Tooth Area Research Articles

Biodentine and Amniotic Membrane to Treat the Hidden Villain- A Rare Case of Labiocervical Vertical Groove

This case report signifies the importance of complications and early diagnosis of radicular groove and to discuss the treatment of combined endo-perio lesion using bone graft mixed with Platelet Rich Fibrin (PRF), amniotic membrane and biodentine. Labiocervical Vertical Groove (LCVG) presents various complications to the patients, especially if it extends to the pulpal space. Labiocervical vertical groove originating near the cervical area of tooth can extend to the radicular surface. These grooves can be mild, moderate or deep based on its extent and depth. This case report deals with the complications, degree of destruction and treatment of an intrabony defect associated with LCVG in maxillary central incisor in a 35-year-old male patient, who reported to the Department of Periodontics and Implantology with the chief complaint of mobility of teeth over a period of past 2 months. In this case report, authors have highlighted the advantages of saucerization, PRF, Amniotic membrane and biodentine to treat the bone loss along with restoration of the groove.

Complicações na técnica de regeneração óssea guiada associada à membrana de PTFE-d: relato de caso

ABSTRACT Guided bone regeneration aims to gain vertical and horizontal bone volume in atrophic ridges, using different regenerative techniques associated with biomaterials, with occasional post-surgical complications. The objective of the case report was to describe the successive approaches to minimize and eliminate the complications presented in the postoperative period of a patient submitted to the guided bone regeneration technique. In the first surgery, the dense expanded polytetrafluoroethylene membrane (d-PTFE), supported by the tent technique and autogenous platelet graft, was used to perform the guided bone regeneration technique. After three months, the membrane was exposed, with the membrane and the retaining screws removed in the seventh month, with the installation of three Internal Hexagon implants in the areas of teeth 13, 14 and 15. The exposed threads were covered with hydroxyapatites resorbable and covered with d-PTFE membrane. A four-month postoperative panoramic radiograph suggested implant osseointegration. The guided bone regeneration technique associated with the d-PTFE membrane enabled bone neoformation, enabling the installation of osseointegrated implants in an aesthetic and functional position. The exposure of the edges of the membrane allowed the penetration of fluids and contamination, suggesting the worsening of the signs of infection and purulent secretion. On the contrary, the exposure of central areas did not cause inflammatory and infectious signs.

Selfie Dental Plaque Index: A New Tool for Dental Plaque Assessment.

Plaque quantification indices are frequently used to evaluate personal oral hygiene. Education in self-care and self-diagnosis is effective in prevention and control of both dental and periodontal disease. Mobile technology has become a ubiquitous technology and can be particularly useful in the self-monitoring of health promotion. To evaluate the selfie dental plaque index compared with O´Leary index (DPI) and visible plaque index (VPI). The secondary outcome was to compare full-mouth and anterior teeth plaque index analysis. A sample of 47 adults were evaluated using a four-stage protocol. All teeth (except third molars) were analyzed for VPI and DPI. A selfie Digital Camera captured the image of the patient's smile (without and with disclosing solution), which was analyzed using Image J software (ImageJ 1.52a, National Institutes of Health). Adobe Photoshop software (Copyright © 2020 Adobe) was used for individual segmentation. The calculation of the selfie index of visible plaque (SVPI) and disclosed (SDPI) was done through the area with plaque of each image in relation to the total teeth area. Spearman's correlation test showed a moderate correlation between VPI and SVPI (rho = 0.6, p<0.001), whereas between DPI and SDPI the correlation was weak (rho = 0.2, p = 0.13). The correlation between the plaque index using all the teeth present, showed a strong correlation with the analysis only of the anterior teeth (rho = 0.8, p<0.001). Our results showed the potential of smiling images as a new tool for quantitative measurements and showed moderate correlation when compared with the visible plaque index. Anterior teeth provided reliable plaque indexes when compared with full mouth analysis. Key words:Dental Plaque Index, dental hygiene, mHealth, health Promotion, oral Health.

Clinical Observation of Flapless Implantation in the Posterior Tooth Area under the Guidance of the Fully Guided Template.

