Post-and-core crown is one of the most common forms of restoration of tooth after root canal therapy (RCT). Infection control is the core objective of RCT, which is usually well realized by endodontists. However, many prosthodontists often neglect the infection control of the tooth and the maintenance of the curative effect of RCT during the process of post-and-core crown, which may lead to the failure of the final restoration. The concept of integrated crown-root treatment advocated recently requires clinicians to consider the RCT and final restoration as a whole, rather than simply divided into two parts-endodontic treatment and restorative treatment. As the core content of integrated crown-root treatment, infection control should be taken seriously by clinicians and implemented throughout the whole treatment process, especially in the restorative treatment that is easily overlooked after RCT. Therefore, this article describes the infection control of post-and-core crown restoration, classifies the tooth requiring post-and-core crown restoration, and puts forward the measures of infection control before and during post-and-core crown restoration, in order to provide reference and guidance for clinical practice.
Humans ; Crowns ; Tooth Crown ; Post and Core Technique ; Root Canal Therapy ; Infection Control ; Tooth Fractures

Objective: To explore and analyze the correlation between labial gingival morphology and alveolar bone morphology of maxillary anterior teeth in patients with posterior dental implant, so as to provide reference basis for restoration design and esthetic reconstruction of anterior teeth. Methods: Sixty-four patients [24 males, 40 females (25.6±3.3) years old] who planned to receive posterior dental implant restoration were recruited randomly with the inclusion and exclusion criteria in Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University from May 2020 to May 2021. According to the visibility of periodontal probe through gingival margin, the subjects were divided into thin and thick gingival biotypes, including 29 cases of thin biotype and 35 cases of thick biotype. The 3Shape software was used to perform oral scanning, and cone beam CT (CBCT) was taken for each patient. Geomagic and Mimics software were used to measure and record the labial crown width and length, gingival papilla height, gingival angle, bone papilla height and bone margin angle of maxillary anterior teeth. Results: The crown width length ratios of maxillary central incisors, lateral incisors and canines were 0.85±0.08, 0.80±0.08 and 0.86±0.09 (F=10.71, P<0.01). The height of gingival papilla between maxillary central incisors, between central incisors and lateral incisors, between lateral incisors and canines were (3.93±0.86), (3.47±0.84) and (3.38±0.91) mm respectively (F=7.44, P<0.01), and the height of corresponding bone papilla were (3.44±0.88), (3.12±0.75) and (2.72±0.63) mm respectively (F=14.26, P<0.01). The gingival margin angles of maxillary central incisors, lateral incisors and canines were 88.3°±7.7°, 84.7°±8.9° and 81.2°±6.6° (F=13.15, P<0.01), and the bone margin angles were 103.2°±13.1°, 99.5°±11.2° and 110.6°±13.0° (F=13.25, P<0.01). The crown width length ratio (0.81±0.08), gingival margin angle (82.2°±7.4°) and bone margin angle (99.4°±12.9°) of thin gingival subjects were significantly lower than those of thick gingival subjects (0.85±0.09, 86.5°±8.6°, 108.5°±11.4°) (t=-2.79, 3.63, 5.20, P<0.01). The height of gingival papilla [(3.93±0.81) mm] and bone papilla [(3.43±0.80) mm] in thin gingival subjects were significantly lower than those in thick gingival subjects [(3.34±0.84) and (2.85±0.71) mm, respectively] (t=-4.89, -5.36, P<0.01). The height of labial gingival papilla of upper anterior teeth was positively correlated with that of bone papilla in all patients (r=0.66, P<0.01); the ratio of crown width to length of upper anterior teeth was positively correlated with the angle of bone margin (r=0.42, P<0.01); the height of anterior gingival papilla was negatively correlated with the angle of bone margin (r=-0.58, P<0.01), and the height of bone papilla was negatively correlated with the angle of bone margin (r=-0.82, P<0.01). Conclusions: The crown shape, gingival shape and alveolar bone shape of maxillary anterior teeth were different in different tooth positions. Patients with different periodontal phenotypes had different crown width length ratio, gingival papilla height, bone papilla height, gingival margin angle, and bone margin angle.
Adult ; Cone-Beam Computed Tomography ; Dental Implants ; Esthetics, Dental ; Female ; Gingiva/anatomy & histology* ; Humans ; Male ; Maxilla/diagnostic imaging* ; Tooth Crown ; Young Adult

