OBJECTIVE: To analyze the effect of ceramic onlay to repair serious defects in young permanent molars. METHODS: Sixty patients with defects in young permanent molars were selected. The patients were randomly divided into two groups. One group was restored with ceramic onlay, and the other used resin composite to direct filling. Follow-up visit was conducted at 3, 6, 12, and 24 months after treatment. Modified USPHS/Ryge criteria were used to evaluate the effect of restoration. The occlusal courses were recorded by the T-Scan Ⅲ system in intercuspal position. Gingival and food impaction were recorded. The effect of the two restorative methods, the recovery of occlusal function, and the gingival and approximal conditions were analyzed. RESULTS: At 12 months after restoration, the marginal fitness in the onlay group was significantly better than that in the resin group (P<0.05). At 12 and 24 months after restoration, the surface smoothness in the onlay group was significantly better than that in the resin composite group (P<0.05). At each follow-up visit, the resin group had significantly lower per-cen-tage of occlusal force than contralateral molar (P<0.05). The percentage of occlusal force in the onlay group and the con-trala-teral molar showed no statistical difference (P>0.05). The gingival and approximal conditions also demon-strated no stati-stical differences (P>0.05). CONCLUSIONS The ceramic onlay repair method is better than resin composite filling in marginal fitness, surface smoothness, and recovery of the occlusal function when restoring young permanent molars with serious defects.
Bite Force ; Ceramics ; Composite Resins ; Dental Restoration, Permanent ; methods ; Humans ; Inlays ; Molar ; Resin Cements

OBJECTIVE: To observe the preoperative sedation, the status of separation from parents, compliance with the mask, hemodynamic parameters and postoperative agitation of intranasal dexmedetomidine (DEX) premedication on children undergoing dental rehabilitation under general anesthesia. METHODS: In the study, 60 children of American Society of Anesthesiology classification (ASA I-II), aged 2-9 years, were randomly assigned to one of two equal groups. Thirty minutes before operation, control group received intranasal placebo (0.9% saline) 0.02 mL/kg, and DEX group received intranasal DEX 2 μg/kg. The preoperative sedation score, the status of separation from parents, compliance with the mask and hemodynamic parameters were recorded by an anesthesiologists until anesthesia induction. Recovery conditions, postoperative agitation were also recorded. RESULTS: There was no significant difference between the two groups in patient characteristics, operation time, extubation time and recovery time. Compared with the children in control group, those in DEX group were significantly more sedated when they were separated from their parents (56.7% vs. 26.7%, P<0.05). Satisfactory compliance with mask application was 40% in control group vs. 73.3% in DEX group (P<0.05). There was no significant difference between the two groups regarding the incidences of postoperative agitation and oxygen saturation (SpO₂). Compared with control group, the heart rate (HR) of DEX group was decreased after 20 minutes of drug administration [(97.13±12.93) beats/min vs.(104.53±11.97) beats/min, P<0.05]. The changes of the HR and SpO2 in the two groups were within the normal range. There were no incidences of bradycardia and hypoxemia in either of the groups during study observation. CONCLUSION Premedication with intranasal DEX 2 μg/kg for children undergoing dental rehabilitation under general anesthesia produces good preoperative sedation. The levels of sedation, scores of parental separation and compliance with the mask were satisfied. The children have good recovery conditions, and no obvious postoperative agitation and respiratory depression after DEX administration. Intranasal DEX 2 μg/kg is an effective and safe alternative for premedication in children.
Administration, Intranasal ; Anesthesia, General ; Child ; Child, Preschool ; Dental Restoration, Permanent/methods* ; Dexmedetomidine/administration & dosage* ; Double-Blind Method ; Heart Rate ; Humans ; Hypnotics and Sedatives/administration & dosage*

Composite Resins ; therapeutic use ; Dental Restoration, Permanent ; methods ; Humans

OBJEVTIVETo evaluate the effect of different restoration methods on fracture resistance of endodontically treated teeth.

