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Clinical Oral Investigations May 2024This study aimed to evaluate the effect of restorations made with a glass-hybrid restorative system (GHRS), a high-viscosity glass ionomer restorative material (HVGIC),...
OBJECTIVES
This study aimed to evaluate the effect of restorations made with a glass-hybrid restorative system (GHRS), a high-viscosity glass ionomer restorative material (HVGIC), a high-viscosity bulk-fill composite resin (HVB), a flowable bulk-fill composite resin (FB), and a nanohybrid composite resin (NH), which are commonly preferred in clinical applications on the fracture resistance of teeth in-vitro.
MATERIALS AND METHODS
One hundred intact human premolar teeth were included in the study. The teeth were randomly divided into ten groups (n = 10). No treatment was applied to the teeth in Control group. Class II cavities were prepared on the mesial surfaces of the remaining ninety teeth in other groups. For restoration of the teeth, a GHRS, a HVGIC, a HVB, a FB, and a NH were used. Additionally, in four groups, teeth were restored using NH, GHRS, and HVGIC with open and closed-sandwich techniques. After 24 h, fracture resistance testing was performed. One-way ANOVA and Tukey HDS tests were used for statistical analysis of the data.
RESULTS
The fracture resistance values of Control group were statistically significantly higher than those of GHRS, HVGIC, FB, NH, HVGIC-CS, GHRS-OS, and HVGIC-OS groups(p < 0.05). There was no statistically significant difference observed between the fracture resistance values of Control, HVB, and GHRS-CS groups (p > 0.05).
CONCLUSION
It can be concluded that the use of HVB and the application of GHRS with a closed-sandwich technique may have a positive effect on the fracture resistance of teeth in the restoration of wide Class II cavities.
CLINICAL RELEVANCE
The use of high-viscosity bulk-fill composite resin and the application of glass-hybrid restorative system with the closed-sandwich technique in the restoration of teeth with wide Class II cavities could increase the fracture resistance of the teeth.
Topics: Composite Resins; Humans; In Vitro Techniques; Dental Restoration, Permanent; Glass Ionomer Cements; Materials Testing; Tooth Fractures; Dental Stress Analysis; Viscosity; Bicuspid; Surface Properties; Dental Cavity Preparation; Acrylic Resins
PubMed: 38809289
DOI: 10.1007/s00784-024-05745-9 -
Cureus Apr 2024Esthetic concerns frequently drive individuals to seek dental treatment, leading to a rising demand for minimally invasive and time-efficient procedures. The Minimal...
Esthetic concerns frequently drive individuals to seek dental treatment, leading to a rising demand for minimally invasive and time-efficient procedures. The Minimal Intervention Dentistry (MID) concept, which employs dental adhesive and resin composites, offers an effective approach for enhancing esthetics while preserving natural tooth structure. This case report outlines the esthetic enhancement of a protruding maxillary right central incisor through a direct composite restoration approach, utilizing a composite injection technique with a digital workflow. A 42-year-old male patient presented with a discolored and protruding maxillary right central incisor. After declining orthodontic treatment due to time and cost constraints, the patient opted for an alternative approach. A digital wax-up was 3D printed to create a clear silicone index, enabling precise resin composite injection to achieve the desired esthetic outcome. After internal bleaching and minimal labial surface reduction, a flowable resin composite was applied freehand to the mesial-proximal surface using a curved plastic matrix manufactured universally. The composite injection technique was subsequently employed through the incisal opening of the clear silicone index to shape the labial surface and incisal edge. In order to address insufficient tooth reduction, an additional partial labial resin composite cutback was performed, ensuring minimal reduction while enhancing esthetics. This direct composite veneer restoration, combining conventional proximal surface creation with a composite injection technique utilizing a custom-made clear silicone index prepared via a digital workflow, emerged as a pragmatic solution in a case where orthodontic treatment was not preferred. Moreover, in situations of insufficient dentin preparation, additional cutback preparation and composite placement can enhance color matching with minimal reduction. The direct composite restoration, facilitated by the composite injection technique and digital workflow, effectively rectified the inclination of the protruding maxillary central incisor, highlighting the potential of this approach in addressing esthetic dental concerns. The research and clinical technique presented in this case report hold clinical importance by offering a minimally invasive and practical alternative to orthodontic treatment and conventional restorations for patients with esthetic concerns. The composite injection technique with a digital workflow preserves natural tooth structure, reduces chair time, and enhances esthetic outcomes. This approach is particularly relevant to esthetic dentistry as it addresses anterior dental malalignment and discolored teeth while prioritizing patient satisfaction and individualized care, aligning with the principles of pragmatic esthetics and MID. The potential for long-term durability and patient satisfaction makes it a valuable addition to esthetic dental practice.
