Evaluation of fracture resistance of zirconia monolithic restorations: an in vitro study / Avaliação da resistência à fratura de restaurações monolíticas de zircônia: um estudo in vitro

Objective: was to evaluate fracture resistance of zirconia monolithic restorations after aging procedures. Material and methods: Monolithic translucent zirconia 3-unit FPDs were fabricated using Cerec inLab CAD/CAM system on 2 stainless steel dies with a uniform 120 degrees circumferential deep chamfer finish line of 1 mm width. FPDs were divided into 2 groups, first group (Group A) was subjected to aging procedures in an autoclave at hydrothermal conditions 134 oC /2 bars for 5 hours. Second group (Group B) was not subjected to any aging procedures (control group). All specimens of each group were loaded compressively in a universal testing machine at cross head speed 0.5 mm/min until fracture occurred. The percentage of monoclinic (m) phase was detected by XRD device. Scanning electron microscope (SEM) was used to examine the fractured surfaces for Aged TZI (Group A) and Non-aged TZI (Group B). Student's t-test was used to compare between fracture resistances of both groups. The significance level was set at P ≤ 0.05. Results: The fracture resistance mean (SD) values of non-aged TZI (Group B) was 2406.9 ± 306.8 N which showed statistically significantly higher than that of aged group (Group A) which was 1964.5 ± 234.5 N. The percentage of monoclinic (m) phase detected by XRD device software in non-aged TZI (Group B) was nearly 0 weight % and in aged TZI (Group A) was about 42 weight %. Conclusions:Accelerated artificial aging decreases the fracture resistance of monolithic TZI FPDs. (AU)

Objetivo: Foi avaliar a resistencia à fratura de restaurações de zircônia monolítica após procedimentos de envelhecimento.Material e Métodos: 3 unidades de FPDs de zircônia monolítica translucida foram fabricadas utilizando o sistema Cerec inLab CAD/CAM com 2 matrizes de aço inoxidável com uma linha de acabamento de chanfro profundo circunferencial de 120 graus de largura de 1 mm. As FPDs foram divididos em dois grupos, primeiro grupo (Grupo A) foi submetido a procedimentos de envelhecimento em autoclave em condições hidrotérmicas de 134 °C /2 bars por 5 horas. O segundo grupo (Grupo B) não foi submetido a nenhum processo de envelhecimento (grupo controle). Todos os espécimes de cada grupo foram carregados compressivamente em uma maquina de teste universal na velocidade de 0.5 mm/min até a fratura ocorrer. A porcentagem da fase monoclínica (m) foi detectada pelo dispositivo XRD. O microscópio eletrônico de varredura (MEV) foi utilizado para examinar as superfícies fraturadas para TZI envelhecido (Grupo A) e TZI não envelhecido (Grupo B). O teste t de estudantes foi usado para comparar as resistências à fraturas de ambos os grupos. O nível de significância foi estabelecido em P ≤ 0.05. Resultados: Os valores médios de resistência à fratura (SD) do TZI não envelhecido (Grupo B) foi 2406.9±306.8 N, o qual se mostrou estatisticamente significativamente maior do que o grupo envelhecido (Grupo A), que foi 1964.5±234.5 N. A porcentagem da fase monoclínica (m) detectada pelo software do dispositivo XRD em TZI não envelhecido (Grupo B) foi próximo de 0% em peso e em TZI envelhecido (Grupo A) foi cerca de 42% em peso. Conclusão: O envelhecimento artificial acelerado diminui a resistência à fratura de FPDs TZI monolítico (AU)

Clinical Evaluation of Wear Behavior of Human Enamel and Chipping of Veneered Zirconia against Monolithic Zirconia (Randomized Controlled Clinical Trial) / Avaliação clínica do comportamento de desgaste do esmalte humano e lascamento da zircônia estratificada contra a zircônia monolítica (ensaio clínico controlado randomizado)