METHODSFifty intact extracted maxillary first premolars were randomly divided into 5 groups. Medial-occlusal cavity models were established in all the test groups (B-E) according to the same standard, followed by treatments with defect exposure only, defect filling with light cured composite resin, indirect resin inlays, or light cured composite resin combined with Biosplint fiber. Each specimen was tested using a universal test machine at 1.00 mm/min until fracture and the fracture load was recorded. The load angle was 45 degree to the long axis of the teeth, and the load was pointed to the middle of the lingual surface on the buccal cusp. The fracture resistance was analyzed statistically.

RESULTSThe mean load to cause fracture of the samples in each group group A to E was 1.27∓0.41, 0.23∓0.17, 0.55∓0.31, 0.89∓0.40, and 0.98∓0.34 kN, respectively, showing significant differences between the groups.

CONCLUSIONThe fracture resistance of the teeth is reduced after endodontic therapy, but can be increased significantly by restoration with composite resin inlay or light cured composite resin combined with Biosplint fiber.

Bicuspid ; physiopathology ; Composite Resins ; chemistry ; Dental Materials ; chemistry ; Dental Restoration, Permanent ; methods ; Dental Stress Analysis ; Humans ; Inlays ; Maxilla ; Tooth Fractures ; physiopathology ; Tooth, Nonvital ; physiopathology ; therapy

OBJECTIVETo evaluate the clinical application value of minimal prepared ceramic veneer in anterior teeth, by analyzing the esthetic effects and success rates.

METHODSForty-four anterior teeth in 30 patients with minor esthetic defect were included in this study. Less than 0.5 mm preparation or no preparaion technique was used in the clinical procedure. Glass ceramics veneers were delivered and 3M Relyx Veneer were used as the adhesive. The final appearance of each restoration was evaluated by patients on visual analogue scales (VAS) and by professional prosthodontists. Evaluation criteria included margin effects, color, shape and translucency. The success rate of all the restoration were analyzed in 6, 12 and 24 month after the treatment.

RESULTSThe patients' degree of satisfaction was 9.2 ± 0.4, while the excellent rate of esthetic effect of margin effect, color, shape and translucency was 89% (39/44), 91% (40/44), 98% (43/44) and 93% (41/44) by professional prosthodontist. The success rate of 6, 12 and 24 month were 100% (44/44), 98% (43/44) and 91% (40/44).

CONCLUSIONSThe minimal prepared venneers have a good esthetic effect and a satisfactory success rate, and is a suitable technique in esthetic treatment under the critical indications.

Ceramics ; Dental Restoration, Permanent ; methods ; Dental Veneers ; Esthetics, Dental ; Humans ; Incisor ; Patient Satisfaction ; Tooth Abnormalities ; therapy ; Tooth Preparation, Prosthodontic ; methods ; Tooth Wear ; therapy

OBJECTIVETo evaluate the reliability and superiority of micro-CT in marginal leakage assessment of Class V restorations.

METHODSClass V preparations with gingival margins in dentin and occlusal in enamel were made in sixteen extracted non-carious human molars and restored with dental bonding agents and composite resin. All teeth were then immersed in 50% ammonia-silver nitrate solution for 12 hours, followed by developing solution for 8 hours. Each restoration was scanned by a micro-CT and silver leakage was measured and three-dimensional image of the silver leakage alone cavity wall were reconstructed. Afterward, all restorations were sectioned and examined for leakage depth using a microscope. The silver leakage depth of each restoration obtained by micro-CT and microscope were compared for equivalency.

RESULTSThe silver leakage depths in gingival wall obtained with micro-CT (0.78 mm) and microscope (0.74 mm) showed no significant difference (P > 0.05), while the judgment of leakage depths in occlusal wall in micro-CT image (0.40 mm) was affected by adjacent enamel structure, giving less leakage depths compared to microscope (0.72 mm)(P < 0.01). The three-dimensional shapes of the microleakages displayed clearly by micro-CT alone wall of Class V restorations were multiform and some leakages showed channels on their way to spreading.

CONCLUSIONSMicro-CT can detect precisely the silver leakage in the dentin wall of a restoration and display its three-dimensional shape fully. Enamel structure affects the detection of the silver leakage next to it.

