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Clinical and Experimental Dental... Dec 2019The aim of this study was to determine the influence of short base lengths and supplemental grooves on surface area and rotational resistance in a simulated-maxillary...
OBJECTIVES
The aim of this study was to determine the influence of short base lengths and supplemental grooves on surface area and rotational resistance in a simulated-maxillary premolar.
MATERIALS AND METHODS
Trigonometric calculations were done to determine the total surface area with and without supplemental grooves. Additional computations were done to determine the maximum wall angle needed to resist rotation displacement in a premolar-sized model. Wall heights of 3.0, 4.0, and 5.0 mm were used in the surface area and rotational axis computations. The rotational axis was located on the lingual restoration margin to produce a buccal-to-lingual rotational displacement.
RESULTS
Total surface area decreased with increasing four-wall taper levels from 2° to 18° and decreasing preparation heights from 5 to 3 mm. Significant surface area improvements were found with the supplemental use of mesial and distal axial grooves compared with the same condition without grooves in all taper levels and preparation height categories. Resistance to rotational displacement was determined to occur at only at very low levels of opposing wall taper angles. The use of supplemental grooves on mesial and distal axial walls significantly improved both total surface area and rotational resistance.
CONCLUSIONS
The vertical wall taper angles, preparation heights, and supplemental grooves play a role in resistance form and restoration stability.
Topics: Bicuspid; Dental Prosthesis Design; Dental Prosthesis Retention; Humans; Maxilla; Models, Theoretical; Rotation; Surface Properties; Tooth Preparation, Prosthodontic
PubMed: 31890300
DOI: 10.1002/cre2.229 -
International Journal of Dentistry 2022The use of technology in bulk-fill composites (BCs) has reduced the stresses caused by polymerization shrinkage, debonding, microleakage, or posttreatment sensitivity in...
INTRODUCTION
The use of technology in bulk-fill composites (BCs) has reduced the stresses caused by polymerization shrinkage, debonding, microleakage, or posttreatment sensitivity in them. This study was conducted to determine whether bleaching affects the microleakage of class II restoration with bulk-fill material.
MATERIALS AND METHODS
This laboratory study was performed on 40 normal human premolars in 4 groups ( = 20). Class II cavities were prepared in mesial and distal surfaces of the teeth with dimensions of 2 × 2 × 4 mm. Then, based on the bleaching process by 20% carbamide peroxide gel and using two types of composites, the restored cavities were randomly divided into 4 groups: (1) CC without bleaching (CC group), (2) BC without bleaching (BC group), (3) CC with bleaching (CCB group), and (4) BC with bleaching (BCB group). Then, the samples were thermocycled for 1000 cycles at a temperature range of 5-55°C, and they were immersed in 0.6% alkaline fuchsine in order to penetrate into the pigment for 24 h. After cutting, the samples were placed under a stereomicroscope (40%) to determine microleakage. The data were analyzed using one-way analysis of variance (ANOVA), and a value <0.05 was considered as statistically significant.
RESULTS
Microleakage was determined in the CC group (0.97 ± 0.42), BC group (1.08 ± 0.54), CCB group (1.19 ± 0.37), and BCB group (0.30 ± 0.47). There were also no significant differences in the mean microleakage between the groups. No cases with zero microleakage (no microleakage) and grade 3 of microleakage (pigment penetration into the axial wall) were observed in the samples. Also, a two-by-two comparison of significant differences between CC and BC groups (=0.89), CC and CCB groups (=0.45), CC and BCB groups (=0.11), BC and CCB groups (=0.87), BC and BCB groups (=0.41), and CCB and BCB groups (=0.86) showed that the difference was not statistically significant.
CONCLUSION
Results showed no difference between microleakage of BC and CC with and without bleaching, and bleaching had the same effect on microleakage of these two types of composites.
PubMed: 35035487
DOI: 10.1155/2022/9924553 -
Journal of Fish Biology Oct 2022Teeth are an integral component of feeding ecology, with a clear link between tooth morphology and diet, as without suitable dentition prey cannot be captured nor broken...
