Abutment margin levels and residual cement occurrence in cement-retained implant restorations: An observational study.

OBJECTIVES: To evaluate the association between different vertical levels of the abutment margin and residual cement prevalence in cement-retained implant restorations with customized abutments. METHODS: One hundred and nine single-unit cement-retained implant restorations with a screw-access channel were included. The crowns were intraorally cemented on the abutments, and excess cement was removed. The abutment-crown complex was unscrewed, and the abutment-crown complex and peri-implant tissue were photographed. Residual cement presence was recorded by dividing the abutment-crown complex and peri-implant tissue into four quadrants: mesial, distal, buccal, and lingual. The prevalence of residual cement was compared according to the height of the custom abutment margin of the corresponding quadrant. A multilevel model was used for statistical analysis (α = .05). RESULTS: Cement remnants were discovered on 72.48% of the dental implants. When the restoration quadrants were compared, cement remnants were present on 51.38%, 39.45%, 20.18%, and 17.43% of the mesial, distal, buccal, and lingual surfaces, respectively (p < .01). Regarding the abutment margin level, cement residues were found in 60.22% and 61.4% of the 0.5 mm subgingival and ≥1 mm subgingival margin groups, respectively, which were significantly more than those in the supragingival (23.65%) and equigingival (26.59%) margin groups (p < .01). After adjustment for confounding factors, the adjusted odds ratio (with 95% confidence interval) for residual cement in the subgingival margin groups was 3.664 (1.71, 7.852) when compared to the supragingival and equigingival margin groups. CONCLUSIONS: The risk of residual cement occurrence was 3.66-fold higher with a subgingival abutment margin than with supragingival and equigingival abutment margins.

Improving wear resistance of acrylic resin denture teeth by using zirconia complete crowns fabricated with a CAD-CAM double-scanning method: A clinical report.

Acrylic resin denture teeth can wear and chip when opposed by zirconia prostheses. This clinical report describes the use of zirconia complete crowns to prevent these problems. The predictability of treatment was improved by using the computer-aided design and computer-aided manufacturing (CAD-CAM) double-scanning method.

Antimicrobial efficacy of self-locomotive manganese oxide nanozyme-doped diatom microbubbler on orthodontic brackets in vitro.

BACKGROUND: Orthodontic brackets provide a favorable environment for Streptococcus mutans biofilm formation, increasing the risk of white spots and dental caries. Manganese oxide (MnO2) nanozyme-doped diatom microbubbler (DM) is a recently developed material for biofilm removal. DM can generate oxygen by catalase-mimicking activity in Hydrogen peroxide (H2O2) solution and move with ejecting oxygen microbubbles to produce a mechanical self-cleansing effect. This study aimed to evaluate the feasibility of DM as a novel bracket cleaner. METHODS: DM was prepared according to the protocol and analyzed using a scanning electron microscope (SEM). We treated S. mutans biofilms grown over bracket with phosphate-buffered saline (PBS group), 0.12% chlorhexidine (CHX group), 3% H2O2 (H2O2 group), and co-treatment with 3 mg/mL of DM and 3% H2O2 (DM group). The biofilm removal effect was analyzed using crystal violet assay, and the results were observed using SEM. The viability of S. mutans in remaining biofilms was evaluated using confocal laser scanning microscopy (CLSM). Finally, we examined the effect of all materials on mature multispecies biofilms formed on debonded brackets. RESULTS: Crystal violet assay results revealed that the CHX group removed more biofilms than the control group, and the DM group removed biofilms more effectively than the CHX group (p < 0.0001). SEM and CLSM images showed that CHX killed S. mutans but failed to remove most biofilms on brackets. However, DM effectively removed biofilms and mature multispecies biofilms on debonded brackets (p < 0.0001). CONCLUSIONS: Co-treatment with DM and H2O2 is effective in removing biofilms on orthodontic brackets compared to conventional antibacterial agents.

Effect of custom abutment data superimposition on the accuracy of implant abutment level scanning: An in vitro study.

