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The Angle Orthodontist 1995The purpose of this study was to examine the esthetic and periodontal differences between two methods of uncovering labially impacted maxillary anterior teeth: the...
The purpose of this study was to examine the esthetic and periodontal differences between two methods of uncovering labially impacted maxillary anterior teeth: the apically positioned flap and closed-eruption techniques. The sample consisted of 30 patients who were recalled a minimum of three months after orthodontic treatment of a unilateral labially impacted maxillary anterior tooth. Eighteen of the patients had undergone an apically positioned flap (APF) procedure, and the remaining twelve had undergone the closed-eruption (CE) technique. In the CE group, clinical examination showed less width of attached gingiva on the distal surface and increased probing bone level on the facial surface of the uncovered teeth relative to their contralateral controls. Uncovered teeth in the APF group showed more apical gingival margins on the mesial and facial surfaces; greater crown length on the midfacial surface; increased probing attachment level on the facial surface; increased width of attached gingiva on the facial surface; increased probing bone level on mesial, facial, and distal surfaces; and gingival scarring. Radiographic examination showed shorter roots on the uncovered teeth in both groups. Photographic examination revealed vertical relapse of the uncovered teeth in the APF group. We conclude that labially impacted maxillary anterior teeth uncovered with an apically positioned flap technique have more unesthetic sequalae than those uncovered with a closed-eruption technique.
Topics: Adolescent; Adult; Alveolar Process; Alveolectomy; Child; Cicatrix; Cuspid; Esthetics, Dental; Gingiva; Gingivoplasty; Humans; Incisor; Orthodontic Appliances; Radiography, Panoramic; Surgical Flaps; Tooth Movement Techniques; Tooth Root; Tooth, Impacted
PubMed: 7726459
DOI: 10.1043/0003-3219(1995)065<0023:ULITAP>2.0.CO;2 -
Journal of Dentistry (Tehran, Iran) May 2015The aim of this study was to determine the cementum thickness in the first molars of patients with localized aggressive periodontitis (LAP) compared to healthy...
OBJECTIVES
The aim of this study was to determine the cementum thickness in the first molars of patients with localized aggressive periodontitis (LAP) compared to healthy individuals.
MATERIALS AND METHODS
This case-control study compared eight first molar teeth affected by LAP with eight third molar teeth of healthy individuals. The teeth were disinfected by immersion in 10% buffered formalin solution for three days and were then sectioned. External mesial root surfaces (middle one-third) were evaluated under a stereomicroscope by a blinded pathologist to determine the mean thickness of cementum. SPSS software (version 16.0) and t-test were used for statistical analysis.
RESULTS
Histological examination revealed a significant difference between the two groups in terms of the amount of cementogenesis (P<0.001) .The thickness of cementum was higher in the control group (105.16±11.5 μm) than in LAP patients (86.44±7.3 μm).
CONCLUSION
This study demonstrated the presence of cementum hypoplasia in mesial root surfaces of first molars affected by LAP.
PubMed: 26877730
DOI: No ID Found -
Caries Research 2020The presence of initial caries accounts for the majority of approximal carious lesions in many countries. The aim of this clustered, split-mouth, randomised, controlled... (Randomized Controlled Trial)
Randomized Controlled Trial
The presence of initial caries accounts for the majority of approximal carious lesions in many countries. The aim of this clustered, split-mouth, randomised, controlled clinical trial was to use a metal separator to widen the approximal space in a one-visit session before sealing and to evaluate patient acceptance, together with the efficacy of the proximal sealing in arresting incipient carious lesions after 2 years. A total of 48 patients with a mean age of 41.9 years were selected. They had at least one pair of proximal initial carious lesions, including the distal surface of the canines to the mesial surface of the third molars (bite-wing score D1-D3). The patient's caries risk at baseline was analyzed using a Cariogram. All surfaces were examined for mutans streptococci (ms) counts. The separator technique made it possible to diagnose whether or not a microcavity was present. After 2 years, 212 surfaces in 45 subjects were examined using the same as baseline standardized digital follow-up radiographs. Two analyses were performed, one sensitive, where a progression or a regression was assessed if one of the examiners made one of those diagnoses, and one conservative, where unchanged. For both analyses, the sealed test surfaces showed a significantly higher regression (67 and 29%) compared to the control group (13 and 2%) p < 0.0001. It did not appear that the baseline variables, such as the caries risk, surface diagnoses, or ms counts, influenced the caries outcome. In the test group, there was no difference in caries progression if there was a microcavity or not. The separation treatment was well accepted by the patients. The method of separation for diagnosis and sealing treatment in a single session appears to be a clinically applicable method for the control of proximal carious lesions.
