Evaluation of the Dentinal Shear Bond Strength and Resin Interface in Primary Molars after Pre-Treatment with Various Dentin Bio-Modifiers: An In Vitro Study.

Dentine adhesives have demonstrated great success with permanent teeth. Though the results in primary teeth are not well documented, some studies have demonstrated lower values of bond strength in primary teeth than those found in permanent teeth. The aim of this study was to compare and evaluate the effect of grape seed extract (6.5%) (Herbal Bio Solutions, Delhi, India), glutaraldehyde (5%) (Loba Chemie PVT. LTD., Mumbai), hesperidin (0.5%) (Herbal Bio Solutions, Delhi, India), and casein phosphopeptide-amorphous calcium phosphate (tooth mousse) (GC Corporation, Alsip, IL, USA) on the shear bond strength of dentine of primary teeth and to evaluate the resin tags at the resin tooth interface. Seventy-five caries-free human primary molars were collected, and their occlusal surfaces were ground flat. Dentin surfaces were etched using phosphoric acid. Then teeth were randomly assigned in sequential order to five groups according to the dentinal treatment method: Group I (Control group) (no treatment), Group II (5% glutaraldehyde), Group III (6.5% grape seed extract), Group IV (0.5% hesperidin), and Group V (CPP-ACP). Ten teeth from each group were assigned for Shear Bond Strength and five for SEM analysis. ANOVA and a post hoc least significant difference test (p < 0.05) were used for statistical analysis of the collected data. The grape seed extract group showed significantly increased shear bond strength than the control group (p < 0.05), and the mean length of resin tags in different dentine bio modifiers groups was also statistically significant (p < 0.05). The use of dentin bio modifiers such as 5% glutaraldehyde, 6.5% grape seed extract, 0.5% hesperidin, and CPP-ACP in the bonding process for primary teeth did not improve the dentinal bond strength.

Using Functionalized Micron-Sized Glass Fibres for the Synergistic Effect of Glass Ionomer on Luting Material.

This laboratory experiment was conducted with the objective of augmenting the mechanical properties of glass ionomer cement (GIC) via altering the composition of GIC luting powder through the introduction of micron-sized silanized glass fibres (GFs). Experimental GICs were prepared through the addition of two concentrations of GFs (0.5% and 1.0% by weight) to the powder of commercially available GIC luting materials. The effect of GF in set GIC was internally evaluated using micro-CT while the mechanical attributes such as nano hardness (nH), elastic modulus (EM), compressive strength (CS), and diametral tensile strength (DTS) were gauged. Additionally, the physical properties such as water solubility and sorption, contact angle (CA), and film thickness were evaluated. Reinforced Ketac Cem Radiopaque (KCR) GIC with 0.5 wt.% GF achieved improved nH, EM, CS, and DTS without affecting the film thickness, CA or internal porosity of the set GIC cement. In contrast, both GF-GIC formulations of Medicem (MC) GIC showed the detrimental effect of the GF incorporation. Reinforcing KCR GIC with 0.5 wt.% silanized GFs could improve the physical and mechanical attributes of luting material. Silanized GF, with optimal concentration within the GIC powder, can be used as a functional additive in KCR GIC with promising results.

Oxidized Natural Biopolymer for Enhanced Surface, Physical and Mechanical Properties of Glass Ionomer Luting Cement.

This laboratory investigation aimed to synthesize and characterize micron-sized Gum Arabic (GA) powder and incorporate it in commercially available GIC luting formulation for enhanced physical and mechanical properties of GIC composite. Oxidation of GA was performed and GA-reinforced GIC in 0.5, 1.0, 2.0, 4.0 & 8.0 wt.% formulations were prepared in disc-shaped using two commercially available GIC luting materials (Medicem and Ketac Cem Radiopaque). While the control groups of both materials were prepared as such. The effect of reinforcement was evaluated in terms of nano hardness, elastic modulus, diametral tensile strength (DTS), compressive strength (CS), water solubility and sorption. Two-way ANOVA and post hoc tests were used to analyze data for statistical significance (p < 0.05). FTIR spectrum confirmed the formation of acid groups in the backbone of polysaccharide chain of GA while XRD peaks confirmed that crystallinity of oxidized GA. The experimental group with 0.5 wt.% GA in GIC enhanced the nano hardness while 0.5 wt.% and 1.0 wt.% GA in GIC increased the elastic modulus compared to the control. The CS of 0.5 wt.% GA in GIC and DTS of 0.5 wt.% and 1.0 wt.% GA in GIC demonstrated elevation. In contrast, the water solubility and sorption of all the experimental groups increased compared to the control groups. The incorporation of lower weight ratios of oxidized GA powder in GIC formulation helps in enhancing the mechanical properties with a slight increase in water solubility and sorption parameters. The addition of micron-sized oxidized GA in GIC formulation is promising and needs further research for improved performance of GIC luting composition.