STATEMENT OF PROBLEM: When scanning implant abutments, an incomplete scan is often obtained because of a subgingival location or restricted accessibility. Whether these problems can be overcome with a novel scanning technique with digital superimposition of the custom abutment is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of the process of superimposing the custom abutment library data onto the scanned abutment data on the accuracy of the digital scan with an intraoral scanner. MATERIAL AND METHODS: A model with a single implant was prepared. The custom abutment of the corresponding implant was produced and was scanned with a laboratory scanner to produce the custom abutment library data. The custom abutment was connected to the implant, and the model was scanned with a laboratory scanner for the reference data. The custom abutment and adjacent teeth were scanned 10 times with an intraoral scanner. Thus, 10 files were saved as the first test group (IOS). After transferring 10 files of the group IOS to a computer-aided design (CAD) software program (exocad DentalCAD), the custom abutment library data were superimposed on the corresponding abutments, and the results were saved as the second test group (S-Exo). For the third test group (S-Den), the same superimposing process was performed as for the group S-Exo but by using another CAD software program (Dental System). The accuracy of the files of the 3 test groups was evaluated by comparing them with the reference file by using a 3D inspection software program. Statistical analysis was performed with 1-way repeated measures ANOVA (α=.05). RESULTS: The RMS of the IOS group decreased significantly from 42.1 ±1.1 µm to 36.37 ±0.74 µm for the S-Exo group and 36.89 ±0.69 µm for the S-Den group after superimposition (P<.05). InTOL increased significantly from 88.17 ±0.75% to 91.57 ±0.56% in the S-Exo group and 91.31 ±0.56% in the S-Den group (P<.05). For the mean 3D discrepancy of all 66 points along the margin and 16 points of interest, the IOS group showed significantly higher discrepancy than the superimposed groups (P<.05), implying that the accuracy of scanned data with the intraoral scanner increased after superimposition with the abutment library data. No significant difference was found according to the type of software program (P>.05). CONCLUSIONS: The process of superimposing the titanium custom abutment with the prescanned custom abutment library data improved the accuracy of a digital scan made with an intraoral scanner.

Evaluation of eccentric tooth contact on a semi-adjustable articulator by using an occlusal analysis system.

STATEMENT OF PROBLEM: Duplicating mandibular movement with a semi-adjustable articulator has been reported to lack accuracy. However, although previous studies have analyzed articulator movement, few have compared excursive tooth contact on the articulator with tooth contact during actual mandibular movement. PURPOSE: The purpose of this clinical study was to evaluate the concordance of semi-adjustable articulator contacts with intraoral contacts during eccentric movements by using a T-scan occlusal analysis system. MATERIAL AND METHODS: Forty-two participants with normal occlusion and without signs of temporomandibular disorder were analyzed for the reproducibility of eccentric tooth contact on a semi-adjustable articulator. Maxillary casts made from irreversible hydrocolloid impressions were mounted on a semi-adjustable articulator with the facebow. The condylar inclination of the articulator was set by using interocclusal records. Three recordings of right and left excursive mandibular movement and protrusive mandibular movement were made in the supine position by using the T-scan v9.1. The same procedure was then performed with the articulator. The results of complete mandibular movement from T-scan measurements were divided into 4 time points for analysis: T0, T1, T2, and T3. The concordance of intraoral and articulator occlusal contacts was evaluated at each point, and the occlusal force for each tooth was compared. Overall concordance and concordance of the working and nonworking sides were also calculated. Repeated measures analysis of variance was used to analyze differences between the concordance of intraoral and articulator contacts according to mandibular movement direction, time, and working and nonworking sides (α=.01). RESULTS: For all teeth, concordance between the intraoral and articulator occlusal contacts during excursive mandibular movement was greatest at T0, decreasing at T1 and T2, and increasing at T3. No significant differences were found in the concordance among the right lateral, left lateral, and protrusive excursion (P>.01). The concordance of working side occlusal contacts during lateral excursion was significantly lower at T3 than that at T0 (P<.01). CONCLUSIONS: When comparing intraoral and articulator contacts during lateral eccentric mandibular movement, concordance was affected by time and working or nonworking side. Reproducibility of initial eccentric tooth contact on a semi-adjustable articulator appeared to be reliable. However, occlusal adjustment of the working side might be required after prosthesis delivery.

Determination of the reliability and repeatability of a quantitative occlusal analyzer by using a piezoelectric film sensor: An in vitro study.

