OBJECTIVES: This study aimed to observe the color rebound and rebound rates of non-pulp discolored teeth within 1 year after routine internal bleaching to guide clinical practice and prompt prognosis. METHODS: In this work, the efficacy of bleaching was observed in 20 patients. The color of discolored teeth was measured by using a computerized colorimeter before bleaching; immediately after bleaching; and at the 1st, 3rd, 6th, 9th, and 12th months after bleaching. The L*, a*, and b* values of the color of cervical, mesial, and incisal parts of the teeth were obtained, and the color change amounts ΔE*, ΔL*, Δa*, and Δb* were calculated. The overall rebound rate (P*) and the color rebound velocity (V*) were also analyzed over time. RESULTS: In 20 patients following treatment, the average ΔE* of tooth color change was 14.99. After bleaching, the neck and middle of the teeth ΔE* and ΔL* decreased in the 1st, 3rd, 6th, 9th, and 12th months, and the differences were statistically significant. Meanwhile, from the 9th month after bleaching, the rebound speed was lower than that in the 1st month, and the difference was statistically significant. The incisal end of the tooth ΔE* and ΔL* decreased in the 6th, 9th, and 12th months after bleaching, and the differences were statistically significant. No significant difference was found in the rebound speed between time points. However, this rate settled after the 9th month, with an average color rebound rate of 30.11% in 20 patients. CONCLUSIONS The results indicated that internal bleaching could cause a noticeable color change on pulpless teeth. The color rebound after bleaching was mainly caused by lightness (L*), which gradually decreased with time, and it was slightly related to a* and b*. The color of the teeth after internal bleaching rebounded to a certain extent with time, but the color rebound speed became stable from the 9th month. Clinically, secondary internal bleaching can be considered at this time according to whether the colors of the affected tooth and the adjacent tooth are coordinated and depending on the patient's needs.
Humans ; Tooth Bleaching/methods* ; Tooth, Nonvital/drug therapy* ; Color ; Tooth Discoloration/drug therapy* ; Tooth ; Hydrogen Peroxide/therapeutic use* ; Tooth Bleaching Agents/therapeutic use*

OBJECTIVES: This study aimed to investigate the common types and directions of root fractures of the maxillary first molar and the influence of root canal treatment on the prevalent sites of root fractures. METHODS: A total of 274 maxillary first molars with root fractures diagnosed via cone beam computed tomography were included. The root fractures of nonendodontically and endodontically treated teeth were identified to be spontaneous and secondary root fractures, respectively. The sites, types, and directions of spontaneous and secondary root fractures were determined. RESULTS: Among the spontaneous root fractures, the proportion of palatal root fractures (56.1%) was higher than those of mesial buccal root fractures (36.1%) and distal buccal root fractures (7.8%). Among the secondary root fractures, the proportion of mesial buccal root fractures (52.7%) was higher than those of palatal root fractures (36.5%) and distal buccal root fractures (10.8%). The distribution of predominant fracture sites was statistically significant ( CONCLUSIONS This study provided an epidemiological basis for the clinical features of root fractures of the maxillary first molar. During the dia-gnosis and treatment of the maxillary first molar, the possibility of palatal root fractures should be considered. The occurrence of mesial buccal root fractures may be related to root canal treatment. Therefore, the risk of mesial buccal root fractures caused by iatrogenic factors should be minimized.
Cone-Beam Computed Tomography ; Humans ; Molar ; Root Canal Therapy ; Tooth Root ; Tooth, Nonvital

PURPOSE: The purpose of present study was to investigate fracture strength and mode of failure of endodontically treated teeth restored with metal cast post-core system, prefabricated fiber post system, and newly introduced polyetherketoneketone (PEKK) post-core system. MATERIALS AND METHODS: A total of 21 mandibular premolar were randomly grouped into 3 groups of 7 each according to the post material. Group A was for metal cast post core; Group B for prefabricated glass fiber post and resin core; and Group C for milled PEKK post cores. All specimens were restored with metal crown. The fracture strength of each specimen was measured by applying a static load of 135-degree to the tooth at 2 mm/min crosshead speed using a universal testing machine. After the fracture strength measurement, the mode of failure was observed. The results were analyzed using Kruscal-Wallis test and post hoc Mann-Whitney U test at confidence interval α = .05. RESULTS: Fracture resistance of PEKK post core was lower than those of cast metal post and fiber reinforced post with composite resin core. In the aspect of fracture mode most of the root fracture occurred in the metal post core, whereas the post detachment occurred mainly in the fiber reinforced post. In the case of PEKK post core, teeth and post were fractured together. CONCLUSION: It is necessary to select appropriate materials of post for extensively damaged teeth restoration and clinical application of the PEKK post seems to require more research on improvement of strength.
Bicuspid ; Crowns ; Glass ; Tooth ; Tooth, Nonvital