Oral-Health-Related Self-Efficacy among the Elderly Population in Riyadh, Saudi Arabia.

Oral health self-efficacy is a fundamental determinant of behavioral changes among elderly patients. Objective: To assess the oral self-efficacy among the Saudi population aged 65 years old and above in Riyadh, Saudi Arabia. Methodology: This was a cross-sectional survey conducted on elderly individuals in Riyadh. An Arabic version of the Geriatric Self-Efficacy Scale for Oral Health (GSEOH) was administered to all participants. The dependent variables included oral function, oral hygiene habits, and dental visits. For the statistical analysis, two independent sample t-tests and a one-way ANOVA test were used. Significance was judged at a p-value less than 0.05. Results: Of 400 participants recruited, 53% were males. About 58% had retained teeth, and 72% had visited a dentist in the past 12 months. Overall, 31.6%, 34.64%, 22.65%, and 11.14% of the participants rated their oral health as good, fairly good, rather poor, and poor, respectively. Age (p < 0.001), educational level (p < 0.001), and working status (p < 0.001) were significantly associated with GSEOH scores. Other sociodemographic characteristics were not found to affect the GSEOH scores. Conclusions: The overall self-efficacy of oral health among Saudi elderly individuals is fairly good. Age, educational level, and occupational status are the main determinants of oral health self-efficacy scores.

Mechanical and antibacterial efficacy of photo-sonodynamic therapy via methylene blue-loaded nanoparticles over dental implants for treating peri-implantitis.

AIM: This study aimed to evaluate the mechanical (i.e., flexural modulus [FM], flexural strength [FS], and surface roughness [Ra]) and antibacterial efficacy of photo-sonodynamic therapy via methylene blue-loaded poly(D,L-lactide-co-glycolide) nanoparticles (MB-loaded PLGA NPs) over dental implants for potential treatment of peri-implantitis. METHODS: PLGA NPs were synthesized via a solvent displacement method. After the synthesis and confirmation of MB-loaded PLGA NPs via physical (Scanning Electron Microscope [SEM]) and chemical characterization (Fourier transform infrared spectroscopy [FTIR]), the mature dental biofilm of Porphyromonas gingivalis was produced over the surfaces of dental implants. Then, the bacterial viability assessment of the following five study groups was performed: group-I (diode laser treatment); group-II (PDT/MB-loaded PLGA NPs treatment; group-III (ultrasound treatment); group-IV (ultrasound/PLGA NPs-MB treatment); and group-V: control group included the samples without any treatment. Finally, the FS, FM, and Ra of the samples was assessed. RESULTS: Under the SEM, the NPs were spherical homogeneous particles having round morphology ranging approximately 100 nm in size without aggregation. The FTIR spectra of PLGA NPs and MB-loaded PLGA NPs demonstrated absorption peaks at approximately 1000 cm-1 to 1200 cm-1 and around 1500 cm-1 to 1750 cm-1. The greatest level of P. gingivalis killing was exhibited by ultrasound/MB-loaded PLGA-NPs-treated samples. The FS was statistically significantly greater for control group samples than any other group (i.e., 100.28 MPa; p<0.05). The FM and Ra ranged between 3.31 and 3.58 GPa and between 0.18 and 0.20 µm without any statistically significant difference between the control and experimental groups (p>0.05), respectively. CONCLUSION: Within the limitations of this study, the application of photo-sonodynamic therapy via MB-loaded PLGA NPs demonstrated the greatest antibacterial activity against P. gingivalis without deteriorating the surfaces and compromising the mechanical properties of dental implants.

