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Hua Xi Kou Qiang Yi Xue Za Zhi = Huaxi... Oct 2019Crown 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... (Review)
Review
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.
Topics: Crown Lengthening; Crowns; Esthetics, Dental; Tooth; Tooth Crown
PubMed: 31721507
DOI: 10.7518/hxkq.2019.05.019 -
The Journal of Clinical Pediatric... May 2022The purpose of this study was to evaluate the effect of different crown materials on the interleukinone beta (IL-1β) content of the gingival crevicular fluid and to...
OBJECTIVE
The purpose of this study was to evaluate the effect of different crown materials on the interleukinone beta (IL-1β) content of the gingival crevicular fluid and to study which crown material causes the highest inflammation on the marginal gingiva on a biochemical basis in pediatric patients.
STUDY DESIGN
Twenty patients in the age group of 4-8 years with endodontically treated primary molars indicated for crown placement were selected for the study which was further divided into 3 groups for sample consideration: group 1-stainless steel crown, group 2-preformed zirconia crown, and group 3- control group (primary second molar). All assay procedures were carried out and the results of the collected samples were calculated using the ELISA-AID TM technique.
RESULTS
On mean comparison among the groups using ANOVA oneway test, P-value turns out to be highly significant, on mean comparison using Tukey's HSD post-hoc test, The p-value was 0.000 ,0.000 ,0.193 on comparing group 1 with group 2, group 1 with group 3, group 2 with group 3 respectively.
CONCLUSION
Preformed zirconia crown can be a relative replacement of SSC in primary molars as it causes comparatively less inflammation and with an advantage of esthetics.
Topics: Child; Child, Preschool; Crowns; Humans; Inflammation; Molar; Stainless Steel; Steel; Tooth, Deciduous; Zirconium
PubMed: 35830632
DOI: 10.17796/1053-4625-46.3.5 -
Clinical Oral Investigations Aug 2023This study aims to investigate the load-to-fracture of procedures changing crown-to-root ratio (R) aimed to restore severely damaged upper central incisors to avoid...
OBJECTIVES
This study aims to investigate the load-to-fracture of procedures changing crown-to-root ratio (R) aimed to restore severely damaged upper central incisors to avoid tooth extraction compared to implant placement. There is no evidence on load capability after apical root resection (AR), orthodontic extrusion (OE), and surgical crown lengthening (SCL) in respect to R, respectively.
MATERIAL AND METHODS
Human maxillary central incisors were endodontically treated, decoronated, and divided into 4 groups (n = 48). The following specimen preparation was performed: (I) adhesive core-and-post build-up (control), (II) as (I) and 2 mm apical root resection (AR), (III) before adhesive core-and-post build-up teeth were shortened 2 mm coronally (OE) (IV) as (I), but specimens were embedded 4 mm instead of 2 mm below the CEJ (SCL), group (V) implant-borne restoration with individual all-ceramic abutments (n = 12; ∅4.1/l = 12 mm) (IBR). All specimens received all-ceramic crowns, thermo-mechanical (TML), and subsequent linear loading (LL) until failure. R were calculated and log-rank, Kruskal-Wallis, Mann-Whitney U, ANOVA, and chi-square tests applied (p = 0.05).
RESULTS
Fracture loads after subsequent LL differed significantly (p = 0.001) between groups, while implants showed the highest values. F median (min/max) were as follows: (I) 252 (204/542), (II) 293 (243/443), (III) 253 (183/371), (IV) 195 (140/274), and (V) 446 (370/539). Pair-wise comparison showed significant differences (p = 0.001) between group I/IV and group V, I, and IV (p = 0.045), II and IV (p = 0.001), and III compared to IV (p = 0.033), respectively. R below 1 significantly increased load capability compared to R = 1.
CONCLUSIONS
OE appears to preferably ensure biomechanical stability of teeth that are endodontically treated and receive core-and-post and crown placement compared to SCL. AR has no adverse biomechanical impact. R < 1 is biomechanically beneficial.
CLINICAL RELEVANCE
For endodontically treated and restored teeth, orthodontic extrusion should be preferred compared to surgical crown lengthening prior single-crown restoration. As orthodontic extrusion, apical root resection has no adverse effect on load capability. Single-crown implant-borne restorations are most load capable.
Topics: Humans; Orthodontic Extrusion; Post and Core Technique; Crown Lengthening; Composite Resins; Tooth, Nonvital; Crowns; Tooth Fractures; Dental Stress Analysis; Dental Restoration Failure
PubMed: 37162571
DOI: 10.1007/s00784-023-05057-4 -
Head & Face Medicine Nov 2022Tooth-colored onlays and partial crowns for posterior teeth have been used increasingly in clinics. However, whether onlays/partial crowns could perform as well as full... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Tooth-colored onlays and partial crowns for posterior teeth have been used increasingly in clinics. However, whether onlays/partial crowns could perform as well as full crowns in the posterior region was still not evaluated thoroughly.
