Tooth Area Research Articles

Mechanical and biological properties of current materials of clear aligner

With the development of new materials related to clear aligners, the physical properties are improving, and the clinical performance of the devices is expected to improve. Clear aligners require constant, controlled force on the teeth to achieve the desired tooth movement. However, unlike superelastic wires for orthodontic treatment, clear aligner materials are characterized by significant short-term or long-term stress relaxation after installation of the device. In addition, clear aligners are a complex manufacturing process that requires creating a tooth model and trimming the aligners, and various degrees of shrinkage and expansion may occur during the thermoforming process or direct printing of device. These changes can affect the thickness or fit of each tooth area and make it difficult to achieve the clinical treatment goals of clear aligner.Recently, multi-layered clear orthodontic products with improved physical properties have been introduced to increase the predictability of aligner treatment, and with the recent introduction of direct printing materials, innovative manufacturing methods for clear orthodontic devices have become possible. As shape memory properties have been reported among direct printing materials, interest in related materials is increasing. In this issue, we will introduce the latest materials related to clear aligners and explain the physical and biological properties that clinicians need to know for proper use.

Application of autogenous dentinal block to increase alveolar bone volume: a clinical case

Introduction. Materials based on extracted teeth in various studies have been radiographically and histologically proven to be effective in osteoplastic operations. These materials can be used in the form of crushed dentin matrix, a fragment of the tooth’s root and an autogenous dentin block. The purpose of this clinical case was to evaluate the effectiveness of using an autogenous dentin block to increase the alveolar process of the jaws in the preimplantation period.Description of a clinical case. Patient F., 30 years old, applied to the clinic of the Clinical Center of Maxillofacial, Plastic Surgery and Dentistry Russian University of Medicine with a complaint of a missing tooth in the frontal region of the lower jaw. At the time of treatment, the patient was already undergoing orthodontic treatment in another medical institution in Moscow. The patient underwent a clinical and radiological examination together with a prosthodontst. A diagnosis of «partial secondary adentia», «atrophy of the alveolar ridge in the frontal part of the lower jaw» and «dystopia of teeth 1.8, 2.8, 3.8, 4.8» was established. A comprehensive treatment plan has been drawn up. At the first stage, the patient underwent extraction of teeth 1.8, 2.8, 3.8, 4.8 for orthodontic indications with simultaneous bone grafting of the alveolar ridge in the area of the missing tooth 3.1. At the second stage, the patient underwent a trephine biopsy in the area of augmentation and installation of a dental implant in the area of missing tooth 3.1. The third stage was rational prosthodontic treatment on a dental implant in the department of prosthodontics.Results. The present study showed that autogenous dentinal block can serve as an alternative material for alveolar ridge augmentation.

An Evaluation Method of Dental Treatment Quality Combined with Deep Learning and Multi-index Decomposition

ABSTRACT Dentists judge that the quality of dental treatment for each patient is very time-consuming and inefficient, lacks quantitative evaluation criteria, and is easy to cause errors. At the same time, the traditional method of extracting tooth and root canal image features based on experience is difficult to accurately extract the tooth area and root canal filling area, resulting in low accuracy of tooth and root canal segmentation, which in turn affects the accuracy of tooth treatment quality evaluation. In this paper, a deep learning convolutional neural network is used to segment the root canal filling area, tooth boundary, and the boundary between tooth and soft tissue for the real patient ‘s root canal treatment and filling image. Finally, the segmented image is quantitatively evaluated according to the multi-evaluation index of professional doctors. The experimental results show that the intelligent evaluation method of dental treatment quality combined with deep learning and multi-index decomposition proposed in this paper not only unifies the evaluation criteria of dental treatment quality but also the therapeutic effect of quantitative scoring can effectively improve the work efficiency of doctors, which has reference significance for the application of artificial intelligence in the medical field.