Teeth are an integral component of feeding ecology, with a clear link between tooth morphology and diet, as without suitable dentition prey cannot be captured nor broken down for consumption. Bull sharks, Carcharhinus leucas, undergo an ontogenetic niche shift from freshwater to marine habitats, which raises the question: does tooth morphology change with ontogeny? Tooth shape, surface area and thickness were measured using both morphometrics and elliptic Fourier analysis to determine if morphology varied with position in the jaw and if there was an ontogenetic change concordant with this niche shift. Significant ontogenetic differences in tooth morphology as a function of position in the jaw and shark total length were found, with upper and lower jaws of bull sharks presenting two different tooth morphologies. Tooth shape and thickness fell into two groupings, anterior and posterior, in both the upper and lower jaws. Tooth surface area, however, indicated three groupings, mesial, intermediate and distal, in both the upper and lower jaws. While tooth morphology changed significantly with size, showing an inflection at sharks of 135 cm total length, each morphological aspect retained the same tooth groupings throughout. These ontogenetic differences in tooth morphologies reflect tooth strength, prey handling and heterodonty.
Topics: Animals; Ecosystem; Jaw; Sharks; Tooth; Diet
PubMed: 35848707
DOI: 10.1111/jfb.15170 -
BMC Oral Health May 2022To evaluate the effect of amalgam contamination, different surface treatments, and adhesive protocols on dentin microleakage to bulk-fill composite resin material.
BACKGROUND
To evaluate the effect of amalgam contamination, different surface treatments, and adhesive protocols on dentin microleakage to bulk-fill composite resin material.
METHODS
Forty teeth were fixed in (polyvinyl siloxane) PVS molds, and the Class II cavities were placed on mesial and distal aspects. Thirty teeth were restored by amalgam and thermocycled to 10,000 cycles (5 and 55 °C, 30-s dwell time). The rest were restored with Filtek one Bulk Fill composite without amalgam predecessor. Samples were divided into: G1 (dentin pretreated with 2% chlorhexidine gluconate), G2 (0.5 mm of dentin was removed), G3 (no surface modification), and G4 (control, where composite was bonded to sound dentin without amalgam predecessor.). Single Bond Universal Adhesive system was used to bond the composite material, by using the etch-and-rinse protocol in the mesial cavity preparation and self-etch protocol in the distal. Specimens underwent thermocycling for 5000 cycles, then embedded in silver nitrate and sectioned for stereomicroscope examination. Descriptive statistics, Mann-Whitney U test, and Kruskal-Wallis test were used to analyze the results at p < 0.05.
RESULTS
The highest microleakage score values (4.00) were found in the G2, and G4 in etch-and-rinse protocol. While the lowest scores were found in G2 when using self-etching protocol (1.5). Lower microleakage values were associated with the chlorhexidine treatment group for both adhesive protocols. No significant differences were found between amalgam contaminated and non-contaminated groups.
CONCLUSIONS
Amalgam contamination did not affect microleakage. Self-etching adhesive protocol significantly reduced microleakage for all groups irrespective of the surface treatment. Chlorhexidine pretreatment improved microleakage for both adhesive protocols but had no significant effect.
Topics: Chlorhexidine; Composite Resins; Dental Cavity Preparation; Dental Cements; Dental Leakage; Dental Restoration, Permanent; Dentin; Dentin-Bonding Agents; Humans; Materials Testing; Resin Cements
PubMed: 35585533
DOI: 10.1186/s12903-022-02214-1 -
Frontiers in Veterinary Science 2021Cheek teeth (second through fourth premolars and first through third molars) diastema is a common and painful equine disorder caused by the absence of effective tight...
BACKGROUND
Cheek teeth (second through fourth premolars and first through third molars) diastema is a common and painful equine disorder caused by the absence of effective tight interdental contact between these teeth. Limited objective information is available on the angulation of equine cheek teeth that control dental drift or on mesial or distal equine cheek teeth drift that should normally prevent this disorder.
OBJECTIVES
To measure the angulation of the mesial and distal cheek teeth in horses of different ages, quantify age-related cheek teeth mesial and distal dental drift, and measure the cheek teeth row length in horses of different ages.
STUDY DESIGN
Retrospective review of computed tomographic images of equine heads.
