Relevant anatomic and biomechanical studies for implant possibilities on the atrophic maxilla: critical appraisal and literature review.

PURPOSE: The purpose of this review was to highlight anatomic and biomechanical aspects of atrophic maxillae for implant possibilities. MATERIALS AND METHODS: A MEDLINE electronic search of the years 1966 to 2009 was conducted with the keywords "atrophic,""resorbed,""edentulous," and "maxilla." RESULTS: Twenty papers presented the following findings: (1) previous use of a removable prosthesis is a risk factor for resorption, with flabby tissues related to the severity of resorption; (2) implants in the reconstructed maxilla (< or =5 mm) and supporting overdentures had a higher risk for bone loss based on the worse periimplant soft-tissue health observed; (3) bleeding on probing was found with pocket depths > or =5 mm in half of the zygomatic implants; (4) prevalence of bone septa is higher in atrophic maxillae, and changes on nasopalatine canal can reduce up to 44.4% of the full length of buccal bone plates; (5) female patients have less medullar bone quantity and connectivity than male patients; (6) transectioning of nutrient vessels is easier and accelerates resorption; (7) stress does not concentrate on maxillary sinus base cortical bone contiguous to trabecular bone; (8) splinted implants receive nine times less load than nonsplinted implants even under oblique loading; (9) implant stability quotient (ISQ) values for implants ranged between 60 and 65; (10) in vivo force transfer to implants is similar between fixed prostheses and overdentures; (11) inclined implants generate better biomechanical responses; (12) masticatory efficiency and bite forces improve in maxillectomized patients who receive obturators with milled bar attachments. CONCLUSION: Sound implant-supported choices for an atrophic maxilla must be made with a thorough understanding of its anatomic and biomechanical factors.

Zirconium Oxide Three-Unit Fixed Partial Denture Frameworks Supported by Dental Implants in Acceptable and Reduced Interocclusal Space Possibilities: Pilot In Vitro Fracture Strength and Fractographic Analyses.

PURPOSE: This study investigated the effect of fracture strength and fracture mode characteristics related to reduced interocclusal space on computer-aided design/computer-aided manufacturing (CAD/CAM). ZrO2 fixed partial denture (FPD) frameworks subjected to quasi-static loads. MATERIALS AND METHODS: First, two dental implants (4 × 10 mm) were positioned simulating a three-unit FPD (second premolar and second molar abutments). The implants were distributed into two groups: control group (n = 10), positioned at the same level; and the test group (n = 10), where the interocclusal space corresponding to the second molar was reduced by 3 mm in relation to the second premolar to simulate a clinical situation. After FPD wax-up (25-mm long; connector height = 5 mm; connector width = 3 mm, proximal and lingual collar reinforcement), casting was made in a Co-Cr alloy to serve as a prototype. Upon scanning, screw-retained CAD/CAM ZrO2 FPDs were fabricated for each group. Then, FPDs were subjected to quasi-static axial loading until fracture in the mid-occlusal pontic area using a universal testing machine at the crosshead speed of 0.5 mm/min. Next, the samples were analyzed by scanning electronic microscopy (SEM) to describe the fracture characteristics. RESULTS: The mean fracture strength values for the control group (1,747.4 ± 122.3 N) and test group (1,817.7 ± 158.9 N) showed no significant difference (Student t test, P < .124). The SEM images of the fracture sites revealed two cleavage areas in the test group, providing representative sites with increased fracture energy storage in this group compared with the control group. CONCLUSION: Within the limitations of this study, the results showed that reduced interocclusal space and reduced length did not decrease the fracture strength of the ZrO2 FPD frameworks.

Maximal bite force and its association with temporomandibular disorders.

Individuals with temporomandibular disorders (TMD) are expected to have decreased maximum bite forces (MBF). This way, this study compared the MBF in subjects with TMD to a control group and also evaluated its association with age, gender, height and weight. Forty healthy adults with complete natural dentition divided into four groups according to gender and presence or absence of TMD signs/symptoms (based on the Research Diagnostic Criteria RDC) underwent a MBF test with a gnathodynamometer in molar and incisal areas. Statistical analysis was performed by ANOVA and Student-Newman-Keuls test (p=0.05), and the relationship between age, gender, weight, height and MBF was verified by Pearson's correlation test. There were no differences in MBF results between TMD and control groups (p>0.05). Female subjects exhibited lower MBF than male and MBF for the anterior area was lower than that for posterior area (p<0.05). Significant correlation was found between MBF and weight in TMD subjects (p<0.05), except for the anterior area in female subjects. There was a positive correlation between MBF and height in TMD male subjects (p<0.05). Within the limitations of this study, it is possible to conclude that bite force was not affected by TMD. Correlation between MBF and weight in TMD subjects and between MBF and height in TMD male subjects was observed.

Effect of cyclic load on vertical misfit of prefabricated and cast implant single abutment.