Objective Compared with the conventional flap implantation, the postoperative effect of flapless implantation of a single posterior tooth under the guidance of the fully guided template was observed. Materials and Methods 67 cases were divided into the template group (n = 35) and the flap group (n = 32) according to the wishes and actual situation of the patients. In the template group, the fully guided template was made by rapid prototyping technology, and the flapless implantation was performed under the guidance of the template in the posterior tooth area. The flap group underwent routine flap implantation. After the operation, the template group took CBCT (cone beam computed tomography) again and fitted it with that before the operation. Neck deviation, apical deviation, depth deviation, and axial angle deviation in buccolingual and mesiodistal directions were measured to observe the accuracy of the fully guided template. At the same time, the postoperative reactions of the two surgical methods were compared by recording the operation time, pain degree 24 hours after the operation, swelling degree 72 hours after the operation, and postoperative satisfaction of patients. Results Whether in buccolingual or mesiodistal directions, the maximum values of neck deviation, apical deviation, and depth deviation were less than 2 mm. The axial angle deviation was 0.07°∼5.93° in the buccolingual direction and 0°∼4.12° in the mesiodistal direction. The guiding effect of the template was relatively reliable, and the implantation site and depth were well controlled. Although there were small deviations, the accuracy of the template could meet the clinical needs. The operation time and the VAS (visual analogue scale) score 24 hours after the operation in the template group were lower than those in the flap group (P < 0.05), and the swelling degree rating 72 hours after the operation and postoperative satisfaction of the patients were better than those in the flap group (P < 0.05). Conclusion Compared with the conventional flap implantation, the flapless implantation in the posterior tooth area under the guidance of the fully guided template could improve the accuracy of the operation, shorten the operation time, and reduce the degree of postoperative pain and swelling, which had a certain positive clinical significance.

The state of the alveolar bone tissue depending on the vitality of the tooth pulp according to the saliva indicators of patients with moderate periodontitis

Aim. To evaluate the results of surgical treatment of patients with moderate chronic periodontitis with different dental pulp status by determining sRANKL, OPG and FGF-2 in mixed saliva and dynamic densitotomometry data.Materials and methods. Surgical treatment of 24 patients with moderate chronic periodontitis was performed. Three months before the operation, according to the indications, endodontic treatment of the examined teeth was performed in some patients. Depending on the status of the dental pulp, the patients were divided into two groups: I – patients with vital teeth, II – patients with teeth after endodontic treatment. Before and after surgery, all patients underwent clinical examination, enzyme immunoassay of saliva remodeling markers and optical densitotomometry of periodontal bone to compare the results of treatment. Results. The OHI-S index showed a significant decrease in the mean value by 12 months of observation in both groups, which was statistically significant. Higher indices of the PI index by the end of the observation period were detected in the area of depulpated teeth. An equivalent dynamics of a decrease in the value of periodontal attachment according to the CAL index was revealed in both groups after treatment. The saliva showed an equivalent decrease in sRANKL, an increase in OPG by the end of the observation period, statistically insignificant when compared between groups. FGF-2 remained undetected at any of the observation periods in all groups. Densitotomometry data indicated an increase in the density characteristics of periodontal bone by the end of observations with a stable dependence on lower values in the area of depulpated teeth. Conclusions. In the saliva of patients, the processes of periodontal bone resorption were found to be statistically equivalent in intensity, regardless of the status of the dental pulp. The absence of FGF-2 content in saliva until the end of the observation period should be considered as an indicator of periodontal healing of vital and depulpated teeth by the formation of fibrous connective tissue. Dynamic densitotomometry of alveolar bone tissue revealed statistically significantly lower density characteristics in the area of teeth with a condition after endodontic treatment.

Design parameters of polylactic acid custom trays manufactured by fused deposition modeling for partial edentulism: Consideration of the accuracy of the definitive cast

Statement of problemThe effects of design parameters of polylactic acid (PLA) custom trays manufactured by fused deposition modeling (FDM) on the accuracy of partially edentulous definitive casts have not been thoroughly explored. PurposeThe purpose of this in vitro study was to explore the effects of the impression gap and base thickness of FDM-printed PLA custom trays on the accuracy of maxillary and mandibular definitive casts with Kennedy class II, modification I partial edentulism and to optimize these 2 design parameters. Material and methodsCustom trays with a 1-mm, 2-mm, or 3-mm impression gap and 1-mm, 1.5-mm, or 2-mm base thickness were designed on a pair of maxillary and mandibular resin casts and printed with PLA materials by using an FDM printer. Two-step silicone impressions were made by using these custom trays or stock metal trays on resin casts. Digital scans of definitive casts from these impressions were aligned one by one with those of resin casts. Three-dimensional deviations of the tooth area, mucosal area, and overall area were analyzed by using root mean square (RMS) as a metric. Two-way and 1-way analyses of variance with the RMSs as the dependent variable were carried out (α=.05). ResultsThe accuracy of definitive casts from custom trays with a 2.0-mm or 3.0-mm impression gap and 1.5-mm or 2.0-mm base thickness was significantly better than that of definitive casts from custom trays with a 1.0-mm impression gap or 1.0-mm base thickness and was not significantly different from that of definitive casts from stock metal trays. ConclusionsConsidering the accuracy of definitive casts, the optimal base thickness of FDM-printed PLA custom trays was 1.5 mm or 2.0 mm and the optimal impression gap was 2.0 mm or 3.0 mm for Kennedy class II, modification I partial edentulism.