PubMed: 38779243
DOI: 10.7759/cureus.58712 -
BMC Oral Health May 2024Periodontal instrument fractures are rare events in dentistry, with limited literature available on their occurrence and management. This case report highlights an...
Periodontal instrument fractures are rare events in dentistry, with limited literature available on their occurrence and management. This case report highlights an incident involving the fracture of a periodontal sickle scaler blade during manual instrumentation for the removal of calculus. The fracture occurred during instrumentation on the mesial surface of the maxillary right second molar, and the separated blade was subsequently pushed into the sulcus. A radiographic assessment was performed to verify the precise location of the fractured segment. Following confirmation, the broken blade was subsequently retrieved using curved artery forceps. The case report highlights factors contributing to instrument fractures, emphasizing the importance of instrument maintenance, sterilization cycles, and operator technique. Ethical considerations regarding patient disclosure, informed consent, and instrument retrieval methods are well discussed. This case underscores the importance of truthful communication, the proper use of instruments, equipment maintenance in dentistry, and the significance of ongoing professional development to enhance treatment safety, proficiency, and ethical standards in dental care.
Topics: Humans; Male; Dental Instruments; Dental Scaling; Equipment Failure; Ethics, Dental; Middle Aged
PubMed: 38773530
DOI: 10.1186/s12903-024-04349-9 -
Cureus Mar 2024Since the beginning of modern endodontics, there have been many concepts, strategies, and techniques for root canal preparation. A mind-boggling variety of files have...
BACKGROUND
Since the beginning of modern endodontics, there have been many concepts, strategies, and techniques for root canal preparation. A mind-boggling variety of files have developed for negotiating and shaping them throughout the years. Today's most secure, most effective, and simplest file system combines the most reliable design elements of the past with the latest technological advances to create the most effective file system. So, the need for the study is to evaluate the fracture strength of tooth roots following canal preparation by three rotary file systems: ProTaper Universal file system (Dentsply, USA), ProTaper Next file system (Dentsply Sirona USA), and Neolix A1 nickel-titanium (NiTi) file system (Orikam Healthcare India Pvt Ltd., New Delhi, India).
METHOD
Ninety human mandibular molars were selected for the study. Inclusion criteria include human mandibular first and second molars and teeth removed for routine clinical reasons, and intact apices were selected, excluding cases with root surface caries, root surface fissures, teeth with immature root apex, mesial canal fusion, extremely short roots, thin roots, or curved roots. All teeth were preserved in a solution of 10% neutral buffered formalin for two weeks and then transferred to distilled water for examination. The teeth were randomly divided into three groups. Access cavities were created, and working lengths were determined. Groups 1, 2, and 3 underwent shaping using ProTaper Universal, ProTaper Next, and Neolix A1 (NiTi) file systems, respectively, following guidelines. Canals were irrigated with sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA) and were obturated up to the mid-root region with AH Plus sealer. To facilitate fracture testing, obturation was performed to distribute the load from the spreader to the canal wall. The EndoSequence and Quick-Fill obturation system were utilized to fill the apical half of the canal with gutta-percha material. After obturation, the distal root of each tooth was cut, while the mesial root was securely positioned in a putty material. A universal testing machine was employed for the fracture tests, operating at a cross-head speed of 1 mm/min. The machine was equipped with a D11 hand spreader tip, which was inserted into the root canal to make contact with the gutta-percha. Gradual force was applied to the root canal until a fracture occurred, at which point the force application was stopped. The amount of force required to cause the fracture was measured in newtons. Data were collected and recorded using IBM SPSS Statistics for Windows, Version 17.0 (Released 2008; IBM Corp., Armonk, New York, United States) and then transferred to Microsoft Excel for analysis. Descriptive statistics, mean, and standard deviation were used for continuous data. The fracture resistance of dental roots treated with three types of files was compared using a one-way ANOVA. Graphs were generated using Excel and Word. A significance level of p<0.01 was chosen.