OBJECTIVES: The purpose of this in vitro study was to evaluate misfit alterations at the implant/abutment interface of external and internal connection implant systems when subjected to cyclic loading. MATERIAL AND METHODS: Standard metal crowns were fabricated for 5 groups (n=10) of implant/abutment assemblies: Group 1, external hexagon implant and UCLA cast-on premachined abutment; Group 2, internal hexagon implant and premachined abutment; Group 3, internal octagon implant and prefabricated abutment; Group 4, external hexagon implant and UCLA cast-on premachined abutment; and Group 5, external hexagon implant and Ceraone abutment. For groups 1, 2, 3 and 5, the crowns were cemented on the abutments and in group 4 crowns were screwed directly on the implant. The specimens were subjected to 500,000 cycles at 19.1 Hz of frequency and non-axial load of 133 N in a MTS 810 machine. The vertical misfit (µm) at the implant/abutment interface was evaluated before (B) and after (A) application of the cyclic loading. Data were analyzed statistically by using two-away ANOVA and Tukey's post-hoc test (p<0.05). RESULTS: Before loading values showed no difference among groups 2 (4.33 ± 3.13), 3 (4.79 ± 3.43) and 5 (3.86 ± 4.60); between groups 1 (12.88 ± 6.43) and 4 (9.67 ± 3.08), and among groups 2, 3 and 4. However, groups 1 and 4 were significantly different from groups 2, 3 and 5. After loading values of groups 1 (17.28 ± 8.77) and 4 (17.78 ± 10.99) were significantly different from those of groups 2 (4.83 ± 4.50), 3 (8.07 ± 4.31) and 5 (3.81 ± 4.84). There was a significant increase in misfit values of groups 1, 3 and 4 after cyclic loading, but not for groups 2 and 5. CONCLUSIONS: The cyclic loading and type of implant/abutment connection may develop a role on the vertical misfit at the implant/abutment interface.

Evaluation of senior Brazilian dental students about mouth preparation and removable partial denture design.

This study aimed to evaluate the knowledge of senior dental students about mouth preparation and removable partial denture (RPD) design. Two hundred sixty-six senior students from eleven dental schools in the State of São Paulo, Brazil, comprised the sample. The subjects examined two partially edentulous casts mounted on a semiadjustable articulator, answered a questionnaire regarding the treatment plan, and drew the RPD design. The casts consisted of Kennedy Class III, modification 1 maxillary arch and Class II mandibular arch. Ninety percent of the students believed that mouth preparation should be performed although no one was able to name all necessary procedures. For the maxillary arch, 12 percent of the denture designs were completely appropriate, 51 percent were partially appropriate, and 37 percent were inappropriate. For the mandibular arch, the results were 3 percent, 40 percent, and 57 percent, respectively.

Atratividade do sorriso: um método simples para melhorar a percepção visual do dentista: desenvolvimento e teste-piloto com estudantes de pós-graduação / Smile attractiveness: a simple method to improve the dentist's visual perception: development and pilot test with postgraduate students

Objetivos: melhorar a percepção do dentista sobre a atratividade do sorriso através de avaliações objetivas. Material e métodos: fotografias frontais de sorrisos (envolvendo a área dos caninos) foram aleatoriamente escolhidas e dispostas em dois sentidos verticais variados (nivelado, abaixo) numa guia personalizada contendo quatro molduras labiais do sorriso (fino, médio, grosso, invertido). Os aspectos que influenciam a atratividade do sorriso (PD = proporção dentária, PV = posicionamento vertical dentário, EL = espessura labial, FG = festonamento gengival) também foram incluídos e uma nota final geral atribuída ao sorriso geral (SG). Adicionalmente, o formulário do exercício continha a opção "existe um implante?" e "qual sua localização?". Todos os itens foram avaliados através de escalas de Likert. A prevalência de respostas foi calculada para cada item. O teste de Wilcoxon (alfa = 5%) foi usado para verificar a possibilidade de diferença de opinião entre os nivelamentos horizontais e para uma mesma moldura de sorriso. Os níveis de confiabilidade (concordância absoluta = ICC e responsividade = Cronbach alfa) também foram avaliados. Resultados: um teste-piloto foi conduzido com 16 estudantes. Trinta e duas combinações foto/moldura labial foram geradas e apresentadas de forma randomizada. A avaliação geral do sorriso ficou em: pobre (11/32), mediano (6/32), bom (15/32) e muito bom (1/32). O número de acertos da possível posição do implante foi 13 em 32 tentativas. Diferenças estatisticamente significativas entre os nivelamentos foram observadas nas situações 1/17 (p=0,0001), 13/29 (p=0,02), 2/18 (p=0,0002), 6/22 (p=0,0001), 14/30 (p=0,0001), 7/23 (p=0,01) e 15/31 (p=0,039). Os maiores coeficientes de ICC e Cronbach alfa foram vistos para o sorriso geral e FG. Conclusão: a percepção visual do dentista pode ser treinada mudando-se a moldura labial e o nivelamento vertical dos dentes e é influenciada pelo festonamento gengival. O teste se mostrou útil na verificação da atratividade do sorriso.

