Serum microRNAs as potential biomarkers of mandibular prognathism.

OBJECTIVES: The aim of the study was to determine whether the expression levels of specific circulating serum microRNAs (miRNAs) are associated with mandibular prognathism (MP). METHODS: Sixty subjects in the early permanent dentition stage and 23 in the mixed dentition stage with MP were identified. Sixty-eight normal control subjects in the early permanent dentition stage and 24 in the mixed dentition stage were recruited for comparison. According to the microarray-based expression profiling, four serum miRNAs (let-7i-3p, miR-595, miR-16-2-3p, and miR-367-5p) were validated. RESULTS: In the MP groups, let-7i-3p was significantly over-expressed in subjects in the early permanent (P < 0.0005) and mixed (P < 0.001) dentitions, and miR-595 was significantly under-expressed (P < 0.004) in subjects in the early permanent (P < 0.004) and mixed (P < 0.0005) dentitions, compared with normal control groups. Multiple logistic regression analysis and receiver operating characteristic curve analysis revealed that let-7i-3p and miR-595 were able to significantly discriminate MP subjects from normal controls. CONCLUSION: Let-7i-3p and miR-595 could be potential, non-invasive biomarkers for the accurate early detection and diagnosis of MP, which may result in improved clinical management.

Patterns and forces of occlusal contacts during lateral excursions recorded by the T-Scan II system in young Chinese adults with normal occlusions.

The objective was to characterise the patterns and forces of occlusal contacts during lateral mandibular excursions in a young Chinese adult population. Angle Class I normal occlusions in 85 dental students aged 20-29 were evaluated using the T-Scan II occlusal imaging and analysis system. The frequency of occlusal contacts was recorded for right and left lateral excursions at the position of lateral disclusion, at the canine-to-canine position and at the lateral maximal position. At the canine-to-canine position, the occlusal contact patterns were classified, and the relative forces were compared by multiple regression analysis, with α = 0·05. At the position of lateral disclusion, a high percentage of canine contacts (58·5%) and individual posterior tooth contacts on the working side was observed. At the canine-to-canine position, the canines on the working side contacted most frequently (68·9%), and the occlusal contact patterns could be classified into six groups. At the lateral maximal position, incisors (39·0%) and canines (32·3%) contacted most frequently. At the canine-to-canine position, subjects with occlusal contacts only on canines or on first premolars on the working side had the lowest relative occlusal forces (P < 0·001). Canine protection and group function do not identify all descriptors for lateral occlusal contact patterns in the natural dentition. Six occlusal contact patterns were found at the lateral canine-to-canine position.

Effect of fluoride iontophoresis on the microtensile bond strength between dentin and two adhesive systems.

AIM: To evaluate the effect of fluoride iontophoresis on the microtensile bond strength (MTBS) between coronal dentin and two resin-based adhesive systems, and to measure quantitatively dentinal tubule occlusion. METHODS: Twelve freshly extracted intact human mandibular third molars were divided randomly into four groups. The superficial occlusal dentin of each tooth was exposed and treated. Group A1: One-Step Plus total-etch adhesive system; group A2: One-Step Plus total-etch adhesive system after fluoride iontophoresis; group B1: ACE BOND SE self-etching adhesive system; group B2: ACE BOND SE self-etching adhesive system after fluoride iontophoresis. A resin composite buildup was made for each tooth, which was then sectioned along its long axis to produce 10 beams (1.0 mm x 1.0 mm) for the microtensile bond strength (MTBS) test. Five dentin disks were cut in half and their occlusal surfaces etched with 6% citric acid. The test halves were treated with fluoride iontophoresis. Four SEM photomicrographs were taken from corresponding sites on each test and each non-treated control half-disk. Image-Pro Plus 4 software quantified the percentage of tubule occlusion. Data were analyzed using one-way ANOVA, chi(2)- and t-tests, with the probability level set at alpha=0.05. RESULTS: The mean MTBS (MPa) for each group was, A1: 30.86 (S.D. 6.84); A2: 25.04 (8.49); B1: 19.22 (6.88); B2: 19.40 (6.92). There were significant differences among all groups (P < or = 0.02), except between groups B1 and B2 (P=0.92). Fluoride iontophoresis resulted in significantly increased dentinal tubule occlusion (P<0.001). CONCLUSIONS: Fluoride iontophoresis treatment reduced significantly the dentin bond strength of One-Step Plus total-etch adhesive, but not that of ACE BOND SE self-etching adhesive. However, the bond strength of the former remained significantly higher than that of the latter adhesive system.

