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Biomechanical three-dimensional finite element analysis of monolithic zirconia crown with different cement type.

The Journal of Advanced Prosthodontics.2015;7(6):475-483. doi:10.4047/jap.2015.7.6.475

PURPOSE: The objective of this study was to evaluate the influence of various cement types on the stress distribution in monolithic zirconia crowns under maximum bite force using the finite element analysis. MATERIALS AND METHODS: The models of the prepared #46 crown (deep chamfer margin) were scanned and solid models composed of the monolithic zirconia crown, cement layer, and prepared tooth were produced using the computer-aided design technology and were subsequently translated into 3-dimensional finite element models. Four models were prepared according to different cement types (zinc phosphate, polycarboxylate, glass ionomer, and resin). A load of 700 N was applied vertically on the crowns (8 loading points). Maximum principal stress was determined. RESULTS: Zinc phosphate cement had a greater stress concentration in the cement layer, while polycarboxylate cement had a greater stress concentration on the distal surface of the monolithic zirconia crown and abutment tooth. Resin cement and glass ionomer cement showed similar patterns, but resin cement showed a lower stress distribution on the lingual and mesial surface of the cement layer. CONCLUSION: The test results indicate that the use of different luting agents that have various elastic moduli has an impact on the stress distribution of the monolithic zirconia crowns, cement layers, and abutment tooth. Resin cement is recommended for the luting agent of the monolithic zirconia crowns.
Bite Force ; Computer-Aided Design ; Crowns* ; Dental Cements ; Dental Stress Analysis ; Finite Element Analysis* ; Glass ; Glass Ionomer Cements ; Polycarboxylate Cement ; Resin Cements ; Tooth ; Zinc Phosphate Cement ; Zirconium

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Partial denture metal framework may harbor potentially pathogenic bacteria.

Cristiane Machado MENGATTO ; Leonardo MARCHINI ; Luciano Angelo de Souza BERNARDES ; Sabrina Carvalho GOMES ; Alecsandro Moura SILVA ; Celia Marisa RIZZATTI-BARBOSA

The Journal of Advanced Prosthodontics.2015;7(6):468-474. doi:10.4047/jap.2015.7.6.468

PURPOSE: The aim of this study was to characterize and compare bacterial diversity on the removable partial denture (RPD) framework over time. MATERIALS AND METHODS: This descriptive pilot study included five women who were rehabilitated with free-end mandibular RPD. The biofilm on T-bar clasps were collected 1 week (t1) and 4 months (t2) after the RPD was inserted (t0). Bacterial 16S rDNA was extracted and PCR amplified. Amplicons were cloned; clones were submitted to cycle sequencing, and sequences were compared with GenBank (98% similarity). RESULTS: A total of 180 sequences with more than 499 bp were obtained. Two phylogenetic trees with 84 (t1) and 96 (t2) clones represented the bacteria biofilm at the RPD. About 93% of the obtained phylotypes fell into 25 known species for t1 and 17 for t2, which were grouped in 5 phyla: Firmicutes (t1=82%; t2=60%), Actinobacteria (t1=5%; t2=10%), Bacteroidetes (t1=2%; t2=6%), Proteobacteria (t1=10%; t2=15%) and Fusobacteria (t1=1%; t2=8%). The libraries also include 3 novel phylotypes for t1 and 11 for t2. Library t2 differs from t1 (P=.004); t1 is a subset of the t2 (P=.052). Periodontal pathogens, such as F. nucleatum, were more prevalent in t2. CONCLUSION: The biofilm composition of the RPD metal clasps changed along time after RPD wearing. The RPD framework may act as a reservoir for potentially pathogenic bacteria and the RPD wearers may benefit from regular follow-up visits and strategies on prosthesis-related oral health instructions.
Actinobacteria ; Bacteria* ; Bacteroidetes ; Biofilms ; Clone Cells ; Databases, Nucleic Acid ; Denture, Partial* ; Denture, Partial, Removable ; DNA, Ribosomal ; Female ; Follow-Up Studies ; Fusobacteria ; Humans ; Oral Health ; Pilot Projects ; Polymerase Chain Reaction ; Proteobacteria ; Trees

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Comparison of intraoral scanning and conventional impression techniques using 3-dimensional superimposition.

