Tooth Area Research Articles

Comparing the accuracy and treatment time of a robotic and dynamic navigation system in osteotomy and root-end resection: An invitro study.

To compare the accuracy and treatment time of a robotic system (RS) and a dynamic navigation system (DNS) in osteotomy and root-end resection in an invitro study. In this study, four identical mandibular models were created using three-dimensional (3D) printing, each model including 18 teeth. In the surgical procedures, teeth #35, #33, #32, #42, #43 and #45, along with the mesiobuccal roots of teeth #36 and #46, were specifically selected for operation on each model. Cone-beam computed tomography (CBCT) and intraoral scans were performed on all models. DentalNavi software was used to plan a drilling path and depth as well as design surgical accessories. In the RS, osteotomy and root-end resection were performed with robotic assistance, whereas in the DNS, these procedures were performed using dynamic navigation. Post-operative CBCT scans were obtained. Global platform deviation, global apex deviation, angular deflection, and time were compared to evaluate the accuracy and treatment time of the surgeries. The treatment time was defined as the registration time and drilling time. Statistical analyses were performed using the Shapiro-Wilk and independent sample t-test. The global platform deviation, global apex deviation and angular deflection in the RS group were significantly smaller than those in the DNS group (p <.05). The registration time in the RS group was significantly longer than that in the DNS group (p <.001), whereas the drilling time was significantly shorter (p <.001). The overall surgical time was significantly longer in the RS group than in the DNS group (p <.001). Subgroup accuracy analysis revealed that in both the anterior and posterior tooth regions, the RS group exhibited significantly smaller apical and angular deviations than the DNS group (p <.001). Additionally, in both the anterior and posterior tooth subgroups, the total time for the DNS group was significantly shorter than that for the RS group in the anterior tooth area (p <.01). RS showed higher accuracy and shorter drilling time in osteotomy and root-end resection compared to DNS. The RS holds promise as a reliable technological advancement in endodontic microsurgery. However, future endeavours should prioritize the reduction in registration time.

FABRICATION OF ALL PORCELAIN CANTILEVER BRIDGE RESTORATION IN CASES OF GINGIVA RECESSION USING ZIRCONIUM DIOXIDE MATERIAL WITH ADDITIONAL RETENSION

Background: Aesthetic and functional dental restoration is a hope for people who have lost teeth, especially in the anterior region. Missing tooth 13 with more than 2 mm gingival recession can be made into a cantilever bridge restoration with the addition of porcelain gingiva. Gingival recession is when the tooth root surface is exposed due to periodontal tissue loss. Zirconia is a dental restoration material often used because of its biocompatibility, strength, and aesthetics. Purpose: To determine the procedure for making all porcelain cantilever bridge restorations in cases of gingival recession using zirconia material. Case analysis: The dental laboratory received a dental cast model of a 39-year-old female patient missing tooth 13 and had gingival recession on tooth 14 of more than 2 mm. Order in the form of restoration of all porcelain cantilever bridges from zirconia. Result: The cantilever bridge coping was made from zirconium dioxide and then layered with feldspathic porcelain to achieve optimal strength and aesthetics. A rest is made on tooth 12 to provide additional retention. Conclusion: The procedure for making all porcelain cantilever bridge restorations includes making diagnostic wax-up, scanning, coping design, milling, sintering, fitting, sandblasting, layering, anatomy, and glazing. Things that must be considered are the design, thickness of the coping, and connectors to achieve a restoration that is strong, resistant to fracture, and has good aesthetics. Porcelain gingiva was added in the cervical area of tooth 14 restorations to cover the recession