Radiation-induced root surface caries restored with glass-ionomer cement placed in conventional and ART cavity preparations: results at two years.

BACKGROUND: There are no published studies comparing the clinical performances of more-viscous glass-ionomer cement (GIC) restorations when placed using conventional and atraumatic restorative treatment (ART) cavity preparation methods to restore root surface caries. METHODS: One dentist used encapsulated Fuji IX GP and Ketac-Molar to restore 72 conventional and 74 ART cavity preparations for 15 patients who had received cervicofacial radiation therapy. Two assessors evaluated the restorations at six, 12, and 24 months for retention, marginal defects and surface wear, and recurrent caries. RESULTS: After two years, the cumulative restoration successes were 65.2 per cent for the conventional and 66.2 per cent for the ART cavity preparations, without statistical or clinical significance (P > 0.50). Restoration dislodgement accounted for 82.8 per cent and marginal defects for 17.2 per cent of all failures. There were no instances of unsatisfactory restoration wear or recurrent caries observed. Teeth with three or more restored cervical surfaces accounted for 79.3 per cent of all failures (P < 0.0001). CONCLUSIONS: For root surface caries restored with GIC, the use of hand instruments only with the ART method was an equally effective alternative to conventional rotary instrumentation for cavity preparation. Larger restorations had higher failures, usually from dislodgement.

Prosthodontic management of older severe hypodontia patients in general dental practice: a case series.

Although a detailed understanding of the etiology of hypodontia is lacking, there is a need for awareness among dental professionals of the social and psychological consequences of severe hypodontia, as well as knowledge of those affected by hypodontia have ongoing dental treatment needs. Although, there may be a need for immediate referral of children to different specialists for optimal multidisciplinary treatment planning, most older patients with severe hypodontia can be treated by general practitioners. Practitioners therefore need to be aware of the ramifications of the condition and be capable of providing adequate oral health care for these patients and referring them for additional services when necessary. A case-report series is used to illustrate routine prosthodontic treatments that can be offered to older patients in general dental practice.

Placement and replacement of dental restorations.

OBJECTIVE: To determine the types of various dental restorative materials used, and the reasons for the placement and replacement of dental restorations in 10 randomly selected polyclinics in Riyadh, Saudi Arabia. DESIGN: A cross-sectional descriptive study. PLACE AND DURATION OF STUDY: Ten selected polyclinics in Riyadh metropolitan area, Saudi Arabia during a period of two weeks in January 2003. PATIENTS AND METHODS: Information was collected by using a specially-designed form that was distributed to one dentist in each selected polyclinic. The dentists were asked to record specific details for all restorations placed in adult patients. Chi-square tests were used to analyze the data. RESULTS: Data were collected for 326 restorations. Amalgam (52.5%) was the most commonly used restorative material followed by resin composite (31.3%) and temporary restorations (14.4%), with a minimal use of glass ionomer cement (1.8%, p<0.001). Most of the restorations (69.9%) were initial placements, while 30.1% were replacement restorations, (p<0.05). Caries was the major reason for the initial placement (92.1%), and for the subsequent replacement (96.9%) of restorations. CONCLUSION: Amalgam and resin composite were the most commonly used restorative materials. Caries was the major reason for the initial restoration placements and subsequent replacements.

Long-term cost-effectiveness of single indirect restorations in selected dental practices.

OBJECTIVE: To determine the relative cost-effectiveness of alternative methods for restoring large tooth substance loss in adults. METHODS: Long-term survival estimates and discounted costs for 245 large indirect restorations were used to calculate their incremental cost-effectiveness over 15 years when compared with direct placement Class II cusp-overlay amalgams and Class IV multisurface resin composites, placed in 100 patients from three private dental practices. RESULTS: The direct placement restorations were more cost-effective than the indirect restorations at all time intervals over the 15-year study period. The full gold crown and the ceramometal crown were the most cost-effective indirect posterior and anterior restorations respectively. The cast gold onlay and the porcelain jacket crown were the least cost-effective indirect posterior and anterior restorations respectively. CONCLUSIONS: When clinically practicable, large direct placement restorations should be placed initially in preference to indirect restorations.