Objective: To evaluate the wear behavior of human enamel and chipping of veneered and monolithic zirconia for posterior full coverage restorations. Material and methods: Thirty-four zirconia full coverage restorations (seventeen in each group) were fabricated. The patients were divided into two groups according to the type of zirconia used; group 1 (comparator group) veneered zirconia crowns and group 2 (intervention group) monolithic zirconia single crowns. All crowns were lab fabricated and polished. For opposing teeth wear measurements 3D non-contact profilometer was used where epoxy resin replicas were constructed for opposing arch immediately after crowns cementation, three, six and twelve months. Restoration chipping was measured using modified United States Public Health Services (USPHS) criteria. Results: All restorations were reported as alpha with no chipping. There was no statistically significant difference between (Group 1) and (Group 2) for wear test. Conclusion: Both monolithic and veneered restorations revealed satisfactory mechanical properties with no chipping after one year of clinical use. Wear of opposing enamel was clinically acceptable for both materials. (AU)

Objetivo: Avaliar o comportamento ao desgaste do esmalte humano e lascamento de zircônia estratificada e monolítica para coroas totais posteriores. Material e métodos: Trinta e quatro coroas totais de zircônia (dezessete em cada grupo) foram fabricadas. Os pacientes foram divididos em dois grupos de acordo com o tipo de zircônia utilizada; grupo 1 (grupo controle) coroas de zircônia estratificada e grupo 2 (grupo de intervenção) coroas de zircônia monolítica. Todas as coroas foram fabricadas e polidas em laboratório. Para medidas de desgaste de dentes opostos, foi utilizado um perfilômetro 3D sem contato, onde réplicas de resina epóxi foram construídas para o arco oposto imediatamente após a cimentação das coroas, três, seis e doze meses após. O lascamento da restauração foi medido usando critérios modificados dos Serviços de Saúde Pública dos Estados Unidos (USPHS). Resultados: Todas as restaurações foram relatadas como alfa sem lascamento. Não houve diferença estatisticamente significativa entre (Grupo 1) e (Grupo 2) para o teste de desgaste. Conclusão: Ambas as coroas monolíticas e estratificadas revelaram propriedades mecânicas satisfatórias sem lascamento após um ano de uso clínico. O desgaste do esmalte oposto foi clinicamente aceitável para ambos os materiais. (AU)

Load to failure of three different monolithic zirconia inlay- retained fixed dental prosthesis designs with three surface treatments / Carga até falha de três diferentes desenhos de inlays de zircônia monolítica com três tratamentos de superfície

Objective: The purpose of the study was to evaluate the effect of different preparation designs and different surface treatments on the fracture resistance of monolithic zirconia inlay-retained fixed dental prosthesis [IRFDP]. Material and methods: Forty-five translucent zirconia IRFDPs were divided into three groups according to preparation designs (n = 15); group I: proximal box, group II: inlay-box and group III: butterfly wing (modified inlay). Each group was further subdivided into three subgroups according to the surface treatments utilized (n = 5); sandblasting, tribochemical silica coating (Cojet system) and erbium, chromium: Yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser irradiation. All zirconia IRFDPs were cemented to their respective resin models using selfadhesive resin cement. All cemented IRFDPs were subjected to fracture resistance test using universal testing machine. The initial fracture site was determined by using a stereomicroscope (x6.7magnification). Two-way analysis of variance (ANOVA) was used to evaluate the effect of different designs, different surface treatments and their interaction on the mean fracture resistance. Bonferroni's post-hoc test was used when ANOVA is significant (P ≤ 0.05). Results: Butterfly wings design showed the highest fracture resistance values followed by inlay and box designs respectively (P ≤ 0.05). Sandblasting and Cojet showed significantly the highest mean fracture resistance values than Laser with no significance difference between them. Conclusion: The butterfly wing design increased the fracture resistance of the zirconia IRFDPs. Sandblasting and tribochemical silica coating of zirconia surfaces had a greater effect than Er, Cr: YSGG laser to gain higher fracture resistance of zirconia IRRDPs (AU)