STATEMENT OF PROBLEM: A digital quantitative occlusal analyzer with claimed lower cost and easier maneuverability has been introduced to replace conventional methods. However, information regarding its performance is scarce. PURPOSE: The purpose of this in vitro study was to evaluate the reliability and repeatability of a newly introduced digital occlusal analysis device (Accura) and to compare it with an established occlusal analyzer (T-scan Novus). MATERIAL AND METHODS: The sensor films of both devices were positioned between titanium maxillary and mandibular models that were equilibrated and arbitrarily mounted on a semiadjustable articulator. Compressive force was applied to the upper arm of the articulator with a universal testing machine, increased gradually to 50 N, and then released automatically. The time and force measurements from the universal testing machine and the tested devices were recorded by operating software programs. Five articulating film sensors of each device were tested 3 times each by 2 examiners and were repeated on consecutive days, totaling 60 trials per device. Reliability was defined as an agreement between the loaded force and measured force. Repeatability was defined as an agreement between repeated measurements of the Accura and T-scan Novus. Intraclass correlation coefficient was calculated for the statistical analysis (α=.05). RESULTS: The calculated intraclass correlation coefficient of the Accura and the universal testing machine was 0.952. The intraclass correlation coefficient of the T-scan Novus and the universal testing machine was 0.963. Intraclass correlation coefficients that were calculated to compare the data acquired from different days were 0.938 for the Accura and 0.911 for the T-scan Novus. CONCLUSIONS: The experimental results indicated that the reliability of both the Accura and T-scan Novus was excellent for measuring occlusal forces. In addition, both the Accura and T-scan Novus exhibited excellent repeatability.

Effect of layer thickness and printing orientation on the color stability and stainability of a 3D-printed resin material.

STATEMENT OF PROBLEM: Although 3-dimensional (3D)-printed resin prostheses are widely used, studies on the effects of the manufacturing parameters of 3D printing on the color stability and stainability of these prostheses are lacking. PURPOSE: The purpose of this in vitro study was to investigate the effects of layer thickness and printing orientation on the color stability and stainability of a 3D-printed resin. In addition, the influence of roughness and water contact angle was evaluated. MATERIAL AND METHODS: Color changes (ΔE00) in tooth-colored resin specimens produced by 3D printing with 2 different layer thicknesses and 3 different printing orientations and immersed in 3 types of aging media (distilled water, coffee solution, and wine) were evaluated (n=10). The CIELab color values were measured with a spectrophotometer at baseline and different time points (1, 3, 7, 15, and 30 days). The surface roughness (Ra) of resin specimens was measured at various time points (baseline, 7, 15, and 30 days) by confocal laser scanning microscopy after immersion in coffee solution (n=15). The water contact angle was determined by using the sessile drop method (n=10). The ΔE00 values were analyzed by using the 3-way repeated measures ANOVA followed by the Bonferroni test and Dunnett T3 test (α=.05). Ra values were analyzed by 3-way repeated measures ANOVA (α=.05). The water contact angle data were analyzed by 2-way ANOVA (α=.05). RESULTS: The 3-way repeated measures ANOVA showed that layer thickness, printing orientation, and storage time significantly influenced the ΔE00 values of the 3D-printed resin specimens in each aging medium (P<.001). The ΔE00 values in the 0-degree subgroups were significantly lower than those in the 45- and 90-degree subgroups (P<.05). The ΔE00 values in the 25-µm thick groups were significantly higher than those in the 100-µm thick groups (P<.05). The ΔE00 values demonstrated an increase up to 15 days in all aging media. In distilled water, the ΔE00 values of the specimens increased or decreased depending on the groups, whereas in the coffee solution, the values decreased after 15 days (P<.001); in red wine, the values demonstrated a continuous increase up to 30 days in all groups (P<.001). The 3-way repeated measures ANOVA showed that the Ra values did not change significantly with immersion time (P=.444). The 2-way ANOVA showed that the water contact angle was not significantly affected by layer thickness (P=.921) or printing orientation (P=.062). CONCLUSIONS: Layer thickness and printing orientation affected the color stability and stainability of the 3D-printed resin. The discoloration of the 3D-printed resin differed with time, depending on the type of aging media used.

Developing a clinical presentation dental education model and a pilot test.