Survival of glass ionomer restorations placed in primary molars using atraumatic restorative treatment (ART) and conventional cavity preparations: 2-year results.

OBJECTIVE: To compare the survival of glass ionomer cement (GIC) restorations placed in a dental clinic setting using both the atraumatic restorative treatment (ART) approach with hand instruments, and conventional cavity preparation with rotary instruments. METHOD AND MATERIALS: Two encapsulated high-strength conventional GICs (Fuji IX GP, Ketac-Molar Aplicap) were placed in 82 Class I and 53 Class II preparations and one encapsulated non-gamma 2 amalgam alloy (GK-amalgam) was placed in 32 Class I preparations, in the primary molars of 60 Chinese children with a mean age of 7.40 +/- 1.24 (SD) years. Thus, 9 treatment groups were formed. RESULTS: After two years, there were no significant survival differences found among 7 of the 9 treatment groups (p = 0.99). However, two groups comprising Fuji IX GP and Ketac-Molar Aplicap placed in Class II cavities prepared using the ART approach showed significantly lower restoration survivals (p < 0.001). Only 3 of the 72 initially sealed fissures adjacent to the restorations appeared to retain any GIC material. CONCLUSIONS: In a clinic setting, both the ART hand instrument and conventional rotary instrument methods were equally suitable for high Class I restoration survival, but not for Class II restoration survival where the conventional cavity preparation method was preferable.

Longevity of a resin-modified glass ionomer cement and a polyacid-modified resin composite restoring non-carious cervical lesions in a general dental practice.

BACKGROUND: Long-term prospective survival studies of resin-modified glass ionomer cements (RMGICs) and polyacid-modified resin composites (compomers) placed in non-carious cervical lesions (NCCLs) are lacking from general dental practice. Short-term studies have shown an unsatisfactory clinical performance for several materials. METHODS: One practitioner placed 87 compomer (Compoglass, Vivadent-Ivoclar) and 73 encapsulated RMGIC (Fuji II LC, GC Int.) restorations in NCCLs for 61 adults. Compoglass was placed using SCA primer, and Fuji II LC using GC Dentin Conditioner. No cavity preparation was undertaken. The Kaplan-Meier method was used for estimating the cumulative survivals for those restorations that were replaced, with the probability level set at alpha = 0.05 for statistical significance. RESULTS: Restorations were judged unsatisfactory (by the practitioner and the subjects) because of surface and marginal loss of material (68.8 per cent), dislodgement (18.8 per cent) and discoloration (12.4 per cent), these modes being similar for both materials (P = 0.35). Unsatisfactory restorations were replaced in 121 (75.6 per cent) instances. After periods of up to five years, cumulative survival estimates were 14.9 (5.8 Standard Error) per cent for Compoglass and zero per cent for Fuji II LC (P = 0.74). Median survivals were 30 months for Compoglass and 42 months for Fuji II LC. CONCLUSION: Both materials had high long-term unsatisfactory performances when placed in non-prepared NCCLs in a general dental practice.

Comparison of pulpal sensitivity between a conventional and two resin-modified glass ionomer luting cements.

This clinical study compared handling and any short-term tooth sensitivity associated with using one conventional and two resin-modified glass ionomer cements marketed for luting gold and ceramometal crowns. The patient's response to a 10-second blast of air applied to the vital tooth was scored pre-operatively and again within a one-to-four week post-cementation recall period. A score was also recorded for any sensitivity present at the time of cementation of the crown on the unanesthetized tooth. All three cements were easy to mix and place. Most of the teeth had no response to pulpal stimulation pre-operatively, associated with the cementation procedure or post-cementation, and there were no instances of severe sensitivity recorded. For all cements, the level of post-cementation tooth sensitivity was similar, and less than that found pre-operatively.

Micro-tensile bond strengths to sclerotic dentin using a self-etching and a total-etching technique.