ИЗМЕНЕНИЕ БИОТИПА ДЕСНЫ В ПРОЕКЦИИ ДЕНТАЛЬНЫХ ИМПЛАНТАТОВ

Deficiency of keratinized gum in the peri-implant zone contributes to bone recession and visualization of implant necks and abutments through its thin layer. To develop clinically effective and scientifically based protocols for the prevention and treatment of pathology of tissues surrounding implants, it is necessary to study the risk factors for the occurrence of mucositis and peri-implantitis, one of which is the deficiency or complete absence of attached keratinized gum in the implant area, as a result of which the mobile mucous membrane is constantly displaced during eating, talking, performing hygiene procedures. The gums are easily injured, which leads to rapid colonization of pathogenic microflora and the development of initial inflammation in the form of mucositis. The inflammatory process is launched, which in turn leads to an increase in the activity of osteoclasts. It should be noted that the rate of development of the inflammatory process in the area of implants is much higher than in the area of teeth. Due to the absence of the periodontal ligament, the inflammatory infiltrate directly spreads to the alveolar bone and penetrates into the medullary spaces. The gum contour in the area of installed implants must be aesthetic, stable and dense. This together will not only provide a cosmetic effect, but will also prevent the development of early and late complications of dental implantation. The paper provides an analysis of various methods of mucogingival surgery in the field of dental implants using an allogeneic graft of the “Alloplant” series. Engraftment of mucosal autografts from the tubercle of the upper jaw after surgery is accompanied by severe inflammation, which can lead to scarring of the mucosa or exposure of the bone. Allografts transplanted to patients to thicken the gums in the area of implantation are completely replaced after 6 months without signs of rejection or inflammatory processes by a full-fledged connective tissue regenerate covered with stratified squamous keratinizing epithelium. In the surgical area, gum tissue is formed in thickness, which can be classified as a “thick” gum phenotype.

Rehabilitation of missing teeth with severely tilted abutment tooth using telescopic bridge: A case report

Background: Prolonged missing teeth can cause the adjacent and or antagonist teeth to migrate towards the edentulous area which then complicate the rehabilitation process. From the patient perspective, it can also affect the functional and aesthetic aspect of their life. Hence, tooth loss whether in small or big number has to be replaced. Telescopic bridge defined as an artificial crown constructed to fit over a coping. It consists of inner and outer coping where the outer coping is cemented over the inner coping. Objective: To rehabilitate posterior missing teeth with severely tilted abutment tooth by fabrication of telescopic bridge. Case Report: A 55-year-old male patient came to prosthodontics specialty clinic at Universitas Airlangga Dental hospital on his volition with a chief complaint of replacement of missing one posterior tooth on both side of lower jaw as he has difficulty in chewing food and recurrence of food entrapment on the missing teeth area. The patient reported to have had missed his lower teeth since 5 years ago. The treatment chosen for this case was telescopic bridge fabrication. This treatment was conducted in order to correct the path of insertion of the prosthesis whilst give a satisfactory aesthetic and functional result. Conclusion: Telescopic bridge can restore aesthetic and functional aspect of missing teeth with a severely tilted abutment tooth.

Parameter Optimization of a Conveying and Separating Device Based on a Five-Stage Screw and Vibrating Screen for Tiger Nut Harvesters

To tackle problems such as the difficult separation from sand and the high power consumption of tiger nut harvesting in the sandy areas of Xinjiang, a conveying and separating device for tiger nut harvesters was designed. The axial and radial migrations of materials under screw action and the separation process of materials under vibratory action were analyzed dynamically. A simulation analysis was carried out on the conveying and separating process based on EDEM software. The migration trajectories of tiger nuts and sand particles were extracted, the displacement variations of sand particles on the X-axis, Y-axis, and Z-axis were analyzed in the action area of the screen-cleaning spike teeth and the screw action area, respectively, and the conveying and separation law of the tiger nut harvest mixture was clarified. With key parameters such as the screw velocity ratio, amplitude, vibration frequency, and machine operation velocity as test factors, and with the sand removal rate, crushing rate, and power consumption as test evaluation indicators, a four-factor, five-level orthogonal central composite test design was implemented. The test results were analyzed via the regression variance analysis method, and relation models between variable factors and evaluation indicators were constructed. The test results show that under the combined conditions of a screw velocity ratio of 0.88, an amplitude of 4.7 mm, a vibration frequency of 7.5 Hz, and a machine operation velocity of 0.92 km/h, the sand removal rate is 90.40%, the crushing rate is 1.66%, and the power consumption is 2.24 kW in theory. The optimized results were verified by tests. The sand removal rate was 88.92%, the crushing rate was 1.71%, the total power consumption was 2.29 kW, and the errors from the predicted values were 1.6%, 3.0%, and 2.2%, respectively, meeting the requirements for tiger nut harvesting conveyance and separation. This research can provide support for the development of technology and equipment for mechanized harvesting of tiger nuts in the sandy areas of Xinjiang.