Impact of Ceramic Material and Preparation Design on Marginal Fit of Endocrown Restorations.

Background: The aim of this study is to investigate the impact of ceramic material and preparation design on the marginal fit of endocrown restorations. Methods: Forty endocrown restorations were CAD/CAM-fabricated for forty extracted maxillary first premolar teeth. Samples were divided into two groups (n = 20) according to the ceramic materials used: Celtra Duo and Vita Enamic. Each group was divided into two subgroups (n = 10) according to the preparation design: with no intraradicular extension and with 3 mm intraradicular extension. The marginal gap was examined using a digital microscope. Results: Celtra Duo without intraradicular extension recorded the least mean marginal gap (7.74 ± 1.55 µm), while Group Celtra Duo with 3 mm intraradicular extension recorded the highest mean marginal gap (29.54 ± 6.32 µm). Group Vita Enamic recorded a lesser marginal gap (18.03 ± 12.11 µm) than group CD (Celtra Duo) (18.64 ± 12.05 µm). There is a statistically non-significant difference between the two groups of materials (p = 0.873). There is a statistically significant difference between the two tested preparation designs (p < 0.001). Conclusion: All groups recorded a marginal gap within clinically accepted values. Material selection may influence the fitting of restorations. Intraradicular extension for endocrown restorations adversely affects the marginal fit, however, the marginal gap is still within the clinically accepted range.

Mechanical Properties of the Modified Denture Base Materials and Polymerization Methods: A Systematic Review.

Amidst growing technological advancements, newer denture base materials and polymerization methods have been introduced. During fabrication, certain mechanical properties are vital for the clinical longevity of the denture base. This systematic review aimed to explore the effect of newer denture base materials and/or polymerization methods on the mechanical properties of the denture base. An electronic database search of English peer-reviewed published papers was conducted using related keywords from 1 January 2011, up until 31 December 2021. This systematic review was based on guidelines proposed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The search identified 579 papers. However, the inclusion criteria recognized 22 papers for eligibility. The risk of bias was moderate in all studies except in two where it was observed as low. Heat cure polymethyl methacrylate (PMMA) and compression moulding using a water bath is still a widely used base material and polymerization technique, respectively. However, chemically modified PMMA using monomers, oligomers, copolymers and cross-linking agents may have a promising result. Although chemically modified PMMA resin might enhance the mechanical properties of denture base material, no clear inferences can be drawn about the superiority of any polymerization method other than the conventional compression moulding technique.

Screening of fluoride analysis as a biochemical parameter in the orthodontic treatment using fixed appliances.

Saliva is a critical and useful biological fluid necessary for good health and for the appropriate execution of mouth activities. Orthodontic biomaterials have a complex relationship with many components, including the oral environment. Treatment with fixed orthodontic appliances may causes dental caries. As a result, it is necessary to comprehend how orthodontic therapy and various fluoride regimens affect the chances of developing dental cavities as well as individual risk factors. Usage of fluoride will tend to reduce the caries in the patients diagnosed with the fixed orthodontic treatment. The aim of this study was to screen the biochemical parameter of the fluoride levels in the patients undergone and completed the treatment of orthodontic fixed appliances. In this study, 35 patients have been visited on day 1 as well as day 35 and categorized as T0 and T1 groups. Saliva samples were collected and fluoride levels were measured between T0 and T1 groups. Using the fluoride kit with the spectrophotometer, fluoride levels were measured. The results confirmed similar fluoride levels between T0 (26.11 ± 4.86) and T1 (27.71 ± 4.40) groups. There was no significant association observed in this study (p = 0.56). Fluoride might have no role in the patients undergoing orthodontic treatment.

Team-Based Learning in Prosthodontics Courses: Students' Satisfaction.