Appropriate fabrication method for pressure-formed mouthguards using polyolefin sheets.

Polyolefin sheet mouthguards are usually formed in the same manner as ethylene-vinyl acetate sheet mouthguards. However, the heating condition of the polyolefin sheet for the pressure-forming process has not been determined. The aim of this study was to examine the appropriate heating condition for polyolefin sheet mouthguards when fabricated with the pressure-formed technique. Mouthguard sheets of 3.0mm polyolefin were pressure formed on working models at three heating temperatures: 90°C, 105°C, and 120°C. The thickness of the mouthguard was measured at the labial surface of the central incisor, and the buccal and occlusal surfaces of the first molar. The fit of the mouthguard was examined at the central incisor and the first molar by measuring the distance between the mouthguard and the cervical margin of the working model. Differences in the thickness and fit of the mouthguards according to the heating conditions and the measured regions were analyzed using two-way analysis of variance. Mouthguard thickness varied among the measured regions of the central incisors and first molars (p<.01). The greatest thickness was found at the labial surface of the central incisor in mouthguards fabricated with the heating temperature of 90°C (p<.01). The greatest thickness was found in mouthguards fabricated with the heating temperature of 105°C at the buccal surface of the first molar (p<.01), and 105°C or 120°C at the occlusal surface of the first molar (p<.01). The fit was not significantly different among the three heating conditions both at the central incisor and the first molar. The appropriate heating condition for pressure-formed mouthguards using polyolefin sheets was 90°C to maintain the mouthguard thickness at the anterior teeth area with proper fit.

Prevalence of Hypodontia in Saudi Arabia: A Retrospective Digital Orthopantomographic Study

Introduction: Hypodontia or Dental agenesis; is defined as a developmental missing of any teeth, excluding the last molars. It may befall as a genetic syndrome or as a non-syndromic isolated trait. However, there is no prevalence available in our city.&#x0D; Aim and Objectives: The tenacity of this research is to assess the frequency of hypodontia among the population who received dental care at King Abdul Aziz University Dental Hospital in the city of Jeddah.&#x0D; Study Design: Retrospective digital orthopantomographic: cross-sectional study.&#x0D; Place and Duration of Study: Oral &amp; Maxillofacial Prosthodontic Department, King Abdulaziz University, between January 2019 and July 2020.&#x0D; Methodology: This research is a retrospective cross-sectional study based on the examination of an archival dental record and 2D panoramic radiographs of patients who are presented at King Abdulaziz University Dental Hospital, Jeddah. A total of 2045 records were reviewed and included in this study. Two general practitioners reviewed patient’s dental charts looking for congenital missing tooth/teeth in a dark room by the method that the practitioners use. Careful reviews of each patient’s record were done to ensure that the cause of the missing tooth/teeth were congenital and not surgical or traumatic. Data were gathered from dental records of patients’ age period 6-9 years since most of the dental follicle of the permanent teeth should be completed or the tooth just erupts, radiographic findings were always compared to the patients’ file and progress notes to ensure the causative factors of missing teeth. The data were recorded in an excel sheet which included gender, age, the type, area and counting of the missing teeth.&#x0D; Results: After collecting the data, the total number of patients after exclusion were 1984. The prevalence of hypodontia in our tested population was %5.39. Statistical analysis were done by using SPSS software to correlate between variables. Varices grades.&#x0D; Conclusion: Within the limitations of this study our data shows that the most common congenitally tooth agenesis is the second premolar %47.6 and the second most common congenitally missing tooth is lateral incisor %18.6.