PURPOSE: The aim of this study was to define a color space of non-vital teeth and to compare it with the color space of matched vital teeth, recorded in the same patients. MATERIALS AND METHODS: In a group of 218 patients, with the age range from 17 to 70, the middle third of the buccal surface of 359 devitalized teeth was measured using a clinical spectrophotometer (Vita Easyshade Advance). Lightness (L*), chromatic parameters (a*, b*), chroma (C*), hue angle (h) and the closest Vita shade in Classical and 3D Master codifications were recorded. For each patient, the same data were recorded in a vital reference tooth. The measurements were performed by the same operator with the same spectrophotometer, using a standardized protocol for color evaluation. RESULTS: The color coordinates of non-vital teeth varied as follows: lightness L*: 52.83–92.93, C*: 8.23–58.90, h: 51.20–101.53, a*: −2.53–24.80, b*: 8.10–53.43. For the reference vital teeth, the ranges of color parameters were: L*: 60.90–97.16, C*: 8.43–39.23, h: 75.30–101.13, a*: −2.36–9.60, b*: 8.36–39.23. The color differences between vital and non-vital teeth depended on tooth group, but not on patient age. CONCLUSION: Non-vital teeth had a wider color space than vital ones. Non-vital teeth were darker (decreased lightness), more saturated (increased chroma), and with an increased range of the hue interval. An increased tendency towards positive values on the a* and b* axes suggested redder and yellower non-vital teeth compared to vital ones.
Humans ; Tooth ; Tooth, Nonvital

OBJECTIVEThis study aimed to evaluate the success and survival rate of endodontically treated premolars restored by ceramic onlays by comparing restored by quartz fiber posts and metal ceramic crowns.

METHODSNinety-four patients with 126 endodontically treated premolars were enrolled in this study and divided into 4 groups according to the remaining axial walls and restorative methods. The observation time was 36 months. The success and survival rates of the restorations, as well as causes of failures, were analyzed.

RESULTSAt the final follow-up, the success and survival rates of the mild defect endodontically treated premolars were restored by quartz fiber posts and the crowns were at 96.3% and 98.1%; the success and survival rates of the severe defect premolars restored by quartz fiber posts and crowns were at 88.5% and 96.2%. The success and survival rates of the mild defect premolars restored by cast ceramic onlays were both at 96.6%, the success and survival rates of the severe defect premolars restored by cast ceramic onlays were at 94.1% and 100%, respectively. The success and survival rates of the different groups were no significant difference (P>0.05).

CONCLUSIONBased on the results and within the limits of this study, cast ceramic onlays is a very reliable method to restore endodontically treated premolars.

Bicuspid ; Ceramics ; Crowns ; Humans ; Inlays ; Post and Core Technique ; Retrospective Studies ; Tooth, Nonvital

OBJECTIVEThis study aims to compare the fracture resistance of teeth restored with different post and core systems by cyclic loading test and to predict long-term effects.

METHODSA total of 15 recently extracted mandibular premolars without crowns were endodontically treated. The teeth were randomly divided into three groups with five teeth in each group. Group A, teeth restored with cast metal post and core. Group B, teeth with fiber post and resin core. Group C, teeth with resin filling. All of the teeth were restored with full-cast metal crowns. The specimens were exposed to 300,000 cyclic loadings in a cyclic loading machine and 1,000 thermal cycles between 5 and 55 °C. All of the samples were loaded in AG-IS mechanical testing machine with a compressive load until fracture occurred. The fracture load and the fracture mode of each tooth were recorded.

RESULTSThe fracture resistance in group B and C were higher than that of the cast metal post and core restoration (P < 0.05). Repairable fractures were observed in group B and C, whereas unrestorable and catastrophic fractures were found in group A.