Analysis of acupoint massage combined with touch on relieving anxiety and pain in patients with oral implant surgery.

Oral implant surgery is an effective procedure for artificial implants in missing tooth areas under local anesthesia. Because patients under local anesthesia are conscious during this procedure, compared with general anesthesia-related operations, they are more likely to experience negative emotions, such as anxiety and tension. These emotional reactions result in shivering and chills in the limbs, leading to poor doctor-patient cooperation and even avoidance of treatment. In traditional Chinese medicine, it is believed that acupoint massage regulates blood and Qi, dredge menstruation, and relieve pain, which is beneficial for patients' emotional adjustment; however, there are few related clinical studies. To observe the changes in anxiety and pain in patients with oral implant after acupoint massage combined with touch therapy. One hundred patients undergoing oral implantation in our hospital between May 2020 and May 2023 were randomly divided into control and study groups, according to a random number table, with 50 patients in each group. The control group received routine intervention, and the study group received acupoint massage combined with touch on the basis of the control group. Anxiety [assessed using the Modified Dental Anxiety Scale (MDAS)], pain severity, blood pressure, heart rate, and satisfaction were compared between the two groups. Before intervention, the difference in MDAS score between the two groups was not significant (P > 0.05), while after the intervention, the MDAS scores decreased in both groups compared with those before the intervention (P < 0.05); the MDAS score of the study group was lower than that of the control group, with a statistically significant difference (P < 0.05). The degree of pain in the intervention group was significantly lower than that in the control group (P < 0.05). Before the intervention, there were no significant differences in systolic and diastolic blood pressures or heart rate between the two groups (P > 0.05). The systolic and diastolic blood pressures and heart rate in the intervention group, during and after the intervention, were significantly lower than those in the control group (P < 0.05). The total degree of satisfaction in the study group was significantly higher than that in the control group (P < 0.05). Acupoint massage combined with touch better relieves anxiety and pain in patients undergoing dental implant surgery, improving the perioperative comfort of these patients and ensuring safety and a smooth operation.

Biometric analysis of furcation area of molar teeth and its relationship with instrumentation

The anatomy of furcation favours the bacterial retention and makes periodontal debridement as well as oral hygiene procedures difficult. Teeth that have lost attachment to a level of the furcation are said to have a furcal invasion or furcation involved.Involvement of furcation in a multi-rooted tooth poses a very different type of clinical situation in terms of establishment of diagnosis, determination of prognosis and of course planning the treatment modality.The present study was carried out on 200 selected extracted human first and second permanent molar teeth based on a predefined criteria. Teeth with prosthetic crowns, fused or fractured roots, those not fully developed, grossly carious or heavily restored at the cementoenamel junction (CEJ) were excluded from the study. The morphology of the root trunk was recorded by measuring various dimensions of the root trunk,including furcal angle and root trunk volume was calculated by using a custom made special apparatus. The furcation areas were debrided with different types of curettes in the market in order to see how best the instrument could be maneuvered in the furcation area. The data so obtained was statistically analysed using SPSS version 22. The highest root trunk volume and the longest root trunk length were found to be in the maxillary second molar. 48.60% furcations didn’t allow instrument engagementof furcation area with standard area specific curettes. The proposal of inclusion of root trunk length (mm) is suggested in addition to classification of FI to have assess prognosis and appropriate treatment for of the involved tooth.

