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International Endodontic Journal Oct 2023To assess the influence of a flat-side design on the geometry, metallurgy, mechanical performance and shaping ability of a novel nickel-titanium rotary instrument.
AIM
To assess the influence of a flat-side design on the geometry, metallurgy, mechanical performance and shaping ability of a novel nickel-titanium rotary instrument.
METHODOLOGY
Sixty-five new 25-mm flat-side rotary instruments (size 25, taper 0.04) and their nonflat-side prototypes (n = 65) were assessed for major deformations and examined regarding macroscopic and microscopic design, determination of nickel and titanium elements ratio, measurement of phase transformation temperature and evaluation of mechanical performance parameters including time/cycles to fracture, maximum torque, angle of rotation, maximum bending and buckling strengths and cutting ability. Additionally, unprepared canal areas, volume of hard tissue debris and percentage reduction of dentine thickness were calculated for each tested instrument after preparing mesial canals of mandibular molars (n = 12), using micro-CT imaging. Statistical analyses were performed using the U-Mann-Whitney test and independent Student t-test (α = 5%).
RESULTS
The number of spirals (n = 8) and blade direction (clockwise) were similar between both flat and nonflat instruments, whilst the helical angles were equivalent (⁓25°). Flat-instruments showed inconsistencies in the homogeneity of the gold colour on the flat-side surface, blade discontinuity, and incomplete and variable S-shaped cross-sections. The titanium-to-nickel ratios were equivalent, but significant differences in the R-phase finish and austenitic start phase transformation temperatures were observed between the flat and nonflat-side instruments. The flat-side instruments demonstrated superior cutting ability compared to the nonflat instruments, as well as, significantly lower values for time to fracture, rotation to fracture and maximum torque to fracture (p < .001). No statistical difference was observed between tested instruments regarding angle of rotation (p = .437), maximum bending (p = .152) and buckling load (p = .411). Preparation protocols using flat and nonflat instruments did not show any statistically significant differences (p > .05). All flat-side instruments exhibited deformation after shaping procedures.
CONCLUSIONS
The flat-side instrument showcased enhanced cutting ability compared to its nonflat counterpart. However, it exhibited inferior performance in terms of time, rotation and maximum torque to fracture, along with distinct phase transformation temperatures. No differences were observed in the titanium-to-nickel ratios, angle of rotation, maximum bending, buckling load, preparation time, percentage of untouched canal walls, volume of hard tissue debris and percentage reduction of dentine thickness.
Topics: Humans; Nickel; Titanium; Dental Pulp Cavity; Metallurgy; Molar
PubMed: 37594701
DOI: 10.1111/iej.13960 -
Clinical Anatomy (New York, N.Y.) Apr 2024Cervical enamel projections (CEPs) represent a unique developmental and anatomical anomaly wherein the enamel structure extends apically beyond the cemento-enamel... (Review)
Review
Cervical enamel projections (CEPs) represent a unique developmental and anatomical anomaly wherein the enamel structure extends apically beyond the cemento-enamel junction of the tooth. In this scoping review, the existing literature on CEPs was evaluated to delineate their characteristics, prevalence, predilection for specific teeth and surfaces, clinical significance, and management approaches. Searches were conducted on MEDLINE (PubMed), Cochrane Library, and Embase databases using the keywords "enamel projection(s)" or "ectopic enamel." In total, 24 studies meeting inclusion criteria were included in the review. The prevalence of CEPs varied widely (8.3%-85.1%), predominantly manifesting as grade I or grade III. Mandibular first and second molars exhibited a higher incidence of CEPs, with a notable predilection for buccal surfaces. The consensus in most studies was that CEPs are associated with localized periodontal diseases. Recommendations inclined toward the removal of ectopic enamel during periodontal surgery to enhance periodontal attachment formation. However, decision-making should involve careful consideration of the benefits and drawbacks based on individual circumstances.
