-
International Journal of Dentistry 2024To determine the minimum dentin thickness in the mesial and distal walls of the mesiobuccal (MB) and mesiolingual (ML) canals of the mandibular first molars using...
AIM
To determine the minimum dentin thickness in the mesial and distal walls of the mesiobuccal (MB) and mesiolingual (ML) canals of the mandibular first molars using cone-beam computed tomography (CBCT).
MATERIALS AND METHODS
CBCT examinations of 624 mandibular first molars from an Indian subpopulation were analyzed. The mesial and distal minimum dentin thickness was evaluated in 1 mm intervals apical to the furcation area. Independent -test was used to analyze the data ( = 0.05). Using Cohen's kappa coefficient, the interexaminer and intraexaminer reliability was evaluated.
RESULTS
The mesial dentin thickness was significantly higher than the distal dentin thickness for MB and ML canals (=0.01). The average dentin thickness in the distal and mesial plane of the MB canal was 1.15 ± 0.15 mm and 1.52 ± 0.19 mm at the 1 mm level and 0.83 ± 0.13 and 1.08 ± 0.18 at the 5 mm level, respectively. For the ML canal, the average dentin thickness in the distal plane and the mesial plane was 1.24 ± 0.18 mm and 1.44 ± 0.21 at the 1 mm level and 0.91 ± 0.16 and 1.01 ± 0.17 at the 5 mm level, respectively. Statistical analysis between the MB and ML canals showed significant differences in the dentin thickness at 4 and 5 mm levels in both the distal and the mesial planes (=0.01). In more than 85% of the cases, the minimum dentin thickness was seen at the 5 mm level in both the distal and mesial planes in MB and ML canals.
CONCLUSION
The distal planes of the mesiolingual and mesiobuccal canals were thinner in most cases, making the distal surface more prone to iatrogenic perforations. Considerably, at 4 and 5 mm from the furcation, the distal wall was significantly thinner than the mesial walls. Understanding the anatomy of the danger zone in the mesial roots of the mandibular first molars may serve to minimize the risk of endodontic mishaps such as strip perforations.
PubMed: 38938693
DOI: 10.1155/2024/8823070 -
Neurocritical Care Jun 2024Depth electroencephalography (dEEG) is a recent invasive monitoring technique used in patients with acute brain injury. This study aimed to describe in detail the...
BACKGROUND
Depth electroencephalography (dEEG) is a recent invasive monitoring technique used in patients with acute brain injury. This study aimed to describe in detail the clinical manifestations of nonconvulsive seizures (NCSzs) with and without a surface EEG correlate, analyze their long-standing effects, and provide data that contribute to understanding the significance of certain scalp EEG patterns observed in critically ill patients.
METHODS
We prospectively enrolled a cohort of 33 adults with severe acute brain injury admitted to the neurological intensive care unit. All of them underwent multimodal invasive monitoring, including dEEG. All patients were scanned on a 3T magnetic resonance imaging scanner at 6 months after hospital discharge, and mesial temporal atrophy (MTA) was calculated using a visual scale.
RESULTS
In 21 (65.6%) of 32 study participants, highly epileptiform intracortical patterns were observed. A total of 11 (34.3%) patients had electrographic or electroclinical seizures in the dEEG, of whom 8 had both spontaneous and stimulus-induced (SI) seizures, and 3 patients had only spontaneous intracortical seizures. An unequivocal ictal scalp correlate was observed in only 3 (27.2%) of the 11 study participants. SI-NCSzs occurred during nursing care, medical procedures, and family visits. Subtle clinical manifestations, such as restlessness, purposeless stereotyped movements of the upper limbs, ventilation disturbances, jerks, head movements, hyperextension posturing, chewing, and oroalimentary automatisms, occurred during intracortical electroclinical seizures. MTA was detected in 18 (81.8%) of the 22 patients. There were no statistically significant differences between patients with MTA with and without seizures or status epilepticus.
CONCLUSIONS
Most NCSzs in critically ill comatose patients remain undetectable on scalp EEG. SI-NCSzs frequently occur during nursing care, medical procedures, and family visits. Semiology of NCSzs included ictal minor signs and subtle symptoms, such as breathing pattern changes manifested as patient-ventilator dyssynchrony.
PubMed: 38918336
DOI: 10.1007/s12028-024-02016-z -
Clinical Oral Investigations Jun 2024We aimed to evaluate changes in the zygomatic pillar during orthodontic treatment involving premolar extraction, analyze the effects of maxillary first molar movement on...