Objectives: to improve the perception of the dentist on the smile attractiveness through objective evaluations. Material and methods: frontal photographs of smiles (involving the canine area) were randomly chosen and arranged in two different vertical directions (leveled, below) in a personalized guide containing four lip architectures (thin, medium, thick, inverted). The aspects that infl uence the smile attractiveness (PD = dental proportion, PV = vertical tooth position, EL = lip thickness, GS = gingival scalloping) were also included and a general final score attributed to the general smile (SA). Additionally, the exercise form contained questions such as "is there an implant?" and "what is your location?". All items were assessed using Likert scales. The prevalence of responses was calculated for each item. The Wilcoxon test was used to verify the possibility of differences between the horizontal leveling for the same smile architecture. The reliability levels (absolute agreement = ICC and responsiveness = Cronbach alpha) were also evaluated. Results: a pilot test was conducted with 16 students. Thirty-two photos/lip architecture combinations were generated and presented at random. The overall smile rating was: poor (11/32), average (6/32), good (15/32), and very good (1/32). The number of positive responses for implant position was 13 in 32 trials. Statistically significant differences were observed in the combinations 1/17 (p=0.0001), 13/29 (p=0.02), 2/18 (p=0.0002), 6/22 (p=0.0001), 14/30 (p=0.0001), 7/23 (p=0.01) and 15/31 (p=0.039). The highest ICC and Cronbach alpha values were seen for the general smile attractiveness (SA) and GS. Conclusion: the visual perception can be trained by changing the lip architecture and vertical leveling of the teeth and is influenced by gingival scalloping. This test proved to be useful in verifying the smile attractiveness.

Reabilitação oral de paciente com fissura palatina e ausência de pré-maxila / Oral rehabilitation of a cleft palate patient without premaxillary bone ­ a clinical report

As fissuras labiopalatais são malformações faciais com sequelas funcionais e estéticas que causam grande impacto na qualidade de vida dos pacientes. O tratamento desses indivíduos requer uma abordagem multidisciplinar, incluindo tratamento plástico cirúrgico, fonoaudiológico e psicológico, além das intervenções odontológicas, ortodônticas e protéticas. Este relato de caso apresentou a reabilitação protética de uma paciente de 57 anos com fissura palatina anterior, com remoção da pré-maxila. Após vários tratamentos, a paciente ainda não havia sido reabilitada, apresentando deformidades provenientes dos tratamentos anteriores incompletos. Uma prótese parcial removível retida por dentes e implantes osseointegrados foi executada, promovendo a melhora na aparência facial, na função mastigatória, na fala e, consequentemente, na qualidade de vida da paciente.

Cleft lip and palate, which is a facial malformation with both functional and aesthetic characteristics, may have a large impact on the lives of those affected. Its correction requires an interdisciplinary approach, which includes surgical, orthodontic and prosthetic treatments. This clinical report presents the prosthetic rehabilitation of a 57-year-old woman with an anterior cleft palate defect that had not been closed completely with surgical repair. In this way, an implant-supported, retained removable partial prosthesis was delivered to improve the patient's facial aspect, masticatory function, speech, and her quality of life.

Mouth floor enlargements related to the sublingual glands in edentulous or partially edentulous patients: a microscopic study.

UNLABELLED: Mouth floor enlargements (MFE) are observed in edentulous and partially edentulous patients, impairing denture fitting, and have recently been described in the literature as hyperplasias of the sublingual glands. OBJECTIVE: This study aims at describing the microscopic aspects of MFE that contribute to their final diagnosis. METHODS: Twenty-four specimens were surgically removed from the enlarged mouth floor of 19 patients (15 females and 4 males). Patient age ranged from 48 to 74 years, with a mean of 57 years. The main surgical indication was to permit or improve the fitting of dentures. Six patients were completely edentulous and 13 were partially edentulous. The material was processed for microscopic examination and stained with hematoxylin-eosin, Mallory's trichrome and periodic-acid Schiff (PAS). RESULTS AND CONCLUSIONS: The epithelium of the mouth floor was normal in 17 cases, hyperplastic in 4 and atrophic in 3. Six of the 24 sublingual glands removed were microscopically normal, while the other specimens presented acinar atrophy with hyperplasia of duct-like structures. Interstitial fibrosis was observed in 18 cases and was accompanied by adipose tissue infiltration in 15. Decreased lymphoid tissue was observed in 16 samples and oncocytosis was present in 5 cases. We suggest that MFE in edentulous or partially edentulous patients should be considered as an entity for the text books.

Effect of cyclic load on vertical misfit of prefabricated and cast implant single abutment

OBJECTIVES: The purpose of this in vitro study was to evaluate misfit alterations at the implant/abutment interface of external and internal connection implant systems when subjected to cyclic loading. MATERIAL AND METHODS: Standard metal crowns were fabricated for 5 groups (n=10) of implant/abutment assemblies: Group 1, external hexagon implant and UCLA cast-on premachined abutment; Group 2, internal hexagon implant and premachined abutment; Group 3, internal octagon implant and prefabricated abutment; Group 4, external hexagon implant and UCLA cast-on premachined abutment; and Group 5, external hexagon implant and Ceraone abutment. For groups 1, 2, 3 and 5, the crowns were cemented on the abutments and in group 4 crowns were screwed directly on the implant. The specimens were subjected to 500,000 cycles at 19.1 Hz of frequency and non-axial load of 133 N in a MTS 810 machine. The vertical misfit (μm) at the implant/abutment interface was evaluated before (B) and after (A) application of the cyclic loading. Data were analyzed statistically by using two-away ANOVA and Tukey's post-hoc test (p<0.05). RESULTS: Before loading values showed no difference among groups 2 (4.33±3.13), 3 (4.79±3.43) and 5 (3.86±4.60); between groups 1 (12.88±6.43) and 4 (9.67±3.08), and among groups 2, 3 and 4. However, groups 1 and 4 were significantly different from groups 2, 3 and 5. After loading values of groups 1 (17.28±8.77) and 4 (17.78±10.99) were significantly different from those of groups 2 (4.83±4.50), 3 (8.07±4.31) and 5 (3.81±4.84). There was a significant increase in misfit values of groups 1, 3 and 4 after cyclic loading, but not for groups 2 and 5. CONCLUSIONS: The cyclic loading and type of implant/abutment connection may develop a role on the vertical misfit at the implant/abutment interface.