OBJECTIVE: To explore the construction process of the digital reference crown models, and to initially establish the digital reference crown models of the primary teeth to lay the foundation for the establishment of the standardized crown models and the future related applications of computer-aided design/computer-aided manufacture (CAD/CAM) technology to pediatric dentistry. METHODS: This study randomly selected children who were caries free, aged from 4 to 5 years in several kindergartens of Haidian District of Beijing.Plaster dental models were made for the children after taking complete impressions.The digital dental models were reconstructed by using the three-dimensional (3D) dental model scanner.And then, Geomagic Studio, a 3D reverse engineering software, was employed to extract the single dental crown data, the mesiodistal and buccolingual diameters and the height of the crowns were measured.The object was reduced or enlarged by a numerical factor, and then the size of each dental crown was standardized.A total of 3-5 points features on the crown were created, and all the objects were aligned through the functions of feature-based alignment.Finally, through average-based object creation and smoothing, the digital models of reference crowns of the primary teeth were established. RESULTS: A total of 40 plaster dental models from 16 boys and 26 girls were selected out for our further study.The digital dental models were reconstructed, and the mesiodistal and buccolingual diameters and the height of the crowns were measured by using reverse engineering technology.Comparing the results of using mesiodistal diameter, buccolingual diameter and height as the standards, we chose the mesiodistal diameters of crowns to do the standardization, and successfully established the digital reference models of 20 primary teeth crowns with detailed surface characteristics. CONCLUSION In this study, the digital reference crown models of the primary teeth were established by reverse engineering technology, providing reference value for the standardized crown models and application for clinical practice, scientific research and teaching.Furthermore, this study also contributes to the extensive application of CAD/CAM technology in pediatric dentistry and the development of CAD/CAM dental systems with independent intellectual property rights.
Child ; Computer-Aided Design ; Crowns ; Dental Prosthesis Design ; Female ; Humans ; Male ; Software ; Tooth Crown ; Tooth, Deciduous

OBJECTIVE: To evaluate the type of wound healing following modified crown lengthening surgery in dog model to provide a biological basis for its clinical application. METHODS: Flap surgery, traditional crown lengthening procedure and modified crown lengthening procedure were performed on the right maxillary central incisor, the left maxillary central incisor and the left maxillary first lateral incisor respectively of five male beagle dogs. The right maxillary first lateral incisors with no surgical intervention were used as controls. Thirty-six weeks after the experimental procedure, tissue blocks were harvested and prepared for histological examination and analysis. RESULTS: Histometric examination of buccolingual sections stained with hematoxylin-eosin demonstrated that the type of wound healing in the flap surgery group was re-attachment, similar to the control group. For the traditional crown lengthening surgery group, all of the five beagle dogs had lamellar cementum defects on root surface, the wound healing of four beagle dogs was new attachment accompanied by new cementum formation at cementum defect areas and the suprac-restal connective tissue was functionally oriented perpendicular to the new cementum. The wound healing of the other beagle dog was long junctional epithelial attachment, in which the junctional epithelium extended to the apical terminus of the cementum defect. In the modified crown lengthening surgery group, four beagle dogs had cementum defects on root surface (two lamellar cementum defects and two shallow platform-like cementum defects), the wound healing of three beagle dogs was new attachment, however, the supracrestal connective tissue was parallel to the root surface. The type of wound healing of another one beagle dog was long junctional epithelial attachment. Wound healing of one beagle dog in this group could not be characterized due to incomplete dissection. CONCLUSION Wound healing in the modified crown lengthening surgery group was similar to the traditional crown lengthening surgery group, and two types of wound healing were observed: new attachment and long junctional epithelium attachment. Neither type of root treatment procedure (root planing or root reshaping) nor root surface defect pattern (the lamellar cementum defect or shallow platform-like cementum defect) influenced the observed type of wound healing.
Animals ; Connective Tissue ; Crown Lengthening ; Dogs ; Eosine Yellowish-(YS) ; Epithelial Attachment/pathology* ; Hematoxylin ; Male ; Tooth Root/surgery* ; Wound Healing