Retrospective analysis and clinical features of periapical tissue regeneration

Background: Chronic periodontitis is associated with changes in periapical tissues. Untimely diagnosis and lack of appropriate mechanical treatment increase the incidence of chronic periodontitis. Periodontitis that causes destructive changes due to long-term inflammation of periapical tissues is of particular concern. Thus, the treatment of destructive periodontal diseases is a pressing issue in modern dentistry. Aim: To assess periapical tissue regeneration following treatment in chronic periodontitis patients. Materials and Methods: A retrospective analysis of the destruction and regeneration of periapical tissues before and after treatment during 3–6 months was performed in 20 patients. Results: A retrospective analysis of X-ray findings in 20 patients revealed bone destruction of varying degrees. Low-quality root canal preparation was due to various factors, primarily the anatomy and topography of root canals. Of the 20 patients who required treatment for chronic periodontitis with varying degrees of destruction, 16 came back for follow-up appointments and received endodontic treatment. Following treatment, X-ray findings were used to identify taper root canal preparation and assess the quality of obturation up to the root apex. X-ray examination was performed after 3 months in patients with clinical signs of periodontitis and after 6 months in patients without clinical signs of periodontitis. After 3 months, X-ray findings showed a reduction in bone destruction in the causative tooth area, indicating an improvement. Conclusion: The study of periapical tissue regeneration following treatment in chronic periodontitis patients revealed that effective apical preparation, as well as appropriate irrigation and root canal filling, promote regeneration in periodontitis. Healing of periapical tissues is essential for effective root canal treatment.

Prevalence of gingival overgrowth among patients at the periodontology clinic of Dental Hospital Universitas Airlangga

Background: The prevalence of dental and oral health problems in Indonesia, including periodontal disease and gingival overgrowth (GO), remains high and requires serious attention from health workers. This study aims to determine the prevalence of GO due to the existing data gap and public concern regarding this condition. Objectives: To determine the prevalence of gingival overgrowth among patients at the periodontology clinic of Universitas Airlangga Dental Hospital. Material and Methods: This study was conducted from August to September 2023 at the Dental and Oral Hospital (RSGM) Universitas Airlangga using a descriptive observational method with a cross-sectional design. The sample was calculated using total sampling from medical record data of patients at the Periodontics Clinic of the Dental and Oral Hospital (RSGM) Universitas Airlangga who met the inclusion criteria in 2022. The study variables included gingival overgrowth (GO), gender, age, and tooth region (sextant). Data were processed using Microsoft Excel and presented as a percentage (%). A descriptive data analysis was carried out to draw a conclusion. Conclusion: The study found that 37.11% of patients at the Dental and Oral Hospital (RSGM) of Universitas Airlangga experienced gingival overgrowth. The percentage of male patients experiencing gingival overgrowth was higher than that of women, with the highest age group being 18-24 years. The tooth area that experienced the most gingival overgrowth was sextant 5, with a total of 29 samples.

Effectiveness of nonsurgical re-instrumentation: Tooth-related factors.

To investigate tooth-related factors that influence pocket closure (PC) and the reduction of pocket probing depths (PPD) after nonsurgical re-instrumentation (NSRI) as part of step 3 therapy. A total of 480 patients (10,807 teeth) presenting with residual pockets 6.33±3.79 months after steps 1 and 2 of periodontal therapy were included and retrospectively analyzed before and 5.93±4.31 months after NSRI. Reduction of PPD and PC rates following NSRI were associated with tooth-related factors, namely tooth type, arch, number of roots, furcation involvement (FI), pulp vitality, mobility, type of restoration, presence of plaque, and bleeding on probing (BOP), using mixed-effects regression models. NSRI reduced periodontal pockets persisting after initial cause-related therapy by (mean±SD) 1.32±1.79mm in PPD, and PC rate was 40%. Moderate pockets (4-5mm) responded better to NSRI than deep pockets (≥6mm) in terms of PC (51% vs. 16%). Both PPD reduction and PC rates of deep residual pockets were significantly influenced by tooth type, arch, number of roots, and presence of BOP. Tooth type, arch, number of roots, and presence of BOP at re-evaluation (before NSRI) had a significant and clinically relevant influence on NSRI as part of step 3 therapy. Considering these factors, particularly for deep residual pockets, may allow more tailored re-intervention. The present study aimed to investigate the influence of tooth-related factors on the outcome of repeated nonsurgical therapy of periodontitis. Therefore, 480 patients (10,807 teeth) presenting with clinical symptoms of persistent periodontitis after initial therapy were administered repeated nonsurgical therapy and retrospectively analyzed. Therapy outcomes were associated with tooth-related factors, namely tooth type, tooth location (maxilla/mandible), number of roots, involvement of the root furcation area in multi-rooted teeth, pulp vitality, mobility, restoration, presence of plaque and bleeding upon periodontal probing, using mixed-effects models. The results revealed that repeated nonsurgical therapy was effective in reducing inflammation and clinical signs of disease, with moderate residual periodontal defects responding better than deep defects. Healing of deep defects after repeated nonsurgical therapy; however, was significantly influenced by the factors: tooth type, location, number of roots, and bleeding on probing. Considering these factors, particularly in deep residual defects which are commonly suggested to be treated surgically, may allow less invasiveness and thus a more tailored re-intervention.

