Animals ; Dental Cements ; chemistry ; Glass ; chemistry ; Humans ; Materials Testing ; Post and Core Technique ; instrumentation ; Quartz ; chemistry ; Root Canal Therapy ; Tooth Fractures ; prevention & control

OBJECTIVETo evaluate the microleakage of fiber post and core systems after high-speed handpiece preparation at different time points.

METHODSThe crowns of forty-five extracted human premolar were removed and the roots were endodontically treated. The samples were devided into five groups. Root canal preparation was performed on each premolar followed by fiber post cementation and core build up. Tooth preparation was applied at 5 min in group 1, at 15 min in group 2 and at 30 min in group 3 after post cementation. Five teeth with only 5 mm apical sealing were served as a positive control group, and ten with fiber post and core build-up but no coronal preparation were taken as a negative control group. Microleakage was evaluated using a fluid filtration system. The bonding interface was observed by scanning electronic microscope (SEM).

RESULTSThe microleakage was significantly increased after coronal preparation with high-speed handpiece. The negative control group has less leakage [(1.50 × 10(-6) ± 0.37 × 10(-6)) µl×min(-1)×Pa(-1)] than the groups with coronal preparation (P < 0.05); Group 1 leaked significantly more [(6.02 × 10(-5) ± 1.02 × 10(-5)) µl×min(-1)×Pa(-1)] than group 2 [(1.50 × 10(-5) ± 0.26 × 10(-5)) µl·min(-1)×Pa(-1)] and group 3 [(1.50 × 10(-5) ± 0.39 × 10(-5)) µl×min(-1)×Pa(-1)] did (P < 0.05). Corresponding to microleakage, the micro gaps between the resin cement and dentine in group 1 were wider than those in the other groups. The coronal section was wider than the apical part.

CONCLUSIONSHigh-speed handpiece had negative effects on microleakage of fiber post and core systems. Coronal preparation should be performed 15 min or more after post cementation.

Cementation ; Dental Bonding ; Dental Leakage ; Dentin-Bonding Agents ; Humans ; Microscopy, Electron, Scanning ; Post and Core Technique ; instrumentation ; Resin Cements ; Root Canal Preparation ; Time Factors

OBJECTIVE: To evaluate the effect of computer aided design and computer aided manufacture (CAD/CAM) one-piece zirconia posts and cores for the restoration of defective teeth. METHODS: In the study, 72 defective teeth of 47 patients who had proper root canal therapy were restored with CAD/CAM one-piece zirconia posts and cores. All the ceramic crowns were finally used to restore contour and function of the teeth. The defective teeth were divided into two groups on the basis of the teeth defect degree. Group A: 39 defective teeth presented with three or four coronal residual walls, and group B: 33 defective teeth presented with less than two coronal residual walls. During the clinical observation period, the stability, dislocation of posts and the occurrence of fractures in either teeth or posts and cores were assessed and analyzed with a paired t test(α=0.05). Meanwhile shade matching was conducted between the restored teeth and normal reference teeth, the marginal fitness of the restored teeth were recorded according to the standard of United States Public Health Service (USPHS) and analyzed with descriptive statistics. RESULTS: The average follow up was (65.0±4.8) months. During the observation period, the restorations were examined both clinically and with periapical radiograph. No incidence of teeth fracture or posts and cores complications were observed in both groups, and all CAD/CAM one-piece zirconia posts and cores remained intact with restored teeth. There were no post and core dislodgement or fracture. There was no difference between group A and group B (P>0.05). The restorative effect of CAD/CAM one-piece zirconia posts and cores with all the ceramic crowns were assessed according to the standard of USPHS, and the number of the restored tooth shade matching with level A was 67, and 5 with level B. The rate of shade matching was 93.06%. As the marginal fitness, 64 restored teeth were level A, and 8 with level B. The rate of restorative teeth marginal fitness was 88.89%. CONCLUSION CAD/CAM one-piece zirconia posts and cores were successfully used to restore defective teeth and received excellent clinical effect. So, it can be a good choice for defective teeth which need post-cores and crowns restoration.
Computer-Aided Design ; Dental Prosthesis Design ; Dental Restoration Failure ; Follow-Up Studies ; Humans ; Incisor ; Post and Core Technique/instrumentation* ; Prospective Studies ; Tooth Fractures ; Zirconium

OBJECTIVEIn order to compare the influence of casting and laser welding on magnetic retentive force, the magnetic retentive forces of laser-melted and cast post-keepers of the magnetic attachments were measured in vitro.

METHODS5 cast and 6 laser-melted post-keeper specimens (Magfit MD800) were formed, respectively. Using untreated keeper as control group, the vertical magnetic retentive forces were measured by a universal testing machine.

RESULTSThe average vertical magnetic retentive force of the laser-melted post-keeper group and the cast post-keeper group in vitro were (4.223 +/- 0.217,0)N, (3.792,9 +/- 0.296,4)N, respectively. Compared with the cast post-keeper group, the average vertical magnetic retentive force of the laser-melted post-keeper groups was much higher in vitro (P < 0.05).

CONCLUSIONLaser welding had less influence on the magnetic retentive force of the magnetic attachments than casting.