CONCLUSIONFiber post and resin filling is a good choice to restore endodontically treated teeth.

Bicuspid ; Dental Stress Analysis ; Humans ; Post and Core Technique ; Tooth Fractures ; Tooth, Nonvital

Coronal restoration of endodontically treated teeth may be viewed as one of the main parameters that influence the outcome of endodontic treatment. The purposes of restoring endodontically-treated teeth include preventing recontamination of the root canal system and periapical area, replacing the compromised dental hard tissue, restoring the coronal morphology and function, providing necessary strength for the restoration/tooth complex for functional stress, and avoiding crown and/or root fracture. This article reviewed recent researches on the restoration of endodontically treated teeth, provided evidence for clinical practice on topics as when to restore them, basic principles to be considered during treatment planning, and specific restoration options for both anterior and posterior teeth under different functional occulsal load conditions. Several issues should be taken into account during the decision making process, such as remaining tooth tissue, functional masticatory forces, comprehensive oral rehabilitation, and esthetic requirements.
Decision Making ; Dental Restoration, Permanent ; Humans ; Root Canal Therapy ; Tooth Crown ; Tooth, Nonvital

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

OBJECTIVETo evaluate the survival rate and complications of endodontically treated residual crowns and roots restored directly or by glass fiber post and core or cast metal post and core.

METHODSIn this study, 96 patients with a total of 142 teeth were selected. All the teeth were undergone root canal therapy. And then, according to different situations, some of them were restored with glass fiber post and core, another with cast metal post and core, the rest were restored directly in the strict controlled indications.

RESULTSThe teeth (135) in 89 patients were divided into three groups. The first group contained 73 (54.1%) teeth restored with glass fiber post and composite resin core. The survival rate reached 97.3% in the average observation period of (5.7 +/- 1.9) years. The second group contained 40 teeth, restored with pure titanium casting post and core. The survival rate reached 87.5% in the average observation period of (6.2 +/- 2.2) years. The last group contained 22 teeth received no treatment. The survival rate reached 90.9% in the average observation period of (5.4 +/- 1.8) years. The success rate had no significant difference among the three groups. The most common complications after restored included root fracture (6.7%), retention loss (2.2%), secondary caries (1.5%) and periapical periodontitis (0.7%).

CONCLUSIONUnder the premise of high quality root canal treatment and standard restoration treatment, the abutment teeth, whether are restored by glass fiber post and core, cast metal post and core or without post, have a higher survival rate over 5 years of observation period and complications especially root fracture still should attract the necessary attention.

Composite Resins ; Crowns ; Dental Abutments ; Dental Stress Analysis ; Glass ; Humans ; Metals ; Post and Core Technique ; Root Canal Therapy ; Tooth Root ; Tooth, Nonvital

This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading. Fifty extracted single-rooted mandibular premolars were randomized into five groups. Each group was prepared according to numbers of residual walls ranged from 0 to 4. Then each group was divided into two subgroups with one restored with quartz fiber posts and the other without posts. In no-post groups, gutta percha point 2 mm below cemento-enamel junction was removed. Composite resin was adapted to the well and used to shape the core directly. Each tooth was restored with a complete metal crown. Dynamic loading was carried out in a masticatory simulator with a nominal load of 50 N at 2 Hz for 300 000 loading cycles. Then a quasi-statically load was applied in a universal testing machine 30° to the long axis with a crosshead speed of 1 mm⋅min(-1) until fracture. Data were analyzed with one-way analysis of variance and pairwise comparison (P<0.05). No specimens failed during dynamic loading. The fracture resistance enhanced with the increase of numbers of coronal walls and the differences were significant (P<0.05). Placement of fiber posts had a significant effect when fewer than two walls remained (P<0.05), but it had no significant influence in groups with two, three or four walls (P>0.05). Fiber post did not change failure mode, and the fracture pattern was mainly favorable. More dentin walls need to be retained in clinic. When no less than two walls remained, a fiber post is not always necessary.
Analysis of Variance ; Bicuspid ; Composite Resins ; Dental Restoration Failure ; Dental Stress Analysis ; Dentin ; physiology ; Humans ; Post and Core Technique ; Quartz ; Tooth Fractures ; prevention & control ; Tooth, Nonvital