OBJECTIVE
We aimed to evaluate changes in the zygomatic pillar during orthodontic treatment involving premolar extraction, analyze the effects of maxillary first molar movement on zygomatic pillar remodeling, and examine occlusal characteristics and stress distribution after remodeling.
METHODS
Twenty-five patients who underwent premolar extraction were included in the study. The zygomatic pillar measurement range was defined, and cross-sectional areas, surface landmark coordinates, alveolar and cortical bone thicknesses, and density changes were assessed using Mimics software based on the cone-beam computed tomography scans taken before (T0) and after the treatment (T1). Multiple linear regression analysis was performed to determine the correlation between changes in the zygomatic pillar and maxillary first molar three-dimensional (3D) movement and rotation. Additionally, the correlation between pillar remodeling and occlusal characteristics was analyzed by Teetester. Pre- and post-reconstruction 3D finite element models were constructed and loaded with an average occlusal force of two periods.
RESULTS
The morphological and structural remodeling of the zygomatic pillar after orthodontic treatment involving premolar extraction showed a decreased cross-sectional area of the lower segment of the zygomatic pillar. The zygomatic process point moved inward and backward, whereas the zygomatico-maxillary suture point moved backward. The thicknesses of the zygomatic pillar alveolar and cortical bones were thinner, and reduced alveolar bone density was observed. Simultaneously, the movement and angle change of the maxillary first molar could predict zygomatic pillar reconstruction to a certain extent. With decreasing the total occlusal force and the occlusal force of the first molar, occlusal force distribution was more uniform. With zygomatic pillar remodeling, occlusal stress distribution in the zygomatic alveolar ridge decreased, and occlusal stress was concentrated at the junction of the vertical and horizontal parts of the zygomatic bone and the posterior part of the zygomatic arch.
CONCLUSIONS
Orthodontic treatment involving premolar extraction led to zygomatic pillar remodeling, making it more fragile than before and reducing the occlusal force of the maxillary first molar and the entire dentition with stress concentrated in weak areas.
CLINICAL RELEVANCE
No other study has focused on the effects of orthodontics on pillar structures. The present study indicates that the mesial movement of the maxillary first molar weakened the zygomatic pillar and reduced occlusal function, thereby providing insights for inserting anchorage screws and facial esthetics.
Topics: Humans; Zygoma; Cone-Beam Computed Tomography; Tooth Movement Techniques; Female; Male; Molar; Finite Element Analysis; Bicuspid; Maxilla; Tooth Extraction; Imaging, Three-Dimensional; Adolescent; Bone Remodeling; Dental Stress Analysis; Adult; Young Adult
PubMed: 38878070
DOI: 10.1007/s00784-024-05713-3 -
The Journal of Prosthetic Dentistry May 2024Some radiographic film holders produce radiographs with geometric distortion that may interfere with diagnosis. However, whether the distortion can be corrected by...
STATEMENT OF PROBLEM
Some radiographic film holders produce radiographs with geometric distortion that may interfere with diagnosis. However, whether the distortion can be corrected by adjusting the design of the radiographic film holder is unclear.
PURPOSE
The purpose of the study was to develop an adapter for a radiographic film holder model aiming to generate radiographs with greater sharpness and a more accurate geometric representation of dental implants.
MATERIAL AND METHODS
The 2-piece adapter was designed using the SketchUp software program and was 3-dimensionally (3D) printed. Implants with internal conical connections were installed in 19 maxillary prototypes in the central incisor region. Five dentists obtained 285 digital periapical radiographs with 3 different radiographic film holders: standard Cone Indicator, Rinn XCP, and adapted Cone Indicator. They then evaluated the radiographic sharpness of the implants threads and their dimensions using the ImageJ software program. The data were analyzed using the Friedman test with the Durbin-Conover post hoc test and MANOVA with the Tukey post hoc test (α=.05).
RESULTS
On the mesial surface of the implants, the threads were sharper for the adapted than for the standard Cone Indicator radiographic film holder (P<.05). The adapted Cone Indicator showed a smaller difference between the radiographic and actual implant diameters compared with the Rinn XCP and standard Cone Indicator radiographic film holders (P<.05).
CONCLUSIONS
The developed adapter provided radiographs of dental implants with improved sharpness and geometric accuracy.
PubMed: 38824111
DOI: 10.1016/j.prosdent.2024.05.003 -
Microscopy Research and Technique May 2024This study aims to compare the shaping ability of three systems using micro-computed tomography (micro-CT). Moderately-curved mesial canals of 36 mandibular molars were...