The goal of this cross-sectional observational study was to assess dental students' satisfaction regarding team-based learning (TBL) methodology in prosthodontics courses taught at College of Dentistry, Princess Nourah bint Abdulrahman University, Saudi Arabia. Undergraduate dental students at second, third, fourth, and fifth years were taught prosthodontics courses through traditional and TBL pedagogies. TBL sessions consisted of preparation, readiness assurance, and application. At the end of each prosthodontics course, the students were asked to complete a self-administered questionnaire that was divided into four sections to assess the effect of TBL on the following parameters: information acquisition, interpersonal skills improvement, classroom environment, and the students-instructors interaction. The responses of the questionnaire followed the Likert scoring method (scaled from 1 to 5). The t-test and ANOVA statistical analyses were performed using SPSS. Results. The response rate to the questionnaire was 86%. There were a significant relationship and correlation between TBL pedagogy and student satisfaction (P values ≤ 0.05) for all levels. The means of the responses for the second and fifth years were 4.36 and 4.56, respectively, where the means for the third and fourth years were 3.54 and 3.59, respectively. The parameter notably affected by TBL was interpersonal skills enhancement. All students strongly agreed that TBL enhances personal flexibility and boosts their self-esteem. Conclusion. Students showed positive perceptions about TBL pedagogy in terms of active engagement, knowledge acquisition, and improvement of interpersonal skills leading to more efficient learning outcome.

Monolithic Endocrown Vs. Hybrid Intraradicular Post/Core/Crown Restorations for Endodontically Treated Teeth; Cross-sectional Study.

The gold standard for restoring Endodontically Treated Teeth (ETT) with successful clinical longevity requires having minimal invasive preparations and maximal tissue conservation. Many dentists still consider hybrid post/core/crown to be the first choice for restoring ETT. Endocrown is a viable alternative treatment modality to hybrid post/core/crown. This study aims to assess the proper judgment of dentists working in Riyadh, Saudi Arabia on the use of monolithic endocrown versus hybrid post/core/crown for restoring ETT. The IRB of Princess Nourah Bint Abdulrahman University (PNU) Institutional Review Board reviewed this study. The questionnaire was validated and electronically distributed. The participants were pre-informed that their responses are completely anonymous and used for professional purposes only. The questionnaire surveyed dentists working in Riyadh, Saudi Arabia, about their preference for different ETT restorative modalities at various clinical scenarios. Data were analyzed using One-way ANOVA and t-test. All P-values of < 0.05 were considered statistically significant. A total of 275 responses were collected; 61.45% were females and 38.55% males. 56% of them were general practitioners, while 16% were consultants. Prefabricated post/core was the most preferred technique among the participants (18.55%), followed by endocrown (12.36%), and lastly, cast post/core (8.73%). The amount of remaining tooth structure was the most influential in the treatment selection (30.18%), followed by the presence or absence of 1-2 mm ferrule (17.82%). Interocclusal space (12.36%) was the least influential factor. Endocrown recorded 63.27% as the most preferred line of treatment in case of insufficient inter-occlusal space. 40.36% preferred endocrown for patients with occlusal risk factors. The amount of the remaining tooth structure and the tooth position significantly affect the treatment options of the participants. Endocrown was the most preferred treatment modality for restoring ETT for patients with occlusal consideration.

Influence of Reinforcing Agents on the Mechanical Properties of Denture Base Resin: A Systematic Review.

Knowledge about the influence of fillers in denture base resin is vague. This systematic review aimed to report the reinforcing effect of fillers on the mechanical properties of denture base resin by following PRISMA guidelines. Two electronic databases (Pubmed/Medline & Web of Science) were searched for articles using the keywords: fibers in denture base, fillers in denture base, and reinforcement of denture base. Laboratory studies complying with the inclusion criteria were reviewed according to the set protocol. The established focus question was: "Do reinforcing fillers positively influence the mechanical properties of polymethyl methacrylate (PMMA) heat polymerized denture base material?" A total of twenty-nine relevant papers qualified for final inclusion. Of these, 24 were determined to have a moderate risk of bias. Micron or nano-sized metal/metal oxides particles and glass fibers were the frequently used reinforcing agents. The trend of evaluating fractural strength (FS) was common. Most of the studies limited the use of reinforcing agents up to 5 wt.%. FS, fracture toughness (FT), and impact strength (IS) tend to increase if the fillers are chemically bonded and well-dispersed in denture base resin. Though fillers with a higher elastic modulus increase the hardness of the reinforced denture base resin, they compromise other mechanical properties. Well-dispersed lower filler loading PMMA denture base resin can enhance the FS, FT, and other related mechanical properties.

