and enlargement available in the RadioImp® Software. With previously defined criteria, the sets of images were evaluated by five radiologists, five implant dentists and five prosthetists, to mark the images that enabled more details of the peri-implant bone structure to be visualized. The image processing methods used were also qualitatively and quantitatively evaluated. According to the results obtained, it could be concluded that when the conventional methods for obtaining the radiographic image were submitted to digital processing and treatments, they could contribute to better visibility of radiographic details, and provide radiologists, implant dentists and prosthetists with better conditions for evaluating the bone/metal contact surface and the cervical region of the implant.

The impossibility of using implants as independent supports of the prosthesis in the patients treatment partially edentulous, mainly in cases of anatomical limitations, makes possible for the implants to be added to the natural teeth, characterizing the tooth-implant-supported prosthesis. The conditions for it to be a viable prosthetic option, justifies knowing its mechanical behavior in order to realize its indication and the cares that should be associated in this prosthesis. The objective of this study was to evaluate the distribution of stress in the support and prosthetic structures in the tooth-implant-supported fixed prosthesis and implant-supported by the finite elements method. A laboratorial model of tooth-implanted-supported prosthesis of four elements, considering the abutments a first inferior premolar and the implant of 3.75 x 10.0 mm inserted in the area of the second inferior molar, was used to the making of eight twodimensional mathematical models of both types of prostheses. Four models were made of tooth-implant-supported (PIDS) prostheses and four of implantsupported (PIS) prostheses, having as variations the number of pontics (prosthesis of three and four elements) and the distal implant diameter (3.75 x 10.0 mm or 5.0 x 10.0 mm). All models were submitted to the same type of occlusal load. The occlusal load was applied on the first third of the slopes mesial and distal of each peak, in each prosthetic element, simulating the occlusal physiologic load. The value of this applied load was 5% of the physiologic masticatory load value. The images plotted were qualitatively analyzed. For the quantitative analysis, points on the implant, cortical bone and structures of the prosthesis from all models were selected. Both analyses were made in Ansys 9.0 software, using the von Mises criterion for the tension distribution analysis. The largest stress concentrations occurred in the implant and in the bone cortical interface with neck of the implant, in all the eight models. In both type of fixed prosthesis, the four elements ones had a lot of concentrated tension among the pontics and in the mesial region of the implant s body, positioned in the second molar region. The fixed prosthesis with the implant of larger diameter (5.0 x 10.0 mm) and smaller extension (fixed prosthesis of three elements), presented more favorable results, considering the stress better distributed by the structures of the prosthesis and the ones of support. Due to the limitations of this study, it can be concluded that the prosthetic extension and the diameter of the implant influenced the distributions of the tensions in both types of prostheses. Besides, the PDIS and PIS that had the same extension (same pontics number), and the distal abutment with the same dimensions, compared by qualitative and quantitative analysis, presented similar mechanical behavior.

Human teeth have been replaced by bovine in laboratory tests and the results questioned due differences in their mechanical properties. The purpose of this study was to investigate and compare the flexural strength (FS), flexural modulus (FM) and stiffness (ST) between species, and the influence of the investigated area and tubule orientation on the properties. Six groups (n=10) were obtained: HPA human crown dentin beams with tubules orientation parallel to the load direction; HPP human crown dentin beams with tubules orientation perpendicular to the load direction; HRO human root dentin beams with tubules orientation parallel to the load direction; BPA bovine crown dentin beams with tubules orientation parallel to the load direction; BPP bovine crown dentin beams with tubules orientation perpendicular to the load direction; BRO bovine root dentin beams with tubules orientation parallel to the load direction. FM and ST values were calculated from FS results obtained from a 3- point bending test following ISO 178 (ISO 178:2001/Amd.1:2004(E)), and submitted to Friedman and Mann Whitney statistical tests (=5%). Median values were: FR: 194,26(HPA); 152,86(HPP); 224,86(HRO); 89,84(BPA); 85,32;(BPP); 350,17(BRO). FM: 3,77(HPA); 2,53(HPP); 3,76(HRO); 2,12(BPA); 1,26(BPP); 6,38(BRO). S:3,95(HPA); 3,02(HPP); 4,30(HRO); 2,43(BPA); 1,82(BPP); 7,56(BRO).There was significant difference for HRO in comparison to HPP (HRO>HPP) in the FS only. In the 3 evaluated properties (BRO>BPA=BPP). Between species, in the 3 evaluated properties (HPA>BPA) and PP (HPP>BPP). However, bovine dentin was significantly higher than human in RO (BRO>HRO), irrespective of the evaluated property. Conclusions were that differences in mechanical properties should be considered between human and bovine dentin and that the investigated area may influence such properties. Tubules orientation seemed not to affect mechanical properties.