INTRODUCTION: Accurate clinical decision-making of dentists should be based on their knowledge and experience. In the past 10 years, interest in competency-based dentistry education has rapidly increased, but there has been little attention paid to methods of improving dental education competency. The purpose of this study was to develop a clinical presentation education model that provides opportunities for students to practice problem-solving from the moment they greet the patient so that students can obtain the practical experience of competency-based education and the effectiveness of this model can be confirmed through pilot test. METHODS: This article is divided two parts: First, developing the clinical presentation dental education model (CPDEM) and Second, a pilot study adopted CPDEM. To confirm the effectiveness of this model, the students' satisfaction, their perception of self-achievement were analysed. RESULTS: Clinical presentation dental education model has been developed to provide practice-related education experience and provide linkage between basic science and clinical science. The result of applying this education model to 10 students as a pilot test was shown an overall high satisfaction level. In addition, self-achievement students' reported of all intended competencies was higher than for non-participating students of this model. CONCLUSIONS: This study focuses on practical education centring on clinical presentation. This model could get a meaningful and realistic experiences through the practice using clinical presentation of patients, use their metacognition for organizing and memorizing the patient's case by using concept map. It can be used as a future instructional method to enhance students' competency.

Effects of abutment screw preload in two implant connection systems: A 3D finite element study.

STATEMENT OF PROBLEM: Finite element analysis (FEA) has been used to evaluate the biomechanical behaviors of dental implants. However, in some FEA studies, the influence of the preload condition has been omitted to simplify the analysis. This might affect the results of biomechanical analysis significantly. The preload condition requires analysis. PURPOSE: The purpose of this FEA study was to evaluate and verify the effects of the presence of the preload condition on abutment screws under the occlusal load for external and internal hexagonal connection systems. MATERIAL AND METHODS: The finite element models consisting of bone blocks, 2 different implant systems (Osstem US and GS system; Osstem Implant Co), and crowns were created. With these components, a total of 6 models with different conditions were constructed for FEA: external hexagonal connection system only with preload (EO), external hexagonal connection system with no preload but occlusal load (EN), external hexagonal system with both preload and occlusal load (EP), internal hexagonal system only with preload (IO), internal hexagonal system with no preload but occlusal load (IN), and internal hexagonal system with both preload and occlusal load (IP). An 11.3-degree oblique load (100 N) to the axis of the implant was applied on the occlusal surface of the crown for the models with occlusal load. A preload of 825 N was applied in the abutment screw of the models EO, EP, IO, and IP. The maximum von Mises stress, maximum principal stress, and maximum displacement of the components of the models were evaluated. RESULTS: Both external and internal connection systems resulted in higher maximum von Mises stress and maximum principal stress values in the presence of preload in the abutment screw. The internal connection system showed higher displacement values than the external system with or without occlusal loading, and values tended to increase with the preload condition. CONCLUSIONS: The presence of a preload condition significantly affected the biomechanical behaviors of the components of 2 different connection systems. The preload condition should be included in FEA to achieve more realistic results.

Augmented reality in dentistry: a current perspective.

Augmentation reality technology offers virtual information in addition to that of the real environment and thus opens new possibilities in various fields. The medical applications of augmentation reality are generally concentrated on surgery types, including neurosurgery, laparoscopic surgery and plastic surgery. Augmentation reality technology is also widely used in medical education and training. In dentistry, oral and maxillofacial surgery is the primary area of use, where dental implant placement and orthognathic surgery are the most frequent applications. Recent technological advancements are enabling new applications of restorative dentistry, orthodontics and endodontics. This review briefly summarizes the history, definitions, features, and components of augmented reality technology and discusses its applications and future perspectives in dentistry.

Vertical repositioning accuracy of magnetic mounting systems on 4 articulator models.

STATEMENT OF PROBLEM: Research of the ability of a cast mounted on an articulator on maintaining the identical position of a cast mounted on an articulator after repeated repositioning is lacking, despite the possible effects this may have on the occlusion of a mounted cast. PURPOSE: The purpose of this in vitro study was to verify and compare the vertical repositioning accuracy of 4 different, commercially available articulator magnetic mounting plate systems. MATERIAL AND METHODS: Four articulators and their associated magnetic mounting plates were selected for the study. These were the Artex AR articulator (Amann Girrbach AG), the Denar Mark II articulator (Whip Mix Corp), the Kavo Protar Evo articulator (Kavo Dental GmbH), and the SAM3 articulator (SAM Präzisionstechnik GmbH). Three new magnetic mounting plates were prepared for each articulator system. The repositioning accuracy of each mounting plate was evaluated by comparing the standard deviation of the vertical distances measured between the mounting plate and a laser displacement sensor. The lower arm of the articulator was secured, and the vertical distance was measured by positioning the laser displacement sensor positioned vertically above the mounting plate. Once the vertical distance was measured, the mounting plate was detached from the articulator and reattached manually to prepare for the next measurement. This procedure was repeated 30 times for each of the 3 magnetic mounting plates. Data were analyzed by ANOVA for 2-stage nested design and the Levene test (α=.05). RESULTS: Significant differences were detected among articulator systems and between magnetic mounting plates of the same type. The standard deviations of the measurements made with the Artex AR articulator, Denar Mark II articulator, Kavo Protar Evo articulator, and SAM3 articulator were 0.0027, 0.0308, 0.0214, and 0.0215 mm, respectively. Thus, the repositioning accuracy could be ranked in the order as follows: Artex AR, Kavo Protar Evo, SAM3, and Denar Mark II. CONCLUSIONS: The position of the magnetic mounting plate after repositioning did not maintain an identical position in the vertical dimension on any of the 4 articulator models tested. The repositioning accuracy of the mounting plates showed significant differences among the articulators tested in this study.