Objetivo: O objetivo do estudo foi avaliar o efeito de diferentes modelos de preparações e diferentes tratamentos de superfície na resistência à fratura de inlays de zircônia monolítica. Material e métodos: Quarenta e cinco inlays translúcidos de zircônia foram divididos em três grupos de acordo com os desenhos de preparação (n = 15); grupo I: caixa proximal, grupo II: inlay convencional e grupo III: asa de borboleta (inlay modificado). Cada grupo foi subdividido em três subgrupos de acordo com os tratamentos de superfície utilizados (n = 5); jateamento de areia, revestimento triboquímico de sílica (sistema Cojet) e érbio, cromo: ítrio, escândio, gálio, granada (Er, Cr: YSGG) irradiação a laser. Todos os inlays de zircônia foram cimentados em seus respectivos modelos de resina usando cimento de resina auto-adesivo. Todos os inlays cimentados foram submetidos a teste de resistência à fratura usando máquina de teste universal. O local inicial da fratura foi determinado usando um estereomicroscópio (ampliação de 6,7x). A análise de variância (ANOVA) de dois fatores foi usada para avaliar o efeito de diferentes desenhos, diferentes tratamentos de superfície e sua interação na resistência média à fratura. O teste post-hoc de Bonferroni foi usado quando a ANOVA foi significativa (P ≤ 0,05). Resultados: O design das asas de borboleta apresentou os maiores valores de resistência à fratura, seguidos pelos designs de inlay convencional e caixa, respectivamente (P ≤ 0,05). O jateamento de areia e o Cojet apresentaram significativamente os maiores valores médios de resistência à fratura do que o Laser, sem diferença de significânc=ia entre eles. Conclusão: O design da asa de borboleta aumentou a resistência à fratura dos inlays de zircônia. O revestimento por jato de areia e triboquímica de sílica das superfícies de zircônia teve um efeito maior que o laser Er, Cr: YSGG para obter maior resistência à fratura dos inlays de zircônia. (AU)

Effect of decontamination methods on shear bond strength of resin cement to translucent monolithic zirconia / Efeito de métodos de descontaminação na resistência ao cisalhamento entre cimento resinoso e zircônia monolítica translúcida

Objective: The aim of this study was to evaluate the effect of decontamination methods on shear bond strength of resin cement to translucent monolithic zirconia. Material and Methods: Eighty 4-mol yttria-stabilized tetragonal zirconia polycrystal specimens were fabricated. All specimens were subjected to saliva contamination and divided into four groups (n = 20) according to the decontamination methods: 70% isopropanol (AL); zirclean (ZC); 5.25% sodium hypochlorite (NaOCL); and no cleaning (NC). All specimens were bonded by using self-adhesive resin cement. Half of the specimens in each group (n = 10) were subjected to aging. All specimens were subjected to shear bond strength test in a universal testing machine. Failure modes were evaluated by using a scanning electron microscope (SEM). The data obtained were statistically analyzed by using one-way ANOVA followed by the HSD Tukey test (p < 0.05). Results: ANOVA test revealed a significant difference among the different decontamination methods (p < 0.05). No significant differences were found among NaOCL, ZC, and AL groups as revealed by the HSD Tukey test (p > 0.05). The effect of aging was significantly different in all groups (p < 0.05); whereas, no significant difference was found in group ZC (p > 0.05). The (SEM) analysis showed mixed failures in all groups, except in group NC where only adhesive failure was observed. Conclusion: Saliva contamination during clinical evaluation significantly decreases the shear bond strength between self-adhesive resin cement and translucent monolithic zirconia. The cleaning methods have an impact on improving the bond strength between resin cement and translucent monolithic zirconia (AU)