Topics: Adult; Dental Caries; Humans; Pit and Fissure Sealants
PubMed: 33147593
DOI: 10.1159/000509679 -
Brain : a Journal of Neurology Apr 2004We studied the generator location of premovement subcomponents of movement-related cortical potentials (MRCPs) [Bereitschaftspotential (BP), negative slope (NS') and...
We studied the generator location of premovement subcomponents of movement-related cortical potentials (MRCPs) [Bereitschaftspotential (BP), negative slope (NS') and motor potential (MP)] associated with voluntary, self-paced horizontal saccade in the human frontal lobe. Self-paced horizontal saccade, wrist (or middle finger) extension and foot dorsiflexion were employed in 10 patients (lateral surface of the frontal lobe in seven and mesial in three) as part of the presurgical evaluation, and data of five patients (lateral in four and mesial in three) were used in the final analysis. On the lateral frontal lobe, the maximum BP, NS' or MP with horizontal saccade was seen at or 1-2 cm rostral to the hand, arm or face area of the primary motor cortex (MI) in all four subjects investigated. This area exactly corresponded to the frontal eye field (FEF) identified by electrical stimulation. The amplitude of MRCPs with saccade was smaller than that with hand movements. On the mesial surface, within the supplementary motor area (SMA) proper, BP and/or NS' for horizontal saccade was located 1-2 cm rostral to that for hand and foot movements. BP and/or NS' delineated the supplementary eye field (SEF) at the rostral part of the SMA proper, and SEF partly overlapped with the hand and foot areas of the SMA proper. At the area just rostral to the vertical anterior commissure line and/or the pre-SMA defined by electrical stimulation, BP and/or NS' was seen invariably, regardless of the sites of movements, and in contrast with the SMA proper, there was no somatotopic representation. No clear MPs were elicited by eye movements on the mesial surface. In one of the two subjects whose MRCPs with horizontal saccade were recorded simultaneously from the lateral and mesial surfaces of the frontal lobe, BP from the SEF and pre-SMA preceded that from the FEF. It is concluded that MRCPs with horizontal saccade are useful for defining the FEF, SEF and pre-SMA, and that the SEF and pre-SMA become active in preparation for horizontal saccade earlier than the FEF.
Topics: Adolescent; Adult; Brain Mapping; Contingent Negative Variation; Epilepsies, Partial; Evoked Potentials, Motor; Female; Foot; Frontal Lobe; Hand; Humans; Male; Movement; Saccades; Signal Processing, Computer-Assisted
PubMed: 14960503
DOI: 10.1093/brain/awh110 -
Heliyon Jan 2024Different CAD software programs used for designing crowns show variations in marginal and internal fit. Marginal and internal discrepancies may cause poorly fitting...
STATEMENT OF THE PROBLEM
Different CAD software programs used for designing crowns show variations in marginal and internal fit. Marginal and internal discrepancies may cause poorly fitting crowns.
PURPOSE
The aim of this study was to compare the marginal and internal fit of single crown temporary restorations designed using three different CAD software programs.
MATERIALS AND METHODS
Dentbird, Exocad and Inlab 20 were used to design temporary single crowns using the same cement gap. Three experimental groups (n = 10/group) were formed based on the CAD software used. Geomagic Control X three-dimensional analysis software was used to compare the marginal and internal fit among the groups. Measurements were obtained at nine different thickness points. IBM SPSS Statistics, version 22 was used for all statistical analyses.
RESULTS
Among the CAD software programs tested, Dentbird produced the best internal fit on the buccal surface and the best marginal fit on both buccal and mesial surfaces. Exocad achieved the best values on the distal surface for both internal and marginal fit, while Inlab showed the best values on the mesial surface for internal fit and on the palatal surface for marginal fit.
CONCLUSIONS
The Dentbird CAD software program provided the most accurate fit values that closely matched the design. The marginal and internal fit oftemporary crowns may vary depending on the CAD software used.
PubMed: 38293389
DOI: 10.1016/j.heliyon.2024.e24205 -
Journal of Endodontics Jul 2022This study aimed to investigate whether the direction of force applied to the occlusal surface influenced the pattern of tensile stresses in roots of sound and root...
INTRODUCTION
This study aimed to investigate whether the direction of force applied to the occlusal surface influenced the pattern of tensile stresses in roots of sound and root canal-prepared mandibular molar teeth. The effect of obturation forces on the development of apical stress was also investigated. To this end, models were constructed using micro-computed tomographic imaging and investigated using finite element analysis.
METHODS
Micro-computed tomographic data established boundaries of internal and external model surfaces to allow finite element analysis. Individually segmented components were modeled based on mechanical properties in precedent literature. The following conditions were considered: axial force directed over the mesial marginal ridge, a mesial or a distal tipping force, a combination of both a torquing force and axial loading, and hydrostatic pressure. The maximum principal stresses were determined.
