Comparison of implant versus tooth-supported zirconia-based single crowns in a split-mouth design: A 4-year clinical follow-up study

WOS: 000388957000017PubMed ID: 26924133This study aims to evaluate the 4-year clinical performance of tooth versus implant-supported single-unit zirconia crowns (LAVA (TM)) placed on posterior region. Twenty-four patients (10 men and 14 women) who had received 48 single crowns (24 implant-supported and 24 tooth-supported) from January 2007 to December 2009, were included. California Dental Association (CDA) quality assessment system, plaque and gingival index scores were used to evaluate the performance of the crowns at baseline and at all follow-up examinations. During the follow-up period, no fracture of zirconia coping has occurred. Major complication was chipping in three patients that required a new crown fabrication. Except for the failure ones, all crowns in both groups were rated as satisfactory at the follow-up examinations based on the CDA quality assessment criteria. There were no statistically significant differences between tooth and implant-supported crowns in terms of periodontal parameters. The present 4-year follow-up clinical study demonstrates that single-unit tooth- and implant-supported zirconia crowns have similar prosthetic and periodontal outcomes. Single-unit implant or tooth-supported zirconia crowns may be considered acceptable treatment modalities for restoration of either missing or compromised posterior teeth

Effect of simulated gastric acid on aesthetical restorative CAD-CAM materials' microhardness and flexural strength

Background: Gastric acid, which is among erosive substances, gradually rises to the mouth in individuals with reflux and bulimia nervosa disorders, and this causes various effects on dental restorations. Aim: The objective of this study is in vitro investigation of gastric acid's effect on flexural strength and hardness on aesthetic restorative computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: For this study, four materials have been used, namely Enamic (Vita), Superfect Zir (Aidite) Zirconia, IPS e.max CAD (Ivoclar Vivadent), and Mark II (Vita). From these four different materials, 24 samples with 14 × 4 × 1 dimensions in rectangular prism form are used, which makes a total of 96 samples. One group was separated as the control group, while the rest was allowed to wait at 37°C, 5 ml gastric acid for 96 hours. Hardness value and flexural strengths were measured as pre-exposure and post-exposure to gastric acid. Results: There is a statistically significant difference between the groups in terms of the amount of decrease in the mean hardness after exposure to gastric acid compared to pre-exposure values (p: 0,000; P 0.05). There is a statistically significant difference between the groups in terms of the average flexural strength after exposure to the acid. Conclusions: According to the data obtained, it was concluded that exposure to gastric acid affects the hardness and flexural strength properties of dental restorative ceramic materials

Evaluation of heat transfer to the implant-bone interface during removal of metal copings cemented onto titanium abutments

WOS: 000376213500018PubMed ID: 27148993Purpose: The aim of this investigation was to measure the temperature increase due to heat transferred to the implant-bone interface when the abutment screw channel is accessed or a metal-ceramic crown is sectioned buccally with diamond or tungsten carbide bur using an air rotor, with or without irrigation. Materials and Methods: Cobalt-chromium copings were cemented onto straight titanium abutments. The temperature changes during removal of the copings were recorded over a period of 1 minute. Results: The sectioning of coping with diamond bur and without water irrigation generated the highest temperature change at the cervical part of the implant. Conclusion: Both crown removal methods resulted in an increase in temperature at the implant-bone interface. However, this temperature change did not exceed 47 degrees C, the potentially damaging threshold for bone reported in the literature

Oral sıcaklık değişikliklerinin farklı yapıdaki restoratif post ve kor materyaller üzerindeki termal stres etkisinin üç boyutlu sonlu elemanlar analizi ile karşılaştırılması