Occlusal consequence of using average condylar guidance settings: An in vitro study.

STATEMENT OF PROBLEM: A simplified mounting technique that adopts an average condylar guidance has been advocated. Despite this, the experimental explanation of how average settings differ from individual condylar guidance remains unclear. PURPOSE: The purpose of this in vitro study was to examine potential occlusal error by using average condylar guidance settings during nonworking side movement of the articulator. MATERIAL AND METHODS: Three-dimensional positions of the nonworking side maxillary first molar at various condylar and incisal settings were traced using a laser displacement sensor attached to the motorized stages with biaxial freedom of movement. To examine clinically relevant occlusal consequences of condylar guidance setting errors, the vertical occlusal error was defined as the vertical-axis positional difference between the average setting trace and the other condylar guidance setting trace. In addition, the respective contribution of the condylar and incisal guidance to the position of the maxillary first molar area was analyzed by multiple regression analysis using the resultant coordinate data. RESULTS: Alteration from individual to average settings led to a positional difference in the maxillary first molar nonworking side movement. When the individual setting was lower than average, vertical occlusal error occurred, which might cause occlusal interference. The vertical occlusal error ranged from -2964 to 1711 µm. In addition, the occlusal effect of incisal guidance was measured as a partial regression coefficient of 0.882, which exceeded the effect of condylar guidance, 0.431. CONCLUSIONS: Potential occlusal error as a result of adopting an average condylar guidance setting was observed. The occlusal effect of incisal guidance doubled the effect of condylar guidance.

Three-dimensional finite element analysis of implant-assisted removable partial dentures.

STATEMENT OF PROBLEM: Whether the implant abutment in implant-assisted removable partial dentures (IARPDs) functions as a natural removable partial denture (RPD) tooth abutment is unknown. PURPOSE: The purpose of this 3-dimensional finite element study was to analyze the biomechanical behavior of implant crown, bone, RPD, and IARPD. MATERIAL AND METHODS: Finite element models of the partial maxilla, teeth, and prostheses were generated on the basis of a patient's computed tomographic data. The teeth, surveyed crowns, and RPDs were created in the model. With the generated components, four 3-dimensional finite element models of the partial maxilla were constructed: tooth-supported RPD (TB), implant-supported RPD (IB), tooth-tissue-supported RPD (TT), and implant-tissue-supported RPD (IT) models. Oblique loading of 300 N was applied on the crowns and denture teeth. The von Mises stress and displacement of the denture abutment tooth and implant system were identified. RESULTS: The highest von Mises stress values of both IARPDs occurred on the implants, while those of both natural tooth RPDs occurred on the frameworks of the RPDs. The highest von Mises stress of model IT was about twice that of model IB, while the value of model TT was similar to that of model TB. The maximum displacement was greater in models TB and TT than in models IB and IT. Among the 4 models, the highest maximum displacement value was observed in the model TT and the lowest value was in the model IB. CONCLUSIONS: Finite element analysis revealed that the stress distribution pattern of the IARPDs was different from that of the natural tooth RPDs and the stress distribution of implant-supported RPD was different from that of implant-tissue-supported RPD. When implants are used for RPD abutments, more consideration concerning the RPD design and the number or location of the implant is necessary.

Time-dependent periimplant bone reaction of acidic monomer-treated injection molded zirconia implants in rabbit tibiae.