Dental Cavity Preparation ; Dental Enamel ; diagnostic imaging ; pathology ; Dental Leakage ; diagnostic imaging ; pathology ; Dental Restoration, Permanent ; methods ; Humans ; Imaging, Three-Dimensional ; Microscopy ; Molar, Third ; diagnostic imaging ; pathology ; X-Ray Microtomography ; methods

OBJECTIVETo evaluate the effect of carbamide peroxide (CP) bleaching agents at different concentrations and with different carriers on the micro-leakage of composite resin interface.

METHODSClass V cavity (2 mm in diameter and 2 mm in depth) preparations were made at the enamelo-cemental junction on the buccal and lingual surfaces of 35 extracted human premolars. The cavities were filled with hybrid composite resin. The teeth were stored for 24 h in distilled water at 37 degrees celsius; before thermocyling for 500 times between 5 and 55 degrees celsius;. The teeth were then randomly assigned into 7 groups, and in groups 1-6, the bleaching gels containing 10% or 20% of CP were applied on the buccal and lingual surface of the teeth for two weeks (6-8 h/day, 37 degrees celsius;, 100% relative humidity) using Carbopol, PVP or Poloxamer as the thickening carriers, respectively. The seventh group served as the control without bleaching treatment. Nail polish was applied to the surface of the tooth, and all the teeth were immersed in ammoniacal silver nitrate solution followed by developing solution. The teeth were finally sectioned through the midline of the restoration and observed under stereomicroscope. SEM micrographs were also made to observe the interface.

RESULTSWith the same bleaching agent, the micro-leakage in the gingival wall was slightly greater than in the occlusive wall, but the difference was not significant. Only 20% CP with Poloxamer as the thickening agent significantly increased the leakage of dentine-resin composite interface, and 10% and 20% CP with Carbopol or PVP as the thickening agents and 10% CP with Poloxamer produced minimal effects on filling the micro-leakage.

CONCLUSIONThickening carriers and the concentration of CP (20% or below) have no significant effect on micro-leakage of composite resin.

Bicuspid ; Bleaching Agents ; chemistry ; Composite Resins ; chemistry ; Dental Caries ; therapy ; Dental Leakage ; chemically induced ; Dental Restoration, Permanent ; methods ; Humans ; Peroxides ; chemistry ; Tooth Bleaching ; adverse effects ; Urea ; analogs & derivatives ; chemistry

Child ; Dental Pulp Exposure ; etiology ; therapy ; Dental Restoration, Permanent ; Dental Restoration, Temporary ; Humans ; Incisor ; injuries ; Pulpotomy ; methods ; Root Canal Therapy

Acrylic Resins ; Dental Materials ; Dental Restoration, Permanent ; methods ; Denture, Partial, Fixed, Resin-Bonded

Damage effects of water sorption on mechanical properties of the hydroxyapatite particle reinforced Bis-GMA/TEGDMA copolymer (HA/Bis-GMA/TEGDMA) have been predicted using 3-D finite cell models. Three different cell models were used to determine the influence of varying particle contents, interphase strength and moisture concentration on the debonding damage. The stress distribution pattern has been examined and the stress transfer mode has been clarified. The Young's modulus and fracture strength of the Bis-GMA/TEGDMA composite were also predicted using the model with and without consideration of the damage. The former results with consideration of the debonding damage are in good agreement with existing literature experimental data. The shielding effect of our proposed model and an alternative approach were discussed. The FCC cell model has also been extended to predict the critical load for the damaged and the undamaged composite subject to the 3-point flexural test.
Bisphenol A-Glycidyl Methacrylate ; chemistry ; Computer Simulation ; Dental Materials ; chemistry ; Dental Restoration, Permanent ; methods ; Finite Element Analysis ; Humans ; Materials Testing ; Models, Theoretical ; Polyethylene Glycols ; chemistry ; Polymethacrylic Acids ; chemistry ; Stress, Mechanical ; Water ; chemistry