RESULT
ANOVA indicated significant differences in mean fracture resistance: Neolix A1 (NiTi) (95.3 N) > NEXT (91.0 N) > universal (86.6 N), with a p-value of 0.004 (<0.001), confirming statistical significance.
CONCLUSION
The study concludes that the canal instrumented with Neolix A1 (NiTi) exhibits higher fracture resistance after canal instrumentation compared to ProTaper Next and ProTaper Universal.
PubMed: 38690448
DOI: 10.7759/cureus.57302 -
Cureus Mar 2024Background This study aimed to compare the radicular dentin thickness in single-rooted maxillary and mandibular anterior and premolar teeth by measuring on four...
Background This study aimed to compare the radicular dentin thickness in single-rooted maxillary and mandibular anterior and premolar teeth by measuring on four different surfaces (buccal, lingual, mesial, and distal) at three different levels (apical, middle, and coronal). Methods A total of 150 single-rooted human anterior and premolar teeth were included in the present study. The teeth were sectioned at the cemento-enamel junction (CEJ; coronal), 4 mm away from the apex (apical), and the midpoint between these two distances (middle). First, the teeth were divided buccolingually into two parts, and the dentin thickness in the mesial/distal region was measured. Subsequently, both parts were divided again to measure the dentin thickness in the buccal/lingual region. All measurements were recorded, and statistical analysis was performed. Results Apical radicular dentin thickness was significantly less than CEJ (p < 0.001). The maxillary central incisor, maxillary, and mandibular canine exhibited the maximum radicular dentin thickness, whereas the mandibular premolars showed the minimum. Radicular dentin thicknesses on the lingual and buccal surfaces were significantly higher than those on other surfaces (p < 0.001). Conclusion The lowest radicular dentin thickness values were observed in the premolars, especially on mesial and distal surfaces. Considering these areas as danger zones and paying attention during dental procedures are essential to avoid possible complications.
PubMed: 38665753
DOI: 10.7759/cureus.56974 -
PloS One 2024The impressive †Oncorhynchus rastrosus of the Pacific Northwest's Miocene and Pliocene eras was the largest salmonid ever to live. It sported a hypertrophied...
The impressive †Oncorhynchus rastrosus of the Pacific Northwest's Miocene and Pliocene eras was the largest salmonid ever to live. It sported a hypertrophied premaxilla with a pair of enlarged teeth which the original describers reconstructed as projecting ventrally into the mouth, leading them to assign the species to "Smilodonichthys," a genus now in synonymy. Through CT reconstruction of the holotype and newly collected specimens, we demonstrate that the famed teeth projected laterally like tusks, not ventrally like sabers or fangs. We also expand the original description to characterize sexual dimorphism in mature, breeding individuals. Male and female †Oncorhynchus rastrosus differ in the form of the vomer, rostro-dermethmoid-supraethmoid, and dentary, much as do other extant species of Oncorhynchus. Male specimens possess a more elongate vomer than do females, and female vomers have concave ventral surfaces and prominent median dorsal keels. The dentary of females has no evidence of a kype, though some specimens of †O. rastrosus have a non-uniform density mesial to the tooth bed, which we interpret as a male kype. Unlike extant Oncorhynchus, male and female †O. rastrosus do not differ in premaxilla shape. Because male and females possess hypertrophied premaxillae and lateral premaxillary spikes, the former common name "Sabertoothed Salmon" no longer reflects our understanding of the species' morphology. Accordingly, we redub †O. rastrosus the Spike-Toothed Salmon and postulate that its spikes were multifunctional, serving as defense against predators, in agonism against conspecifics, and as a practical aid to nest construction.