Effects of occlusal hypofunction on root surface area in patients exhibiting anterior crossbite in skeletal Class III malocclusion: a CBCT study

ABSTRACT Purposes To evaluate and compare the effects of occlusal hypofunction on root surface areas (RSAs) of permanent teeth in patients with Class III and Class I skeletal relationships. Materials and Methods Thirty-two CBCT images of all permanent maxillary and mandibular teeth, except the third molars, from 16 patients (mean age 23.71 ± 4.04 years) exhibiting Class III skeletal relationships and 16 patients (mean age 24.53 ± 4.91 years) exhibiting Class I skeletal relationships were imported into the Mimics software version 15.01. The outer boundaries of the teeth in two-dimensional images were manually identified on each CBCT slice along the coronal, sagittal, and axial planes to construct three-dimensional models. The tooth models were transferred into 3-matic version 7.01 to specify cementoenamel junctions and calculate RSAs. Intra-examiner reliability was assessed using the intra-class correlation coefficient. The RSAs of each tooth type from the two groups were illustrated and compared using independent t-tests (p < 0.05). Results The RSAs of the maxillary second molars in the skeletal Class III group were significantly higher than those in the skeletal Class I group. There were no significant differences in RSAs between the two groups regarding other tooth types. Conclusions Young adults exhibiting Class III skeletal relationships exhibited significantly greater RSAs in the maxillary second molars. This might be related to occlusal hypofunction during dental root formation.

Analysis and comparison of tooth wear in late antiquity and early middle age in populations that lived in continental and coastal Croatia using digitized VistaMetrix method.

Tooth wear is a non-pathological loss of hard tissues on the incisal and occlusal tooth surface. In archaeology, the loss of dental tissue through attrition is associated with living opportunities and habits, availability, characteristics and methods of food preparation. In forensics, tooth wear is used to estimate the dental age on cadavers. For this study, we used an archaeological sample from two sample collections. In this study, tooth wear was compared in archaeological samples of well-preserved maxilla and mandible specimens (n=392) from Croatian coastal and continental populations from Late Antiquity (LA) and the Early Middle Ages (EMA). The computer system VistaMetrix 1.38 was used to analyse the abrasion and attrition of hard dental tissues. The Shapiro-Wilk and chi-square tests were performed for categorical data to test the difference between two historical periods and two geographical locations, while the Kruskal-Wallis test was performed for continuous data. There was a statistically significant difference in the proportion of tooth wear in total teeth area (P < 0.001) when comparing continental and coastal Croatia in LA and coastal Croatia between LA and EMA (P = 0.006 and P < 0.001, respectively). Samples from coastal Croatia from the LA period had the lowest percentage of tooth wear with a median of 8.35%, while samples from coastal Croatia from the EMA had the highest percentage of tooth wear with a median of 18.26%. Our results generally show greater tooth wear in the EMA period in male subjects. The results of the tooth wear research obtained with the Vista Metrix software can contribute to the study of life circumstances and changes that the analysed population has experienced in its historical development.