Comportamento de desgaste “in vitro” de encaixes de precisão extracoronários / “In vitro” wear behavior of extracoronal precision attachments

The objective of this study was to evaluate the retentive ability and weight change of two extracoronal attachments after repeated insertion/removal cycles. Material and methods: Two extracoronal attachments were used, one with plastic inserts and the other one with conventional metal-alloy. Initial retentive ability was checked under a 20kgf load cell at 5mm/min. The weight of the fixed/removable pairs was verified with an electronic mass comparator. Fixed/removable pairs were tested with an insertion/removal cycling machine, for 5800 cycles (corresponding to 5 years) at a speed of 32 rpm speed. Insertion/ removal cycles were performed under artificial saliva. Weight change and retentive ability of attachments were verified at baseline, six-month, one-year, two-year, three-year, four-year and five-year time intervals. The two-way ANOVA for repeated measurements test was used to verify possible interactions between precision attachment type and retentive ability/weight change over time. Statistically significant associations were found between attachment type and retentive ability over time (P=0.006). Metal-alloy group showed signifi cant differences between baseline and first year (P=0.005), baseline and second year (P=0.001), and between baseline and five years (P=0.035) of insertion/removal cycles. In the plastic insert group, no significant differences were found over time. No statistically significant associations were found between precision attachment types and weight change over time (P=0.643). Initial retentive ability can not be standardized for both attachments; the metal-alloy showed better performance than the plastic insert after five years. Both attachments did not show weight change after five years of simulated use.

O objetivo deste estudo foi avaliar a capacidade retentiva e a alteração do peso de dois encaixes extracoronários após repetidos ciclos de inserção e remoção. Materiais e métodos: Dois encaixes extracoronários foram usados, um com fêmea em plástico e o outro em metal. A capacidade retentiva inicial foi verificada em uma máquina de ensaio universal com célula de carga de 20kgf a velocidade de 5mm/min. O peso do conjunto macho/fêmea foi verificado com uma balança eletrônica. Os conjuntos macho/fêmeas foram testados em um simulador de ciclos por 5800 vezes (correspondendo a 5 anos) a uma velocidade de 32 rpm. Os ciclos de remoção e inserção foram realizados com saliva artificial. A alteração de peso e a capacidade retentiva dos encaixes foi verificada inicialmente e nos intervalos de tempo de 6 meses, um, dois, três, quarto e cinco anos. O teste ANOVA foi usado para verificar possíveis interações entre o tipo de encaixe e a capacidade retentiva/alteração de peso com o tempo de uso. Associação estatisticamente significativa foi encontrada entre o tipo de encaixe e a capacidade retentiva com o tempo de uso (P=0.006). O grupo metálico mostrou diferença significante entre o tempo inicial e o primeiro ano (P=0.005), tempo inicial e o segundo ano (P=0.001), e entre o tempo inicial e cinco anos (P=0.035) de inserção e remoção. No grupo com fêmea de plástico, não foram encontradas diferenças significativas. Associações estatisticamente significativas não foram encontradas entre os tipos de encaixes e a alteração de peso em tempo algum. (P=0.643). A capacidade retentiva inicial não pode ser padronizada nos dois encaixes; o grupo com fêmea em metal mostrou melhor performance retentiva que o grupo com fêmea em plástico após cinco anos. Ambos encaixes não mostraram alteração no peso após uso simulado de cinco anos.

The influence of screw type, alloy and cylinder position on the marginal fit of implant frameworks before and after laser welding.

UNLABELLED: Misfit at the abutment-prosthetic cylinder interface can cause loss of preload, leading to loosening or fracture of gold and titanium screws. OBJECTIVES: To evaluate the influence of screw type, alloy, and cylinder position on marginal fit of implant frameworks before and after laser welding. METHODS: After Estheticone-like abutments were screwed to the implants, thirty plastic prosthetic cylinders were mounted and waxed-up to fifteen cylindrical bars. Each specimen had three interconnected prosthetic components. Five specimens were one-piece cast in titanium and five in cobalt-chromium alloy. On each specimen, tests were conducted with hexagonal titanium and slotted gold screws separately, performing a total of thirty tested screws. Measurements at the interfaces were performed using an optical microscope with 5mm accuracy. After sectioning, specimens were laser welded and new measurements were obtained. Data were submitted to a four-way ANOVA and Tukey's multiple comparisons test (alpha=0.05). RESULTS: Slotted and hexagonal screws did not present significant differences regarding to the fit of cylinders cast in titanium, either in one-piece casting framework or after laser welding. When slotted and hexagonal screws were tested on the cobalt-chromium specimens, statistically significant differences were found for the one-piece casting condition, with the slotted screws presenting better fit (24.13 microm) than the hexagonal screws (27.93 microm). Besides, no statistically significant differences were found after laser welding. CONCLUSIONS: 1) The use of different metal alloys do exert influence on the marginal fit, 2) The slotted and hexagonal screws play the exclusive role of fixing the prosthesis, and did not improve the fit of cylinders, and 3) cylinder position did not affect marginal fit values.