Topics: Animals; Male; Female; Sex Characteristics; Oncorhynchus; Fossils; Tooth; Salmon
PubMed: 38656950
DOI: 10.1371/journal.pone.0300252 -
Journal of Conservative Dentistry and... Mar 2024The purpose of the study was to radiographically evaluate the prevalence of palatogingival groove (PG) in the East Indian population in the maxillary anterior teeth in...
Cone-beam computed tomographic evaluation to estimate the prevalence of palatogingival groove in the maxillary anterior teeth and its radiographic characteristics: An institutional retrospective study.
AIM
The purpose of the study was to radiographically evaluate the prevalence of palatogingival groove (PG) in the East Indian population in the maxillary anterior teeth in different genders, its unilateral/bilateral presentation, classified based on its radiographic characteristics, to determine the prevalence of different types, which could help in future treatment planning.
STUDY DESIGN
The design of the study was a retrospective study.
MATERIALS AND METHODS
Analysis of 429 maxillary anterior teeth (144 central incisors, 145 lateral incisors, and 139 canines) in 72 cone-beam computed tomography scans was done (31 males and 41 females, mean age 27.3 ± 7.63). Demographic details of patients and characteristics of PG, i.e. location, extension, depth, and type, were recorded. The presence of alveolar bone loss and periapical pathology was noted.
RESULTS
An overall prevalence of PG was found to be 2.33% ( = 10), with PG being detected in 2 (1.388%) central incisors, 8 (5.51%) lateral incisors, and 0 (0%) canines. Eight of the patients had a unilateral presence, while one patient reported with bilateral presence, implying a significantly higher predilection of unilateral occurrence ( = 0.02). The prevalence was found to be higher in females ( = 8). The teeth were categorized as either having Type I (6 teeth), Type II (3 teeth), or Type III (1 teeth). Three of the 10 PGs were present in the mesial, six in the mid-palatal, and one in the distal portion of the palatal surface.
CONCLUSIONS
The prevalence of PG in the maxillary incisors in this cohort is 2.33%. The maxillary lateral incisors are the most affected teeth. Unilateral presentation is more common.
PubMed: 38634028
DOI: 10.4103/JCDE.JCDE_347_23 -
PloS One 2024Myelin and iron are major contributors to the cortical MR signal. The aim of this study was to investigate 1. Can MP2RAGE-derived contrasts at 7T in combination with...
BACKGROUND
Myelin and iron are major contributors to the cortical MR signal. The aim of this study was to investigate 1. Can MP2RAGE-derived contrasts at 7T in combination with k-means clustering be used to distinguish between heavily and sparsely myelinated layers in cortical gray matter (GM)? 2. Does this approach provide meaningful biological information?
METHODS
The following contrasts were generated from the 7T MP2RAGE images from 45 healthy controls (age: 19-75, f/m = 23/22) from the ATAG data repository: 1. T1 weighted image (UNI). 2. T1 relaxation image (T1map). 3. INVC/T1map ratio (RATIO). K-means clustering identified 6 clusters/tissue maps (csf, csf/gm-transition, wm, wm/gm transition, heavily myelinated cortical GM (dGM), sparsely myelinated cortical GM (sGM)). These tissue maps were then processed with SPM/DARTEL (volume-based analyses) and Freesurfer (surface-based analyses) and dGM and sGM volume/thickness of young adults (n = 27, 19-27 years) compared to those of older adults (n = 18, 42-75 years) at p<0.001 uncorrected.
RESULTS
The resulting maps showed good agreement with histological maps in the literature. Volume- and surface analyses found age-related dGM loss/thinning in the mid-posterior cingulate and parahippocampal/entorhinal gyrus and age-related sGM losses in lateral, mesial and orbitofrontal frontal, insular cortex and superior temporal gyrus.