METHODS
A literature search was conducted without language restrictions in Pubmed, Embase, Cochrane Central Register of Controlled Trial and Web of science until September 2021. RCTs, prospective and retrospective observational studies with a mean follow-up of 1 year were selected. Cochrane Collaboration's tool was adopted for quality assessment of the RCT. The quality of observational studies was evaluated following Newcastle-Ottawa scale. The random-effects and fixed-effects model were employed for meta-analysis.
RESULTS
Four thousand two hundred fifty-seven articles were initially searched. Finally, one RCT was identified for quality assessment and five observational studies for qualitative synthesis and meta-analysis. The RCT was of unclear risk of bias while five observational studies were evaluated as low risk. The meta-analysis indicated no statistically significant difference in the survival between onlays/partial crowns and full crowns after 1 year (OR = 0.55, 95% CI: 0.02-18.08; I = 57.0%; P = 0.127) and 3 years (OR = 0.65, 95% CI: 0.20-2.17; I = 0.0%; P = 0.747). For the success, onlays/partial crowns performed as well as crowns (OR = 0.58, 95% CI: 0.20-1.72; I = 0.0%; P = 0.881) at 3 years. No significant difference of crown fracture existed between the two methods (RD = 0.00, 95% CI: - 0.03-0.03; I = 0.0%; P = 0.972).
CONCLUSIONS
Tooth-colored onlays/partial crowns performed as excellently as full crowns in posterior region in a short-term period. The conclusions should be further consolidated by RCTs with long-term follow-up.
Topics: Humans; Retrospective Studies; Prospective Studies; Crowns; Tooth Crown
PubMed: 36411462
DOI: 10.1186/s13005-022-00337-y -
Journal of Dentistry Jun 2022To test the failure load and failure mode of a novel implant-crown interface specifically designed for the fabrication of fully personalized, abutment-free monolithic...
OBJECTIVES
To test the failure load and failure mode of a novel implant-crown interface specifically designed for the fabrication of fully personalized, abutment-free monolithic zirconia CAD-CAM crowns compared to conventional implant-abutment interfaces involving prefabricated or centrally manufactured abutments for zirconia CAD-CAM crowns.
METHODS
Implants (N=48) were divided into groups (n=12) according to different implant-abutment interface designs: (1) internal implant connection with personalized, abutment-free CAD-CAM crowns (Abut-Free-Zr), (2) internal conical connection with customized, centrally manufactured zirconia CAD-CAM abutments (Cen-Abut-Zr), (3) prefabricated titanium base abutments from manufacturer 1 (Ti-Base-1), (4) additional prefabricated titanium base abutments from manufacturer 2 (Ti-Base-2). All specimens were restored with a screw-retained monolithic zirconia CAD-CAM molar crown and subjected to thermomechanical aging (1.200.000 cycles, 49 N, 1.67 Hz, 30° angulation, thermocycling 5-50°C). Static load until failure was applied in a universal testing machine. Failure modes were analyzed descriptively under digital microscope. Mean failure load values were statistically analyzed at a significance level of p<0.05.
RESULTS
All specimens survived thermomechanical aging. The mean failure loads varied between 1332 N (Abut-Free-Zr) and 1601 N (Ti-Base-2), difference being significant between these groups (p<0.05). No differences between the other groups were seen. The predominant failure mode per group was crown fracture above implant connection (Abut-Free-Zr, 75%), abutment fracture below implant neck (Cen-Abut-Zr, 83%), crown fracture leaving an intact abutment (Ti-Base-1/Ti-Base-2 100%).
CONCLUSIONS
Implant-crown interface with fully personalized, abutment-free monolithic CAD-CAM zirconia crowns exhibited similar failure loads as conventional implant-abutment interfaces (except group Ti-Base-2) involving CAD-CAM crowns with prefabricated or centrally manufactured abutment.
CLINICAL SIGNIFICANCE
The new implant connection simplifies the digital workflow for all-ceramic implant reconstructions. The specific design of the implant-crown interface allows the fabrication of fully personalized, abutment-free zirconia implant crowns both in-house and in-laboratory without the need of a prefabricated abutment or central manufacturing.