Effect of silica coating and silanization on flexural and composite-resin bond strengths of zirconia posts: An in vitro study.

STATEMENT OF PROBLEM: The bond strength of composite resin cores to the smooth surface of prefabricated zirconia-based ceramic posts is problematic because it might not be sufficient to ensure stability of the post-and-core system. It is also not clear whether any alteration of the post surface to provide additional mechanical or chemical retention would compromise flexural strength of the posts. PURPOSE: This study tested the effect of a tribochemical treatment on the bond strength (BS) between zirconia-based ceramic posts and composite resin and on the flexural strength (FS) of the posts. MATERIAL AND METHODS: For the BS test, 2 groups of specimens (n = 10) were prepared as follows: In the experimental (E) group, zirconia-based ceramic posts (Cosmopost), 21 mm long and 1.7 mm in diameter, were treated with a tribochemical silica coating and silanization system (Rocatec). For the control (C) group, zirconia-based ceramic posts were used as supplied by the manufacturer. For the 2 groups, posts were centered and vertically positioned in a metal mold, and composite resin (Tetric Ceram) was polymerized around the posts to form rings (6 mm diameter x 4 mm height). All specimens were positioned in a universal testing machine, and a load was applied axially on the protruding heads of posts in a shear push-out mode test until bond failure (MPa). Fracture mode was assessed as cohesive, cohesive/adhesive, or adhesive. Following this, the FS of the posts was measured in MPa using a 3-point bending test. Data were recorded and statistically analyzed using the Student t test for both tests (alpha = .01). RESULTS: Mean fracture load values +/- SDs for the BS test were 28.1 +/- 2.3 MPa and 8.9 +/- 3.97 MPa for the E and C groups, respectively. The mean FS values were 1544.9 +/- 214.1 MPa and 844.8 +/- 50.8 MPa for the E and C groups, respectively. The tribochemically treated posts exhibited significantly higher values for both bond strength to composite resin and resistance to fracture when compared to posts in the control group (P < .001). Fracture analysis showed 100% cohesive/adhesive fractures for group E specimens and 100% adhesive fractures for group C specimens. CONCLUSIONS: The use of a tribochemical silica coating process and silanization on zirconia-based ceramic posts increased both the bond strength to composite resin as well as the fracture strength of posts.

Dispositivo acrílico simples para medir as alterações nos tecidos moles da maxila após procedimentos implantares ou restauradores protético-periodontais / A simple acrylic device to measure maxillary soft tissue alterations after implant and/or restorative periodontal and prosthetic procedures

Alterações nos tecidos moles, na zona estética, podem ocorrer por procedimentos restauradores associados ou não à Implantodontia. Os autores propuseram um dispositivo acrílico simples associado a uma sonda periodontal, para verificação destes níveis em todos os momentos do tratamento reabilitador. O dispositivo em questão também pode ser desenhado e confeccionado em qualquer sistema CAD/CAM.

Soft tissue changes in the esthetic zone can occur after restorative procedures associated or not to implant dentistry. The authors describe a simple acrylic device associated to a periodontal probe to verify those levels during all treatment procedure steps. Also, this device can be design and milled at any CAD/CAM system.

Efeitos positivos preliminares de estratégias cirúrgicas e peri-implantares, combinadas para redução dos defeitos alveolares na zona estética provocados após trauma de avulsão, reimplantação dentária e reabsorção radicular / Positive preliminary effects of combined surgical and peri-implant strategies to reduce the alveolar defects at the esthetic zone after avulsion trauma, tooth replantation, and root resorption ­ a case report

Este relato de caso demonstra uma combinação de estratégias de RTG para alívio do defeito residual na zona estética. Um paciente do sexo masculino havia sofrido um acidente traumático no dente 11 durante a infância, com tratamento endodôntico e reimplantação imediata. Dez anos depois, o desnível entre as margens gengivais era de 10 mm, e uma reabsorção radicular estava presente. Para tentar diminuir a recessão de tecido mole e o contorno ósseo deficiente, uma matriz colágena suína (MucoGraft) foi montada no sentido vertical substituindo a parede vestibular, e o alvéolo de extração foi preenchido com osso bovino inorgânico (Bio-Oss). A coroa dentária natural foi usada como pôntico no aparelho ortodôntico de contenção. Três meses depois, e após um exame por tomografia computadorizada feixe cônico para determinação dos níveis ósseos resultantes, o conjunto implante dentário (3,4 mm x 10 mm)/pilar (platformswitching) e osso bovino foi colocado no alvéolo cicatrizado, e a coroa natural foi trocada por uma coroa provisória cimentada. Seis meses depois, um enxerto gengival livre foi aplicado. Após o condicionamento do tecido mole, o desnivelamento gengival entre as margens reduziu-se para 2 mm. A restauração definitiva recebeu infraestrutura em zircônia CAD/CAM recoberta por porcelana feldspática. Mesmo que a estratégia combinada tenha se mostrado útil no alívio da situação clínica, estudos longitudinais com amostras maiores são necessários para comprovar sua eficácia.