Objetivo: O objetivo deste estudo foi avaliar o efeito dos métodos de descontaminação na resistência ao cisalhamento entre cimento resinoso e zircônia monolítica translúcida. Material e métodos: Foram fabricados oitenta espécimes policristalinos de zircônia tetragonal estabilizada com ítria a 4 mol. Todas as amostras foram submetidas à contaminação salivar e divididas em quatro grupos (n = 20) de acordo com os métodos de descontaminação: isopropanol a 70% (AL); zircleano (ZC); Hipoclorito de sódio a 5,25% (NaOCL); e sem limpeza (NC). Todas as amostras foram cimentadas utilizando um cimento resinoso autoadesivo. Metade das amostras de cada grupo(n = 10) foram submetidas ao envelhecimento. Todas as amostras foram submetidas ao teste de resistência ao cisalhamento em uma máquina de teste universal. Os módulos de falha foram avaliados usando um microscópio eletrônico de varredura (MEV). Os dados obtidos foram analisados estatisticamente utilizando ANOVA de uma via, seguida pelo teste de HSD Tukey (p < 0,05). Resultados: O teste ANOVA revelou diferença significativa entre os diferentes métodos de descontaminação (p < 0,05). Não foram encontradas diferenças significativas entre os grupos NaOCl, ZC e AL, conforme revelado pelo teste HSD Tukey (p> 0,05). O efeito do envelhecimento foi significativamente diferente em todos os grupos (p < 0,05); enquanto nenhuma diferença significativa foi encontrada no grupo ZC (p > 0,05). A análise (SEM) mostrou falhas mistas em todos os grupos, exceto no grupo NC, onde apenas foi observada falha adesiva. Conclusão: A contaminação por saliva durante a avaliação clínica diminui significativamente a resistência ao cisalhamento entre o cimento resinoso autoadesivo e a zircônia monolítica translúcida. Os métodos de limpeza têm um impacto na melhoria da resistência da união entre o cimento resinoso e a zircônia monolítica translúcida. (AU)

Effect of Finish Line Design and Cement Space Thickness on the Marginal Accuracy of Monolithic Zirconia Crowns / Efeito do desenho da linha de término e da espessura do espaço de cimento na precisão marginal de coroas monolíticas de zircônia

Objective: The purpose of this study was to evaluate the effect of finish line design and cement space thickness on the marginal accuracy of monolithic zirconia crowns. Materials and methods: Thirty crowns were fabricated from translucent zirconia (inCoris TZI) using Cerec in-Lab system and divided into three main groups (10 each) according to the finish line type of the die (knife-edge, chamfer, and shoulder). Every group was divided into two subgroups (5 each) according to cement space thickness (20 and50µm). Optical impressions were taken for the dies using the Cerec scanner and cement space was set twice for every finish line design; 20 and 50 µm. The completed crowns were cemented to the dies and the marginal gap was evaluated. The collected data was statistically analyzed using Mann-Whitney U test and Kruskal-Wallis test and the significance level was set at P ≤ 0.05. Results: Regarding the marginal gap; there was no statistically significant difference between different finish line designs or between different cement space thicknesses. Conclusion: Neither finish line design nor cement space thickness has an effect on the marginal gap of inCoris TZI crowns. (AU)

Declaração do problema: A necessidade de um método minimamente invasivo de preparação de coroa única é inevitável, principalmente com dentes enfraquecidos e com alta probabilidade de irritação pulpar. Portanto, é necessária uma restauração durável e adaptada, com preparação menos invasiva da linha de término. Objetivo: O objetivo deste estudo foi avaliar o efeito do design da linha de término e da espessura do espaço de cimento na precisão marginal das coroas monolíticas de zircônia. Material e Métodos: Trinta coroas foram fabricadas a partir de zircônia translúcida (inCoris TZI) usando o sistema Cerec em laboratório, e divididas em três grupos principais (n = 10), de acordo com o tipo de linha de término da matriz (lâmina, chanfro e ombro). Cada grupo foi dividido em dois subgrupos (5 cada), de acordo com a espessura do espaço do cimento (20 e 50 µm). Impressões ópticas foram obtidas para as matrizes usando o scanner Cerec e o espaço de cimento foi definido duas vezes para cada projeto de linha de chegada: 20 e 50 µm. As coroas confeccionadas foram cimentadas nos moldes e a diferença marginal foi avaliada. Os dados coletados foram analisados estatisticamente pelo teste U de Mann-Whitney e Kruskal-Wallis e o nível de significância foi estabelecido em P ≤ 0,05. Resultados: Em relação ao gap marginal não houve diferença estatisticamente significante entre diferentes projetos de linha de acabamento ou entre diferentes espessuras de espaço de cimento. Conclusão: nem o design da linha de término, nem a espessura do espaço de cimento afetam a folga marginal das coroas inCoris TZI. (AU)