RESULTS
The highest root stress occurred in the cervical third of root surfaces (ie, not apically) under all loading conditions. Importantly, mesial tipping forces resulted in tension on distal roots, whereas distal tipping resulted in tension in the mesial roots. Intracanal pressures produced tensile stress on the internal root canal walls in the cervical third of the root. Stresses were calculated to be less than the fatigue tensile strength of dentin.
CONCLUSIONS
Static loading, under the conditions modeled, does not result in stress concentration at the root apices that would cause root fracture under normal masticatory loads. Stress patterns developing from mesial and distal tipping forces help to explain the appearance of vertical root fractures reported in sound nonrestored molar teeth.
Topics: Dental Stress Analysis; Finite Element Analysis; Molar; Root Canal Preparation; Root Canal Therapy; Stress, Mechanical; Tooth Root
PubMed: 35405160
DOI: 10.1016/j.joen.2022.03.009 -
Journal of Dentistry (Tehran, Iran) 2010Better understanding of the furcation anatomy may serve to decrease the risk of root perforation. The purpose of this study was to measure the thickness of root walls in...
OBJECTIVE
Better understanding of the furcation anatomy may serve to decrease the risk of root perforation. The purpose of this study was to measure the thickness of root walls in the danger zone in mandibular first molars.
MATERIALS AND METHODS
The roots of 53 extracted human mandibular first molars were sectioned in the horizontal plane 4 mm below the orifice of the mesial and distal root canals. For each cut surface buccal, lingual, mesial, and distal thickness of the root wall was measured. Mean values of the thickness at each location were calculated and compared by ANOVA and t-test.
RESULTS
The results showed that the mean thickness in the distal portion of the mesial root was smaller in comparison to all other portions of the roots (P<0.05) and this difference was statistically significant except for the mesial portion of the distal root (P=0.463). The mean thickness of radicular dentin at the distal aspect of mesial roots was 1.2 millimeter.
CONCLUSION
Our study suggests that knowledge of the root dentin thickness in the danger zone is essential for preventing endodontic mishaps leading to failure.
PubMed: 21998796
DOI: No ID Found -
The International Journal of Oral &... 2017To test whether a Maryland bridge-type splint provides adequate stability for a custom root-shaped implant to osseointegrate in a manner substantially equivalent to that...
OBJECTIVE
To test whether a Maryland bridge-type splint provides adequate stability for a custom root-shaped implant to osseointegrate in a manner substantially equivalent to that of a threaded implant.
METHODS
Six beagle dogs were subjected to intraoral impressions and cone beam scans that were used to fabricate custom root-shaped implants (RTIs) and crowns. Premolars in the mandible (P4) and in the maxilla (P3) were extracted, and 24 RTIs were immediately placed in extraction sockets. Splint extensions of the crowns were bonded to mesial and distal teeth. Twelve mandibular molars (M2) were extracted, and threaded implants (DXI), serving as controls, were placed immediately. Animals were placed on a soft diet after surgery. Weekly intraoral photographs and radiographs were taken, and animals were sacrificed at 4 months. Fluorescent labels were injected 35, 21, and 7 days before sacrifice. Clinical implant stability and vertical pullout forces were tested, and loss of vertical bone height was measured on radiographs. Histomorphometric measurements of percent bone-to-implant contact (BIC) and mineral apposition rates were made from undecalcified sections.
RESULTS
Three RTI splints broke or debonded, and the implants were removed. No loss of DXI implants was noted. All remaining implants were clinically stable. Mean pullout forces were 366.7 ± 182.8 N for RTI (no pullout data for the threaded DXI). Mean vertical bone loss was 0.4 ± 0.6 mm mesially and 0.2 ± 0.7 mm distally for RTI and 0.8 ± 1.1 mm mesially and 0.8 ± 1.0 mm distally for DXI, with no significant differences between groups. BIC values were 70.8% ± 12.7% for mandibular RTI, 68.3% ± 11.6% for maxillary RTI, and 78.8% ± 5.5% for DXI. Mineral apposition rates within local osteons were 1.9 ± 0.5 μm for RTI and 1.7 ± 0.3 μm for DXI; at the implant surface, they were 2.5 ± 1.2 μm for RTI and 3.3 ± 1.8 μm for DXI, with no significant differences between groups.
CONCLUSION
All RTIs with intact splints exhibited clinically successful integration, similar to that of control threaded implants. The RTI may be a viable option for single-tooth replacement.