Understanding the Effect of Drilling Parameters on Hole Quality of Fiber-Reinforced Polymer Structures.

Hole quality in composite materials is gaining interest in aerospace, automotive, and marine industries, especially for structural applications. This paper aims to investigate the quality of holes performed without a backup plate, in thin plates of glass fiber-reinforced polymer (GFRP). The samples were manufactured by two different technologies: vacuum bagging and an innovative method named vacuum mold pressing. Three experiments were designed choosing the control factors that affect the maximum cutting force, delamination factor, and surface roughness of drilled holes in composite materials based on twill fabric layers. Quality analysis of the hole features was performed by microscopy investigations. The effects of the main factors on the targets are investigated using the statistical design of experiments, considering control factors, such as support opening width, weight fraction (wf), feed per tooth, and hole area. The results showed that the feed per tooth and hole area had a more significant influence on the delamination factors and surface roughness (Sa). The best quality of the holes drilled in twill-based GFRP was achieved for a lower feed rate of 0.04 mm/tooth and used a support opening width of 55 mm.

Evaluation of the efficacy of different irrigation activation techniques in removing of calcium hydroxide on teeth with the simulated internal root resorption cavity: a confocal laser scanning microscope analysis.

The aim of this study is to evaluate the effect of different irrigation activation methods on root canal sealer penetration in teeth with simulated internal root resorption (IRR) and calcium hydroxide (CH) applied using a confocal laser scanning microscope (CLSM). 60 incisors with a single root and a single canal were included in the study. IRR cavities were created in the middle third of the root canal, and CH was placed. The samples were randomly divided into 4 groups (n = 15) according to the irrigation activation method to be tested: standard needle irrigation (SNI), sonic activation (EDDY), photon-induced photoacoustic flow (PIPS), and shock wave enhanced emission photoacoustic flow (SWEEPS). After irrigation activation applications, the root canals were obturated. Sections of 1.0 ± 0.1mm were taken from the apical, middle, and coronal regions of each sample. The penetration area (µm2) and maximum penetration depth (µm) of the root canal sealer were examined by CLSM and analyzed using ImageJ software. Statistical analysis was performed with a one-way ANOVA and post-hoc Tukey test at the P < 0.05 significance level. Among all irrigation activation methods tested, both the penetration area and maximum penetration depth of the root canal sealer were greater in the coronal region than in the apical region (p < 0.05). In the IRR region, there was no difference in terms of maximum penetration depth between PIPS and SWEEPS (p > 0.05), it was highest in SWEEPS (p < 0.05). PIPS and SWEEPS were better than other irrigation activation methods in the penetration of root canal sealer in the resorption areas of teeth with IRR.

Histological and chemical view on parotid duct sialolithiasis in the Slovakian warmblood mare

The parotid duct has been reported to be the most common site of sialoliths in horses. In this case report, we described the first confirmed case of the equine sialolithiasis in Slovakia. The work was aimed to describe the transcutaneous approach to removing the sialolith, which manifested as a hard painless mass in the area of the maxillary cheek teeth, in a 14-year-old Slovakian warmblood mare. Pathological-anatomical and histological examination after extirpation confirmed the presence of parotid duct ectasia resulting from calculus. The mineral composition of the sialolith was determined with atomic absorption spectroscopy using X-ray powder diffraction. The sialolith was successfully extirpated transcutaneously, without complications or recurrence.

Post-surgical complications of supernumerary teeth in the mandibular premolar area: A systematic review

In the mandibular premolar area, supernumerary teeth are a rare disorder that are rarely documented in the literature. The purpose of this study was to evaluate the post-surgical problems associated with the buccal and lingual techniques used to treat the extra teeth in this area. Using PubMed, PubMed Central, Science Direct, Cochrane, Wiley, and manual search, a thorough search was done to locate and identify cases and case series with extra teeth in the mandibular premolar region. For every study that was included, data on the surgical technique and postoperative problems were documented. Seven studies involving 90 patients were included. Supernumerary teeth in the mandibular premolar region were predominantly found in male patients (65.55 %), with most cases occurring in the right mandibular region (77.16 %). Postoperative complications after removing supernumerary teeth using buccal and lingual approaches were similar, with only one complication reported among the 90 cases reviewed. Although the findings suggest that surgical management of supernumerary teeth in the mandibular premolar region is relatively safe, caution is advised due to the limited sample size. Detailed pre-operative evaluation, a comprehensive treatment plan, and regular follow-up can minimize postoperative complications.