Total or parcial teeth loss on posterior area of maxilla alveolar process leads to pneumatization of maxillary sinuses, inducing bone turnover, difficulting rehabilitation through prostheses on implants. The maxillary sinus floor elevation surgery was developed to overcome this problem. The perforation of scheneiderian membrane is the most common complication during maxillary sinus floor elevation procedure, with reported literature incidence between 10% and 44%. The proposition of this work was to analyze the clinical feasibility of polycrystalline diamond burs obtained by CVD (Chemical Vapor Deposition) technique, used in a conventional piezoelectric ultrasound device during the osteotomy of maxillary sinus floor elevation surgery and the possible use of a blunt tip insert in the same ultrasound device to perform the elevation of scheneiderian membrane, verifying the occurrence or non-occurrence of membrane perforation during surgical procedure. The used technique showed to be viable, allowed better operatory visibility; reduction of noise and vibration; bone cut precision, with no harm to soft tissue; little bleeding; non-occurrence of excessive heating in the operated area, non-occurrence of perforation of the scheneiderian membrane during osteotomy and only 1 perforation of the schneiderian membrane at the site of an Underwood septa during the elevation procedure of scheneiderian membrane, among 12 maxillary sinuses submitted to surgery, resulting in 100% of success during the osteotomy and 91,67% clinical success rate of the used techinique.

Most of the dentistry professionals indicate the replacement of Complete Denture (TRPs) after five years of useful life, for they believe that that it is the time, on average, of durability of a removable prosthesis. The main complaint of the patient's expressed desire in modifying or keeping the buccal reality, the morpho-functional conditions of TRP, are factors that influence on decision making regarding the type of planning of mucous supported and/or implanted TRP's on keeping, repairing or replacing them. The analysis shows that a meticulous anamnesis and clinical exam are essential, in order to know and list data collected to be set as favorable or unfavorable. This way, decision making on (non) replacing TRPs is a difficult task and not yet defined in the specialized literature. For this reason, we intended, in this study, to verify the pertinence of subjects that includes physical and functional data of the prosthesis, the opinion and the patient's physiologic condition, with the purpose of elaborating a work instrument that could, in future studies, support the difficult decision taking in maintaining, repairing or substituting PRT. This way, it was elaborated, in a first moment, a quality evaluation instrument of PRT with questions about anamnesis, questionnaires on chewing ability, visual analogical scale, satisfaction with the prosthesis; and still, important items on the base and the TRP teeth. Later, with the internal teachers' aid of the University of Dentistry of the Federal University at Uberlândia and external teachers, respecting the inclusion and exclusion criteria, a note was checked to each subject in agreement with its pertinence and inclusion. The results were analyzed by a descriptive statistics, where the participation of 77,8% internal and 11,8% external educational ones was observed. The subjects suffered some alterations in agreement with its punctuation, in order to adapt the original instrument giving it a new critical format.

Epidemiologic aspects of traumatic dental injuries were evaluated in permanent dentition in a sample of 847 patients treated at the Emergency Service at the Dentistry School of the Federal University of Goias (UFG), from year 2000 to 2008. The statistical treatment analyzed data from frequency distribution, chi-square test and multiple logistic regression. The level of significance was p<0,05. The results showed a greater incident among males (72,01%) with the mean age of 6-10 year-old. The crown fracture without pulp exposure (502; 26,95%), avulsion (341; 18,30%) and crown fracture with pulp exposure (330; 17,71%) constituted the most prevalent traumatic dental injuries. The prevalence of traumatic injuries throughout the years showed proportionality, being observed a greater number of cases between July and September (249; 29,39%). The most affected tooth was the central incisors (65,65%), followed by the lateral incisors (19,67%). In 311 participants (18,25%), only one tooth was involved, while in most of the patients (536; 81,75%), traumatic dental injuries occurred in more than one tooth. Significant proportion (82,27%) of traumatized teeth presented root apex completely formed. The main etiologic factors involved in dental traumatism were falls (51,71%), motor vehicle accidents (22,90%) and violence (5,67%). Politics of health promotion have to be institutionalized, capable to stimulate the creation of secure environments and spread protocols of appropriate management of traumatic dental injury.

Oral cancer is one of the most common neoplasia in head and neck region, presenting high incidence in population and being responsible for high rates of deaths. Exposure to the products of tobacco and alcohol has been considered the major cause for the development of this disease. Though, some evidences indicate that Human Papillomavirus (HPV) can act in its genesis and progression. The objective of this work was to verify the frequency and the types of HPV in cases of oral squamous cell carcinomas and to verify its association with the disease. We accomplished a case-control study using 50 samples of squamous cell carcinomas that were diagnosed and treated in Federal University of Uberlândia, and a control group of 150 patients without cancer, matching from sex and age of the case patients. For identification and evaluation of the frequency of HPV in the different groups, the technique of Nested-PCR was used (Polimerase Chain Reaction, type Nested) for identification and typing of viral DNA. The reaction was developed using consensus primers MY09/MY11, following by the HPV typing through primers combined in eight multiplex kits, making possible the identification and typing of 40 types of HPV. The results showed that the sample of squamous cell carcinoma presented a relationship man:homan of 2,8:1, with a pick of cases for patients in the seventh decade of life. The frequency of HPV in cases was 22,0% (11 samples) and 9,3% in the controls (14 samples). The identified types in cases of squamous cell carcinoma were 16 and 31 (high risk) and 6, 44, 54 and 55 (low risk); in the patients of the control group were found types 33, 35, 45, 52, 62, 66 (high risk) and 42 (low risk). The univariate analysis showed association only among oral cancer and HPV and exposure to tobacco and alcohol. Though, the logistic regression evidenced a direct association among exposure to alcohol and cancer. No association was observed among age, sex, exposure to the products of tobacco and alcohol, location of the lesions (oropharynx and other), clinical stage of squamous cell carcinoma and the presence of HPV. These data allowed the conclusion that the development of oral cancer doesn't seem to be associated to the presence of HPV.