Incident angle optimization with multiple conflicting objectives based on BP-MOPSO in oblique laser interferometry

The oblique incident phase-shifting interferometric measurement method is an effective technique for assessing gear tooth form deviation. In the measurement process, the tooth flank incident angle is a crucial factor determining the quality of interferograms. Addressing the challenge in traditional optical path design, where the selection of the tooth flank incident angle encounters a trade-off among quality features such as measurable tooth area (MTA), interference fringe density (IFD) and interferogram compression ratio (ICR), this paper proposes an optimized method for the tooth flank incident angle. Firstly, a comprehensive evaluation model is established to calculate and analyze the MTA, IFD and ICR of the helical gear. Secondly, by integrating BP neural network and Multi-Objective Particle Swarm Optimization (MOPSO) algorithm, a tooth flank incident angle optimization method is devised to simultaneously optimize the measurement light incident angle γ and the rotation angle of the gear axis β. Finally, simulation analyses and physical experiments are employed to demonstrate the feasibility of the proposed method, compared to before optimization, the pseudocorrelation (PSD) value has increased by an average of 34%, and the residual points have decreased by an average of 80%, confirming its capability to improve quality interferogram and measurement accuracy.

Reliability of Radiovisiography and Cytomorphometry in Determining the Age of an Individual: A Clinical Comparative Study.

The oral cavity can be explored as an area to identify the impacts of aging. Exfoliative cytology is a painless, rapid, and effective method for collecting intact cells from various epithelial layers for microscopic examination. Therefore, the current study's objective was to determine the average cell size using morphometric analysis and radiovisiography (RVG) to estimate an individual's age utilizing buccal smears and the pulp/tooth ratio. A software program was utilized to determine the cell size using exfoliative cytology, and the pulp and tooth area was measured using RVG of mandibular canine with the help of an image analysis software. Appropriate statistical tests were performed using IBM SPSS statistical software for Windows (version 25). The patient's chronological age, pulp area, and the associated pulp-tooth area ratio values were determined, along with Karl Pearson's correlation coefficient. It was discovered by using a paired t-test to compare chronological age to the age deduced from cell size and pulp-tooth area ratio. According to the current study, age estimation could be done based on average cell size, pulp size, and pulp-tooth area ratio for forensic odontology. Studies with bigger sample sizes and diverse population would help achieve definitive conclusions about the reliability of this particular method.

Retrospective study evaluating dental side effects of radiotherapy in patients treated for head and neck cancer