Topics: Humans; Furcation Defects; Molar; Tooth Cervix; Neck; Dental Enamel
PubMed: 38348736
DOI: 10.1002/ca.24141 -
Acta Odontologica Scandinavica Oct 2023Rapid maxillary expansion (RME) is a routine method for correcting transverse maxillary deficiency. This paper investigated the effect of RME on anchorage alveolar bone... (Meta-Analysis)
Meta-Analysis
PURPOSE
Rapid maxillary expansion (RME) is a routine method for correcting transverse maxillary deficiency. This paper investigated the effect of RME on anchorage alveolar bone and examined the differences between micro-implant-assisted RME and conventional RME.
METHODS
Relevant articles were selected from the PubMed, EMBASE and Cochrane Central Register of Controlled Trials databases. Review Manager software (v.5.3) was used for the pooled analysis and Cochran and statistic tests were used to assess the heterogeneity.
RESULTS
Following conventional RME, the distal buccal alveolar bone thickness and the mesiobuccal alveolar thickness of the maxillary first molars were significantly reduced. Hyrax (standard mean difference [SMD]: -0.93, 95% confidence interval [CI]: -1.20-0.66) and Haas procedures (SMD: -0.88, 95% CI: -1.40-0.36) significantly reduced the buccal vertical alveolar height of the maxillary first molars. Similar results were obtained for the maxillary first premolars following RME. The thickness of the buccal alveolar bone decreased with conventional RME compared to when using the method assisted by micro-implants.
CONCLUSIONS
Conventional RME can reduce the thickness and vertical height of maxillary alveolar bone, and there is less loss of alveolar bone when using micro-implant-assisted RME. Further research is needed to validate the findings.
Topics: Humans; Palatal Expansion Technique; Molar; Bicuspid; Maxilla; Orthodontic Anchorage Procedures
PubMed: 37074788
DOI: 10.1080/00016357.2023.2199862 -
BMC Oral Health Nov 2023This study aimed to assess the correlation between maxillary sinus proximity to root apices of maxillary molars and root resorption during molar distalization using...
BACKGROUND
This study aimed to assess the correlation between maxillary sinus proximity to root apices of maxillary molars and root resorption during molar distalization using clear aligner therapy (CAT).
MATERIALS AND METHODS
Thirty-eight cone beam computed tomography scans (CBCTs) obtained pre- (T0) and post-treatment (T1) from 19 adult patients (36.68 ± 13.50 years), who underwent maxillary molar distalization using Invisalign® aligners (Align Technology, Inc., San José, CA, USA) with a minimum of 2 mm distalization, were evaluated in this study At least 22 h of aligner wear per day was a main inclusion criterion. Sinus proximity and changes in root lengths were measured for 61 molars (183 roots). Spearman coefficient analysis was used for assessing correlation between sinus proximity and root resorption. The level of significance was set at p ≤ 0.05. The reproducibility of measurements was assessed by intraclass correlation coefficient (ICC).
RESULTS
Spearman coefficient revealed no significant correlation between sinus proximity and molar root resorption for mesiobuccal, distobuccal or palatal roots (p = 0.558, p = 0.334, p = 0.931, respectively).
CONCLUSION
There was no correlation between maxillary sinus proximity to root apices of maxillary molars and root resorption.
Topics: Adult; Humans; Root Resorption; Maxillary Sinus; Reproducibility of Results; Spiral Cone-Beam Computed Tomography; Maxilla; Tooth Root; Molar; Cone-Beam Computed Tomography; Orthodontic Appliances, Removable
PubMed: 37990186
DOI: 10.1186/s12903-023-03672-x -
International Orthodontics Sep 2023The alveolar bone loss (ABL) and external apical root resorption (EARR) depict the safety of mesialization of mandibular second molars into the extraction space of...
Alveolar bone loss and root resorption in mesialized second molars in mandibular first molar extraction cases as compared to contralateral non-extraction side in young adults: A retrospective cross-sectional study.
INTRODUCTION
The alveolar bone loss (ABL) and external apical root resorption (EARR) depict the safety of mesialization of mandibular second molars into the extraction space of mandibular first molars. The aim of this study was to evaluate the ABL and EARR after closure of mandibular first molar extraction space by mesialization of second molar on extraction side (ES) as compared to the contralateral non-extraction side (NES).