METHODS
Case details and CT images from clinical equine cases that had undergone standing CT head examination were collated.Three sets of measurements were acquired from each head. "Head size" calculated as the distance between the caudal aspect of the orbit and the caudal aspect of the naso-incisive notch was used to standardize measurements in different sized heads. The length of the cheek teeth rows measured from the mesial aspect of the Triadan 06 occlusal surface to the distal aspect of the Triadan 11 occlusal surface. The rostro-caudal (antero-posterior) position and angulation of the mandibular and maxillary Triadan 06 and 11 teeth were measured in relation to reference lines drawn on CT images.
RESULTS
Significant mesial drift occurred in the maxillary and mandibular Triadan 11s. Despite their distal angulation, the upper and lower Triadan 06s also drifted mesially. The mean angulation of Triadan 06 and 11 mandibular teeth (17.8 and 26.2°, respectively) was almost double that of maxillary teeth (9.2 and 13.3°, respectively) with both Triadan 11s having greater angulation than the 06s. Cheek teeth angulation only significantly decreased in the mandibular 06s. Cheek teeth arcade lengths decreased with age, but these decreases were not significant.
MAIN LIMITATIONS
Limitations include the relatively small sample size.
CONCLUSIONS
In the population of horses used for this study, age related mesial drift occurred in both Triadan 06 and 11s, and the angulation of these teeth did not decrease with age in most arcades.
PubMed: 35242831
DOI: 10.3389/fvets.2021.804061 -
Hua Xi Kou Qiang Yi Xue Za Zhi = Huaxi... Jan 2022This study aimed to investigate the quality of single crown digital models, enhance communication between clinicians and technicians, and improve the quality of...
OBJECTIVES
This study aimed to investigate the quality of single crown digital models, enhance communication between clinicians and technicians, and improve the quality of restorations to further reduce remake rate.
METHODS
A total of 1 312 single crown digital models (180 anterior teeth, 294 premolars, and 838 molars) were randomly selected from a large commercial dental factory. The digital models were evaluated by three investigators with the same working experience with the same intraoral scanning system (CEREC). CEREC SW 4.4 was used in capturing the images of single crown preparations, and prepCheck 3.1 was used in evaluating the quality of single crown digital models.
RESULTS
Approximately 6.55%, 0.08%, 81.17%, 19.59%, and 22.48% of 1 312 single crown digital models did not meet the standards of the undercut, surface quality, margin quality, buccal-lingual taper, and mesiodistal taper, respectively. Moreover, 23.25%, 28.51%, 28.43%, and 28.35% of the investigated single crown digital models did not meet the standards of the buccal inclination taper, lingual inclination taper, mesial inclination taper, and distal inclination taper, respectively. The quality of anterior teeth, premolars, molars at the margin quality, buccal-lingual taper, mesiodistal taper, buccal inclination taper, lingual inclination taper, mesial inclination taper, and distal inclination taper significantly varied in the evaluation results (<0.01).
CONCLUSIONS
In addition to the undercut and surface quality met the standard, the overall situation of the quality of the single crown digital preparation model was poor, and the quality of the preparation needs to be improved urgently.
PubMed: 38596993
DOI: 10.7518/hxkq.2022.01.008 -
Neurological Sciences : Official... Nov 2022The anatomy of the cortico-bulbar tract that drives voluntary movements of mimic muscles is well described. Some cases of facial palsy with inverse automatic-voluntary... (Review)
Review
The anatomy of the cortico-bulbar tract that drives voluntary movements of mimic muscles is well described. Some cases of facial palsy with inverse automatic-voluntary dissociation (emotional facial palsy; EFP) are reported in the literature. These cases suggested a completely independent path of the fibers whose lesion results in EFP. We aimed to review the clinical reports of EFP available in the literature to characterize the anatomical aspect of the fibers whose lesion results in the isolated impairment of spontaneous smiling. Cortico-pontine fibers that control spontaneous smiling arise from the medial surface of the prefrontal cortex and descend through the anterior limb of the internal capsule, thalamus, and brain steam, independently from those that control voluntary movement. The mesial temporal lobe, particularly the amygdala, plays a crucial role in the network driving emotionally evoked facial expressions. We would highlight the relevance of an unusual and rarely explored neurological sign that could be added to clinical examination in ruling out focal brain pathology, such as stroke, tumors, or multiple sclerosis.