Practice with confidence: Analyzing confidence level of final year dental students from four Saudi dental colleges in Riyadh.

OBJECTIVE: To investigate the confidence level of final year dental students in Riyadh. MATERIALS: Cross-sectional study was conducted at four dental colleges in Riyadh (N = 312, 220 and 70,5% responded). Oneway ANOVA and post hoc Tukey-Kramer was used. RESULTS: The greatest self-reported confidence scores were for pit fissure sealent (4.6(0.7)). Whereas, students reported least confidence in conducting surgical extractions (2.7 (1.2)). Females were found more confident in conducting preventive resin restorations, oral hygiene instructions, and rubber dam placement as compared to male who were more confident in surgical extraction, copy dentures, veneer preparation and managing orthodontic emergencies. CONCLUSION: All students were confident in performing essential dental procedures however higher confidence was observed in performing simple procedures compared to more complex ones.

Structural integrity of extracted teeth restored using three different post-and-core systems: An in vitro comparative study.

AIM: The objective of the study was to assess the in vitro fracture resistance of endodontically treated teeth restored using different post-and-core materials. MATERIALS AND METHODS: Extracted human mandibular premolars (n = 36) were extracted teeth and equally distributed into four (4) treatment groups: cast metal post-and-core, milled zirconia post-and-core, pre-fabricated post with composite resin core and control group. These samples were then each subjected to the load to fracture test using a universal testing machine. Fracture resistance data were compared among groups by analysis of variance and Fisher's exact test. RESULTS: The highest mean fracture resistance value was observed in the zirconia post-and-core treatment group (1567.26 ± 317.66 N), followed by the cast metal (1355.92 ± 621.56 N) and lastly the pre-fabricated post with composite resin core (725.67 ± 251.05 N) treatment group. Differences among groups were not statistically significantly different (P = 3.77). CONCLUSION: Endodontically treated mandibular premolars with a zirconia post-and-core system exhibited the highest robustness against structural failure based on its mean fracture resistance value. In addition, extracted teeth restored with cast post-and-core resisted a greater stress load than those restored with fiber-reinforced posts. Zirconia showed a more favorable fracture mode than the other restorations.

Antimicrobial Capacity and Surface Alterations Using Photodynamic Therapy and Light Activated Disinfection on Polymer-Infiltrated Ceramic Material Contaminated with Periodontal Bacteria.

This study determined the antimicrobial efficiency of light-activated disinfection (LAD) and photodynamic therapy (PDT) on polymer-infiltrated ceramic network (PICN) material contaminated with three periodontal bacteria and explored if PDT and LAD cause PICN surface alterations. Sixty PICN discs were contaminated with Tannerella forsythia, Porphyromonas gingivalis, and Treponema denticola and randomly divided into five groups (n = 12 samples/each) according to the treatment groups: Group PDT-PDT (630 ± 10 nm diode laser) with methylene blue; Group DL-808 nm diode laser in contact mode without photosensitizer; Group MB-methylene blue without light application; Group CHX-0.12% chlorhexidine digluconate solution and; Group NT-no treatment. Each disc was then placed in tubes containing phosphate buffered saline (PBS) and vortexed for 30 s to remove the remaining bacteria from the discs. A total of 10× serial dilutions were performed followed by plating of 30 µL of suspension on Brucella agar plates. The colony forming units (CFU) were calculated after 72 h. PICN discs with the attached biofilms were used for confocal microscopy investigation for live/dead bacterial viability. A random single sample from each group was selected to study the bacterial adherence and topographical alterations on PICN discs under scanning electron microscope (SEM). The PDT group showed higher reduction for each bacterial species and total counts of bacteria assessed followed by the DL group (p < 0.05). When compared with MB group, the two laser groups were significantly superior (p < 0.05). The MB group did not show significant differences for any bacteria when compared to NT. The bacteria with the CHX group and DL groups appeared dead with few areas of surviving green stained bacteria. The PDT group showed the highest dead cell count (p < 0.05). PDT and DL groups indicate no significant changes on the surface compared to the sterile PICN discs on visual assessment. Photodynamic therapy produced superior periodontal bacteria reduction over the surface of PICN surface. PDT group showed higher reduction for each bacterial species and total counts of bacteria assessed followed by the DL group. Both PDT and DL treatment strategies are effective without producing surface alterations on PICN.