MATERIAL AND METHODS
A retrospective cross-sectional study was carried out using the pre and posttreatment orthodontic records of young adults with complete set of permanent dentitions treated with extraction of unilateral mandibular first molar and non-extraction treatment on the contralateral side. All patients underwent mini-implant supported mesialization of second molar on ES. The ABL and EARR of second molar on ES and contralateral NES were measured on digital orthopantomograms. The ABL and EARR of second molars on ES and contralateral NES were compared using independent sample t-test.
RESULTS
A total of 36 subjects (14 males and 22 females) were included in the study. The mean treatment duration for molar mesialization was 28.75±8.05months. The mean crown and root movements of mandibular second molar on ES were 10.94±1.25mm and 9.04mm±1.14mm, as compared to 0.91±1.01mm and 0.77±0.83mm on contralateral NES, respectively. The mean ABL and EARR at mandibular second molar were found to be significantly greater on the ES than the contralateral NES (P<0.001 and<0.05, respectively). A total of seven patients (19.4%) experienced ABL≥1mm on ES as compared to none in the contralateral NES. EARR of>2mm of at least one root was found in seven patients (19.4%) in ES as compared to four (11%) in contralateral NES.
CONCLUSION
There was small but statistically significant difference in the ABL and EARR of mesialized mandibular second molar at first molar ES as compared to the contralateral NES. For majority of patients this difference was small but few isolated cases experienced severe ABL and EARR.
Topics: Male; Female; Humans; Young Adult; Root Resorption; Cross-Sectional Studies; Alveolar Bone Loss; Retrospective Studies; Molar
PubMed: 37257394
DOI: 10.1016/j.ortho.2023.100774 -
Archives of Oral Biology Sep 2024This paper investigates whether deciduous upper molars and lower canines have sexual dimorphic features, exploring these teeth' dimensions and the presence of...
OBJECTIVE
This paper investigates whether deciduous upper molars and lower canines have sexual dimorphic features, exploring these teeth' dimensions and the presence of Zuckerkandl's tubercle and Carabelli's cusp on the first and second upper molars.
DESIGN
We analyzed 64 pairs of dental plaster casts from 34 females and 30 males aged between 3 and 12 years. We measured the first and second deciduous upper molars and the lower deciduous canines (maximum mesiodistal and buccolingual length), and we registered the presence of the Zuckerkandl's tubercle and the Carabelli's cusp on the first and second upper molars, respectively.
RESULTS
Regarding the differentiation between sexes using Carabelli's cusp and Zuckerkandl's tubercle, the classification was not independent of Carabelli's cusp presence only for tooth 65 (p = 0.035). In all other teeth, whether for Carabelli's cusp or Zuckerkandl's tubercle, their presence was similar for both sexes. There were statistically significant differences between sexes (p < 0.05) for the buccolingual measurements of both upper second molars, the first right upper molar, and the right canine. The developed model allowed for a 64.1% accuracy in sex estimation.
CONCLUSIONS
The study suggests that while Carabelli's cusp and Zuckerkandl's tubercle in upper deciduous molars don't consistently differ between sexes, tooth size, particularly the buccolingual measurements of certain teeth, including upper deciduous molars and lower canines, may provide a more reliable criterion for sex estimation. The developed model depicted moderate accuracy, underscoring the need for a multifactorial approach when estimating sex from skeletal remains. It suggests that while dental features can contribute to sex estimation, they should be used in conjunction with other skeletal or molecular markers to improve accuracy.
Topics: Humans; Male; Female; Cuspid; Tooth, Deciduous; Molar; Child; Child, Preschool; Models, Dental; Odontometry; Sex Characteristics
PubMed: 38810388
DOI: 10.1016/j.archoralbio.2024.106006 -
Journal of Human Evolution Feb 2024Cercopithecins differ from papionins in lacking a M hypoconulid. Although this loss may be related to dietary differences, the functional and developmental ramifications...