Topics: Humans; Facial Paralysis; Emotions; Facial Expression; Brain; Stroke
PubMed: 35819562
DOI: 10.1007/s10072-022-06256-9 -
Molecules (Basel, Switzerland) Sep 2021Recently, translucent zirconia has become the most prevalent material used as a restorative material. This study aimed to compare the crown fracture load of the four... (Comparative Study)
Comparative Study
Recently, translucent zirconia has become the most prevalent material used as a restorative material. This study aimed to compare the crown fracture load of the four most common different translucent zirconia brands available in the market at 1.5 mm thickness. Standardized tooth preparations for a full ceramic crown were designed digitally with software (AutoCAD) by placing a 1.0 mm chamfer margin and 1.5 mm occluso-cervical curvature for the crown sample manufacturing. Stylized crowns were chosen to control the thickness of the crown. The axial and occlusal thickness were standardized to 1.5 mm thickness except at the central pit, which was 1.3 mm thick. The STL file for the tooth dies was prepared using software (3Shape TRIOS Patient Monitoring, Copenhagen, Denmark). The tooth dies were printed with a resin material (NextDent Model 2.0, Vertex-Dental B.V., Soesterberg, The Netherlands) using a 3D printing software (3D Sprint Client Version 3.0.0.2494) from a 3D printer (NextDent™ 5100, Vertex-Dental B.V., Soesterberg, The Netherlands). The printing layer thickness was 50 µm. Then, a total of twenty-eight ( = 28) stylized crowns were milled out of AmannGirrbach (Amann Girrbach GmbH, Pforzheim, Germany) ( = 7), Cercon HT (Dentsply Sirona, Bensheim, Germany) ( = 7), Cercon XT (Dentsply Sirona, Bensheim, Germany) ( = 7), and Vita YZ XT (Zahnfabrik, Bäd Sackingen, Germany) ( = 7). Following sintering the crowns, sandblasting was performed and they were bonded to the tooth dies with the resin cement (RelyX U-200, 3M ESPE, Seefeld, Germany) and permitted to self-cure under finger pressure for 6 min. The crowns were loaded on the occlusal surface in a universal testing machine (MTS Centurion) with a stainless-steel ball indenter (7 mm radius) with a loading rate of 1 mm/min to contact the stylized crowns on each of the four cusps until failure. A rubber sheet (1.5 mm thickness) was positioned between the crown and indenter, which helped with the load distribution. Statistical analysis was done using SPSS version 20 (IBM Company, Chicago, USA). The fracture loads were analyzed using Dunnett's T3 test, and the number of cracks was analyzed using the Mann-Whitney U test among the groups. The significant level was set at value = 0.05. The mean fracture loads were 3086.54 ± 441.74 N, 4804.94 ± 70.12 N, 3317.76 ± 199.80 N, and 2921.87 ± 349.67 N for AmannGirrbac, Cercon HT, Cercon XT, and Vita YZ XT, respectively. The mean fracture loads for the surfaces with the greatest number of cracks (excluding the occlusal surfaces) were on the lingual surface for AmannGirrbach and Cercon HT, on the distal and mesial for Cercon XT, and on the buccal for Vita YZ XT. We found that the AmannGirrbach had the most overall cracks. Cercon XT had the greatest number of occlusal cracks and appeared to be the most shattered. Cercon HT had the least number of cracks. In conclusion, Cercon HT presented the best strength properties, the highest fracture load, and no visible cracks. AmannGirrbach presented the lowest strength properties.
Topics: Particle Size; Zirconium
PubMed: 34500741
DOI: 10.3390/molecules26175308 -
Beijing Da Xue Xue Bao. Yi Xue Ban =... Feb 2020To evaluate the short-term outcome of regenerative surgery for peri-implantitis therapy.
OBJECTIVE
To evaluate the short-term outcome of regenerative surgery for peri-implantitis therapy.