A case report of three supernumerary teeth in the maxillary anterior tooth area formed at different stages

A case report of three supernumerary teeth in the maxillary anterior tooth area formed at different stages

Evaluation of Microstrain in the Regions Surrounding Morse Taper and External Hexagon Implants.

The aim of this study was to compare the Morse taper (MT) + titanium base (Ti-Base) abutment with the external hexagon (EH) + Ti-Base abutment by using the strain gauge method in the mesial, distal, and apical-buccal areas around these types of implants. This study investigated two groups, MT and EH, each comprising five polyurethane samples with a dental implant in the area of artificial tooth 15 (3.75 × 11.5 mm) of a dental manikin. The strain gauges were glued to the mesial, distal, and apical-buccal polyurethane areas of all samples in relation to the implant. Ti-Base nonangled abutments measuring 5.0 × 4.7 × 1.0 mm (DSP, Brazil) were installed on the implants in each group. Ten identical zirconia crowns were constructed by scanning and milling and were subsequently cemented onto the Ti-base abutments with calcium hydroxide cement. Then, an axial load of 100 N was applied to the occlusal region of the zirconia crowns, and strain gauge measurements were taken. Strain gauge data were assessed by a two-way analysis of variance (ANOVA) with "implant connection" and "strain gauge position" factors, followed by the Bonferroni test (p < 0.05). The MT group exhibited a statistically significant reduction in microstrain in the mesial and apical strain gauge measurements compared to the EH group. The MT group exhibited less microstrain in the mesial and apical areas of the polyurethane samples near the implant. Consequently, the MT connection was considered more biomechanically advantageous.

In vitro Comparison of the Efficiency of Celluloid and Metallic Matrices in Proximal Restorations with a Bulk Polymer-based Biomaterial

The purpose of the study was the comparison of the contact tightness of the restored proximal area of lateral teeth with celluloid and metallic matrices and a bulk polymer-based biomaterial using an original in vitro assessing method.In 300 plastic right upper molars, mesial and distal vertical boxes (4 mm width in all directions) were prepared. 150 teeth were restored using circumferential celluloid bands and the rest were restored with sectional metallic saddle bands with the same thickness. The mesial/distal contact tightness was measured, before preparations and after restorations using dental floss and an original system consisting in a dynamometer connected to the model fixed on a plate that could slide gravitationally on vertical metallic rails actioned by a mass of 850 g attached with a string. The passing through force was recorded. For the mesial surfaces, the force varied from 4.782 � 0.014 N (sound) to 5.086 � 0.011 N (restored) (p [ 0.05) for circumferential celluloid matrix while for the sectional metallic matrix, the values varied from 4.787 � 0.016 N (sound) to 5.596 � 0.01 N (restored) (p [ 0.05). For the distal surfaces, the force varied from 5.589 � 0.01 N (sound) to 4.777 � 0.011 N (restored) (p [ 0.05) for circumferential celluloid matrix while, for the sectional metallic matrix, the values varied from 5.586 � 0.012 N (sound) to 5.793 � 0.015 N (restored) (p [ 0.05). Comparing to the sound surfaces, the bulk polymer-based material with high consistency and the circumferential celluloid matrices generated poorer distal and slightly stronger mesial contact area tightness while the sectional metallic ones drove to stronger mesial and distal contacts. However, the celluloid bands are often preferred because they allow the photopolymerization process and permit a good visual control during most of the steps of the working protocol.