IntroductionHead and neck cancer squamous cell carcinoma (HNSCC) is the seventh most common cancer worldwide with around 600,000 new diagnosis each year. Nowadays, in locally advanced disease, radiotherapy (RT) play an important role, this with or without chemotherapy in organ preservation strategies. More specific for early stage localized disease, RT (or surgery) seems to give similar results on locoregional control (LRC) and choice is made according to the organ preservation issue. Despite the fact that technical improvements have been made to optimize the radiation dose delivery and minimize the normal tissue toxicity, RT is associated with potential early and late toxicities. Osteoradionecrosis of the jaw (ORNJ), especially seen after teeth extraction, is one of the associated toxicities and can significantly impair the patient's quality of life. Because of the fear of developing ORNJ, one is very reluctant to extract or place a dental implant post-radiotherapy, especially in high irradiation dose zones (>40 Gy). Hence, it is important to define teeth at risk of future extraction before initiating RT and to handle those in high-risk irradiation zones. In order to optimise extractions, we created a predictive model of the expected irradiation dose, and thus the need for extraction, to the teeth bearing bones. The aim of this study is to validate our model and to define the potential relationship between the radiation dose received by each tooth and the dental complications observed. Material and methodsBetween March 2012 and March 2018, patients with HNSCC treated by intensity modulated RT were retrospectively analysed. The mean irradiation dose for each tooth was generated on the administered treatment plan by contouring each tooth separately on each dosimetric scan section using dedicated software (Eclipse, Varian). In order to validate our predictive model, we compared the actual generated/administered teeth irradiation doses with the irradiation doses predicted by our model. ResultsOur predictive model was accurate in 69.6% of the cases. In 12.5% of cases the predicted dose was higher than the calculated dose and lower in 17,8% of the cases. A correct- or over-estimation (is the latter being clinically less worrying than an underestimated dose) was achieved in 82% of cases. For the 18% of cases underfitting, the mean margin of error was 5.7 Gy. No statistically significant association was found between the development of caries and doses to the teeth, doses to the parotid glands or dental hygiene. However, a significant association between dental irradiation at more than 40 Gy and the occurrence of dental fractures (p = 0.0002) were demonstrated. ConclusionsOur predictive model seems to be 82% accurate for dose prediction, hence might be helpful for optimizing/minimizing prophylactic extractions. Indeed, following our model, professionals could decide not to extract damaged teeth in areas not at risk of ORNJ, lowering morbidity during and after RT. Contrary to the literature, no relationship was found between the occurrence of dental caries and parotid irradiation and the patient's oral hygiene. However, for the first time, a highly significant correlation between the occurrence of dental fracture and dental irradiation at more than 40 Gy was observed.

Morphometric Measurements of Root Anatomic Areas of Maxillary First Premolar Teeth in a Representative Nepalese Population

Background The prognosis of furcation involved maxillary first premolar is typically guarded to poor. The presence of concavities in the root trunk and the positioning of the roots in the buccal and palatal regions of the teeth are responsible for its challenges during instrumentation and control plaque. We aimed to access the presence of concavities on the root surface as well as morphometric measurement of the root trunk dimensions in the maxillary first premolar teeth in Nepalese population.MethodsA cross-sectional quantitative study was conducted in the Department of Periodontics and Oral Implantology, College of Medical Sciences (CoMS). Extracted Maxillary first premolar teeth were evaluated for the number of roots, morphometric measurement of the root trunk, root divergence, and root length. The presence of concavities was recorded on the mesial and distal root surface at cervical, middle, and apical thirds of the root.ResultsThe overall mean root trunk length was less on the mesial aspect than on the distal aspect (6.39 ± 2.54 and 8.08 ± 3.48 respectively). The prevalence of root surface concavity on the cervical third at the mesial aspect (90 %) was found to be higher than in the distal aspect (15%) Conclusions Owing to the higher prevalence of root surface concavity on the cervical third of mesial aspect, use of mini-bladed curettes is recommended for the effective root surface debridement of the periodontally involved maxillary first premolar tooth. Patients with periodontally involved maxillary first premolar should be advised to use interdental brushes rather than dental floss.

ORTHODONTIC EXTRUSION TECHNIQUE AS A METHOD FOR ALVEOLAR BONE VOLUME INCREASE BEFORE DENTAL IMPLANTATION. CLINICAL CASE

Objectives: Tooth extraction and replacement with dental implant represents a common treatment choice, when teeth are hopeless. We presented a clinical case, the treatment of which was carried out by the method of orthodontic extrusion technique. This technique can increase alveolar bone level and also soft tissue level. The increased amount of alveolar bone can improve primary implant stability and be compared with bone regeneration techniques. The purpose of presenting this clinical case is to emphasize the efficiency of orthodontic extrusion. Methods and materials: A 45-year-old female patient referred by the general dentist regarding cosmetic defect and tooth mobility in the area of the anterior upper teeth. During the examination, her upper right central incisor was found to be mobile, with diastema and slight congestion in the anterior teeth Photographs, CT and X-ray studies of the patient were used. The patient was bonded with .018 slot Roth prescription ceramic brackets (Dentaurum, Germany). After achieving the optimal results of orthodontic treatment and the necessary extrusion of the upper right central incisor, the tooth was removed and replaced with a dental implant. After six months, the patient had a crown with a screw fixation of zirconium dioxide with ceramic application Results: As a result of orthodontic extrusion, clinically significant increase in alveolar bone and gingival tissue was reported. This resulted significant qualitative and quantitative improvements in the implant site. As the clinical case was in aesthetic zone, we could also rehabilitate beautiful smile of patient and increase her self-esteem. Conclusions: Summing up the above and the results of the treatment of this patient, we can definitely say that orthodontic extrusion technique is effective for implant site development. As we have described, this can effectively move the facial gingival margin and allow for esthetic restoration of implant placed in the extruded tooth position without any bone graft.