OBJECTIVES: To evaluate the in vitro regional micro-tensile bond strengths of a self-etching/self-priming adhesive system to sclerotic dentin, in the absence or presence of phosphoric acid conditioning. METHODS: Naturally-occurring, non-carious cervical lesions on extracted premolars were hand-cleaned with a slurry of pumice and chlorhexidine, then bonded without further cavity preparation. One group was bonded using Clearfil Liner Bond 2V (Kuraray Co. Ltd., Osaka, Japan). The other group was first conditioned with K-etchant; 40% phosphoric acid gel (Kuraray) prior to the application of the self-etching primer. Artificially prepared wedge-shaped cavities were also made in sound premolars and bonded with the two methods as controls. Resin composite build-ups were made using Clearfil Protect Liner F and AP-X resin composite (Kuraray). After storage in water for 24h, the teeth were sectioned into 0.7 x 0.7 mm composite-dentin beams along the occlusal and gingival walls, and at the apex of the lesions. The use of two conditioning methods, two substrate types, and three different locations yielded 10-14 beams for each of the 12 groups. After testing for the microTBS, representative beams that were stressed to failure were examined with SEM. Remaining fractured beams were demineralized and processed for TEM examination. Statistical analysis was performed using a three-way ANOVA and Student-Newman-Keuls tests. RESULTS: Regardless of the conditioning methods, bond strengths to sound dentin were significantly higher than to sclerotic dentin (P< 0.05). With sclerotic dentin, there was no significant difference for the conditioning methods used, except that K-etchant significantly improved the bond strength at the gingival aspect of the lesions. Fractographic analysis revealed that the self-etching primer could not etch beyond the surface hypermineralized layer of sclerotic dentin. Interfacial failure occurred along the surface of the mineralized intermicrobial matrix and/or hypermineralized layer. With the use of phosphoric acid, a hybrid layer was only seen when the surface layers were thin. Incompletely removed sclerotic casts were evident in both groups. SIGNIFICANCE: Removal of the surface layers of sclerotic dentin and/or conditioning with stronger acids may be beneficial to obtain stronger bonding to sclerotic dentin.

Glass ionomer cements used as fissure sealants with the atraumatic restorative treatment (ART) approach: review of literature.

AIM: To review the success of newer, more-viscous aesthetic conventional glass ionomer cements (GICs), that have been marketed specifically for the atraumatic restorative (ART) technique or approach, when used as pit and fissure sealants. As part of this approach, enamel fissures adjacent to the ART restorations are conditioned with poly (acrylic) acid (PAA) and then usually sealed with a GIC, using the finger-press method. RESULTS: The newer GICs appear in vitro to penetrate adequately and seal occlusal fissures in permanent molar teeth, and clinical studies of the ART approach over three years have found sealant retention (full and partial) to be approximately 70%, with fissure caries approximately 0-4%. In two studies, fissure caries was significantly reduced in sealed as compared with unsealed teeth over three years. CONCLUSIONS: Although the results appear to be better with the newer than with earlier conventional GIC products, the ART studies have generally involved populations at low-risk to caries, and further improvements in the mechanical properties of the cements are required for optimal long-term clinical success. Etching the enamel fissures with phosphoric acid, instead of conditioning with PAA, before GIC sealant placement warrants clinical investigation.

Restoration of teeth with more-viscous glass ionomer cements following radiation-induced caries.

OBJECTIVE: To assess the suitability of more-viscous conventional restorative glass ionomer cements (GICs) in a high-caries risk group of patients. METHODS: Fifteen adult patients with radiation-induced caries were treated at a dental hospital by one dentist. Two encapsulated aesthetic GICs were used in each patient to restore 146 carious lesions in the exposed dentine and cementum of 93 teeth. The restorations were assessed directly over two years for their retention, secondary caries, anatomic form, marginal integrity, marginal discolouration, and surface texture. RESULTS: Both GICs were placed in similar sized cavities (P = 0.63). After two years, although 30.0% of Ketac-Molar Aplicap and 12.5% of Fuji IX GP restorations had been lost (P = 0.01), there were no instances of secondary caries. The remaining GICs showed ongoing marginal deterioration, but there were very few instances where this required the repair or replacement of the restorations. No restorations failed from surface erosion. CONCLUSIONS: In these high-caries risk patients the placement of more-viscous GICs appeared to prevent secondary caries, even when the restorations were subsequently lost.

Competency-based education in a clinical course in conservative dentistry.