Surgical Management of Impacted Supernumerary Tooth and Odontome under General Anesthesia in an Emotionally Immature Child: A Case Report

Abstract The disorder known as hyperdontia is characterized by an excess of teeth or teeth that appear to be added to the normal amount of teeth. With a frequency ranging from 0.1% to 3.9% in permanent dentition and from 0.3% to 1.8% in deciduous dentition, it affects males more often than women. Since children’s cognitive abilities are still developing in comparison to adults’, children freely communicate their worry and anxiety and frequently exhibit uncooperative behavior patterns while undergoing treatment. A 7-year-old child who was emotionally immature reported with a principal complaint of missing tooth in his left upper front tooth area for 2 years. Cone-beam computed tomography was advised to verify location and structural interaction with neighboring structures. Due to his lack of emotional sensitivity and cooperation with others, we planned the surgical extraction under general anesthesia. In the present case, it was deemed preferable to wait for a spontaneous eruption, and the patient was observed for a month on a regular basis.

Oral inoculation of Enterococcus faecalis, DNA quantification and histopathological evaluation of gingival, heart and kidney tissue samples in rats.

Enterococcus faecalis is known as common pathogen for endodontic infections and cause secondary and refractory pulp periapical periodontitis. The bacteria can opportunistically colonize periodontal pockets and presents a possibility of infection developing in other organs. This research will investigate the dissemination of E. faecalis from the gingival tissue to the heart and kidney. Three groups were formed, consisting of twelve male Sprague Dawley rats: a control group designated as 0-day, and experimental groups labeled as 7-days and 14-days. Periodontitis induced by concurrent infection with sterile wire 0.2 mm insertion and E. faecalis inoculation is performed into the gingival sulcus located between the maxillary right 1st and 2nd molar teeth area. After euthanasia, tissue samples around the maxillary gingiva, maxillary jaw samples, kidney and heart tissues were obtained for quantitative Real-Time PCR assay and histopathological analysis. Results showed at 7-days, there was an upregulation of E. faecalis gene expression in the gingiva, heart, and kidney samples as well as infiltration of the inflammatory cells at 7-days post induction, which consequently decreased at 14-days. Thus, the study suggests dissemination of E. faecalis from gingival tissue to the heart, kidney which could be probable link between periodontal disease, heart, and kidney disease.

Population differences in dental cementum growth rates: Implications for using cementum thickness as a method for age estimation.

Age at death estimation is a key element to many research questions in biological anthropology, archeology, and forensic science. Dental cementum is a tissue of choice for the estimation of age at death in adult individuals as it continues deposition for the entirety of an individual's life. Previous works have devised regression formulas correlating cementum thickness to age at death. However, interpopulation variances are unknown, and it is therefore not clear whether regressions based on a single population are applicable to individuals with different ancestries. Here, we use a sample (n = 52) of teeth from individuals with known age at tooth extraction/death of European, African, and East Asian ancestry to assess whether there are interpopulations differences in cementum growth rate. We measured growth rate in four different areas (2nd and 5th decile of both the lingual and buccal aspect of the root) of each tooth and used nonparametric tests to evaluate population differences in growth rate between homologous regions of the teeth. The results of the analyses show that, even after controlling for tooth size, individuals of European ancestry have significantly lower growth rates than those of both African and East Asian ancestry across all four tooth areas. These results call into question the applicability of the regression formulas derived from European ancestry individuals to individuals of other ancestries.

Use of thigh fascia autograft for repairing a through-and-through soft tissue defect in the alveolar process: a clinical case

Relevance. In most cases, soft tissue defects can be addressed using standard local flap transposition methods. However, large defects and/or those with scar tissue changes, through-and-through defects involving destruction of both vestibular and palatal cortical plates, defects penetrating into the nasal cavity, and similar situations necessitate unconventional solutions utilizing external graft materials.Clinical case description. This clinical case details the use of an autograft from the wide fascia of the thigh (Fascia lata) to repair an atypical defect of the alveolar process in the maxilla, specifically in the area of teeth 1.2 and 1.1. This defect exhibited through penetration between the vestibule of the oral cavity and the oral cavity proper, along with a significant deficiency of local tissues required for defect closure. The results of clinical, instrumental, and CT examinations conducted before and after the surgical intervention are presented.Results. Objective clinical studies conducted three months post-operation showed complete closure of the defect in the alveolar process of the maxilla, with full epithelization in the postoperative intervention area.