OBJECTIVE: To explore the correlation among gingival thickness (GT), underlying alveolar bone thickness (BT), and other periodontal biotype characteristics in the maxillary anterior. METHODS: A total of 40 young volunteers with healthy periodontal were involved in this research. The periodontal probe was previously used to divide the gingiva from thick to thin. Two records were measured by cone beam CT (CBCT) GT, which was measured at the cement-enamel junction level; and BT, which was measured at 3 locations: 1, 3, 5 mm below the alveolar crest. Oral and gypsum measurements were used to analyze the associations of the crown width/crown length ratio (CW/CL), the keratinized mucosa width (KM), and the free gingival margin curvature. RESULTS: Significant difference in the GT was observed between the thick and thin biotypes, which were divided by periodontal probe (P<0.01). Difference was observed in each periodontal biotype characteristic between the thick (GT≥1 mm) and thin biotypes (GT<1 mm) (P<0.05). BT was positively associated with GT (r=0.293, P=0.001), CW/CL (r=0.273, P=0.003), KM (r=0.291, P=0.001), and free gingival margin curvature (r=0.290, P=0.001). CONCLUSIONS The transparency of the probing in the sulcus could analyze the GT qualitatively. The thick and thin biotypes have different periodontal biotype characteristics. Compared with individuals with thick biotype, those with thin biotype are susceptible to risk dental aesthetic.
Alveolar Process ; Cone-Beam Computed Tomography ; Gingiva ; Humans ; Maxilla ; Tooth Crown

With the evolution of the computer-aided design/computer-aided manufacturing (CAD/CAM) technology, the intraoral scanners are playing an increasingly important role, as they are the first step towards a completely digital workflow. The CAD/CAM double scanning technique has been used to transfer the information from provisional restorations to definitive restorations. In this case, a 67-year-old male with esthetically compromised anterior teeth, generalized severe attrition of teeth, and reduced vertical dimension was treated with full mouth rehabilitation including a re-establishment of the lost vertical dimension of occlusion assisted by the crown lengthening procedure. The provisional restorations were fabricated using an intraoral scanner and the CAD/CAM double scanning technique. After the period of adaption, the definitive monolithic zirconia restorations were delivered. The CAD/CAM double scanning technique successfully transferred the occlusal and morphological characteristics, obtained from the provisional restorations, to the definitive restorations.
Aged ; Crown Lengthening ; Dentition ; Humans ; Male ; Mouth Rehabilitation ; Mouth ; Tooth ; Tooth Wear ; Vertical Dimension

OBJECTIVE: To analyze the esthetic proportions of maxillary anterior teeth in term of the apparent widths proportion of the adjacent teeth and width/height ratio of the clinical crown in 120 Chinese adults. METHODS: Maxillary gypsum casts were obtained from the dental laboratories of stomatological hospitals in North China, Southeast China, and Southwest China, according to the inclusion criteria and exclusion criteria. Standardized digital photographs of each cast were recorded. The apparent widths and actual widths and heights of the central incisors, lateral incisors and canines were determined by ImageJ software for the calculation of apparent widths proportion of the adjacent teeth and width/height ratio of the clinical crown. The ideal apparent widths proportion (Golden proportion and Preston proportion) and width/height ratio (0.80) were tested. The gender, arch side, and regional differences were investigated. RESULTS: The apparent widths proportion of the lateral/central incisor was 0.724±0.047, of the canine/lateral incisor was 0.814±0.092. The width/height ratio of the central incisor was 0.848±0.072, of the lateral incisor was 0.834±0.094, of the canine was 0.883±0.098. The esthetic proportions were different from the predicted ideal ratio (P < 0.001). The apparent widths proportion of lateral/central incisor was significantly larger in the right side than that in the left side (0.730± 0.044 vs. 0.718±0.050), and was significantly smaller in North China than that in Southwest China (0.711±0.051 vs. 0.731±0.044). The width/height ratio of the central incisor was significantly larger in the female than that in the male (0.855±0.074 vs. 0.835±0.068), and in the right side than that in the left side (0.855±0.073 vs. 0.842±0.072). The width/height ratio of the lateral incisor was significantly larger in the female than that in the male (0.843±0.097 vs. 0.817±0.084). CONCLUSION The apparent widths proportion of adjacent teeth and the width/height ratio of the clinical crown in Chinese adults are different from the foreigner's. The esthetic proportion parameters have significant population specificity, and the measurements cannot be generalized as well as it should be applied with caution.
Adult ; Asians ; China ; Cuspid ; Esthetics ; Esthetics, Dental ; Female ; Humans ; Male ; Maxilla/anatomy & histology* ; Odontometry ; Tooth Crown/anatomy & histology*