Ye Kyu RHEE ; Yoon Hyuk HUH ; Lee Ra CHO ; Chan Jin PARK

The Journal of Advanced Prosthodontics.2015;7(6):460-467. doi:10.4047/jap.2015.7.6.460

PURPOSE: The aim of this study is to evaluate the appropriate impression technique by analyzing the superimposition of 3D digital model for evaluating accuracy of conventional impression technique and digital impression. MATERIALS AND METHODS: Twenty-four patients who had no periodontitis or temporomandibular joint disease were selected for analysis. As a reference model, digital impressions with a digital impression system were performed. As a test models, for conventional impression dual-arch and full-arch, impression techniques utilizing addition type polyvinylsiloxane for fabrication of cast were applied. 3D laser scanner is used for scanning the cast. Each 3 pairs for 25 STL datasets were imported into the inspection software. The three-dimensional differences were illustrated in a color-coded map. For three-dimensional quantitative analysis, 4 specified contact locations(buccal and lingual cusps of second premolar and molar) were established. For twodimensional quantitative analysis, the sectioning from buccal cusp to lingual cusp of second premolar and molar were acquired depending on the tooth axis. RESULTS: In color-coded map, the biggest difference between intraoral scanning and dual-arch impression was seen (P<.05). In three-dimensional analysis, the biggest difference was seen between intraoral scanning and dual-arch impression and the smallest difference was seen between dual-arch and full-arch impression. CONCLUSION: The two- and three-dimensional deviations between intraoral scanner and dual-arch impression was bigger than full-arch and dual-arch impression (P<.05). The second premolar showed significantly bigger three-dimensional deviations than the second molar in the three-dimensional deviations (P>.05).
Axis, Cervical Vertebra ; Bicuspid ; Dataset ; Humans ; Molar ; Periodontitis ; Temporomandibular Joint Disorders ; Tooth

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Effect of different veneering techniques on the fracture strength of metal and zirconia frameworks.

Ayse Gozde TURK ; Mubin ULUSOY ; Mert YUCE ; Hakan AKIN

The Journal of Advanced Prosthodontics.2015;7(6):454-459. doi:10.4047/jap.2015.7.6.454

PURPOSE: To determine whether the fracture strengths and failure types differed between metal and zirconia frameworks veneered with pressable or layering ceramics. MATERIALS AND METHODS: A phantom molar tooth was prepared and duplicated in 40 cobalt-chromium abutments. Twenty metal (IPS d.SIGN 15, Ivoclar, Vivadent, Schaan, Liechtenstein) and 20 zirconia (IPS e.max ZirCAD, Ivoclar) frameworks were fabricated on the abutments. Each framework group was randomly divided into 2 subgroups according to the veneering material: pressable and layering ceramics (n=10). Forty molar crowns were fabricated, cemented onto the corresponding abutments and then thermocycled (5-55degrees C, 10,000 cycles). A load was applied in a universal testing machine until a fracture occurred on the crowns. In addition, failure types were examined using a stereomicroscope. Fracture load data were analyzed using one-way ANOVA and Tukey HSD post-hoc tests at a significance level of 0.05. RESULTS: The highest strength value was seen in metal-pressable (MP) group, whereas zirconia-pressable (ZP) group exhibited the lowest one. Moreover, group MP showed significantly higher fracture loads than group ZP (P=.015) and zirconia-layering (ZL) (P=.038) group. No significant difference in fracture strength was detected between groups MP and ML, and groups ZP and ZL (P>.05). Predominant fracture types were cohesive for metal groups and adhesive for zirconia groups. CONCLUSION: Fracture strength of a restoration with a metal or a zirconia framework was independent of the veneering techniques. However, the pressing technique over metal frameworks resisted significantly higher fracture loads than zirconia frameworks.
Adhesives ; Ceramics ; Compressive Strength ; Crowns ; Dental Porcelain ; Molar ; Tooth

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Bonding values of two contemporary ceramic inlay materials to dentin following simulated aging.