Accuracy of Complete-Arch Scans Obtained by Intraoral Scanner and Smartphone Three-Dimensional Scanning Applications With Different Smartphone Position Setups: An In Vitro Study.

The high cost of intraoral scanners (IOS) for complete-arch scans makes them less accessible for many dental practitioners. As a viable alternative, smartphone scanner applications (SMP) provide comparable scanning capabilities at a significantly low cost. However, there is limited data on the accuracy of SMP, especially when used in various smartphone positions. This study aimed to compare the three-dimensional (3D) and linear accuracy of complete-arch scans acquired by an IOSand SMP (KIRI Engine, KIRI Innovations, Guangdong, China) at three shooting angles (0°, 45°, and 90° for SMP_3A) and two shooting angles (30° and 60° for SMP_2A). A stone dental cast was scanned with a laboratory scanner as a reference, with 11 scans performed by an IOS, SMP_2A, and SMP_3A. In 3D analysis, trueness and precision were evaluated through superimposition with the reference scanand within each group, respectively, using the best-fit algorithm of Geomagic Wrap software (3D Systems, Inc., Rock Hill, SC). Trueness in linear discrepancy was assessed by comparing the occlusal-cervical and mesiodistal dimensions of reference teeth (canine, premolar, and molar), intercanine width, and intermolar width on the digital casts to measurements of the stone cast, while precision was measured using the coefficient of variance. Differences between groups were analyzed using the Friedman test, followed by the Dunn-Bonferroni post hoc test with a significance level set at 0.05. IOS exhibited significantly lower trueness than SMP_2A (p = 0.003) with significantly greater width discrepancies on canines (p = 0.001) and molars (p < 0.001). Discrepancy patterns differed among the three scanning methods. The IOS showedgreater discrepancieson the occlusal surfaces of posterior teeth. While SMP_3A demonstrated higher variation on the palatal surfaces and interproximal areas of posterior teeth. For precision,SMP_3A (p = 0.028) and SMP_2A (p = 0.003) showed a significantly lower precision in 3D analysis, but a comparable reproducibility in linear measurement to IOS. TRIOS IOS (3Shape,Copenhagen, Denmark) exhibited lower trueness in 3D and linear accuracy analyses for complete-arch scans. The positions of the smartphonesignificantly enhanced trueness at the undercut region. SMP_2A and SMP_3A can be a potential alternative for precise linear measurement in complete-arch scans with selective use.

Accuracy evaluation of a universal dental implant guide for simulating implantation in posterior area on dental molds.

This study aims to compare the accuracy of self-developed universal implant guide (SDG), 3D printed digital guide (DG), and free hand (FH) simulated implantation in the posterior tooth area of dental models. Ten junior dentists were selected to place three implants in the 35, 37, and 46 tooth sites of the mandibular models (35, 36, 37, and 46 missing teeth) by using SDG, DG, and FH, and the process was repeated again to take the average value. Cone beam computed tomography (CBCT) was used to evaluate the global coronal deviation, global apical deviation, depth deviation, and angular deviation between the actual position and preoperative planned position. The coronal deviation and apical deviation of the three implant sites in the SDG group were not significantly different from those in the two other groups (P>0.05). The depth deviation and angular deviation in the SDG group were smaller than those in the DG group (P<0.05) and FH group (P<0.05), respectively. All deviations at site 37 in the SDG group were not different from those at site 35 (P>0.05), while the depth and angular deviation at site 37 in the DG group were higher than those at site 35 (P<0.05). The precision of the self-developed universal dental implant guide can meet the requirements of clinical posterior implantation.