METHODS
From March 2018 to January 2019, 9 patients with 10 implants who suffered from peri-implantitis were included in the present research. Vertical bone defect at least 3mm in depth with 2 or more residual bone walls was confirmed around each implant by radiographic examination. Restorations were replaced by healing abutments on 3 implants with the consent of the patients. Guided bone regeneration surgery was performed after a hygienic phase. During surgery, full thickness flaps were elevated on both buccal and lingual aspects. Titanium curette was used for inflammatory granulation tissue removal and implant surface cleaning. The implant surface was decontaminated by chemical rinsing with 3% hydrogen peroxide solution. After being thoroughly rinsed with saline, the bone substitutes were placed in bone defects which were covered by collagen membranes. 6 months after non-submerged healing, the clinical parameters including peri-implant probing depth (PD, distance between pocket bottom and peri-implant soft tissue margin) and radiographic bone level (BL, distance form implant shoulder to the first bone-to-implant contact) were used to evaluate the regenerative outcome. PD was measured at six sites (mesial, middle and distal sites at both buccal and lingual aspects) around each implant, and BL was measured at the mesial and distal surfaces of each implant on a periapical radiograph.
RESULTS
The deepest PD and largest BL of each implant ranged from 6-10 mm and 3.2-8.3 mm respectively. All the implants healed uneventfully after surgery. The mean peri-implant PD at baseline and 6 months after surgery were (6.2±1.4) mm and (3.1±0.6) mm respectively, and a mean (3.0±1.5) mm radiographic bone gain was observed, P<0.01. Treatment success was defined as: no sites with residual PD≥6 mm, no bleeding on probing, and BL elevation of at least 1 mm. Nine implants from 8 patients fulfilled the success criteria. Residual pockets with 6 mm in depth and bleeding on probing could be detected in only one implant.
CONCLUSION
Within the limitation of the present research, guided bone regeneration surgery can be used for the treatment of bone defect that resulted from peri-implantitis. Significant PD reduction and radiographic bone gain can be obtained after 6 months observation.
Topics: Alveolar Bone Loss; Bone Substitutes; Collagen; Dental Implants; Humans; Peri-Implantitis; Surgical Flaps; Treatment Outcome
PubMed: 32071464
DOI: 10.19723/j.issn.1671-167X.2020.01.009 -
Dentistry Journal Apr 2022The purpose of this study was to investigate the volumetric stability around immediate implants, in which a 360-degree socket-shield was retained using the CastleWall...
OBJECTIVE
The purpose of this study was to investigate the volumetric stability around immediate implants, in which a 360-degree socket-shield was retained using the CastleWall Surgical Technique (CWST).
MATERIAL AND METHODS
This retrospective study examined the results of the CWST used for 25 consecutive patients, involving 31 immediate implants. Silicone impressions taken prior to extraction, and at a review appointment were converted to STL files and compared. The median follow-up time was 14.2 ± 5.5 months. Volumetric changes and gingival recession on both buccal and lingual sites were measured. Papillary height changes were also evaluated from available photographs taken before and after treatment. Patients in the study completed a Visual Analogue Scale (VAS) for evaluation of post-operative discomfort and overall satisfaction with this procedure.
RESULTS
All implants integrated successfully without complications. Mean loss of buccal and lingual tissue was 0.30 ± 0.32 mm and 0.17 ± 0.27 mm, respectively. Mean recession at the mid-buccal and mid-lingual gingival margin was 0.66 ± 0.64 mm and 0.87 ± 0.84 mm, respectively. Mean recession of the mesial and distal papilla was 0.26 ± 0.55 mm and 0.29 ± 0.52 mm, respectively. Patients reported 97.74 ± 5.60% satisfaction with this procedure using the Visual Analogue Scale (VAS), with minimal post-operative discomfort.
CONCLUSIONS
The results of this study showed excellent soft tissue stability and aesthetics were achieved using the CWST, with minimal postoperative pain. The other main advantage of retaining a 360-degree socket-shield, is there is more available surface area to lock the implant to the shield to prevent shield migration over time.
PubMed: 35448056
DOI: 10.3390/dj10040062