Topics: Computer-Aided Design; Crowns; Dental Abutments; Dental Implant-Abutment Design; Dental Restoration Failure; Dental Stress Analysis; Materials Testing; Titanium; Zirconium
PubMed: 35395344
DOI: 10.1016/j.jdent.2022.104121 -
BMC Oral Health Jun 2021The anatomical features of the gingiva and the clinical crowns and their interrelation, especially in aesthetically and functionally demanding areas, are important in... (Observational Study)
Observational Study
BACKGROUND
The anatomical features of the gingiva and the clinical crowns and their interrelation, especially in aesthetically and functionally demanding areas, are important in complex dental or implant-retained prosthetic rehabilitations. This observational cross-sectional study was designed to evaluate gender- and age-related differences in the width of attached gingiva (WAG), the clinical crown length (CCL), and their interrelation in the anterior teeth to determine the relationship between the pink and white aesthetics.
METHODS
Eighty (54 females, 26 males) fully dentate Caucasian participants between the ages of 20 and 25 years and 36 probands (23 females, 13 males) between the ages of 45 and 55 years were included in the present study. The CCL of the maxillary and mandibular canines, as well as the central incisors of the maxilla and mandible, were determined with a dental sliding caliper measuring from the middle margin of the gingiva at its deepest point to the incisal edge. The clinical investigation of the WAG was performed by inserting a periodontal probe into the gingival sulcus in the middle of the buccal surface to firstly measure the probing pocket depth. The distance between the gingival margin and mucogingival junction (MGJ) was then measured with a Beerendonk sliding caliper in the middle of the labial curvature, and the clinical WAG was determined by subtraction of the measured probing depth. For the statistical analysis, the Mann-Whitney U test, the Wilcoxon-Test, the Spearman's rank correlation, and a two-factorial non-parametric analysis were used.
RESULTS
There was no correlation between the CCL and the WAG in a healthy periodontium. Gender influenced the CCL, with men having significantly longer teeth than women in both maxilla (P ≤ 0.01) and mandible (P ≤ 0.05). Age did not influence the CCL significantly neither in the upper (P = 0.06) nor in the lower jaw (P = 0.33). Gender did not show to have a significant influence on the WAG of maxilla (P = 0.69) and mandible (P = 0.26). But differences in the WAG between young and old participants were observed in both upper (P ≤ 0.01) and lower jaw (P ≤ 0.05).
CONCLUSION
The present observational study demonstrated that the mean values of cohorts with mixed age groups and genders should not be considered when attempting to determine the ideal relationships between the pink and white aesthetics since the statistical analyses showed significant differences between different age groups and genders.
Topics: Adult; Crowns; Esthetics, Dental; Female; Gingiva; Humans; Incisor; Male; Maxilla; Odontometry; Young Adult
PubMed: 34088298
DOI: 10.1186/s12903-021-01639-4 -
BMC Oral Health Mar 2021The present study aimed to quantitate the wear of the highly transparent Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) ceramic monolithic zirconia crown on...
BACKGROUND
The present study aimed to quantitate the wear of the highly transparent Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) ceramic monolithic zirconia crown on the enamel in vivo and discuss the prone position of the wear and the underlying mechanism.
METHODS
A total of 43 patients with 43 posterior teeth were selected for full zirconia crown restoration and examined immediately, at 6 months, and at 1 year after restoration. During the follow-up visit, the fine impression of the patients' monolithic zirconia crowns, the antagonist teeth, the corresponding contralateral natural teeth, the super plaster cast, and epoxy resin model was ontained. The model of epoxy resin was observed under a stereo microscope, and the microstructure parts were observed under a scanning electron microscope.
RESULTS
After 1 year, the mean depth and volume of wearing of the monolithic zirconia crown were the smallest (all P < 0.01), while those of the antagonist teeth were significantly larger than those of the natural teeth (P < 0.0001), and no significant difference was found among the natural teeth (P = 0.3473, P = 0.6996). The amount of wear after one year was remarkably higher than that at 6 months (P < 0.0001). The microscopic observation revealed the tendency of wearing of the monolithic zirconia crown on the antagonist teeth at the protruding early contact points. Electron micrographs of tooth scars showed that the wearing mechanism of the monolithic zirconia crown on natural teeth was mainly abrasive and fatigue wear.
CONCLUSIONS
Although the self-wearing is insignificant, the monolithic zirconia crown can cause wear of the antagonist teeth via occlusal or early contact significantly; the amount of wearing is higher than that of natural teeth and increases over time. The wearing mechanism is mainly abrasive and fatigue wear.
Topics: Crowns; Dental Restoration Wear; Humans; Materials Testing; Tooth Wear; Zirconium
PubMed: 33663477
DOI: 10.1186/s12903-021-01452-z -
Wiadomosci Lekarskie (Warsaw, Poland :... 2021The aim: The paper was aimed at the study of the processes of mineralization of the enamel of the permanent tooth after its eruption.
OBJECTIVE
The aim: The paper was aimed at the study of the processes of mineralization of the enamel of the permanent tooth after its eruption.