Influencing factors and esthetic considerations of emergence profile of implant dentures in the anterior teeth area

The emergence profile of implant restorations plays an important role on the final esthetic outcome. This article intends to review the emergence profile design of implant restorations in the anterior teeth area, and analyse the factors that affect the emergence profile of implant restorations: implant neck design (non-platform-switching bone level implants, platform-switching implants, and soft tissue level implants), implant position and inclination (implant depth, buccal-lingual position, mesiodistal position, and axial inclination), the type of the abutment, quality and quantity of peri-implants soft tissues. The article aims to provide clinical guidelines for the emergence profile design of implant prostheses based on existing literatures and clinical experiences.

Learning an Optimal Operational Strategy for Service Life Extension of Gear Wheels with Double Deep Q Networks

One failure mechanism of gear wheels is pitting. If the gear wheel is case hardened, pitting degradation dominates normally at one tooth only. All the other teeth are still intact at the standardized end of life criterion of 4 % pitting area based on the total tooth area.&#x0D; Using an operational strategy that was developed at the Institute of Machine Components, the service life of gear wheels can be extended by a local stress reduction at the weakest tooth. This is accomplished by applying an adapted torque at the transmission input that shifts a minimum torque in the area of the pre-damaged, and thus, weakest tooth. Consequently, all remaining teeth with higher load bearing capacity are subjected to higher torque. Prerequisite for the described theoretical operational strategy is knowledge on pitting-size and -position. The detection of these properties in operation is not state of the art yet.&#x0D; In this work, only the gearbox vibration signal is known without explicit knowledge about the inside pitting. So the challenge is to determine the health for each individual tooth and to choose an optimal adapted torque based on this. This is especially difficult due to differing growth rates of pittings on one individual gear wheel. Hence, different pittings dominate over the service life, which results in the need of a continuous optimization of the torque control.&#x0D; Algorithms of Reinforcement Learning (RL) are particularly suitable for this challenge. In this branch of Machine Learning (ML), an agent interacts inside an environment and learns by getting rewards for taking actions at given states. In this study, the environment is a gearbox-simulation-model, the state is the current vibration signal, and the action is the chosen adapted torque. Thus, it is possible to let the algorithm learn the whole operational strategy, from online failure detection to an adapted torque at the transmission input.&#x0D; The results of this study show the theoretical feasibility of the operational strategy using Double Deep Q Networks as the RL Algorithm. The algorithm is able to learn a suitable reaction to pittings that increase linearly or progressively at an early stage and therefore delays their growth within the defined limits. Thus, the lifetime of the gearbox is extended while maintaining the same total power of the gearbox. As an outlook, the results will be examined for their sensitivity on several influencing factors in a further study. The wider view is to use this simulation on a test rig and validate the results.

Er:YAG Laser-Activated Irrigation in Comparison with Different Irrigation Systems for Cleaning the Apical Root Canal Area Beyond Ledge.

Objective: To evaluate the effectiveness of erbium:yttrium aluminum garnet (Er:YAG) laser-activated irrigation (LAI) for cleaning the apical root canal area beyond a ledge. Background data: This was the first study that evaluated the efficacy of LAI in debris and smear layer removal from such hard-to-reach canal areas in human teeth. Methods: Eighty-eight human maxillary molars with either a mesiobuccal or distobuccal canal with 25°-35° curvature and mature apices were used. Following instrumentation to a size 25/0.02 taper, a ledge was created at 2.2 ± 0.7 mm short of the apex and checked using microcomputed tomography. Samples were divided into four groups: syringe irrigation (SI), ultrasonic-activated irrigation (UAI), agitation with the XP-endo Finisher (XP), and LAI. Each group was subdivided based on the irrigation regimen: 9 mL of 6% sodium hypochlorite (NaOCl), and 6 mL of 6% NaOCl +3 mL of 14.3% ethylenediaminetetraacetic acid (EDTA) (n = 11). The apical 1-mm region was examined using scanning electron microscopy to evaluate the remaining debris and smear layer. Data were analyzed using the Kruskal-Wallis test and Mann-Whitney U test (a = 0.05). Results: Regardless of the irrigants used, LAI showed significantly lower smear layer scores than SI and XP (p < 0.05), with insignificant difference as compared with UAI. LAI showed significantly better debris removal than SI (p < 0.05) when NaOCl alone was used. Conclusions: In the apical area of ledged canals, the cleaning efficacy of Er:YAG LAI with/without EDTA was higher than SI and XP, but was comparable with UAI. Clinical Trial Registration number D2014-33.