Background and Aim: The purpose of this study was to compare thermal stress on various restorative post and core materials generated by oral temperature changes using three dimensional finite element analysis. Materials and Methods: Three dimensional model of a mandibular right first premolar restored with a metal-ceramic crown and a dowel – core system was constructed. The thermal load applied to the three dimensional tooth model simulated the draught of hot (60°C) and cold (15°C) food or beverages for 5 seconds. Temperature distribution and thermal stress was calculated at 8 points in von Mises value of MPa, determined on the buccolingual plane using thermal loading function of finite element analysis programme. Results: The temperature gradient of the metal post and cores was smaller than that of the resin cores because of the high thermal conductivity of the former materials. Thermal changes and post-core materials have a significant effect on the thermal stress concentrations particularly located in the restorations. The gold post and core system showed the smallest thermal stress. The combination of prefabricated stainless steel post and amalgam core generated the highest thermal stress in the restoration and dentin. Cast post-core systems generated lower thermal stress when compared to prefabricated dowel and core materials. Conclusions: Cast gold post-core or non-metallic prefabricated posts-composite core materials generated better thermal stress distribution and their use in clinical practice could be recommended.Amaç: Bu çalışmanın amacı, oral sıcaklık değişikliklerinin farklı yapıdaki restoratif post ve kor materyaller üzerinde meydana getirdiği termal stresleri üç boyutlu sonlu elemanlar analizi ile karşılaştırmaktır. Gereç ve Yöntem: Termal stres analizi için, içinde post ve kor bulunan alt sağ 1. premolar dişe ait anatomik ve protetik yapılar ile birlikte, dişi çevreleyen sert ve yumuşak dokuların üç boyutlu sonlu elemanlar modeli oluşturulmuştur. Modele 5 saniye süreyle soğuk (15°C) ve sıcak (60°C) olmak üzere iki farklı sıcaklık koşulu uygulanmış ve sıcaklık dağılım ve termal stres analizi gerçekleştirilmiştir. Sıcaklık dağılım ve termal stres ölçümleri von Mises MPa değeri ile bukko-lingual model kesiti üzerinde belirlenen 8 noktada sonlu eleman analizi metodunun termal yükleme fonksiyonu kullanılarak yapılmıştır. Bulgular: Tek parça döküm post-kor ve prefabrik metal postamalgam kor sistemleri, yüksek termal iletkenlik katsayıları sebebiyle, metal post-kompozit kor ve metal olmayan postkompozit kor sistemlerine göre, incelenen model katmanları arasında daha düşük sıcaklık farklılıklarının oluşmasına yol açmışlardır. En düşük termal stres oluşumu, döküm altın post ve altın kor sisteminde, en yüksek termal stres oluşumu, prefabrik paslanmaz çelik post ve amalgam kor sisteminde meydana gelmiştir. Tek parça döküm post-kor sistemleri, iki parça prefabrik post–kor sistemlerine kıyasla, daha avantajlı termal stres sonuçları vermektedir. Sonuçlar: Döküm altın post-kor ve metal olmayan postkompozit kor kombinasyonu daha olumlu termal stres dağılımı göstermişlerdir. Bu sebeple klinikte kullanımları tavsiye edilebilir

Orthodontic bonding to acid- or laser-etched prebleached enamel

WOS: 000320910000006PubMed ID: 23814709Objective: Bonding forces of brackets to enamel surfaces may be affected by the procedures used for bleaching and enamel etching. The aim of this study was to investigate the bonding strength of orthodontic brackets to laser-etched surfaces of bleached teeth. Methods: In a nonbleached control group, acid etching (group A) or Er:YAG laser application (group B) was performed prior to bracket bonding (n = 13 in each group). Similar surface treatments were performed at 1 day (groups C and D; n = 13 in each subgroup) or at 3 weeks (groups E and F; n = 13 in each subgroup) after 38% hydrogen peroxide bleaching in another set of teeth. The specimens were debonded after thermocycling. Results: Laser etching of bleached teeth resulted in clinically unacceptable low bonding strength. In the case of acid-etched teeth, waiting for 3 weeks before attachment of brackets to the bleached surfaces resulted in similar, but not identical, bond strength values as those obtained with nonbleached surfaces. However, in the laser-etched groups, the bonding strength after 3 weeks was the same as that for the nonbleached group. Conclusions: When teeth bleached with 38% hydrogen peroxide are meant to be bonded immediately, acid etching is preferable