Resin bonded bridges in patients with hypodontia: Clinical performance over a 7 year observation period.

PURPOSE: Resin bonded bridges (RBBs) are considered a conservative option in the management of hypodontia. This study targeted to analyze the survival of resin bonded bridges provided to patients with Hypodontia by staff and students at the Department of Restorative Dentistry, University Dental School and Hospital Cork, Ireland. It was also to determine the factors that may influence the survival of RBBs in patients with hypodontia. METHODS: Forty patients with hypodontia who received 65 RBBs from 2001 to 2007 were identified and contacted to be recruited for this study. Of these, nine were not contactable, and five failed to attend. Accordingly, 26 patients (65%) participated in the study, with a total of 51 RBBs. RESULTS: Of the 51 RBBs evaluated, 44 (86%) were still in situ and functional and 7 (14%) failed. The main reason for failure was repeated debonding. The effect of age, gender, the grade of operator and experience, bridge location, design of the bridge, span length and moisture control during cementation, could not be demonstrated. CONCLUSION: The effect of age, gender, the grade of operator and experience, bridge location, design of the bridge, span length and moister control on RBB survival could not be demonstrated. Majority of patients with hypodontia showed satisfaction with resin bonded bridges. In replacing congenitally missing teeth in patients with hypodontia, resin-bonded bridges would be an acceptable treatment option.

Familiarity and implementation of academicians of dental schools regarding the application of photodynamic therapy in dentistry: A need to incorporate in the dental curriculum.

BACKGROUND: The present cross-sectional study aimed to evaluate the knowledge, behavior, and attitudes of academicians from dental schools in Riyadh, Saudi Arabia towards the use of photodynamic therapy (PDT) in dentistry. METHODS: A self-administered questionnaire to a total of 289 academicians from the dental training faculty (DTF) was distributed to six dental schools in Riyadh, Saudi Arabia during 3 months of the study period. The questionnaire consisted of four main sections with 17 items that dealt with: demographic data, awareness, and knowledge of dental academician regarding PDT technique, and the interest of the dental academician in implementation the PDT technique, detailed knowledge, and background about PDT use followed by the role and integration of PDT technique and its theoretical knowledge in the curriculum and clinical practice. Quantitative data were analyzed using frequency distribution. To estimate if general demographics of the participants affect DTF responses regarding PDT knowledge and teaching experience multivariate statistical analyses were carried out according to gender, age, professional experience, and academic rank regarding selected questions. RESULTS: A total of 238 questionnaires (response rate: 82.3 %) were returned for the analysis. Females responded higher than males. More than 50 % of respondents were age 50 years and less. It is shown that 63 % of DTF indicates familiarization regarding PDT and 67 % and 70 % strongly agree to the fact that PDT should be incorporated in the dental curriculum and important to acquire knowledge regarding PDT for teaching undergraduate. A remarkable number of 87 % and 74 % showed high interest in participating in lectures and workshops related to PDT and therefore clinically applying the technique in clinical practice, respectively. Multivariate analysis showed a statistically significant difference between the level of knowledge and correct answers with age, professional experience of teaching and academic rank. CONCLUSION: Although the DTF involved in the present study demonstrated average knowledge regarding PDT, they, however, consider significantly important and showed a keen interest in acquiring PDT knowledge and adding it in the dental curriculum.

Golden proportion evaluation in maxillary anterior teeth amongst Saudi population in Riyadh.

INTRODUCTION: In achieving pleasing dental aesthetics, the maxillary anterior teeth are essential. Numerous methods are used to measure their dimensions, including the golden proportion between their perceived widths and the width-to-height ratios, referred to as the golden proportion and is considered as a gold standard for esthetic evaluation.The objective of this study was to evaluate the existence of the golden proportion between the width of the maxillary anterior teeth of Saudi males and females. METHODS: This clinical observational study included a total of 61 participants that met the inclusion criteria having 36 females and 25 males, all Saudi nationals, presented to Princess Nourah bint Abdulrahman University (PNU), College of dentistry, clinics. Dental casts of the maxillary arches for each participant were made after taking digital impressions in addition to taking photographs. The dimensions and the perceived width of the anterior teeth viewed from the front were measured using a digital caliper. SPSS was used to analyze the data. RESULTS: There were significant differences between the subject's width-to-height ratios and the golden proportion of 0.80 where (p-value < 0.05). Thus, indicating that no golden ratio was observed except in case of tooth number 12 in male subjects where mean value was (0.83) with a standard deviation of (0.09) and the p-value of (p = 0.144) > 0.05. CONCLUSIONS: From the perceived widths of maxillary anterior teeth, the golden proportion was not found to exist. No gold standard was detected for the width-to-height proportions of maxillary incisors. Therefore, in addition to anterior teeth measurements, specific population characteristics and perception of an agreeable smile should be considered for evaluating esthetics.