Long-term evaluation of factors affecting removal torque of microimplants

BackgroundThe current study aimed to evaluate factors affecting the long-term stability of microimplants using removal torque and the correlation between removal torque and clinical variables.Materials and methodsThis research evaluated 703 microimplants placed in 354 patients (mean age: 30.4 ± 12.1 years). The removal torque was evaluated according to various clinical variables including sex, age, placement site, microimplant size, and placement method (self-drilling versus pre-drilling). Pearson correlation and stepwise multiple linear regression analyses were performed to investigate different variables and their association with removal torque.ResultsThe mean removal torque was significantly higher in the mandible (4.46 N cm) than in the maxilla (3.73 N cm). The values in the posterior teeth/retromolar areas were significantly higher than those in the anterior teeth area. There were no significant difference in terms of sex. Teenagers had a lower removal torque than older adults in the mandible, but not in the maxilla. Microimplants with a greater length and diameter, except for those with a greater diameter in the maxilla, was associated with a higher removal torque. Regardless of placement torque, the removal torque convergently reached approximately 4 N cm in both placement methods. The removal torque was significantly correlated with screw length in the self-drilling group and with diameter in the pre-drilling group.ConclusionsRemoval torque was related with placement site, age, placement method, and length and diameter of microimplants.

Plaque accumulation at the fitting surface and cleaning status in patients with full-arch implant-supported fixed prostheses: a cross sectional study

Objective: To observe the plaque accumulation at the fitting surface and oral hygiene status in patients with full-arch implant-supported fixed prostheses, and explore the possible influencing factors. Methods: Twenty-eight patients [17 males and 11 females, (63.0± 10.8) years old] with 40 full-arch implant-supported fixed prostheses (18 maxillary and 22 mandibular) were collected from January 2012 to September 2020 in Department of Implantology, Peking University School and Hospital of Stomatology. Plaque accumulation at the fitting surfaces were evaluated during the follow-up visit after 6 months following definitive prostheses delivery, by analyzing the digital photographs recorded by ImageJ. Meanwhile, the cleanliness of the fitting surface of prostheses and oral hygiene status were recorded. The oral hygiene habits and the patients' satisfaction with the prostheses were investigated by questionnaire, and the difference of plaque accumulation between different cleaning habits of dentures were compared. Results: The debris index of the fitting surface of the 40 full-arch implant-supported fixed prostheses were 3.28±0.75, and the percentage of area covered with plaque was (51.6±19.0)%. The debris index and plaque accumulation of the mandibular prostheses were significantly higher than that of the maxillary prostheses (P<0.05). In most mandibular prostheses (16/22), calculus was attached to the lingual side of the anterior tooth area. The reserved cleaning space of the restoration showed more plaque accumulation than in other parts. There was no significant difference in the percentage of area covered with plaque between groups with different cleaning habits. The satisfaction survey results indicated the "clean" project had a lowest score. Conclusions: The cleanliness of patients with full-arch implant-supported fixed prostheses was poor, and the hygiene status of the mandibular prostheses was worse than that of maxillary, especially in the anterior tooth area of mandibular prostheses. The influence of different cleaning habits on plaque accumulation was not observed.

Initial Change in the Occlusal Force and Occlusal Contact Area Following Single Molar Implant Restoration.

The occlusal force and occlusal contact area may be used to evaluate oral function following restoration of a missing tooth. This study aimed to monitor the initial changes in these factors after single molar implant restoration. Patients who underwent single implant restoration between December 2018 and September 2019 were recruited for this study. Occlusal force was measured before, immediately after, and 1 month after prosthesis placement. The occlusal contact area was evaluated immediately and 1 month after the placement. Data were grouped by sex, restored tooth, and restored side for analysis. In most groups, occlusal force was significantly increased 1 month after the placement compared with that before placement (P < .05), and the change was more significant in the first molar group than in the second molar group. There was a significant difference in the occlusal contact area of the implant prosthesis immediately and 1 month after placement when a thickness of 9 μm was used. The occlusal contact area of the natural tooth in the mesial side was significantly increased 1 month after placement (P < .05). Occlusal force was significantly increased 1 month after implant restoration, and restoration of the first molar had the most significant effect on the occlusal force. Occlusal contact areas may differ according to the occlusal indicator used in the clinical setting because the changes were significant with only 0 to 9 μm.

