Dental Porcelain ; Dental Prosthesis ; Dental Restoration, Permanent ; methods ; Humans

Composite Resins ; Dental Bonding ; methods ; Dental Restoration, Permanent ; methods

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

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

OBJECTIVETo evaluate the efficacy of flowable composite resin(FCR) as stress-absorbing liners in Class I cavity restorations in vitro.

METHODSThirty Class I cavities of 4 mm in diameter and 2 mm in depth were prepared in polycarbonate (PC) plates and divided into three groups, ten each. After application of an adhesive, cavities in each group were restored using one of the following methods: A: restored with Charisma without any lining of FCR; B: lined with Revolution Formula 2 twice before restoration with Charisma; C: lined with Teric Flow twice before restoration with Charisma. All cavities were observed under a photoelastic microscope and photoelastic images were recorded at 3 min and 24 h after curing and the shrinkage stresses on the cavity wall were calculated. The polymerization shrinkage(v%) of the three composite resins was measured using bonded discs method and their elastic moduli were measured according to ISO standard.

RESULTSThe shrinkage stresses at 3 min and 24 h of the three methods were as follows,A: (4.93 ± 0.28), (5.87 ± 0.40) MPa, B: (4.90 ± 0.30), (5.84 ± 0.33) MPa, and C: (4.76 ± 0.28),(5.83 ± 0.37) MPa.No significant difference was found in results among different groups. The polymerization shrinkage(v%) in group A,B, and C were (2.63 ± 0.04)%, (4.56 ± 0.06)%, and (3.98 ± 0.02)%. The elastic modulus in group A, B, and C were (9.59 ± 0.65), (4.25 ± 0.51), and (5.41 ± 0.79) GPa.

CONCLUSIONSUnder present study condition, using a FCR as stress-absorbing liner under composite resin restoration does not significantly decrease the polymerization shrinkage stresses at the cavity wall.

Composite Resins ; chemistry ; Dental Cavity Lining ; Dental Restoration, Permanent ; methods ; Dental Stress Analysis ; Materials Testing ; Polymerization

OBJECTIVETo investigate the influence of the consistency of resin composite and insertion techniques on the homogeneity of the Class I restorations.

METHODSStandardized Class I cavities were prepared in polymethyl methyacrylate (PMMA) blocks and restored with three resin composites (Prodigy, Tetric EvoCeram and Tetric Ceram HB) using either a packing or an injection technique by six operators. Then the restorations were sectioned longitudinally and inspected for the presence of porosities and voids with microscope. The consistence of the three resins was tested using an area method.

RESULTSThere is little porosity in original resin. After insertion, large numbers of porosities were observed in restorations, with Tetric EvoCeram presented much more porosities (1137.1 +/- 365.0 for packing and 566.1 +/- 206.4 for injection) than Prodigy (241.0 +/- 116.1, 195.8 +/- 28.7) and Tetric Ceram HB (193.1 +/- 35.8, 156.3 +/- 33.0). Tetric Ceram HB showed the highest consistency, followed by Tetric EvoCeram and Prodigy. No linear correlation was found between the consistency of the composite and the porosity of their restorations. For Tetric EvoCeram, the restorations inserted with packing showed significant more porosity than that with injection. Contrastively, the restorations of Prodigy or Tetric Ceram HB presented no apparent difference for the two filling techniques.

CONCLUSIONSThe porosity in restoration was primarily created during the insertion. There was no linear correlation between the consistency of the composite and the porosity of their restorations. The porosity of composite resin is material-brand dependent. The influence of filling techniques on the porosity of restoration is depending on the composite used.

Composite Resins ; Dental Cavity Preparation ; methods ; Dental Restoration, Permanent ; methods ; Porosity

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

Seeing that the manual method to restore tooth has the disadvantages such as long "lead-time", assurance of quality highly depending on operator's technology, and real-time cure difficulty met by lots of dental patients coming up for tooth restoration, we put forward an algorithm of tool-path generation based on STL data model for roughing dental restoration. The algorithm can reconfigure the STL data of dental crown restoration quickly, can generates the multi-level offset wire-loop by the use of horizontal plane cutting triangle facets; and then on the basis of offset wire-loop, it can plan Zigzag and follow the contour machining tool path. The algorithm has been applied to Dental CAM software, through simulation machining, the result shows that it can not only generate interference-free tool path, but also save a lot of "lead-time" for dental restoration. Accordingly, the algorithm is of great value for reference in clinical application.
Algorithms ; Crowns ; Dental Restoration, Permanent ; methods ; Humans ; Software ; Therapy, Computer-Assisted ; methods

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

OBJECTIVETo develop a dental CAD/CAM system with the autonomic intellectual property.

METHOD28 standard teeth crowns were scanned using a newly 3-D laser scanner. As a development platform the Matlab 5.3 were used to process the acquired data, also be used to define the characterized areas on the surfaces of the crowns and to change the crowns form. The software of Surfacer 10.5 to develop a new CAD software for fixed prosthetics, and the 3.5 axis numerical controlled machine to manufacture the prosthetics were used.

RESULTIt is the first time, the 3D graphic data bank of Chinese teeth crowns with a standard form was established. A software of the occlusal adjustment and the form modification were developed. It is also the first time, the authors realized the whole process to use the CAD-CAM for the manufacture of a crown.

CONCLUSIONThe successful result shows, that we have already mastered well the base theory, the mathematics method, the technology of a CAD-CAM system. It provides the basics for the future development.

Computer-Aided Design ; Dental Prosthesis Design ; methods ; trends ; Dental Restoration, Permanent ; methods ; Dentistry, Operative ; methods ; Humans ; Research ; trends ; Research Design