Ashraf Abdelfattah KHALIL ; Khalid Mohamed ABDELAZIZ

The Journal of Advanced Prosthodontics.2015;7(6):446-453. doi:10.4047/jap.2015.7.6.446

PURPOSE: To compare the push-out bond strength of feldspar and zirconia-based ceramic inlays bonded to dentin with different resin cements following simulated aging. MATERIALS AND METHODS: Occlusal cavities in 80 extracted molars were restored in 2 groups (n=40) with CAD/CAM feldspar (Vitablocs Trilux forte) (FP) and zirconia-based (Ceramill Zi) (ZR) ceramic inlays. The fabricated inlays were luted in 2 subgroups (n=20) with either etch-and-bond (RelyX Ultimate Clicker) (EB) or self-adhesive (RelyX Unicem Aplicap) (SA) resin cement. Ten inlays in each subgroup were subjected to 3,500 thermal cycles and 24,000 loading cycles, while the other 10 served as control. Horizontal 3 mm thick specimens were cut out of the restored teeth for push out bond strength testing. Bond strength data were statistically analyzed using 1-way ANOVA and Tukey's comparisons at alpha=.05. The mode of ceramic-cement-dentin bond failure for each specimen was also assessed. RESULTS: No statistically significant differences were noticed between FP and ZR bond strength to dentin in all subgroups (ANOVA, P=.05113). No differences were noticed between EB and SA (Tukey's, P>.05) bonded to either type of ceramics. Both adhesive and mixed modes of bond failure were dominant for non-aged inlays. Simulated aging had no significant effect on bond strength values (Tukey's, P>.05) of all ceramic-cement combinations although the adhesive mode of bond failure became more common (60-80%) in aged inlays. CONCLUSION: The suggested cement-ceramic combinations offer comparable bonding performance to dentin substrate either before or after simulated aging that seems to have no adverse effect on the achieved bond.
Adhesives ; Aging* ; Ceramics* ; Dentin* ; Inlays* ; Molar ; Resin Cements ; Tooth

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Impact of a "TED-Style" presentation on potential patients' willingness to accept dental implant therapy: a one-group, pre-test posttest study.

Henry GHANEM ; Kelvin Ian AFRASHTEHFAR ; Samer ABI-NADER ; Faleh TAMIMI

The Journal of Advanced Prosthodontics.2015;7(6):437-445. doi:10.4047/jap.2015.7.6.437

PURPOSE: A survey was conducted to assess the impact of a TED-like educational session on participants' willingness to accept dental implant therapy. MATERIALS AND METHODS: Volunteers interested in having information about dental implant therapies were recruited and asked to complete a two-part survey before and after an educational session. The initial survey elicited demographic information, self-perceived knowledge on dental implants and willingness to this kind of treatment. A "TED-style" presentation that provided information about dental implant treatments was conducted before asking the participants to complete a second set of questions assessing the impact of the session. RESULTS: The survey was completed by 104 individuals, 78.8% were women and the mean age was 66.5+/-10.8. Before the educational session, 76.0% of the participants refused dental implants mainly due to lack of knowledge. After the educational session, the rejection of dental implants decreased by almost four folds to 20.2%. CONCLUSION: This study proved that an educational intervention can significantly increase willingness to accept treatment with dental implants in a segment of the population who is interested in having information about dental implant therapy. Furthermore, educational interventions, such as TED-like talks, might be useful to increase popular awareness on dental implant therapy.
Dental Implants* ; Disulfiram ; Education, Dental ; Female ; Humans ; Volunteers

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Evaluation of biogeneric design techniques with CEREC CAD/CAM system.

Yeliz ARSLAN ; Secil KARAKOCA NEMLI ; Merve BANKOGLU GUNGOR ; Evsen TAMAM ; Handan YILMAZ

The Journal of Advanced Prosthodontics.2015;7(6):431-436. doi:10.4047/jap.2015.7.6.431

PURPOSE: The aim of this study was to evaluate occlusal contacts generated by 3 different biogeneric design modes (individual (BI), copy (BC), reference (BR)) of CEREC software and to assess the designs subjectively. MATERIALS AND METHODS: Ten pairs of maxillary and mandibular casts were obtained from full dentate individuals. Gypsum cast contacts were quantified with articulating paper and digital impressions were taken. Then, all ceramic crown preparation was performed on the left first molar teeth and digital impressions of prepared teeth were made. BI, BC, and BR crowns were designed. Occlusal images of designs including occlusal contacts were superimposed on the gypsum cast images and corresponding contacts were determined. Three designs were evaluated by the students. RESULTS: The results of the study revealed that there was significant difference among the number of contacts of gypsum cast and digital models (P<.05). The comparison of the percentage of virtual contacts of three crown designs which were identical to the contacts of original gypsum cast revealed that BI and BR designs showed significantly higher percentages of identical contacts compared with BC design (P<.05). Subjective assessment revealed that students generally found BI designs and BR designs natural regarding naturalness of fissure morphology and cusp shape and cusp tip position. For general occlusal morphology, student groups generally found BI design "too strong" or "perfect", BC design "too weak", and BR design "perfect". CONCLUSION: On a prepared tooth, three different biogeneric design modes of a CAD/CAM software reveals different crown designs regarding occlusal contacts and morphology.
Calcium Sulfate ; Ceramics ; Crowns ; Dental Occlusion ; Dental Prosthesis Design ; Humans ; Molar ; Tooth