CONCLUSION
The MP2RAGE derived UNI, T1map and RATIO contrasts can be used to identify dGM and sGM. Considering the close relationship between cortical myelo- and cytoarchitecture, the findings reported here indicate that this new technique might provide new insights into the nature of cortical GM loss in physiological and pathological conditions.
Topics: Young Adult; Humans; Aged; Adult; Middle Aged; Myelin Sheath; Magnetic Resonance Imaging; Gray Matter; Aging; Gyrus Cinguli; Brain
PubMed: 38626149
DOI: 10.1371/journal.pone.0299670 -
Journal of Dental Sciences Apr 2024Nowadays, zirconia-based framework has been used for longspan or full-arch fixed dental prostheses (FDPs). This study aimed to evaluate the effect of pontic distribution...
BACKGROUND/PURPOSE
Nowadays, zirconia-based framework has been used for longspan or full-arch fixed dental prostheses (FDPs). This study aimed to evaluate the effect of pontic distribution on marginal and internal gaps of five-unit anterior zirconiabased DPs.
MATERIALS AND METHODS
Right maxillary central incisor and second premolar were selected as terminal abutments and three different edentulous conditions with one nonterminal abutment were simulated. Marginal and internal gaps in each zirconia-based samples(n = 10) were examined by computer-aided replica technique. Five regions, including marginal gaps at mesial or distal finishing line, internal gaps at the mesial or distal axial wall, and occlusal surface, were statistically analyzed (α = .05).
RESULTS
Most of marginal gaps and internal gaps at axial wall were clinically acceptable, but larger at occlusal surface. For the three experimental groups, clinically accepted percentage with qualified gaps were less than 30%.There were statistical differences at axial wall over pontic side and marginal gaps over non-pontic side between groups (<0.05). For sum of gaps of all abutments in each group, statistical differences were found at marginal and axial wall ( < 0.05). As for those on terminal and non-terminal abutments, statistical differences were found on second premolar ( < 0.05).
CONCLUSION
Except for occlusal surface, the overall marginal gaps and internal gaps at axial wall of five-unit anterior zirconia-based FDPs with different pontic distribution were clinically acceptable. However, the percentage with qualified gaps were low (<30%). Greater gaps were noted when adjacent pontic existed. Different pontic size and distribution with curvature had an influence on the gaps.
PubMed: 38618091
DOI: 10.1016/j.jds.2023.12.008 -
Dental Materials Journal Jun 2024The aim of this study was to evaluate how preset torque settings influence the torque, vertical force, and root canal-centering ability of ProGlider and ProTaper NEXT...
Effect of preset torque setting on torque/force generation, shaping ability and surface changes of nickel titanium rotary instrument in different root canal curvature locations: An ex vivo study.
The aim of this study was to evaluate how preset torque settings influence the torque, vertical force, and root canal-centering ability of ProGlider and ProTaper NEXT nickel-titanium rotary instruments in canals with different curvature locations. Based on micro-computed tomography, mesial roots of human mandibular molars (25°-40° curvature) were allocated to the apical curvature (apical 1-5 mm) or the middle curvature (apical 5-9 mm) groups, and mandibular incisors (curvature <5°) to the straight canal group. Each group was subjected to automated instrumentation and torque/force measurement with the preset torque of 1, 2.5, or 5 N•cm. Canal-centering ratios were determined with micro-computed tomography. Instrument fracture occurred only in the 2.5 and 5 N•cm groups in curved canals. The preset torque setting and curvature location did not influence canal shaping ability.
Topics: Torque; Humans; Titanium; Nickel; Root Canal Preparation; X-Ray Microtomography; Surface Properties; In Vitro Techniques; Dental Pulp Cavity; Molar; Dental Instruments; Materials Testing; Equipment Design; Dental Alloys; Dental Stress Analysis
PubMed: 38583993
DOI: 10.4012/dmj.2023-244