Prevalence of cervical enamel projections and enamel pearls on furcation area of Iraqi molar teeth

Cervical enamel projections and enamel pearls in relation to molar furcationsmay act as predisposing factors in periodontal attachment loss. The objectives of thisstudy were to investigate the prevalence of cervical enamel projections and enamelpearls on furcation areas of molar teeth of Iraqi population. The material consisted of(465)extracted upper and lower molars. They were (200) upper molars and (200) )lower molars extracted because of` caries and pulp lesions(groupl), while the othermolars extracted because they were periodontally diseased(group2). The cervical )64(enamel projections were classified into three grades(described according to peter et al 2000)For group l the results showed that (5l%) of upper molars and (66%) of lowermolars had cervical enamel projections. Enamel pearls were identified on (1.5%) ofupper molars and (2.5%) of lower molars. Maxillary molars had (59.8%) grade Icervicaljnamel pro`ections and 28.4%) grade ll and (ll.7%) rade III. Whilemandibular molars showed (66.6%) teeth with grade I, (24.2%) teeth with grade IIand (9%) teeth with grade III .For grou 2 cervical enamel rojcctions were identifiedon (70.7%) ofthe collected molarsThe results of the present study give an indication that cervical enamelprojections are frequent enough to be of clinical importance&#x0D;

Biomechanical analysis of total arch maxillary distalization using infrazygomatic crest miniscrews: a finite element analysis study

AimTo evaluate the maxillary incisors and canine’s immediate movement tendency using three different power arms (PA) height levels during total arch maxillary distalization supported on infrazygomatic crest (IZC) miniscrews according to finite element analysis (FEA).MethodsThree finite element models of the maxilla were developed based on CBCT imaging of a teenage male patient presenting a Class II Division 1 malocclusion in the early permanent dentition. Maxillary complex, periodontium, orthodontic accessories, IZC miniscrews and an orthodontic wire were digitally created. The PAs were placed between canines and lateral incisors and projected at 4, 7, and 10 mm height distances. After that, distalization forces were simulated between PA and IZC miniscrews.ResultsThe anterior teeth deformation produced in the FEA models was assessed according to a Von Mises equivalent. The stress was measured, revealing tendencies of initial maxillary teeth movement. No differences were found between the right and left sides. However, there was a significant difference among models in the under-stress areas, especially the apical and cervical root areas of the maxillary anterior teeth. More significant extrusion and lingual tipping of incisors were observed with the 4 mm power arm compared to the 7 mm and 10 mm ones. The 10 mm power arm did not show any tendency for extrusion of maxillary central incisors but a tendency for buccal tipping and intrusion of lateral incisors.ConclusionThe maxillary incisors and canines have different immediate movement tendencies according to the height of the anterior point of the en-masse distalization force application. Based on the PA height increase, a change from lingual to buccal tipping and less extrusion tendency was observed for the incisors, while the lingual tipping and extrusion trend for canines increased.