PubMed: 28518183
DOI: 10.11607/jomi.5416 -
BMC Oral Health Apr 2021This study assessed retrospectively the clinical outcomes of single implant-supported crowns and implant-supported fixed dental prostheses (FDPs).
BACKGROUND
This study assessed retrospectively the clinical outcomes of single implant-supported crowns and implant-supported fixed dental prostheses (FDPs).
METHODS
This case series compared biological and technical complications in single implant-supported crowns and implant-supported bridges in a time framed sample of all patients who received dental implants between 2009 and 2016 in Dubai Health Authority. Only 3-unit implant-supported prostheses (FDPs) with one intervening pontic and an implant each end were included for comparison to single crown supported implants. Cantilevered implants, implant-supported dentures and cases involving bone grafts or sinus lifts were excluded. The primary outcome measure was marginal bone loss, measured on digital radiographs taken after prosthesis placement at baseline and one year after implant loading, whilst peri-implantitis and technical complications were secondary outcomes. Mixed regression models adjusted for clustering of implants within patients was used for patient and implant factor associations.
RESULTS
A total of 454 patients (152 males; 302 females) had 1673 implants. The mean age of males (53.7 years, SD 14.6) was significantly greater than females (49.3 years, SD 12.9, p < 0.001). Mean mesial bone loss on the FDPs was significantly greater at 1 year (1.14 mm, SD 0.63) compared with the mesial surface of single implant-supported crowns (0.30 mm, SD 0.43, p < 0.001). Mean distal bone loss was also significantly greater at 1 year on the distal surfaces of implants supporting bridgework (1.29 mm, SD 0.71) compared with distal surfaces on single implant-supported crowns (0.36 mm, SD 0.54, p < 0.001). Mean marginal bone loss mesially and distally around implants placed in the lower anterior sextant was significantly greater compared to all other sites (p < 0.001). Bone loss by gender, patient's age and medical condition was not different between the 2 implant groups. Screw loosening was the main technical complication (11.5%) whilst peri-implantitis occurred rarely (0.5%). The 66 cement retained implants had significantly more complications compared to the 1607 screw retained implants (p < 0.001).
CONCLUSIONS
Mean marginal bone loss around the supporting implants of FDPs (3-unit fixed bridgework) was greater than on single implant-supported crowns at one year after implant loading. Position in the mouth was associated with bone loss. Biological and technical complications occurred rarely.
Topics: Alveolar Bone Loss; Crowns; Dental Implants; Dental Prosthesis Design; Dental Prosthesis, Implant-Supported; Dental Restoration Failure; Denture, Partial, Fixed; Female; Follow-Up Studies; Humans; Male; Middle Aged; Retrospective Studies
PubMed: 33794841
DOI: 10.1186/s12903-021-01530-2 -
American Journal of Orthodontics and... Oct 2022The objective of this study was to evaluate the effects of the torqued cantilever (TC) and conventional tip-back cantilever (CC) made of stainless steel (SS) and...
INTRODUCTION
The objective of this study was to evaluate the effects of the torqued cantilever (TC) and conventional tip-back cantilever (CC) made of stainless steel (SS) and titanium-molybdenum alloy (TMA) on the uprighting of mesially impacted mandibular molars using three-dimensional finite element analysis.
METHODS
The 3-dimensional mandibular model included part of the mandible with mesially tipped and impacted mandibular second molar, periodontal ligament (PDL), molar tube, mini-implant, and cantilevers. Four finite element method models (TC-SS, TC-TMA, CC-SS, and CC-TMA) were created to simulate different skeletally anchored uprighting mechanics. CC mechanics involved a known 0.019 × 0.025-in helical cantilever acting on a buccal molar tube. TC mechanics included a 0.019 × 0.025-in cantilever capable of producing mesial root torque by acting on a tube positioned on the molar disto-occlusal surface with the slot in a buccolingual direction. Three-dimensional molar displacement and stress distribution on the molar PDL were recorded.
RESULTS
The SS cantilever produced almost twice as much molar displacement as the TMA. TC mechanics showed more evident mesial displacement of the molar root apexes. CC mechanics had greater molar rotation. TC uprighting moment produced greater molar mesial extrusion and greater intrusion of the distal root apex. The dual deflection system of the TC mechanics induced the lowest stress on the PDL, regardless of the metallic alloy.
CONCLUSIONS
TC delivered a more efficient uprighting moment to the molar with less unwanted tooth movement and stress on the PDL and a more accessible site for bonding the molar tube.
Topics: Finite Element Analysis; Humans; Mandible; Molar; Molybdenum; Stainless Steel; Titanium; Tooth Movement Techniques; Tooth, Impacted; Torque
PubMed: 35999156
DOI: 10.1016/j.ajodo.2022.07.014