Influence of preparation design on fracture resistance of different monolithic zirconia crowns: A comparative study

PURPOSE: The aim of the study was to evaluate and compare the fracture resistance and modes of fracture of monolithic zirconia crowns with two preparation designs.MATERIALS AND METHODS: Forty human maxillary first premolar teeth were extracted for orthodontic purposes and divided into two main groups (n=20): Group A: monolithic traditional zirconia; Group B: monolithic translucent zirconia. The groups were further subdivided into two subgroups (n=10): (A1, B1) shoulder margin design; (A2, B2) feather-edge margin design. Teeth were prepared with either a 1 mm shoulder margin design or a feather-edge margin design. The prepared teeth were scanned using a digital intraoral scanner. The crowns were cemented using self-adhesive resin cement. All cemented teeth were stored in water for 7 days and thermocycling was done before testing. All samples were subjected to compressive axial loading until fracture. The fractographic analysis was done to assess the modes of fracture of the tested samples.RESULTS: The highest mean values of fracture resistance were recorded in kilo-newton and were in the order of subgroup A1 (2.903); subgroup A2 (2.3); subgroup B1 (1.854) and subgroup B2 (1.523). One-way ANOVA showed a statistically significant difference among the 4 subgroups. Concerning modes of fracture, the majority of samples in subgroups A1 and B1 were fracture of restoration and/or tooth, while in subgroups A2 and B2, the majority of samples fractured through the central fossa.CONCLUSION: Even though all the tested crowns fractured at a higher level than the maximum occlusal forces, the shoulder margin design was better than the feather-edge margin design and the monolithic traditional zirconia was better than the monolithic translucent zirconia in terms of fracture strength.

Two-body wear behavior of human enamel versus monolithic zirconia, lithium disilicate, ceramometal and composite resin

PURPOSE: To investigate and compare the surface roughness (SR), weight and height of monolithic zirconia (MZ), ceramometal (CM), lithium disilicate glass ceramic (LD), composite resin (CR), and their antagonistic human teeth enamel. MATERIALS AND METHODS: 32 disc shaped specimens for the four test materials (n=8) and 32 premolars were prepared and randomly divided. SR, weight and height of the materials and the antagonist enamel were recorded before and after subjecting the specimens to 240,000 wear-cycles (49 N/0.8 Hz/5℃/50℃). SR, height, weight, and digital microscopic qualitative evaluation were measured. RESULTS: CM (0.23 + 0.08 µm) and LD (0.68 + 0.16 µm) exhibited the least and highest mean difference in the SR, respectively. ANOVA revealed significance (P=.001) between the materials for the SR. Paired T-Test showed significance (P < .05) for the pre- and post-SR for all the materials. For the antagonistic enamel, no significance (P=.987) was found between the groups. However, the pre- and post-SR values of all the enamel groups were significant (P < .05). Wear cycles had significant effect on enamel weight loss against all the materials (P < .05). CR and MZ showed the lowest and highest height loss of 0.14 mm and 0.46 mm, respectively. CONCLUSION: MZ and CM are more resistant to SR against the enamel than LD and CR. Enamel worn against test materials showed similar SR. Significant variations in SR values for the tested materials (MZ, LD, CM, and CR) against the enamel were found. Wear simulation significantly affected the enamel weight loss against all the materials, and enamel antagonist against MZ and CM showed more height loss.

Effect of additional firing process after sintering of monolithic zirconia crown on marginal and internal fitness / 대한치과보철학회지

PURPOSE: To evaluate an effect of additional firing process after sintering of monolithic zirconia crown on marginal and internal fit through three-dimensional analysis. MATERIALS AND METHODS: Ten monolithic zirconia crowns were fabricated using titanium abutment model. Monolithic zirconia crowns were designed, milled, and sintered as a control group, and additional firing with coloring was performed as a test group. Three dimensional analysis were performed by using triple-scan protocol, and cross-section analysis on mesio-distal and disto-lingual section was evaluated to measure marginal and internal fitness. Then, three-dimensional surface difference on between two groups was evaluated (α=.05). RESULTS: There was statistically significant difference between the control group (32.0 ± 24.3 µm) and the test group (17.0 ± 10.8 µm) in the mesial axial wall (P < .02) and the control group (60.2 ± 24.3 µm) and the test group (71.8 ± 21.5 µm) in the distal axial wall (P < .01). There was no statistically significant difference at the remaining point. CONCLUSION: There was no statistical significance on the deviation of inner surface of crown according to firing number, and the results of both group were considered clinically acceptable.