This case report demonstrates a combination of RTG strategies to alleviate a residual defect in the esthetic zone. A male patient had suffered a traumatic accident at the tooth 11 during childhood, with endodontic treatment and immediate replantation. Ten years later, the unbalance between the gingival margins was 10 mm, and a root resorption was detected. In an attempt to reduce the soft tissue recession and poor bone contour, a porcine collagen matrix (MucoGraft) was mounted vertically replacing the labial wall, and the alveolar extraction socket fi lled with xenogeneic bovine bone (Bio-Oss). The natural dental crown was used as the pontic in the orthodontic device. Three months later and after a cone beam computerized tomography to determine the resulting bone levels, the dental implant (3.4 mm x 10 mm)/abutment (platform-switching) assembly and bovine bone were placed in the healed socket, and the natural crown was replaced by a cemented temporary crown. Six months later, a free gingival graft was applied. After soft tissue conditioning, the unbalance between gingival margins between was reduced to 2 mm. The final restoration received a CAD/CAM zirconia infrastructure veneered with feldspathic porcelain. Even that the combined strategy has proven useful in this clinical situation. Longitudinal studies with larger samples are needed to confi rm its effectiveness.

Efeito da soldagem híbrida (plasma + maçarico) na suavização da assinatura torque-ângulo em supraestruturas de COCR sobre minipilares de zircônia ­ parte 1 / Effect of hybrid soldering (plasma + gas torch) technique on suavization of torque-angle signatures at Co-Cr frameworks over zirconia mini-abutmets ­ part I

Objetivo: avaliar as desadaptações em supraestruturas de implantes e a curva de assinatura torque-ângulo dos parafusos protéticos nas condições monobloco e pós-soldagem. Material e métodos: uma base retangular de aço inox recebeu três implantes de hexágono externo (4,1 mm x 10 mm), onde foram parafusados minipilares de zircônia. Após o enceramento e inclusão, as supraestruturas foram fundidas em monobloco com uma liga de cobalto-cromo, e os cilindros foram numerados sequencialmente (1, 2 e 3). A leitura na interface supraestrutura/pilar foi realizada com um microscópio comparador (precisão de 1 µm), três vezes em cada cilindro. A tensão de torque nos parafusos foi medida com um torquímetro eletrônico odontológico (OsseoCare, Nobel Biocare). Depois, as supraestruturas foram seccionadas e soldadas a plasma (pontos de estabilização) e maçarico (preenchimento da área restante). Novamente, as desadaptações e assinaturas dos parafusos foram avaliadas pela mesma metodologia. Resultados: as médias de desadaptações foram maiores nas supraestruturas em monobloco (C1=3,5 µm; C2=0 µm; C3=31,2 µm) do que nas supraestruturas pós-soldagem (C1=3,0 µm; C2=2,9 µm; C3=18,1 µm). Dentro de cada condição, o teste de Kruskal-Wallis mostrou diferença estatisticamente significativa apenas para o cilindro 3 (monobloco: p < 0,00003 / pós-soldagem: p=0,008) em relação aos cilindros 1 e 2. Uma diferença estatisticamente significante foi encontrada apenas no C3, comparando as condições monobloco e pós-soldagem (teste t pareado, p=0,03). A assinatura dos parafusos se mostrou melhor na condição pós-soldagem. Conclusão: a fundição monobloco gera instabilidade na assinatura dos parafusos. A desadaptação nos parafusos protéticos de supraestruturas sobre minipilares de zircônia melhora após secção e soldagem híbrida.

Objective: to evaluate the misfi t at implant frameworks and the torque-angle signature curves at the prosthetic screws at one-piece and after soldering conditions. Material and methods: a stainless steel rectangular base received 3 external hex implants (4.1 x 10 mm) where zirconia mini-abutments were fastened. After wax-up and investing, the frameworks were one-piece cast with a Co-Cr alloy, and the prosthetic cylinders sequentially identified (1, 2, and 3). The misfit at the framework/abutment interface was measured with a microscope (reading error 1 µm) 3 times for each cylinder. The screw tension was investigated with an electronic torqued device (Osseocare, Nobel Biocare). After, the frameworks were sectioned and soldered with plasma (stabilization points) and gas torch (filling of the remaining areas). Again, the misfit and torque-angle signatures were measured as described. Results: mean misfit values were greater for one-piece castings (C1=3.5 µm; C2=0 µm; C3=31.2 µm) than after soldering (C1=3.0 µm; C2=2.9 µm; C3=18.1 µm). Within each condition, the Kruskal-Wallis test demonstrated a statistically significant difference only for C3 (one-piece casting: p < 0.00003 / after soldering: p=0.008) compared to C1 and C2. Between each condition, a significant difference was seen only for C3 in the one-piece and after soldering conditions (paired t test, p=0.03). The torque-angle signatures demonstrated a better behavior after soldering. Conclusion: one-piece castings provide instability at torque-angle signatures. Thus, the seating of the prosthetic abutments over the zirconia mini-abutments improves after sectioning and hybrid soldering.