Success and Survival of Various Types of All-Ceramic Single Crowns: A Critical Review and Analysis of Studies with a Mean Follow-Up of 5 Years or Longer.

PURPOSE: The aim of this critical review was to assess the survival and success rates of all-ceramic single crowns manufactured using different ceramic materials with a mean follow-up time of 5 years or longer. MATERIALS AND METHODS: An electronic search of studies published between 1980 and 2014 complemented by manual searching was conducted in Medline and Scopus. The terms ceramic, crown, survival, success, longevity, and complications were selected as keywords. Predetermined inclusion and exclusion criteria guided the search. Data were extracted and assessed by two independent reviewers. The results were statistically analyzed according to the type of material, and survival/success rate was calculated by assuming a Poisson-distributed number of events. RESULTS: The initial search yielded 972 articles. After subsequent filtering, 14 studies were selected. The inter-reviewer agreement was rated as good (κ = 0.65) and very high agreement (κ = 0.93) during the identification and screening phases, respectively. No studies on densely sintered zirconia or feldspathic crowns satisfied the minimum follow-up time. Only one study of each of the following materials satisfied the inclusion criteria: lithium disilicate, leucite reinforced, pressed Al2O3, and sintered Al2O3. Meta-analysis of the included studies on other materials resulted in the following estimated survival and success rates: for densely sintered alumina crowns, 93.8% and 92.75%, respectively; for fluoromica reinforced, 87.7% and 87.7%, respectively; and for glass-infiltrated alumina core, 94.4% and 92%, respectively. Crown fracture was considered the most frequent complication. CONCLUSION: Based on the present critical review, there was no evidence to support the superior application of a single ceramic system or material. Further long-term prospective studies are required.

Wear behavior of zirconia substrates against different antagonist materials.

OBJECTIVE: This study assessed the wear behavior of different zirconia substrates with distinct surface roughness against different antagonist materials. METHOD: Hemisphere-shaped specimens (diameter 5 mm) made out of different materials (VM9, Vintage ZR, IPS e.max Press, and human enamel) were used as antagonists against plates of three zirconia materials (P-NANOZr, Cercon HT, and Zenostar) with different surface roughness (smooth [Ra = 0.01], moderate [Ra = 0.1], and rough [Ra = 1]). Each group (n = 7) was exposed to thermomechanical fatigue in a mastication simulator to simulate 5 years of clinical service. All specimens were scanned using a laser scanner and volumetric loss was quantified. Scanning electron microscopy was used to evaluate wear pattern, while Raman spectroscopy was employed to determine the crystalline property of zirconia specimens. RESULTS: For zirconia, the smallest volumetric loss was recorded with smooth P-NANOZR against enamel antagonists (0.002 ± 0.002 mm³), whereas the greatest loss was observed with rough Cercon HT against Vintage antagonists (0.37 ± 0.14 mm³). For antagonists, smooth Zenostar against enamel antagonists yielded the smallest volumetric loss (0.03 ± 0.02 mm³), whereas the greatest loss values were recorded with rough Zenostar against VM9 antagonists (2.67 ± 0.35 mm³). A positive correlation was found between surface roughness of zirconia specimens and volume loss of base and antagonist specimens. PNANOZR showed less wear compared to other zirconia materials. The wear pattern was comparable among different specimens. Artificial aging did not influence the levels of tetragonal and monoclinic phases of different zirconia materials. CONCLUSION: While microstructure shows a relatively smaller effect, surface roughness of zirconia has the greatest effect on its wear and on the wear of antagonists.