The conceptual difference between a competency-based education and an education based upon a conventional dental curriculum is, perhaps, the starting point for the development of new curricula. The two systems are not, in themselves, exclusive. There is common ground to be found, and the concept of combining instruction with competency-based learning experiences is emerging in recent publications. This paper describes a competency-based approach applied to a clinical course in conservative dentistry. The learning outcomes of the fourth-year dental students in the new course were assessed using methods that included continuous clinical assessments, student presentations and peer-group reflective evaluations, patient management reviews, a clinical progress examination, the range and amount of work completed, and a written examination and viva voce. Different weightings were given to various elements of the assessment. A formal student assessment of the course rated it as being satisfactory.

Effect of different conditioning protocols on adhesion of a GIC to dentin.

PURPOSE: This study examined the ultrastructure and microtensile bond strength (microTBS) of a restorative glass-ionomer cement (GIC; Dentsply) to sound dentin that was conditioned with various techniques. MATERIALS AND METHODS: Dentin surfaces from extracted human third molars were abraded with 180-grit SiC paper. Five groups of three teeth each were prepared: C - no acid pretreatment (control); P - 10% polyacrylic acid (PAA) for 10 s, no rinsing; R - 10% PAA for 20 s, rinsed; K - 25% PAA for 25 s, rinsed; and H -32% phosphoric acid for 15 s, rinsed. TEM was performed on a bonded specimen from each group, using unstained, undemineralized sections. GIC buildups were made on the remaining teeth, and after storage at 100% humidity for 24 h, the teeth were sectioned for microTBS and SEM evaluation. RESULTS: TEM revealed the presence of a structure known as the intermediate layer in all groups. This layer contains metallic salts contributed by both the GIC and dentin. In group C, this layer was restricted to the smear layer. In groups P and R, intermediate layers could be found above partially demineralized zones within the intertubular dentin. In groups conditioned with more aggressive protocols (K and H), the intermediate layers shifted downward to reside within the superficial portions of completely demineralized collagen. Group C had statistically lower microTBS (p < 0.05), while the other groups were not significantly different from each other. SEM revealed adhesive failures along the dentin surface in group C and mixed failures in the other groups. CONCLUSION: The lower microTBS observed in the control group reflects the weakness of the smear layer attachment to dentin. The higher microTBS in the other groups probably represent the cohesive strength of GIC under tension, rather than its true adhesive strength to dentin. Acid pretreatment dissolves the smear layer, creates a zone of partially demineralized dentin, and allows the PAA to interact with dentin via the intermediate layer. Overly aggressive conditioning renders the dentinal tubules patent, and leaves deeper demineralized dentin that does not form part of the intermediate layer.

Fluoride release/uptake of conventional and resin-modified glass ionomers, and compomers.

OBJECTIVES: To assess the levels of fluoride ions released from a range of freshly-prepared aesthetic restorative materials, and then the effects of a topical acidulated phosphate fluoride (APF) gel. METHODS: Five specimens each of four conventional GICs, two resin-modified GICs, two compomers, and a resin composite (control) were assessed for their fluoride ion release over 6 weeks, before being exposed to 1.23% APF gel for 4 min and then measuring their fluoride ion levels for another 6 weeks. RESULTS: Following an initial brief, variable burst of fluoride ion release, the rates then fell quickly for most materials and, although high rates of fluoride ion release were measured immediately following the application of APF gel, these rates also fell quickly for most materials. After 12 weeks, the mean fluoride ion levels were much lower than immediately before gel application. The APF gel treatment caused surface damage to all materials, especially to the conventional GICs. CONCLUSION: The results of this study suggested that much of the increased fluoride ion release found following topical exposure of the fluoridated restorative materials to APF gel was caused by surface effects rather than by chemical recharging.

Assessment of clinical preparations for single gold and ceramometal crowns.

OBJECTIVE: Single-crown preparations at a dental teaching hospital were compared with guidelines advocated in the dental literature. METHOD AND MATERIALS: Sixty-three single complete gold crown and 151 single ceramometal crown preparations were evaluated. Impression silhouettes were measured for occlusal and axial wall tooth reductions, shoulder widths, internal shoulder angles, and axial wall convergence angles. Marginal designs, the presence of retention grooves and undercuts, and the types of cores present were also recorded. RESULTS: Cuspal reduction was generally inadequate for the ceramometal crowns, and central fossa reduction was insufficient for both complete gold crowns and ceramometal crowns. The facial shoulder widths were also generally underprepared for the ceramometal crowns. Axial wall convergence angles for both complete gold crowns and ceramometal crowns were generally much greater than recommended. Large faciolingual convergence angles for anterior ceramometal crowns were associated with the absence of cingulum walls. Few preparations had retention grooves or undercut areas. CONCLUSION: Although strict guidelines for tooth preparations for complete crowns are available and well known to dentists, the preparations in this study did not always conform to these recommendations.