Cercopithecins differ from papionins in lacking a M hypoconulid. Although this loss may be related to dietary differences, the functional and developmental ramifications of hypoconulid loss are currently unclear. The following makes use of dental topographic analysis to quantify shape variation in a sample of cercopithecin Ms, as well as in a sample of Macaca, which has a hypoconulid. To help understand the consequences of hypoconulid loss, Macaca Ms were virtually cropped to remove the hypoconulid and were also subjected to dental topographic analysis. The patterning cascade model and the inhibitory cascade model attempt to explain variation in cusp pattern and molar proportions, respectively. These models have both previously been used to explain patterns of variation in cercopithecines, but have not been examined in the context of hypoconulid loss. For example, previous work suggests that earlier developing cusps impact the development of later developing cusps (i.e., the hypoconulid) and that cercopithecines do not conform to the predictions of the inhibitory cascade model in that the size of the molars is not linear moving distally. Results of the current study suggest that the loss of the hypoconulid is associated with a reduction in dental topography among cercopithecins, which is potentially related to diet, although the connection to diet is not necessarily clear. Results also suggest that the loss of the hypoconulid can be explained by the patterning cascade model, and that hypoconulid loss explains the apparent lack of support for the inhibitory cascade model among cercopithecines. These findings highlight the importance of a holistic approach to studying variation in molar proportions and developmental models.
Topics: Animals; Molar; Diet; Macaca
PubMed: 38181576
DOI: 10.1016/j.jhevol.2023.103479 -
Journal of the Mechanical Behavior of... Apr 2024The existing knowledge is insufficient for comprehending the fatigue survival and fracture resistance of molars that have deep approximal direct and indirect...
STATEMENT OF PROBLEM
The existing knowledge is insufficient for comprehending the fatigue survival and fracture resistance of molars that have deep approximal direct and indirect restorations, whether with or without deep margin elevation (DME).
PURPOSE
The aim of this laboratory and in silico study is to investigate the fatigue survival, fracture strength, failure pattern and tooth deformation of molars restored with DME in combination with a direct or indirect restoration.
MATERIAL AND METHODS
This study utilized 45 extracted sound human molars, divided into three groups (n = 15). Standardized 100% inter-cuspal inlay preparations were performed, extending 2 mm below the CEJ and immediate dentin sealing (IDS) was applied. Group 1 (Co_1) was restored with direct composite; Group 2 (Hyb_2) with a 2 mm DME of direct composite and a glass-ceramic lithium disilicate restoration; Group 3 (Cer_3) a glass-ceramic lithium disilicate restoration. All specimens were exposed to a fatigue process involving thermal-cyclic loading (50N for 1.2 × 10 cycles at 1.7 Hz, between 5 and 55 °C), if teeth survived, they were fractured using a load-to-failure test and failure types were analyzed. Finite element analysis (FEA) was conducted to assess tooth deformation and tensile stress in the restorations. Statistical evaluation of fracture strength was conducted using the Kruskal-Wallis test. Fisher's exact test was utilized to analyze the fracture types and repairability. A statistical significance level of α < 0.05 was set for all analyses.
RESULTS
All specimens successfully withstood the fatigue testing procedure, and no statistically significant differences in fracture strength were observed among the three groups (P > 0.05). The Fisher's exact test indicated a significant association between the restorative material and fracture type (F = 18.315, df = 2, P = 0.004), but also for repairability (F = 13.725, df = 2, P = 0.001). Crown-root fractures were significantly more common in the Cer_3 group compared to the Co_1 group (P = 0.001) and the Co_1 group had significantly more repairable fractures (F = 13.197, df = 2, P = 0.001). FEA revealed comparable outcomes of deformation among models and higher maximum tensile stress on models with higher frequency of catastrophic failures.
CONCLUSIONS
All tested restoration materials exhibited comparable fatigue survival and fracture strength in this laboratory and in silico study. However, it is important to recognize the potential for more severe and irreparable fractures when opting for deeply luted glass-ceramic inlay restorations in clinical practice. In such cases, it would be prudent to consider the alternative option being a direct composite approach, because of its more forgiving fracture types and repairability.
CLINICAL IMPLICATIONS
Molars with deep approximal direct and indirect restorations, whether with or without DME, are comparable in their fatigue survival and fracture resistance to withstand intra-oral forces. Deep direct restorations exhibit more repairable fractures compared to deeply luted glass-ceramics.