OBJECTIVES: The objective of this study was to assess coronal discoloration induced by the following intracanal medicaments: calcium hydroxide (CH), a mixture of CH paste and chlorhexidine gel (CH/CHX), and triple antibiotic paste (3Mix). MATERIALS AND METHODS: Seventy extracted single-canal teeth were selected. Access cavities were prepared and each canal was instrumented with a rotary ProTaper system. The specimens were randomly assigned to CH, CH/CHX, and 3Mix paste experimental groups (n = 20 each) or a control group (n = 10). Each experimental group was randomly divided into 2 subgroups (A and B). In subgroup A, medicaments were only applied to the root canals, while in subgroup B, the root canals were completely filled with medicaments and a cotton pellet dipped in medicament was also placed in the pulp chamber. Spectrophotometric readings were obtained from the mid-buccal surface of the tooth crowns immediately after placing the medicaments (T1) and at 1 week (T2), 1 month (T3), and 3 months (T4) after filling. The ∆E was then calculated. Data were analyzed using 2-way analysis of variance (ANOVA), 3-way ANOVA, and the Scheffé post hoc test. RESULTS: The greatest color change (ΔE) was observed at 3 months (p < 0.0001) and in 3Mix subgroup B (p = 0.0057). No significant color change occurred in the CH (p = 0.7865) or CH/CHX (p = 0.1367) groups over time, but the 3Mix group showed a significant ΔE (p = 0.0164). CONCLUSION: Intracanal medicaments may induce tooth discoloration. Use of 3Mix must be short and it must be carefully applied only to the root canals; the access cavity should be thoroughly cleaned afterwards.
Calcium Hydroxide ; Chlorhexidine ; Dental Pulp Cavity ; Reading ; Tooth Crown ; Tooth Discoloration ; Tooth

OBJECTIVE: This study evaluates the effects of different endodontic access methods and full-ceramic crown on the stress distribution in the maxillary central incisor by using three-dimensional finite element analysis. METHODS: Computed tomography scans of the maxillary central incisor were used to construct a three-dimensional finite element model of the maxillary central incisor. According to the different methods of endodontic and the prosthetic treatments, four models were established, namely, group A (traditional access cavity preparation with resin filling), group B (traditional access cavity preparation restored full-ceramic crown), group C (minimally invasive endodontics with resin filling) and group D (minimally invasive endodontics restored full-ceramic crown). A static force of 100 N and a direction of 45° was applied to the long axis of the tooth at the junction of the incisal section one-third and middle section one-third. The maximum principal stress, the von Mises stress and the modified von Mises stress of the tooth tissue were analyzed using the finite-element analysis software. RESULTS: 1) Stress peaks: the stress peaks of the maximum principal stress, the von Mises stress and the modified von Mises in group A were the largest, except that the stress peak of von Mises stress in group D was slightly lower than that in group C. The stress peaks of the maximum principal stress and the modified von Mises in group C were the lowest. The stress peaks of the maximum principal stress and the modi-fied von Mises stress in group D were lower than those in groups A and B. 2) Stress distribution: compared with group A, the stress distribution of cervical dentin and the area of stress concentration in group C was lower and smaller. In the root dentin, the stress distribution in group C was more uniform than that in group A, and the stress was dispersed to several areas of the root apex. After crown restoration, no significant difference was observed in stress distribution between groups B and D in the root region. The stress distribution state of group B was not significantly different from that of group A. No significant difference was observed in the stress distribution state between groups D and C. CONCLUSIONS 1) From the perspective of biomechanics, the minimally invasive access was adopted for the maxillary central incisor. 2) Full crown restoration is recommended after traditional access cavity preparation. No obvious advantage is observed in stress analysis for minimally invasive endodontics-restored full-ceramic crown.
Crowns ; Dental Stress Analysis ; Dentin ; Finite Element Analysis ; Incisor ; Post and Core Technique ; Stress, Mechanical ; Tooth Crown

Crown lengthening is one of the most common surgeries in clinical practice. Under the premise of ensuring the biologic width, the adequate crown is exposed by resecting the periodontal soft tissue and (or) hard tissue to meet the prosthodontic and (or) aesthetic requirements. Considering the various advantages of oral laser, such as safe, precise, minimally invasive and comfort, laser has become a promising technology which can be used to improve the traditional crown lengthening. In this review, the principles and characteristics of laser application in crown lengthening, especially in the minimally invasive or flapless crown lengthening will be reviewed. Its pros and cons will also be discussed.
Crown Lengthening ; Crowns ; Esthetics, Dental ; Tooth ; Tooth Crown