Bonding of contemporary glass ionomer cements to dentin.

OBJECTIVE: The objective of this study was to investigate the microtensile bond strength (microTBS) of contemporary glass ionomer cements (GIC) to sound coronal dentin. METHODS: Three specimen teeth were prepared for each material tested: Fuji IX GP (GC), ChemFlex (Dentsply) and Ketac-Molar Aplicap (ESPE). GIC buildups were made according to the manufacturers' instructions. After being stored at 37 degrees C, 100% humidity for 24h, the teeth were vertically sectioned into 1x1mm beams for microTBS evaluation. Representative fractured beams were prepared for scanning (SEM) and transmission electron microscopic (TEM) examination. RESULTS: Results of the microTBS test were: Fuji IX GP (12.4+/-8.6MPa), ChemFlex (15.0+/-9.3MPa) and Ketac-Molar Aplicap (11.4+/-7.7MPa). One-way ANOVA and a multiple comparison test showed that ChemFlex had a statistically higher microTBS (p<0.05). SEM fractographic analysis showed that the predominant failure modes were interfacial and mixed failures. The GIC side of the fractured beams revealed dehydration cracks, a high level of porosity, and voids with an eggshell-like crust. TEM analysis of the demineralized dentin sides of the fractured beams revealed the presence of an intermediate layer along the GIC-dentin interface. This zone was present on the fractured dentin surface in the case of interfacial failure, and beneath GIC remnants in specimens that exhibited a mixed failure mode. SIGNIFICANCE: The findings suggest that the bonding of GIC to dentin is not weak and that the microTBS values probably represent the weak yield strengths of GICs under tension.

Occlusal wear of a resin-modified glass ionomer cement following three surface treatments.

Unacceptable occlusal wear has been reported for resin-modified glass ionomer cements (RMGICs) placed in permanent molar teeth. Three different surface treatments of a RMGIC were evaluated over periods of up to 2 years for their effects on restoration wear behaviour: (a) sealing with a thin layer of low viscosity unfilled resin (sealed restoration), (b) sealing with a thicker layer of a lightly-filled pit and fissure sealant (sealant restoration), and (c) co-curing the RMGIC with a posterior resin composite (co-cured restoration). After 2 years the cumulative median (quartiles) wear was for (a) 100 (50-150) microns, (b) 25 (0-50) microns, and (c) 25 (25-38) microns. Although method (b) effectively reduced the surface wear of the RMGIC, this treatment required frequent re-sealing, involving 52% of the restorations. Sealing the surface of a RMGIC placed in permanent molars was not a satisfactory method for reducing occlusal wear. However, co-curing the RMGIC with a posterior resin composite reduced occlusal wear significantly (P < 0.0001), without the need for frequent reapplications of a pit and fissure sealant to the RMGIC.

Effects of APF gel on the physical structure of compomers and glass ionomer cements.

This study assessed the effect of an acidulated phosphate fluoride (APF) gel on the surfaces of eight modern esthetic restorative materials. Five specimens each of three high powder: liquid ratio conventional glass ionomer cements (ChemFlex, Fuji IX GP, Ionofil Molar), four polyacid-modified resin composites (compomers) (Compoglass F, Dyract AP, Freedom, F2000) and an alkaline glass filled resin composite (Ariston pHc) were prepared and immersed at 37 degrees C in 2 mL of artificial saliva for six weeks. The aged specimens were then coated with 1.23% APF gel for four minutes, rinsed and again immersed in artificial saliva for another six weeks. The immersed, fresh specimens for each material were then examined with SEM and surface profilometry. After APF gel application, mean surface roughness (Ra) measurements and SEMs showed that roughness increased significantly, generally from the resin composite and compomers to the conventional glass ionomer cements (p < 0.05).