Topics: Humans; Molar; Finite Element Analysis; Flexural Strength; Fractures, Bone; Laboratories; Tooth Fractures
PubMed: 38394767
DOI: 10.1016/j.jmbbm.2024.106459 -
Journal of Endodontics Dec 2023This study investigates the feasibility of integrating a piezoelectric device (PIEZO) into a dynamic navigation system (DNS) for bone-window guided surgery. It compares...
INTRODUCTION
This study investigates the feasibility of integrating a piezoelectric device (PIEZO) into a dynamic navigation system (DNS) for bone-window guided surgery. It compares the accuracy and efficiency of PIEZO + DNS to PIEZO + Freehand (FH) procedure for bone-window cutting and root-end resection (RER).
METHODS
Forty-eight mandibular molars of 3D-printed surgical jaw models were divided into two groups: PIEZO + DNS (n = 24) and PIEZO + FH (n = 24). Cone-beam computed tomography scans were taken before and after the procedure. The procedure was virtually planned on X-guide software. The bone-window cutting and RER were conducted with a PIEZO under dynamic navigation in the PIEZO + DNS group and using the dental operating microscope in the PIEZO + FH group. The 2D- and 3D-accuracy deviations and angular deflection were measured for the bone window cut. The root length resected and resection angle were calculated. The bone window cut, RER, total operating time, and number of mishaps were recorded.
RESULTS
PIEZO + DNS was more accurate than PIEZO + FH for bone-window cutting, showing fewer 2D and 3D deviations and less angular deflection (P < .05). The resection angle was lower in the PIEZO + DNS (P < .05). The bone-window cut and total operating time were significantly reduced using a DNS (P < .05). There was no difference in the number of mishaps (P > .05).
CONCLUSIONS
Within the limitations of this in vitro study, the integration of a PIEZO into a DNS is feasible for bone-window guided surgery. The DNS improved the accuracy and efficiency of bone-window cutting.
Topics: Surgery, Computer-Assisted; Tooth; Cone-Beam Computed Tomography; Molar; Apicoectomy
PubMed: 37804944
DOI: 10.1016/j.joen.2023.09.013 -
Lasers in Medical Science Aug 2023This study aimed to evaluate the efficacy of Shock Wave Enhanced Emission Photoacoustic Streaming (SWEEPS) in the removal of remaining pulp tissue from the root canal...
The efficacy of a novel SWEEPS laser-activated irrigation compared to ultrasonic activation in the removal of pulp tissue from an isthmus area in the apical third of the root canal.
This study aimed to evaluate the efficacy of Shock Wave Enhanced Emission Photoacoustic Streaming (SWEEPS) in the removal of remaining pulp tissue from the root canal isthmus area in lower molars and compare it with ultrasonically activated irrigation (UAI) and conventional needle irrigation (NI). Forty-one lower molars with isthmuses between mesial canals were included in the study. The teeth were randomly distributed into experimental groups (n = 12/each) based on the final irrigation protocol (SWEEPS, UAI, or NI) and a control group (C) (n = 5). The traditional access cavity of the mesial part of each tooth was made in all samples. The mesial root canals in the experimental groups were instrumented with a Wave One Gold Primary (25/.07) file using 3% sodium hypochlorite (NaOCl) while the distal canal served as a control for the presence of pulp tissue. No treatment was performed in the C group. Sections from the isthmus region were processed for histopathology to measure the remaining pulp tissue (RPT). The results were analyzed using analysis of variance and the Kruskal-Wallis test (α = 0.05). There were no significant differences in the relative surface area of root canals and isthmus among the groups (p > 0.05). Samples in the SWEEPS group had significantly less RPT than UAI, NI, and C (p = 0.003, 0.014, 0.003, respectively). There were no significant differences between the UAI and NI (p = 0.583). SWEEPS was the most efficient in debridement of the root canal isthmus area. UAI and NI showed similar but lower efficiency.
Topics: Dental Pulp Cavity; Gold; Lasers; Root Canal Therapy; Ultrasonic Waves; Molar; Humans
PubMed: 37599293
DOI: 10.1007/s10103-023-03857-4