PURPOSE: The aim of this study was to evaluate and compare the osseointegration of zirconia implants in rabbit tibiae with and without 10-methacryloyloxydecyl dihydrogen phosphate (MDP) treatment. MATERIALS AND METHODS: Twenty-eight rabbits received a total of 112 external hex-type implants made by the powder injection molding technique with and without MDP treatment before installation in the tibiae. The contact angles on the zirconia implants and zirconia discs before and after MDP application were evaluated. Removal torque (RT) and bone-implant contact (BIC) ratios were measured. RESULTS: The MDP treatment markedly enhanced the hydrophilicity and seemed to alter the topography and chemical composition of the implant and disc surface. As the healing time increases, the BIC and RT were increased in both groups. The MDP-treated implants exhibited higher BIC values than the control implants after 2 and 4 weeks of healing. The RT was higher in MDP-treated implants after 2 weeks of healing but not after 4 weeks of healing. CONCLUSION: The 10-MDP treatments made the surface more hydrophilic and enhanced the osseointegration of the implants in the early healing phase.

Submorphotypes of the maxillary first molar and their effects on alignment and rotation.

INTRODUCTION: The aim of this study was to explore the shape differences in maxillary first molars with orthographic measurements using 3-dimensional virtual models to assess whether there is variability in morphology that could affect the alignment results when treated by straight-wire appliance systems. METHODS: A total of 175 maxillary first molars with 4 cusps were selected for classification. With 3-dimensional laser scanning and reconstruction software, virtual casts were constructed. After performing several linear and angular measurements on the virtual occlusal plane, the teeth were clustered into 2 groups by the method of partitioning around medoids. To visualize the 2 groups, occlusal polygons were constructed using the average data of these groups. RESULTS: The resultant 2 clusters showed statistically significant differences in the measurements describing the cusp locations and the buccal and lingual outlines. The rotation along the centers made the 2 cluster polygons look similar, but there was a difference in the direction of the midsagittal lines. CONCLUSIONS: There was considerable variability in morphology according to 2 clusters in the population of this study. The occlusal polygons showed that the outlines of the 2 clusters were similar, but the midsagittal line directions and inner geometries were different. The difference between the morphologies of the 2 clusters could result in occlusal contact differences, which might be considered for better alignment of the maxillary posterior segment.

3D finite element analysis of stress distribution on the shape of resected root-end or with/without bone graft of a maxillary premolar during endodontic microsurgery.

Background/purpose: Apical root resection pattern affects the stress distribution behavior in the apical region of the resected tooth. The purpose of the study was to compare the biomechanical responses of resected teeth between endodontic microsurgery (horizontal resection) and targeted endodontic microsurgery (round resection). Materials and methods: Five different models were developed. The basic model without resection (NR) was regarded as the control model, and the others involved: horizontal resection without bone grafting (HN), horizontal resection with bone grafting (HG), round resection without bone grafting (RN), and round resection with bone grafting (RG) models. A static load of 100 N was applied to the buccal and palatal cusps of all the teeth in a 30° oblique direction. The maximum von-Mises stress and tooth displacement values were analyzed and compared. Results: Both the HN and RN models exhibited lower stress distribution values on bone compared with the NR (control) model. Regarding maximum stress distribution at the root apex, the stress value of the RN model was slightly higher compared to the HN model, whereas the RG model displayed a slightly lower stress value in comparison with the HG model. For maximum tooth displacement value, there were no significant differences between the HN and RN models, as well as the HG and RG models. Conclusion: The round resection pattern had comparable stress distribution behaviors at the root apex and tooth displacement values with the horizontal resection pattern. Targeted endodontic microsurgery might provide better biomechanical response of the resected tooth after root-end resection.

A One-Year Randomized Controlled Clinical Trial of Three Types of Narrow-Diameter Implants for Fixed Partial Implant-Supported Prosthesis in the Mandibular Incisor Area.

Narrow-diameter implants (NDI) serve as a solution for treating limited bone volume in the anterior mandible. This study aimed to evaluate the one-year clinical outcomes of various NDIs in the mandibular incisor area after immediate loading in partially edentulous patients. This single-center, prospective, single-blinded, randomized controlled trial study included 21 patients, with 7 patients in each of the following groups: control (BLT NC SLActive®; Straumann), experimental group 1 (CMI IS-III Active® S-Narrow; Neobiotech), and experimental group 2 (CMI IS-III Active® Narrow; Neobiotech). Using full digital flow, two fixtures were placed in each patient and immediately provisionalized on the day of surgery. Evaluations encompassed periapical radiographs, implant stability quotient (ISQ), implant stability test (IST) readings, per-implant soft tissue health, patient satisfaction surveys, and esthetic score assessments. Definitive prostheses were delivered twelve weeks post-surgery (CRiS, number: KCT0007300). Following exclusions due to low stability values (n = 2), fixture failure (n = 5), and voluntary withdrawal (n = 1), the implant success rate for patients completing all clinical protocols stood at 100%. The resulting patient failure rates in the control, experimental group 1, and experimental group 2 were 50.0%, 42.9%, and 14.3%, respectively. There were no significant differences between the groups in terms of marginal bone loss, soft tissue health, patient satisfaction, and esthetic scores. Narrow implants showed superior clinical outcomes, followed by S-Narrow and Straumann implants. Calculated one-year survival rates at the implant level were 66.7% for the control group, 85.7% for experimental group 1, and 100% for experimental group 2. All three types of NDIs showed acceptable clinical and radiographic results during the year-long observation period.