Oral hygiene practices and associated factors among rural communities in northwest Ethiopia

BackgroundPoor oral hygiene affects the overall health and quality of life. However, the oral hygiene practice in rural communities and contributing factors are not well documented. Accordingly, this study was conducted to assess oral hygiene practices and associated factors among rural communities in northwest Ethiopia.MethodsA cross-sectional study was conducted among 1190 households. Data were collected using a structured and pretested questionnaire, prepared based on a review of relevant literature. The questionnaire comprises socio-demographic information, access to health and hygiene messages, oral hygiene practices, and water quality. We assessed oral hygiene practices with these criteria: mouth wash with clean water in every morning, mouth wash with clean water after eating, brushing teeth regularly, and avoiding gum pricking. Gum pricking in this study is defined as sticking needles or wires into gums to make the gums black for beauty. Multivariable logistic regression was used to identify factors associated with oral hygiene practices. Significant associations were declared on the basis of adjusted odds ratio with 95% confidence interval and p-values < 0.05.ResultsResults showed that all the family members usually washed their mouth with clean water in everyday morning and after eating in 65.2% and 49.6% of the households, respectively. Furthermore, 29.9% of the households reported that all the family members regularly brushed their teeth using toothbrush sticks and one or more of the family members in 14.5% of the households had gum pricking. Overall, 42.9% (95% CI: 39.9, 45.6%) of the households had good oral hygiene practices. Health and/or hygiene education was associated with good oral hygiene practices in the area (AOR: 1.66, 95% CI: 1.26, 2.21).ConclusionMore than half of the households had poor oral hygiene practices in the area and cleaning of teeth with toothpastes is not practiced in the area, where as gum pricking is practiced in more than one-tenth of the households. The local health department needs provide community-level oral health education/interventions, such as washing mouth with clean water at least twice a day, teeth brushing using indigenous methods such as toothbrush sticks or modern methods such as toothpastes, and avoiding gum pricking to promote oral health.

Clinical analysis of the tooth-implant papilla for two narrow-diameter titanium-zirconium implants in the anterior area: prospective controlled clinical study

BackgroundRehabilitation of the anterior area when the mesio-distal space is reduced is a challenge for the clinician, due to the patient’s anatomical limitations and aesthetic requirements. Narrow Diameter Implants (NDI) are an option of treatment when the standard diameter implant is not possible, but the evidence is scarce. This prospective clinical study aims to analyze the formation of the tooth-implant papilla between the implant and the adjacent natural tooth in the maxillary lateral incisors and mandibular incisors.MethodsA total of 40 patients treated with NDI, of titanium-zirconium (Ti-Zr) alloy i.e., 2.9 mm Test Group (TG) and 3.3 mm Control Group (CG), were included. The mesiodistal distance between the adjacent natural teeth was used for implant selection, maintaining 1.5 mm between the fixation and the adjacent tooth. Clinical assessment was performed by a clinical examiner at 6 and 12 months after the final prosthesis. The primary variable was the Jemt Papillary Index. Also, implant survival rate (SR), complications, Implant Stability Quotient (ISQ), and patient-reported outcomes measures (PROMs) such as aesthetics, chewing, phonation, comfort, and self-esteem were analyzed.ResultsA significant amount of papilla filling was observed concerning the baseline, with a trend towards more formation of the papilla in the TG, with a JPI score of 3. No significant differences were observed between the two groups regarding implant SR, clinical parameters, and complications. In terms of PROMs, a higher satisfaction in the TG was observed, with significant intergroup differences for aesthetics, comfort, self-esteem, and primary stability ISQ (TG: 59.05 (SD: 5.4) vs. CG: 51.55 (SD: 5.7)).ConclusionsThe 2.9 mm diameter Ti-Zr implants achieved a formation of papilla similar to 3.3 mm implants in the anterior region at 12 months of follow-up after the final prosthetic restoration. The use of Ti-Zr implants with a diameter of 2.9 mm to rehabilitate single teeth in areas of the anterior region, where the mesiodistal distance is limited, showed favorable clinical results and a high degree of satisfaction during 1 year of observation similar to 3.3 mm dental implants.Trial registrationThis study was retrospectively registered in ClinicalTrials.gov with the number NCT05642520, dated 18/11/2022.