Full-mouth rehabilitation with implant-supported fixed dental prostheses for the edentulous maxilla and partially edentulous mandible: A case report / 대한치과보철학회지

A conventional approach for the treatment of long-span edentulous areas is the use of removable dentures. However, placing implants in these areas results in superior functional outcomes by increasing the stability, support, and resistance of the prostheses and improving the masticatory efficiency. Treatment modalities utilizing implants can be further classified into either removable or fixed-type prostheses. Several factors such as the amount of alveolar bone resorption, inter-arch relationship, patient preferences, and socioeconomic status should be considered when determining the appropriate treatment approach. Monolithic zirconia has been considered a suitable material for implant-supported fixed dental prosthesis, because of the drastic improvement in its mechanical properties. It exhibits fewer incidences of fracture and chipping of the prostheses, and has greater bulk of material than metal-ceramic crowns and zirconia-veneered ceramics. Moreover, highly translucent monolithic zirconia is also available in the market, and its application is gradually increasing for anterior tooth rehabilitation. The present report describes a patient who underwent full-mouth rehabilitation with fixed dental prostheses (eight upper and three lower implant placements). All teeth, except bilateral mandibular canines and left mandibular first and second premolars, were extracted after the diagnosis of generalized chronic moderate-to-advanced periodontitis of the remaining teeth. The patient reported satisfactory esthetic and functional outcomes during the one-year follow-up visit.

Influence of heating rate on the flexural strength of monolithic zirconia

PURPOSE: Fabrication of zirconia restorations with ideal mechanical properties in a short period is a great challenge for clinicians. The purpose of the study was to investigate the effect of heating rate on the mechanical and microstructural properties of monolithic zirconia. MATERIALS AND METHODS: Forty monolithic zirconia specimens were prepared from presintered monolithic zirconia blanks. All specimens were then assigned to 4 groups according to heating rate as Control, Group 15℃, Group 20℃, and Group 40℃. All groups were sintered according to heating rates with the sintering temperature of 1500℃, a holding time of 90 minutes and natural cooling. The phase composition was examined by XRD analysis, three-point bending test was conducted to examine the flexural strength, and Weibull analysis was conducted to determine weibull modulus and characteristic strength. Average grain sizes were determined by SEM analysis. One-way ANOVA test was performed at a significance level of 0.05. RESULTS: Only tetragonal phase characteristic peaks were determined on the surface of analyzed specimens. Differences among the average grain sizes of the groups were not statistically significant. The results of the three-point bending test revealed no significant differences among the flexural strength of the groups (P>.05). Weibull modulus of groups was ranging from 3.50 to 4.74. The highest and the lowest characteristic strength values were obtained in Group 20℃ and Control Group, respectively. CONCLUSION: Heating rate has no significant effect on the flexural strength of monolithic zirconia. Monolithic zirconia restorations can be produced in shorter sintering periods without affecting the flexural strength by modifying the heating rate.

Esthetic anterior restoration using 3M Lava™ Esthetic monolithic zirconia

Monolithic zirconia has been widely used in fixed partial dentures due to high strength and fracture toughness. Nevertheless, the usage of monolithic zirconia in anterior restoration was limited because of opacity. Recently, esthetic monolithic zirconia blocks are developed by improving translucency and using various shading systems. Manufacturer introduces 3M Lava™ Esthetic with increased cubic phase and fluorescent ingredients is more esthetic than previous monolithic zirconia. This case report describes favorable anterior restorations using translucent monolithic zirconia.