Gender differences in dentofacial characteristics of adult patients with temporomandibular disc displacement.

PURPOSE: The purpose of this study was to assess gender differences in dentofacial characteristics of adult patients according to temporomandibular joint (TMJ) disc displacement (DD) status. MATERIALS AND METHODS: The sample consisted of 293 adult patients (80 male and 213 female). Male and female patients were divided into 3 groups based on magnetic resonance images of bilateral TMJs: bilateral normal disc position (BN), bilateral DD with reduction (DDR), and bilateral DD without reduction (DDNR). Seventeen variables from lateral cephalograms were analyzed by 2-way analysis of variance to identify differences in dentofacial morphologies with respect to gender and TMJ DD status. RESULTS: Patients with TMJ DD had short ramus height, short mandibular body length, and backward positioning of the ramus and mandible. These dentofacial characteristics became more severe as TMJ DD progressed to DDNR. In addition, dentofacial characteristics associated with TMJ DD were not significantly different between men and women except for effective mandibular length (Articulare to pogonion). Effective mandibular length even tended to decrease as TMJ DD progressed, but male patients showed a larger difference in effective mandibular length between BN and DDR than female patients. CONCLUSIONS: This study's findings suggest that dentofacial morphology is strongly associated with TMJ DD status and that skeletal Class II hyperdivergent pattern with a short ramus and mandible may be a potential indicator of TMJ DD regardless of gender.

Panoramic radiographic evaluation of the mandibular morphological changes in elderly dentate and edentulous subjects.

OBJECTIVE: The aim of the present study was to analyze the changes in the gonial angle, ramus height, condyle height and cortical bone thickness in relation to gender and dental status in elderly patients. MATERIALS AND METHODS: The study population comprised 240 patients (age ranged from 60-69 years) who had digital panoramic radiographs taken for various purposes. One group consisted of 120 patients, 60 men and 60 women, who had all natural teeth present except for third molars. The second group consisted of the remaining 120 patients (60 men and 60 women) who were in a completely edentulous state (maxilla and mandible). The gonial angle, ramus height, condylar height and cortical bone thickness of the mandible were measured by computer software on their panoramic radiographs. RESULTS: Women showed larger gonial angles than men, while men had greater cortical bone thickness and ramus height (p < 0.05). However, no significant difference in condylar height was found between both genders (p > 0.05). Edentulous subjects had a larger gonial angle than dentate subjects, while dentate subjects had greater cortical bone thickness on both sides and left side of condylar height (p < 0.05). The gonial angle had statistically negative correlations with cortical bone thickness and ramus height, regardless of gender. CONCLUSIONS: The outcomes of the present study indicate that the edentulous women undergo morphological changes of the mandible influenced by the dental status more than men.

Different mandibular first molar shapes according to groove and cusp configuration in relation to suggested bracket position.

The aim of this study was to explore the shape differences in the mandibular first molars through orthographic measurements using three-dimensional (3D) virtual models, and study the possibility of new morphologic categories that require more than subjective visual inspection. A total of 164 mandibular first molars with five cusps were selected for classification. Using 3D laser scanning and reconstruction software, virtual casts were constructed. After several linear and angular measurements on the virtual occlusal plane, the teeth were clustered using the partitioning around medoids methods-an unsupervised classification. The cluster analysis presented two clusters that showed statistically significant differences in the measurements over the cusp locations and groove configurations. However, gender differences were not shown in the angular groove and cusp configurations. Two clusters were found in the population of the present study, and this result suggested the existence of a diverse morphologic trait in the mandibular molar even in the same origin and could be considered in positioning orthodontic brackets that have built-in prescriptions.