Influence of fixed orthodontic steel retainers on gingival health and recessions of mandibular anterior teeth in an intact periodontium - a randomized, clinical controlled trial

ObjectiveAim of this randomized clinical controlled trial was to evaluate the influence of fixed orthodontic steel retainers on gingival health and recessions of mandibular anterior teeth.Materials and methodsAfter end of the orthodontic treatment, patients were randomly assigned into the test (fixed steel retainer) or control group (modified removable vacuum-formed retainer). Periodontal parameters (periodontal probing depth: PPD; recession: REC; bleeding on probing: BOP) as well as plaque and gingival index were assessed on mandibular anterior teeth directly before attaching/handing over the retainer (baseline: BL), 6 and 12 months after orthodontic treatment.Results37 patients (test: n = 15, mean age: 16.1±4.2 years; control: n = 17, mean age: 17.1±5.4 years) completed the study. REC and PPD failed to show significant pairwise differences. The number of patients showing gingival health in the area of the mandibular anterior teeth (test: BL n = 10, 6 months n = 9, 12 months n = 11; control: BL n = 10, 6 months n = 16, 12 months n = 15) revealed a significant difference for the intra-group comparison between BL and 6 months in the control group (p = 0.043). The inter-group comparisons failed to show significant differences.ConclusionYoung orthodontically treated patients with fixed steel retainers show in 73.3% healthy gingival conditions after one year which are comparable to the control group (88.2%). Gingival recessions were in a clinically non-relevant range at any time of the examination.Clinical trial numberDRKS00016710.

Experimental study on wear failure of spindle hook teeth of cotton picker

Introduction: The wear failure of spindle will lead to a decrease in cotton harvesting rate of the cotton picker during field operation and serious wastage.Method: Three types of spindle samples at different installation positions and working areas were obtained through field experiments to explore the wear failure law of spindle hook teeth of cotton picker during field operation. Hardness of hook tooth coating and substrate of spindles were tested, surface and cross-section microstructure of the spindle hook teeth were characterized, and wear area and width of the spindle hook teeth were extracted.Results: Results showed that the hardness of the hook tooth coating is evidently higher than that of the substrate; the average coating hardness of the No. 3 spindle hook teeth reaches the maximum at 1033.6 HV0.1; defects, such as microcracks and micropores, exist in the coating of the three types of spindle hook teeth; and the thickness of the coating is between 70 and 130 μm. The wear area of spindle hook tooth changes exponentially and the wear width changes linearly with the increase of field operation area at the same installation position. The wear area and width of the spindle hook teeth gradually increase with the decrease of the installation height and the wear change of the hook teeth is negatively correlated with the installation height in the same field operation area.Discussion: The wear failure of spindle hook tooth is mainly caused by abrasive, fatigue, and oxidation wear. The results of this study can provide a reference for improving the wear resistance of spindle hook teeth.

Comparison of plaque control record measurements obtained using intraoral scanner and direct visualization.

Intraoral scanner (IOS) can acquire three-dimensional color images of teeth. Thus, the detection of areas with plaque adhesion stained by plaque-disclosing solutions using an IOS could be a potential oral hygiene evaluation method. This study aimed to verify the usefulness of obtaining O'Leary's plaque control record (PCR) measurements using an IOS in clinical practice. Twenty patients with >20% PCR measurements who underwent oral prophylaxis were enrolled in this study. A plaque-disclosing gel was applied to stain the areas with plaque adhesion, and the dentition was scanned using the IOS. The PCR values obtained via the direct method and those obtained using the digital image were compared for the entire dentition, maxillary total area, the labial and palatal aspects of the maxillary anterior teeth, the buccal and palatal aspects of the maxillary posterior teeth, mandibular total area, the labial and lingual aspects of the mandibular anterior teeth, and the buccal and lingual aspects of the mandibular posterior teeth. The IOS group tended to have higher values than the direct observation group. The labial and palatal aspect of the maxillary anterior teeth, the labial and lingual aspects of the mandibular anterior teeth did not differ significantly between the groups. Plaque adhesion was visualized easily and conclusively using an IOS. As the large tip size often hinders its use, it is necessary to develop a smaller IOS tip in the future.