Interdisciplinary treatment of a patient with bilateral cleft lip and palate and congenitally missing and transposed teeth

2014 IEEE Global Communications Conference, GLOBECOM 2014 -- 8 December 2014 through 12 December 2014 -- 110905The comprehensive treatment of a patient with cleft lip and palate requires an interdisciplinary approach for functional and esthetic outcomes. A 20-year-old woman with bilateral cleft lip and palate had a chief complaint of unesthetic appearance of her teeth and the presence of oronasal fistulae. Her clinical and radiographic evaluation showed a dolichofacial growth pattern, a Class II skeletal relationship with retroclined maxillary central incisors, 5 mm of negative overjet, maxillary constriction, maxillary and mandibular crowding, congenitally missing maxillary right incisors and left lateral incisor, and a transposed maxillary left canine. Her treatment plan included the extraction of 3 premolars, maxillary expansion, segmental maxillary osteotomy, repair of the oronasal fistulae, rhinoplasty, periodontal surgery, and prosthodontic rehabilitation. To obtain a better occlusion and reduce the dimensions of the fistulae, orthognathic surgery comprising linear and rotational movements of the maxillary segments (premaxilla, right and left maxillary alveolar segments) in all 3 axes was planned by performing 3-dimensional virtual surgery on 3-dimensional computerized tomography. At the end of the interdisciplinary treatment, a functional occlusion, a harmonious profile, and patient satisfaction were achieved. Posttreatment records after 1 year showed stable results

Implant-supported extra-orally cemented monolithic zirconia crowns: A prospective controlled clinical study up to 18 months in function

This study evaluated the clinical performance of implant supported, extra-orally cemented, monolithic zirconia crowns after a follow-up to 18 months. Thirty-one patients with 50 posterior dental implants were consecutively selected for this study. A total of 50 crowns were cemented onto titanium abutments extra-orally and then screwed to the implants with the required torque intra-orally. The patients were followed at 12 months and 18 months after placement of restorations. During the follow-up period, all restorations were evaluated according to following technical parameters: implant failure, crown fracture, screw loosening, loss of retention due to decementation, fracture of antagonist tooth or restoration. Data were analyzed using Kaplan Meier method. One implant and its corresponding crown was lost during the follow-up period, yielding a 18 months survival rate of 98%. During the study, 2 complication events were observed, including one screw loosening and one veneering porcelain chipping in an antagonist bilayered zirconia restoration. The overall success rate of the observed prosthesis was 96%. According to the results of this study, the extra-orally cemented, monolithic zirconia crowns resulted in a favorable short-term outcome for posterior implant supported restorations within this short observation time

Effects of various denture cleansers on surface roughness of hard permanent reline resins

WOS: 000355962800016PubMed ID: 25740306The aim of this study was to investigate the influence of denture cleansers on surface roughness (Ha, mu m) of two hard permanent reline resins and a conventional acrylic denture base resin. Fifty specimens of each material, measuring 10 mmx2 mm were randomly divided into 1 control and 4 experimental subgroups (n=10). Surface roughness values were measured using profilometer before and after immersion in distilled water and in 4 different denture cleansers for 8 h for 140 days. The Kruskal Wallis and Wilcoxon Signed Ranks tests were used for comparison among groups with a significance level of alpha=0.05. Immersion in denture cleansers significantly increased the surface roughness of reline resins and the difference among the cleansers was statistically significant (p=0.059). Denture cleansers can cause significant surface roughness alterations on hard permanent reline resins and denture base resin where their effect may differ according to the selected resin material

Comparison of autoclave and microwave postpolymerization treatments on flexural strength of hard reline resins