Avaliação de implante dental comprometido empregando microscopia eletrônica de varredura e espectrometria dispersiva de raio X / Evaluation of compromised dental implant by using scanning electron microscopy and energy-dispersive spectrometer X-ray

O sucesso e durabilidade dos implantes dentais são observados na maior parte dos tratamentos para reposição de dentes, entretanto, algumas fallhas, relatadas na literatura, podem comprometer a reabilitação dos pacientes. Um paciente de 46 anos de idade foi reabilitado com uma prótese clássica de Brånemark, entretanto, um implante da região anterior da mandíbula, que sustentava a mesma, após 18 meses da instalação apresentou mobilidade, dor, e exsudação, sendo necessária sua remoção. O processo de osseointegração se dá entre as superfícies ósseas e óxidos formados sobre a superfície do titânio comercialmente puro, utilizado na fabricação dos implantes dentais. Entretanto, agentes contaminantes podem se desprender da camada superficial dos implantes, potencializar a resposta inflamatória e alterar o processo de cicatrização, o que pode levar à perda do implante. Com o objetivo de avaliar a presença de possíveis contaminantes na superfície do implante perdido, o mesmo foi encaminhado ao Centro de Caracterização e Desenvolvimento de Materiais (CCDM) para análise, por microscopia eletrônica de varredura e espectrometria dispersiva de raio X (MEV/EDS). Verificou-se a presença de elementos, como C, Ca, Na, Cl e Si. Esses elementos podem ser originários dos fluidos corporais ou dos processos finais de fabricação, não sendo possível, pelas técnicas utilizadas, estabelecer sua origem.

The success and durability of dental implants are observed in the most part of treatments to replace missing teeth, however, some failures of them, described in the literature, can compromise the patient's rehabilitation. A 46-years-old patient was rehabilitated with a Brånemark classical prosthesis. However one implant in the anterior region of the mandible, that sustained the prosthesis, after 18 months of the installation showed mobility, pain and exsudation, being necessary to retrieve it. The osseointegration process is established between bone tissue and oxides formed on surface of commercially pure titanium, used in the manufacture of the dental implants. However, contaminants agents can be released from superficial layer of dental implants, potencialize inflammatory response and modify the healing process, causing dental implant loss. Aiming to evaluate the presence of possible contaminants in the surface of the lost dental implant, it was sent to CCDM for analysis by using scanning electron microscopy and energy-dispersive spectrometer X-ray (SEM/EDS). It was verified the presence of elements, as C, P, Ca, Na, Cl, Si. These elements can be originated from body fluids or final stages of manufacture, not being possible, for the used techniques to conclude their origin.

Análise comparativa da percepção estética entre estudantes de odontologia e seus pacientes em relação à seleção de cor e forma de dentes artificiais / Comparative analysis of the aesthetic perception between dental students and their patients regarding of color and shape of artificial teeth

A presente pesquisa teve por objetivo analisar a percepção estética entre estudantes de odontologia e seus pacientes em relação à seleção da cor e forma de dentes artificiais e avaliar a aplicabilidade clínica da régua TTI - Trubyte Tooth Indicator (Dentsply, York, PA, Estados Unidos), a qual se propõe a determinar as proporções do incisivo central superior e a classificação das formas faciais. Participaram deste estudo 60 pacientes dentados, de 19 a 59 anos e 60 estudantes de odontologia, de 18 a 25 anos. Ambos responderam a um questionário sobre seleção de dentes, e nos pacientes foram realizadas fotos da face com a utilização da régua para análise das medidas e formas faciais, como também foi mensurada com paquímetro digital a altura e largura do incisivo central esquerdo superior. As medidas obtidas através da régua foram comparadas com as proporções reais dos dentes naturais dos pacientes. Os resultados mostraram uma preferência por dentes da forma ovóide, tanto pelos alunos (51,7 por cento), como pelo pacientes (46,7 por cento); em relação à cor, houve uma preferência pela cor 1A, tanto por pacientes (55 por cento) como pelos alunos (31,7 por cento). Houve concordância entre a escolha da forma do dente pelo aluno e a forma da face do paciente observada através da régua Trubyte Tooth Indicator. Não houve diferença estatística entre os dois métodos na comparação da largura dos dentes. Observou-se, pela amostra avaliada, que o instrumento Trubyte Tooth Indicator pode ser utilizado como um meio auxiliar na seleção da largura dos dentes artificiais.