PATIENTS AND METHODS
Materials and methods: To study the structure of the enamel of permanent teeth has been carried out using light and electron microscopy. The study of the process of the development of the primordia of the permanent teeth involved 10 culled puppies of 30-40 days of age. Microscopic, electron microscopic, immunohistochemical methods of research have been used to study the processes of histogenesis.
RESULTS
Results: The studies show that in the postnatal period, the formation of the crown, externally covered with cuticular epithelium, marks the formation of the primordium of the permanent tooth at the follicle stage. After eruption of a tooth, different parts of its crown have three individual structural and functional barriers to enamel biomineralization. The first one is provided by the cuticular epithelium of the pitted areas of the crown, which ensures filtering of the salivary fluid from the protein deposit in the form of a pellicle. The second barrier is defined on the lateral and cuspidate surfaces of the enamel, where the cuticle is erased or poorly expressed. The third structural and functional barrier of enamel biomineralization is located in the cervical portion of teeth of different classes.
CONCLUSION
Conclusions: Different areas of the enamel in the tooth crown have specific filtration barriers, which can be distinguished as follows: pit-and-fissure-and-groove, cuspidateand-approximal, and cervical barriers. The cuticle is poorly expressed or totally absent on the cusps of the tooth crowns in contrast to pitted areas.
Topics: Animals; Crowns; Dental Enamel; Dogs; Microscopy, Electron; Tooth; Tooth Eruption
PubMed: 34159907
DOI: No ID Found -
Journal of Dentistry Oct 2022The aim of this retrieval study was to analyze the fracture features and identify the fracture origin of zirconia-based single crowns that failed during clinical use.
OBJECTIVES
The aim of this retrieval study was to analyze the fracture features and identify the fracture origin of zirconia-based single crowns that failed during clinical use.
METHODS
Thirty-five fractured single crowns were retrieved from dental practices (bi-layered, n = 15; monolithic, n = 20). These were analyzed according to fractographic procedures by optical and scanning electron microscopy to identify fracture patterns and fracture origins. The fracture origins were closely examined. The crown margin thickness and axial wall height were measured.
RESULTS
Three types of failure modes were observed: total fractures, marginal semilunar fractures, and incisal chippings. Most of the crowns (23) had fracture origins at the crown margin and seven of them had defects in the fracture origin area. The exact fracture origin was not possible to identify due to missing parts in four crowns. The crown wall thickness was 20% thinner and wall height 30% shorter in the fracture origin area compared to the opposite side.
CONCLUSIONS
The findings in this study show that fractography can reveal fracture origins and fracture modes of both monolithic and bi-layered dental zirconia. The findings indicate that the crown margin on the shortest axial wall is the most common fracture origin site.
CLINICAL SIGNIFICANCE
Crown design factors such as material thickness at the margin, axial wall height and preparation type affects the risk of fracture. It is important to ensure that the crown margins are even and flawless.
Topics: Ceramics; Crowns; Dental Porcelain; Dental Prosthesis Design; Dental Restoration Failure; Dental Stress Analysis; Materials Testing; Zirconium
PubMed: 36041673
DOI: 10.1016/j.jdent.2022.104271 -
Beijing Da Xue Xue Bao. Yi Xue Ban =... Feb 2012To compare the difference of clinical and technical processes of full-crown restorations by using traditional and Triple-tray impression techniques, consumed materials... (Comparative Study)
Comparative Study
OBJECTIVE
To compare the difference of clinical and technical processes of full-crown restorations by using traditional and Triple-tray impression techniques, consumed materials and time estimated in every procedure of these two methods.
METHODS
Four veteran clinicians were selected to carry out full-crown restorative treatment for 124 patients (130 crowns). From one impression, dentists could make casts of prepared teeth and the opposing dentition and register the interocclusal relationship.After tooth preparation,Impregum Penta polyether impression was fabricated for 76 cases(80 crowns) by Triple-tray method and 48 cases (50 crowns)by conventional method. During the whole processes, the consumption of impression materials and plaster, the time of fitting on the articulator, manufacturing procedure and try-in in clinical practice were recorded. The differences of material and time consumption in every procedure of these two methods were evaluated by Independent-Samples t test.
RESULTS
The consumption of impression materials and plaster of Triple-tray impression technique was significantly less than that of traditional impression technique(P<0.01), and average time in every procedure of Triple-tray impression technique was remarkablely reduced compared with that of the traditional impression technique (P<0.01). Triple-tray impression technique reduces operating costs and the possibility of error.
CONCLUSION
Compared with traditional impression technique, Triple-tray impression technique could reduce the consumption of time and materials in clinical and technical processes.
Topics: Crowns; Dental Impression Materials; Dental Impression Technique; Humans; Models, Dental; Time Factors
PubMed: 22353920
DOI: No ID Found