This study aims to compare the shaping ability of three systems using micro-computed tomography (micro-CT). Moderately-curved mesial canals of 36 mandibular molars were assigned to three groups (n = 24); Protaper Next (PTN, 0.25, 0.06), WaveOne Gold (WOG, 0.25, 0.07), TruNatomy (TRN, 0.25, 0.04), and instrumentation was performed. Pre- and post-micro-CT scans were obtained. Canal volume and surface, structure model index (SMI), centroid shift, canal transportation, and untouched canal were analyzed. One-way ANOVA and Student's t-test were used for statistics. There was no difference in SMI, centroid shift, and centering ability between the study groups (p > .05). Removed dentin and canal surface changes were lower in TRN, while untouched dentin walls were higher (p < .05). Cross-sections became more rounded (p < .05), but not significant between groups (p > .05). Considering the removed dentin by TRN, it can be used in critical dentin thickness, such as the danger zone (DZ). PTN, WOG, and WOG kept the original canal course similarly. Untouched dentin by TRN (41%) was wider than PTN and WOG, consequently, meticulous irrigation is recommended. TRN, which provides a controlled increase in canal volume, can be used in thin dentin such as the DZ, however, its use should be supported by copious irrigation and brushing considering the rate of untouched dentin walls. RESEARCH HIGHLIGHTS: TRN presented a higher untouched dentin wall compared to PTN and WOG. Canal volume and surface changes were the lowest in the TRN group. The centering abilities were similar in PTN, WOG, and TRN.
PubMed: 38813968
DOI: 10.1002/jemt.24613 -
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 -
European Archives of Paediatric... May 2024To compare the shear bond strength and penetration ability of self-etch sealant with and without enamel deproteinization.
AIM
To compare the shear bond strength and penetration ability of self-etch sealant with and without enamel deproteinization.
MATERIALS AND METHODS
A total of 37 sound extracted teeth were selected and 31 teeth were used for testing shear bond strength of self-etch sealant. For this, crowns portions of selected teeth were cut longitudinally with a diamond disc into a mesial and distal half, thereby yielding 62 samples. They were further divided into two groups; in Group 1, samples were deproteinised with 5.25% sodium hypochlorite and a sealant cylinder was built on the proximal surface. In Group 2, sealant cylinders were built without deproteinising the surface. Shear bond strength was tested using Universal Testing Machine. The remaining six teeth were used for penetration evaluation of self-etch sealant. In Group 1, the occlusal surface was deproteinised with 5.25% sodium hypochlorite and self-etch sealant was directly applied. In Group 2, sealant was applied without deproteinisation. The samples obtained after sectioning were observed under scanning electron microscope for sealant penetration. Mann-Whitney test and Chi-square analysis were utilised for statistical analysis.
RESULTS
The results showed that the shear bond strength of the two groups was statistically not significant (p = 0.23). However, the comparison of % penetration revealed a statistically significant difference between the groups (p = 0.016).
CONCLUSION
Deproteinising the enamel surface prior to application of self-etch sealant enhanced the penetration ability of the sealant but did not show any effect on shear bond strength.
PubMed: 38755490
DOI: 10.1007/s40368-024-00907-5 -
Australian Endodontic Journal : the... May 2024This study assessed canal preparation effects on disinfection and dentin preservation. Thirty mandibular incisors were paired into two experimental groups (n = 10)....
This study assessed canal preparation effects on disinfection and dentin preservation. Thirty mandibular incisors were paired into two experimental groups (n = 10). Following contamination, the initial microbial sample was collected. Instruments 30/0.03 (Group 1) and 30/0.05 (Group 2) were employed and a second sample was obtained. Canals were enlarged using instruments 40/0.03 and 40/0.05, respectively, and a third sample was collected. Final irrigation was performed, and sample S4 obtained. A final scan evaluated volume, surface area, unprepared areas, removed dentin and dentin thickness. Data were analysed using Student t-test, Mann-Whitney, Kruskal-Wallis and Dunn tests. A significant difference was observed between S1 and other time points (p < 0.05). Comparison between groups showed no differences in bacterial loads and in the percentage of microbial reduction (p > 0.05). Group 2 exhibited greater reduction in dentin thickness than group 1 in the mesial aspect of the root (p < 0.05). Instrument 30/0.03 might provide effective disinfection and safety during mandibular incisors canal preparation.
PubMed: 38715465
DOI: 10.1111/aej.12851