Full mouth rehabilitation of a patient using monolithic zirconia and dental CAD/CAM system: a case report

An accurate implant placement with ideal location is significant for long-term success of the implant. An exact evaluation of nearby anatomic structures such as quality of residual bone, an inferior alveolar bone and a maxillary sinus is required. For a prosthetic-driven treatment, planned surgery, precise prosthesis and communication with the patient are significant requisites especially for full-mouth rehabilitation. In this case, the patient with severe alveolar bone resorption had a CT guided surgery supported by CT data and the data from scanning diagnostic wax-up. Afterward, edentulous area was restored by full mouth implant-supported prosthesis by using monolithic zirconia and CAD/CAM technique. This paper reports the outcome of the procedure which was remarkable both esthetically and functionally.

Full mouth rehabilitation of the patient with severe tooth loss and tooth wear with vertical dimension gaining: A case report / 대한치과보철학회지

Multiple tooth loss and excessive occlusal wear can result in damage to occlusal disharmony, functional disorders and esthetic problems, requiring comprehensive prosthetic treatments. Changing vertical dimension harmonized with surrounding muscle tissue is important. In this case, the patient with loss of vertical dimension caused by severe tooth loss and tooth wear was treated with the analysis of vertical dimension, such as diagnostic model, radiography and various clinical exams. the patient was satisfied with favorable functions and esthetics for 1 years of follow-up.

A case of full mouth rehabilitation with orthodontic treatment in patient with extensive tooth erosion and wear using monolithic zirconia prostheses / 대한치과보철학회지

Extensive dental erosion and wear will cause serious loss of function and aesthetics in the mouth. In order to recover this condition, careful analysis of the patient's bite relationship is required. In particular, a treatment plan should be established considering the possibility of reproduction of the vertical dimension and centric relation, and appropriateness of the occlusal plane and anterior guidance. Also, the choice of prosthetic materials is an important consideration in patients with severe wear. In this case, patients with overall wear and erosion on tooth was established anterior guidance by orthodontic treatment and fully restored with monolithic zirconia, without increasing vertical dimension.

The effect of various polishing systems on surface roughness and phase transformation of monolithic zirconia

PURPOSE: The purpose of this study was to evaluate and compare three polishing systems on the surface roughness and phase transformation of monolithic zirconia. MATERIALS AND METHODS: 100 disk shaped specimens (10 mm diameter, 3 mm thickness) were fabricated from monolithic zirconia blocks. 20 specimens were left as a control group and remaining specimens were grinded by diamond bur to simulate the occlusal adjustments. Grinded specimens were randomly divided into 4 groups: group G (no polishing), group M (Meisinger, zirconia polishing kit), group E (EVE Diacera, zirconia polishing kit), and group P (EVE Diapol, porcelain polishing kit). Surface roughness was measured with profilometer and surface topography was observed with SEM. XRD analysis was performed to investigate the phase transformation. Statistical analysis was performed with one-way ANOVA and Tukey's post hoc tests at a significance level of P=.05. RESULTS: All polishing groups showed a smoother surface than group G. Among 3 polishing systems, group M and group E exhibited a smoother surface than the group P. However, no significant differences were observed between group M and group E (P>.05). Grinding and polishing did not cause phase transformations in zirconia specimens. CONCLUSION: Zirconia polishing systems created a smoother surface on zirconia than the porcelain polishing system. Phase transformation did not occur during the polishing procedure.

Full mouth rehabilitation of the patient with severely worn dentition using monolithic zirconia prosthesis: A clinical report / 대한치과보철학회지

Excessive occlusal wear causes loss of tooth structure, occlusal plane disharmony, impaired function and esthetic problems. Although the decrease of occlusal vertical dimension may be compensated by the growth of alveolar bone and tooth eruption, minimal increase of occlusal vertical dimension may be required for esthetics and retention of prosthesis. In this case, a 44-year-old male patient visited Seoul National University Dental Hospital with chief complaint of severe tooth wear and shade disharmony. Based on assessment of diagnostic wax-up, 3 mm increase of occlusal vertical dimension was determined. Removable occlusal splint and interim prosthesis was used to ascertain patient's comfort and adaptation. After the adaptation period, definitive prosthesis fabricated with full-contour monolithic zirconia were delivered and the patient was recommended to wear a nightguard device for prosthesis protection. This report presents a case of full mouth rehabilitation with the elevation of patient's occlusal vertical height, resulting in satisfactory esthetics and functions.