The aim of this work was to analyze the aesthetics perception among dental students and their patients in relation to color and shape of prosthetic teeth, and the practice applicability of the Trubyte Tooth Indicator - TTI (Dentsply, York, PA, United States) guide, in correlation of measures and classification of patients' faces. Sixty patients dentate were 19 to 59 years old and 60 dental students were 18 to 25 years old participated in this study. Every one had answered a questionnaire on teeth selection, and only the pictures of the patients were made with the use of device for face measures analysis, as well the height and width of upper left incisor was measured with a digital caliper. The results showed that a preference for ovoid form teeth as by students (51.7 percent) as by patients (46.7 percent); with regards to color there was a preference for 1A color as by patients (55 percent) as by students (31.7 percent). There was concordance between choice of the tooth form by student and the patient face form observed through Trubyte Tooth Indicator guide. There were no differences between both methods comparing width of the teeth. For assessed sample, it was concluded that the Trubyte Tooth Indicator guide is able to be used as an auxiliary means in selecting width of artificial teeth.

Evaluation of fracture resistance of endodontically treated teeth restored with prefabricated posts and composites with varying quantities of remaining coronal tooth structure.

OBJECTIVES: The aim of this study was to evaluate the influence of remaining coronal tooth structure on endodontically treated teeth restored with prefabricated posts and two different composites for core build-up: dual-cured resin (Enforce Core) and light-cured resin (Z-250). METHODS: Fourty freshly extracted canines were endodontically treated and divided into four groups: Group I - teeth with 3mm remaining coronal structure, restored with Enforce Core; Group II - teeth with 3mm remaining coronal structure, restored with Z-250; Group III - teeth with no remaining coronal structure, restored with Enforce; Group IV - teeth with no remaining coronal structure, restored with Z-250. After restoration, the teeth were embedded in acrylic resin and the fracture resistance was measured on a universal testing machine at 45 degrees to the long axis of the tooth until failure. RESULTS: Data were analyzed by two-way analysis of variance, which showed significant differences between groups (p=0.00). The Tukey test did not show significant differences between specimens with and without remaining coronal structure. Conversely, significant difference was observed between groups with different core build-up. The highest values of fracture resistance were found in the group restored with light-cured resin. SIGNIFICANCE: The remaining coronal tooth structure did not influence the resistance of endodontically treated teeth; however, the change of core build-up was able to modify this resistence.

Marginal fit at cylinder-abutment interface before and after overcasting procedure.

The aim of this study was to measure marginal fit at cylinder-abutment interface, before and after overcasting procedure. A hexagonal implant was fixed to a stainless steel base and a Estheticone-like abutment used during all the experiment. Before casting procedure, gold (Group I) and Ni-Cr-Be (Group II) premachined cylinders were tightened to the abutment with gold and titanium screws (in both groups), with 10Ncm and 20Ncm torque values for the same screw type. Vertical measures were taken at the light microscope (Mitutoyo 5050, Tokyo, Japan) three times in six different parts along the abutment-cylinder interface for each torque value. Cylinders were overcast with Ag-Pd (Group I) or Ni-Cr-Be (Group II) alloy. After casting, the same measures and torque values were repeated. Intragroup differences (10 or 20Ncm torque values, before and after casting) and intergroup differences (10 and 20Ncm torque values, before or after casting) were analyzed by the Paired t Test; (p<0.05). Intragroup differences were observed for G-I (gold, 20Ncm, titanium screw, p=0.044) and for G-II (Ni-Cr-Be, 10Ncm, gold screw, p=0.002). Intergroup differences only were not observed in the G-II group (Ni-Cr-Be, 10 and 20Ncm, titanium screw, p=0.534). Within the limits of this study, the following conclusions can be drawn: 1) Regardless of screw type, marginal misfit was higher for Ni-Cr-Be cylinders after casting, but within acceptable levels of fit; 2) The combination of gold cylinders with gold or titanium screws was the most effective to reduce marginal misfit; 3) Both screw types did not improve marginal fit of Ni-Cr-Be cylinders after overcastting, and 4) Although a 20Ncm torque improved marginal fit in all situations, its use is not recommended due to the increased risk of prosthesis failure. Ni-Cr-Be alloys may be successfully used in single-tooth implant restorations, with no damage to the fit between abutment and prosthetic cylinder.

[Comparative evaluation of retention loss in four types of attachments used on overdentures in function of time of use]. / Avaliação comparativa da perda de retenção de quatro sistemas de encaixes do tipo ERA e O-Ring empregados sob overdentures em função do tempo de uso.

The aim of this study was to evaluate and compare the retentive capacity between two O-ring and O-SO system (Group I), and two ERA system types - white and gray retention caps - (Group II), respectively, in simulated function in database, 6 months, 1, 2, 3, 4, and 5 years later, with insertion and removal cycles. Two Brånemark implants were fixed in two trapezoidal metallic bases for the tests. Removal and insertion tests were done in a sewing machine, adjusted for this purpose using a belt and a pulley system, moving a steel crankshaft. A delineator platinum hold was used for body trial fixation to the metallic base of the sewing machine. Resistance test to axial movement of the caps by tension was done in a Universal test machine in an established period of time, before and after the cycle accomplishments in the adapted sewing machine. Based on the results, this study concludes that all the attachment systems tested showed retention loss during the experiment; the ERA system showed, since the beginning, higher retention compared to the other systems and the gray colored attachment showed the best result in the end of the simulated use test.