Amaç: Otoklav ve mikrodalga post-polimerizasyon uygulamalarının sert besleme akriliği ve ısı ile polimerize olan akriliğin bükülme direnci üzerine etkisinin karşılaştırılması. Gereç ve Yöntem: Sert besleme akriliği ve ısı ile polimerize olan akrilik malzemeden 64x10x3.3 mm boyutunda örnekler hazırlandı. Her iki akrilikten 80 adet örnek hazırlandı ve 4 alt gruba ayrıldı (n=20). Örnekler, mikrodalga ve otoklavda (kısa ve uzun programda) kullanılarak otoklav post-polimerizasyonuna tabi tutuldu ve 5 mm/dak hızla 3 nokta bükülme testi uygulandı. İstatistiksel analiz için iki yönlü ve tek yönlü ANOVA ve Tukey’s HSD testleri kullanıldı. Bulgular: Mikrodalga ile post-polimerizasyon, her iki akriliğin bükülme direncini anlamlı olarak arttırmıştır (p0.05). Sonuç: Otoklav ile post-polimerizasyon yöntemi, direkt yöntemle besleme yapılmış hareketli protezin bükülme direncini arttırabilecek bir uygulama olarak önerilebilir.Purpose: To compare the effect of autoclave and microwave post-polymerization treatments on flexural strength of hard reline and heat-polymerized acrylic resins. Material and Methods: Hard chairside reline and heat-polymerized acrylic resin specimens (64x10x3.3 mm) were fabricated. 80 specimens with 4 subgroups for each acrylic (n=20) received post-polymerization treatment by microwave irradiation and two autoclave post-polymerization mo- dalities (short and long). Specimens were subjected to flexural strength testing using 3-point bending with a crosshead speed of 5 mm/min. Two-way, one-way ANOVA and Tukey’s HSD tests were used for statistical analysis of data. Results: The microwave post-polymerization significantly increased the strength of heat polymerized acrylic resin and hard chairside reline resin specimens where its effect was significantly higher than the autoclave and control groups (p<0.01). Both autoclave groups presented higher strength values than the control group (p<0.01). For both materials, the difference between the mean flexural strength values of short and long autoclave application was statistically insignificant (p>0.05). Conclusion: Using autoclave, may be considered as a viable post-polymerization treatment alterna- tive in order to increase the flexural strength of relined dentures

Evaluation of the effect of anodization-colored titanium abutments and zirconia substructure thickness on zirconia substructure color: An in vitro study

Background and Aim: The aim of this study is to evaluate the effect of anodized titanium abutments and zirconia substructure thickness on the color of zirconia substructure. Materials and Methods: In this study, an electrochemical anodization setup was prepared for titanium coloring. Commercial titanium, anodization-colored yellow and pink titanium, and zirconia were used as different abutment specimens. Thirty zirconia discs in 0.7, 0.9, and 1.1 mm thickness were prepared from zirconia blocks as zirconia substructure specimens (n = 10). Zirconia substructure specimens of different thicknesses were placed on abutment specimens of different colors and L∗, a∗, b∗ values were measured with a spectrophotometer device. Color difference (ΔE) was calculated according to the CIELab formula by comparing the L∗, a∗, and b∗ values obtained on the zirconia abutment with the L∗, a∗, and b∗ values obtained on the other abutments. Statistical analyzes were performed with two-way analysis of variance and Tukey Honestly Significant Difference (HSD)test (p < 0.05). Results: The increase in the thickness of the substructure resulted in a statistically significant difference on ΔE, L∗, a∗, and b∗ values (p < 0.001). The effect of abutment color had no significant effect on ΔE values. The highest ΔE value was 18.10 at zirconia substructure with 0.7 mm thickness when paired with pink-anodized titanium abutment specimens. Conclusion: The thickness of zirconia substructure and the color of titanium abutments affect zirconia substructure color