Diagnosis of Pulpitis from Dental Panoramic Radiograph Using Histogram of Gradients with Discrete Wavelet Transform and Multilevel Neural Network Techniques

Radiograph plays the major role of diagnosis, treatment and surgery in the Dental field. There are many types of Intra and extra oral radiographs in which Dental Panoramic Radiograph helps in visualising the full view of the oral cavity. Pulpitis is the dental diseases caused due to the inflammation of the dental pulp from untreated caries, trauma or multiple restorations which leads to Apical Periodontitis. To predict the severity of pulp vitality pulp inflammation has to be evaluated. Radiographs helps the dentist in diagnosing the extent of tooth decay and inflammation. An automatic diagnostic model is proposed using robust algorithms to diagnose pulpits. Dental Panoramic Radiograph is used in the proposed research to diagnose the pulpitis and to classify the normal teeth from the pulpitis. The collected images are pre-processed using Histogram Equalization and filtered using Gaussian and Median filters. Modified K-Means algorithm is applied to segment the bony and teeth area from the oral cavity area. Integral Histogram of Gradients with Discrete Wavelet Transform feature extraction techniques and Multi-Layer Neural Network Classifier is proposed to achieve the accuracy of 91.09% which can be used as an assistive tool by the dentist to diagnose pulpitis.

Body dysmorphic disorder (BDD) in the orthodontic and orthognathic setting: A systematic review

General prevalence of Body Dysmorphic Disorder (BDD), a psychiatric disorder in which patients focus on an imagined body defect not visible to others, varies between 0.7 and 2.5%. Up to 86% present with complaints in the area of teeth or face. Patients with BDD pursue an aesthetic rather than functional recovery, making BDD a possible contraindication to treatment. The aim of this systematic review was to review prevalence of BDD within the orthodontic and/or orthognathic population, to describe diagnostic tools for early detection of patients with BDD and to assess the outcome after treatment. A systematic search was conducted up to November 2020 using PubMed, Embase, Web of Science Core Collection and Cochrane Library. Following the screening of 1423 articles, 5 prospective studies were included. Prevalence of BDD within the orthodontic and orthognathic population varied from 5.2% to 13% (average of 6.2%). Literature showed a trend of higher BDD prevalence within younger, female and single patient population, although results are not conclusive. Questionnaires can be useful for preliminary detection of BDD. General anamnesis with questioning medical or psychiatric history, medication and personal expectations remains very important. Red flags could be previous consultations for the same problem or presence of psychiatric comorbidities. Prospective studies are necessary to map satisfaction of these patients and need for re-interventions after treatment.

The Effect of Ultrasonic Instrumentation on Finish Line Integrity

Purpose: Ultrasonic scaler is frequently used for temporary cement remnants removal from abutment teeth. A major concern is the alteration of the structural integrity of the abutment finishing line by the ultrasonic scaler. The current study evaluates the influence of ultrasonic scaling on the integrity of the finish line. The effect of finish line design (chamfer or feather edge), and its location (dentin or enamel) was also evaluated. Methods: Intact 22 human extracted molars were divided into 2 groups: finish line was prepared on enamel (n=11) and dentin (n=11), and further subdivided to finish line configuration groups (chamfer or knife-edge). Preparation of finish line was preformed following a standard repetitive procedure. 3D scans of the same tooth before and after ultrasonic instrumentation were performed. Pre and post scaling images were superimposed. The finish line alterations were evaluated and measured. The significance of the differences was evaluated using Students’ t-test. Results: The average alteration at the finish line area following ultrasonic scaling was 71.5 ± 24.6 μm. Higher alterations were found for enamel and for chamfer finish lines compared to dentin and knife edge, 134.4 ± 61.4 μm and 30.3 ±11.7 μm respectively. The highest change (228.6μm) was found for chamfer finish line located on enamel. The differences between groups were statistically significant (p&lt;0.05). Conclusion: Ultrasonic scaling alters the topography of the finish line area of abutment teeth and thus may compromise marginal fit and integrity of the final restoration.