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Long-term cumulative survival and mechanical complications of single-tooth Ankylos Implants: focus on the abutment neck fractures.

Hye Won SHIM ; Byoung Eun YANG

The Journal of Advanced Prosthodontics.2015;7(6):423-430. doi:10.4047/jap.2015.7.6.423

PURPOSE: To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth Ankylos(R) implants. MATERIALS AND METHODS: This was a retrospective clinical study that analyzed 450 single Ankylos(R) implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to age, sex, implant length or diameter, bone graft, arch, and position. RESULTS: The 8-year CSR was 96.9%. Thirteen (2.9%) implants failed because of early osseointegration failure in 3, marginal bone loss in 6, and abutment fracture in 4. Screw loosening occurred in 10 implants (2.2%), and 10 abutment fractures occurred. All abutment fractures were located in the neck, and concurrent screw fractures were observed. The CSR and rate of screw loosening did not differ significantly according to factors. The CFR was higher in middle-aged patients (5.3% vs 0.0% in younger and older patients); for teeth in a molar position (5.8% vs 0.0% for premolar or 1.1% for anterior position); and for larger-diameter implants (4.5% for 4.5 mm and 6.7% for 5.5 mm diameter vs 0.5% for 3.5 mm diameter) (all P<.05). CONCLUSION: The Ankylos(R) implant is suitable for single-tooth restoration in Koreans. However, relatively frequent abutment fractures (2.2%) were observed and some fractures resulted in implant failures. Middle-aged patients, the molar position, and a large implant diameter were associated with a high incidence of abutment fracture.
Bicuspid ; Dental Implant-Abutment Design ; Dental Implants ; Humans ; Incidence ; Molar ; Neck* ; Osseointegration ; Periprosthetic Fractures ; Retrospective Studies ; Survival Rate ; Tooth ; Transplants

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Study of the most frequent natural tooth colors in the Spanish population using spectrophotometry.

Cristina GOMEZ-POLO ; Miguel GOMEZ-POLO ; Juan Antonio MARTINEZ VAZQUEZ DE PARGA ; Alicia CELEMIN VINUELA

The Journal of Advanced Prosthodontics.2015;7(6):413-422. doi:10.4047/jap.2015.7.6.413

PURPOSE: To identify the most frequent natural tooth colors using the Easyshade Compact (Vita -Zahnfabrik) spectrophotometer on a sample of the Spanish population according to the 3D Master System. MATERIALS AND METHODS: The middle third of the facial surface of natural maxillary central incisors was measured with an Easyshade Compact spectrophotometer (Vita Zahnfabrik) in 1361 Caucasian Spanish participants aged between 16 and 89 years. Natural tooth color was recorded using the 3D Master System nomenclature. The program used for the present descriptive statistical analysis of the results was SAS 9.1.3. RESULTS: The results show that the most frequent dental color in the total sample studied is 3M1 (7.05%), followed by the intermediate shade 1M1.5 (6.91%) and 2L1.5 (6.02%). CONCLUSION: According to the research methodology used, and taking into account the limitations of this study, it can be proposed that the most frequent color among the Spanish population is 3M1; the most common lightness group is 2; the most frequent hue group according to the 3D Master System is M and the most frequent chroma group is 1.5.
Incisor ; Research Design ; Spectrophotometry* ; Tooth*

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Evaluation of proximal contact strength by postural changes.

Hee Sun KIM ; Hyun Joon NA ; Hee Jung KIM ; Dong Wan KANG ; Sang Ho OH

The Journal of Advanced Prosthodontics.2009;1(3):118-123. doi:10.4047/jap.2009.1.3.118

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

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