Evaluation of translucency of monolithic zirconia and framework zirconia materials

PURPOSE: The opacity of zirconia is an esthetic disadvantage that hinders achieving natural and shade-matched restorations. The aim of this study was to evaluate the translucency of non-colored and colored framework zirconia and monolithic zirconia. MATERIALS AND METHODS: The three groups tested were: non-colored framework zirconia, colored framework zirconia with the A3 shade according to Vita Classic Scale, and monolithic zirconia (n=5). The specimens were fabricated in the dimensions of 15×12×0.5 mm. A spectrophotometer was used to measure the contrast ratio, which is indicative of translucency. Three measurements were made to obtain the contrast ratios of the materials over a white background (L*w) and a black background (L*b). The data were analyzed using the one-way analysis of variance and Tukey HSD tests. One specimen from each group was chosen for scanning electron microscope analysis. The determined areas of the SEM images were divided by the number of grains in order to calculate the mean grain size. RESULTS: Statistically significant differences were observed among all groups (P<.05). Non-colored zirconia had the highest translucency with a contrast ratio of 0.75, while monolithic zirconia had the lowest translucency with a contrast ratio of 0.8. The mean grain sizes of the non-colored, colored, and monolithic zirconia were 233, 256, and 361 nm, respectively. CONCLUSION: The translucency of the zirconia was affected by the coloring procedure and the grain size. Although monolithic zirconia may not be the best esthetic material for the anterior region, it may serve as an alternative in the posterior region for the bilayered zirconia restorations.

Superimposition: a simple method to minimize occlusal adjustment of monolithic restoration / 대한치과보철학회지

The development of translucent zirconia enabled clinicians to choose a monolithic zirconia crown as one treatment modality in the posterior dentition. Careful occlusal adjustments are recommended for monolithic zirconia crowns because grinding zirconia inevitably causes phase transformation, which may deteriorate mechanical properties. intraoral scanners enable the clinician to scan and superimpose a complete tooth structure before preparation onto the prepared abutment. This technique helps to reproduce the original tooth form and occlusion of the patient. In this case report, prostheses were fabricated for patients with cracked or fractured tooth by applying intraoral scanner, Computer aided design-computer aided manufacturing (CAD-CAM) and monolithic zirconia crown to reproduce the occlusion of original tooth and to minimize occlusal adjustment. The clinical results were satisfactory in both esthetic and functional aspects.

Oral rehabilitation of a patient with severely worn dentition using monolithic zirconia / 대한치과보철학회지

Severe tooth wear may lead to pathological changes of pulp, imbalance in occlusion as well as functional and esthetic problems. In this case, 34-year-old male came to the hospital because of generally worn dentition due to attrition and erosion. After evaluation, a full mouth restoration with elevation of the vertical dimension of occlusion was planned. After occlusion was stabilized by an occlusal stabilization appliance, centric relation position was recorded and subsequent provisional restorations were fabricated. After evaluation, a CAD-CAM (computer aided design-computer aided manufacturing) prosthetic restoration was carried out using monolithic zirconia. After 12 months of follow up observation, the patient was satisfied with function and esthetic appearance.

Fabrication of a CAD/CAM monolithic zirconia crown to fit an existing partial removable dental prosthesis

Fabricating a surveyed prosthesis beneath an existing partial removable dental prosthesis (PRDP) is a challenging and time-consuming procedure. The computer-aided design/computer-assisted manufacturing (CAD/CAM) technology was applied to fabricate a retrofitted, surveyed zirconia prosthesis to an existing PRDP. CAD/CAM technology enabled precise and easy replication of the contour of the planned surveyed crown on the existing abutment tooth. This technology ensured excellent adaptation and fit of newly fabricated crown to the existing PRDP with minimal adjustments. In this case report, a seventy-year-old male patient presented with fractured existing surveyed crown. Because the existing PRDP was serviceable, new crown was fabricated to the existing PRDP.