Dental Alloys ; Dental Casting Investment ; Dental Casting Technique ; Dental Prosthesis Retention ; instrumentation ; Dental Soldering ; methods ; Denture Precision Attachment ; Electromagnetic Fields ; Lasers ; Magnetics ; instrumentation ; Post and Core Technique ; Stainless Steel ; Welding ; methods

OBJECTIVEThis study was to compare the retention of posts fabricated by different methods and cemented with various cements in order to provide a guidance for clinical choice of post fabrication methods and luting cements.

METHODSNinety human maxillary anterior teeth were sectioned by the cementoenamel junction and post-holes were prepared. All roots were embedded in the center of plastic cylinders and paralleled with the cylinder. All samples were divided into 9 groups randomly and equally. Posts fabricated with different methods were then cemented with different luting cements. Each sample was placed into a specialized jig and mounted on a tensile testing machine with crosshead speed of 5 mm/min. Constant tensile force was applied until the post was dislodged, and the tensile force required to dislodge the cemented post was recorded.

RESULTSThe mean retention force of parapost and direct post demonstrated significantly higher than that of indirect post did (P < 0.05), but there was no significant difference between parapost and direct post(P > 0.05). The mean retention of parapost cement demonstrated significantly higher than that of ZPC and HY-Bond cement did (P < 0.05), but there was no significant difference between ZPC and HY-Bond cement (P > 0.05).

CONCLUSIONDifferent fabrication methods and luting cements significantly affect the retention of posts; and there exists an interaction between different fabricating methods and luting cements.

Cementation ; methods ; Dental Bonding ; Dental Cements ; chemistry ; Dental Prosthesis Design ; Dental Prosthesis Retention ; Dental Stress Analysis ; Dentin-Bonding Agents ; chemistry ; Glass Ionomer Cements ; chemistry ; Humans ; Materials Testing ; Post and Core Technique ; instrumentation ; Resin Cements ; chemistry ; Tensile Strength ; Zinc Phosphate Cement ; chemistry

In this study, we evaluate the influence of post surface pre-treatments on the bond strength of four different cements to glass fiber posts. Eighty extracted human maxillary central incisors and canines were endodontically treated and standardized post spaces were prepared. Four post pre-treatments were tested: (i) no pre-treatment (NS, control), (ii) sandblasting (SA), (iii) silanization (SI) and (iv) sandblasting followed by silanization (SS). Per pre-treatment, four dual-cure resin cements were used for luting posts: DMG LUXACORE Smartmix Dual, Multilink Automix, RelyX Unicem and Panavia F2.0. All the specimens were subjected to micro push-out test. Two-way analysis of variance and Tukey post hoc tests were performed (α=0.05) to analyze the data. Bond strength was significantly affected by the type of resin cement, and bond strengths of RelyX Unicem and Panavia F2.0 to the fiber posts were significantly higher than the other cement groups. Sandblasting significantly increased the bond strength of DMG group to the fiber posts.
Aluminum Oxide ; chemistry ; Composite Resins ; chemistry ; Curing Lights, Dental ; classification ; Cuspid ; pathology ; Dental Bonding ; Dental Etching ; methods ; Dental Materials ; chemistry ; Dental Stress Analysis ; instrumentation ; Glass ; chemistry ; Humans ; Incisor ; pathology ; Materials Testing ; Microscopy, Electron, Scanning ; Polymerization ; Post and Core Technique ; instrumentation ; Resin Cements ; chemistry ; Root Canal Preparation ; methods ; Self-Curing of Dental Resins ; methods ; Silanes ; chemistry ; Stress, Mechanical ; Surface Properties ; Tooth, Nonvital ; therapy

To investigate whether masticatory fatigue affects the fracture resistance and pattern of lower premolars restored with quartz-fiber post-core and full crown, 44 single rooted lower premolars recently extracted from orthodontic patients were divided into two groups of 22 each. The crowns of all teeth were removed and endodontically treated and then restored with quartz-fiber post-core and full crown. Twenty-two teeth in one group were selected randomly and circularly loaded at 45° to the long axis of the teeth of 127.4 N at a 6 Hz frequency, and the other group was not delivered to cyclic loading and considered as control. Subsequently, all teeth in two groups were continually loaded to fail at 45° to the long axis of the teeth at a crosshead speed of 1 mm⋅min(-1). The mean destructive force values were (733.88±254.99) and (869.14±280.26) N for the experimental and the control group, respectively, and no statistically significant differences were found between two groups (P>0.05). Bevel fracture and horizontal fracture in the neck of root were the major fracture mode of the specimens. Under the circumstances of this study, it seems that cyclic loading does not affect the fracture strength and pattern of the quartz-fiber post-core-crown complex.
Acid Etching, Dental ; methods ; Adult ; Bicuspid ; Bite Force ; Chromium Alloys ; chemistry ; Crowns ; Dental Prosthesis Design ; Dental Restoration Failure ; Dental Stress Analysis ; instrumentation ; Humans ; Materials Testing ; Methacrylates ; chemistry ; Phosphoric Acids ; chemistry ; Post and Core Technique ; instrumentation ; Quartz ; chemistry ; Resin Cements ; chemistry ; Stress, Mechanical ; Tooth Fractures ; physiopathology ; Tooth Root ; injuries ; Tooth, Nonvital ; rehabilitation