Comparative Analysis of the Wear Performance of Spindle Hook Teeth During Fieldwork

Abstract The wear performance of the spindle hook teeth during fieldwork was compared, and the causes of the wear failure of the spindle hook teeth were analyzed. Samples of three kinds of spindle were obtained from the fixed installation position under continuous field operation conditions. The hardness, phase structure, elemental composition, and micromorphology of the spindle hook teeth were characterized using microhardness, X-ray diffractometer (XRD), energy spectrum analyzer (EDS), and scanning electron microscope (SEM) after cutting of the spindles. Results show that the coating hardness and element penetration zone of No.3 spindle hook tooth are the largest, and the surface coating phase structure of the three kinds of the spindle is mainly a body-centered cubic structure of Cr (211). Micro-crack and hole defects exist in the coating of all three kinds of the spindle. The thicknesses of the coating of No.1, No.2, and No.3 spindles are 74, 100, and 130 µm, respectively. During the field operation, the wear of the spindle hook tooth coating is caused by abrasive wear and fatigue wear, while the wear of the substrate is the result of the combined effect of abrasive wear and oxidation wear. Extracting the wear area and width of spindle hook teeth shows that the wear area of all three kinds of spindle hook teeth increases exponentially and the wear width changes linearly with the increase in the field operation area.

Evaluation and Comparison of Stress Patterns and Teeth Displacement with Intrusion of Maxillary Posterior Segment by Skeletal Anchorage System (Infrazygomatic Crestal Bone Screw) and High Pull Headgear: A 3D Finite Element Study

Introduction: In the last decades the application of the Finite Element Methodology (FEM) has become popular. It can calculate stresses and displacement in complex structures and can anticipate the tissue responses to orthodontic mechanics applied for treating different malocclusions. This study evaluated and compared the stress patterns and teeth displacement with application of 450g of intrusive force bilaterally on maxillary posterior segment utilizing a conventional old method, High-Pull Headgear (HPHG) and a newer method, Infrazygomatic Crestal Bone Screw (IZC-BS) using 3D-FEM. Method: A 3D-FEM model of the craniomaxillary segment with maxillary teeth was reconstructed from the Cone Beam Computed Tomographic image of a patient with class II div I malocclusion on class II skeletal base with anterior open bite and 450g of intrusive force was applied bilaterally on maxillary posterior segment utilizing HPHG and IZC-BS and stress patterns and teeth displacement were studied and compared. Result: Von Mises stresses on Zygomaticomaxillary, Zygomaticotemporal and Pterygomaxillary sutures and surface landmarks on maxillary, zygomatic, temporal and sphenoid bones were more pronounced and generalized for HPHG group. Intrusion, expansion and sagittal displacement of maxillary posterior segment were also more pronounced with HPHG group. Stresses weren’t present at the apical root areas of the maxillary posterior teeth for both the groups. Conclusion: On applying equal amount of intrusive force bilaterally to the maxillary posterior segment, stress patterns and teeth displacement were more pronounced and effective for HPHG group however; apical root areas of the maxillary posterior teeth in both the groups didn’t show any stresses.

Examination of the stresses of the implants applied to the atrophic edentulous maxilla on the maxillary bone

Aim: In advanced atrophy of the posterior maxilla, applied zygoma implants increase the success of the surgical procedure by reducing morbidity and procedure time. In our study, using tomographic records, a model with posterior atrophy was obtained in a computer environment, and zygomatic and dental implants in different numbers and localizations were applied to this model. The aim of our study was to choose the most accurate surgical planning according to the stresses arising from the applied forces.&#x0D; Methodology: In our study, one zygoma implant on the right and left in Group 1, two zygoma implants in Group 2, one zygoma implant in Group 3 and one dental implant in the first premolar tooth area, one zygoma implant in Group 4 and one dental implant in the lateral tooth area and one zygoma implant in Group 5 and one dental implant in the lateral and a first premolar tooth area were applied. 150 N were applied vertically to the prosthetic superstructure from the lateral tooth, 1st premolar tooth, 1st molar tooth and 2nd molar tooth. As a result of the applied forces, the maximum stress values ​​in the maxilla molar region were examined by finite element stress analysis.&#x0D; Results: In our study, it was observed that Group 1 had the highest stress value, followed by Group 3. Stress values in Groups 2, 4 and 5 were low and they were measured close to each other.&#x0D; Conclusion: As a result of our study, it was seen that zygomatic and dental implants applied in addition to the zygomatic implant reduce stress and the localization of dental implants affect the stress values.&#x0D; &#x0D; How to cite this article: Gülsün B, Çetindağ A. Examination of the stresses of the implants applied to the atrophic edentulous maxilla on the maxillary bone. Int Dent Res 2021;11(Suppl.1):210-5. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.30&#x0D; &#x0D; &#x0D; Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.