Incisal Edge Research Articles

Immediate skeletal effects of rapid maxillary expansion at midpalatal suture opening with Differential, Hyrax and Haas expanders.

The aim of this study was to test the null hypothesis that there is no difference at the midpalatal suture opening after rapid maxillary expansion (RME) using Expander with Differential Opening (EDO), Hyrax-type and Haas-type expanders. Occlusal radiographs of 52 patients (19 males and 33 females; average age= 9.46?1.20 years) treated with RME were divided into three groups, according to the expander used: EDO (n=17), Hyrax-type (n=21) and Haas-type (n=14). The evaluated variables were: A) Distance between the maxillary central incisors at the incisal edge; B) Distance between the alveolar ridges at the midpalatal suture; C) Suture opening at 10-mm distance from the crest to posterior, at the midpalatal suture; D) Suture opening at 20-mm distance from the crest to posterior, at the midpalatal suture; and E) Suture opening at 30-mm distance from the crest to posterior, at the midpalatal suture. To assess the normality of variables, the Shapiro-Wilk test was performed. For intergroup comparison, ANOVA with a significance level of 5% was used. At the region A, Hyrax-type (4.66 mm) and EDO (4.87 mm) groups presented larger openings than the Haas-type group (3.43 mm). In regions B and C, EDO showed a statistically significant greater opening than the Haas-type group. In region D, a smaller opening of the midpalatal suture was observed in the Haas-type group, compared to the Hyrax-type and EDO groups. EDO and Hyrax-type produced greater immediate skeletal effects, compared with Haas-type, but these differences were about 1 mm and might not be clinically significant.

Biomechanical evaluation of different fixation techniques following modified sagittal split ramus osteotomy using buccal step: An in vitro study.

This study was to evaluate the efficacy of three different designs of rigid fixation using polyurethane hemimandible replicas following modified sagittal split ramus osteotomy with buccal step. Forty-eight polyurethane hemimandible replicas have been used. Following the osteotomy and fixation, each specimen has been mounted on a Universal Testing unit using a prefabricated customized jig and has been tested to a range of vertical forces starting from 0 N on the incisal edge of lateral incisor and lateral forces of on lateral surface of mandibular first molar. Progressive load has been applied until a deflection of 10 mm was observed. SPSS version 20 has been used for analyzing the data. The biomechanical stability of different osteosynthesis has been compared using a one-way ANOVA with post hoc Bonferroni test. P ≤ 0.05 will be considered statistically significant. After advancement of 7 mm, comparison of vertical load and lateral load among different miniplate systems showed that load was maximum in bicortical screws in inverted L pattern followed by T-shaped miniplate system and was least in single six-hole straight plate (0.001) at P ≤ 0.05. Our study concludes that bicortical screws in inverted "L" pattern are more resistant to lateral load as well as on the application of vertical load when compared to other fixation techniques and statistical difference was evident.

Determining the desired position of mini-implants in an orthodontic treatment for correction of deep overbite

• The equation to compute co-ordinates of attachment of mini-implant was formulated. • Four possible positions of mini-implant placements were considered. • Finite element analysis was carried out with an intrusive force of 50 g-force (gf). • The applied force system was verified successfully with finite element analysis. • Recommendations about feasibility of different positions of mini-implant were given. Deep overbite problem leads to gummy smile in orthodontic patients. The simultaneous intrusion of maxillary (upper) six anterior teeth with mini-implants is a common treatment method for this purpose. Till date, no study has stated desired position of attachment of mini-implant. This is an important parameter as intrusive force vector must pass through centre of resistance (C res ) of maxillary six anterior teeth. Thus, the aim of this study is to obtain the co-ordinates of desired positions of mini-implant with reference to incisal edge of first anterior tooth (maxillary central incisor) from the side view of maxillary six anterior teeth. The purpose is to achieve the effective simultaneous intrusion of maxillary (upper) six anterior teeth. For this purpose, co-ordinates of incisal edge of first anterior tooth (maxillary central incisor), point of attachment of elastomeric chain on the archwire and C res of maxillary anterior teeth were considered. From these points, the equation to compute co-ordinates of attachment of mini-implants was formulated. Additionally, the required angle of intrusive force was estimated to be 45°. To verify this computation, finite element analysis was performed on the computer aided design (CAD) structures of maxillary six anterior teeth, surrounding tissues and appliance structures. From the formulated equation, four possible positions of mini-implant placements were considered with reference to incisal edge of first anterior tooth (maxillary central incisor). The co-ordinates of these positions were (11, 10.5) - Position {1}, (12, 11.5) - Position {2}, (13, 12.5) - Position {3}, (14, 13.5) - Position {4} with units in mm. From the photographic results of these positions, different statements of recommendations were given in this study from feasibility point of view. Positions {2} and {3} were highly recommended. Position {4} was moderately recommended. Position {1} was least recommended.

Guided endodontic access of severe calcified tooth without incisal edge case report

Pulp tissue may suffer calcification because of trauma, operative procedures or carious lesions. This paper aimedto report and discuss the guided endodontic access as an alternative treatment. A 52 years old female patient hadsevere root canal calcification of tooth #11 associated with a radiolucent periapical lesion. Firstly, the crown andmetal post and core were removed. A digital impression and cone-beam computed tomography “CBCT” scanswere performed and imported to implant planning software (SimPlant Version 11; Materialise Dental, Leuven,Belgium).The guided endodontic access template was designed to allow the drill to reach a distance of 2 mmshort of the apical foramen, once printed, it was tested in the mouth to evaluate its insertion and stability in thedental arch. The calcified root canal was penetrated using the access drill rotating by a low-speed hand-piece(10,000 rpm) under saline solution irrigation through advancing movements. Then, the apical foramen wasnegotiated with C-Pilot files #10 and #15. The working length was measured using the iPex-II apex locator.The instrumentation was carried out with Reciproc R50 and 2.5% sodium hypochlorite. One week later, a fullceramiccrown preparation was performed, and polyvinyl siloxane impression was carried out. A total of threefollow-up sessions were performed after one week, one and twelve months. Bone neoformation was observed inthe site of the periapical lesion and the patient had no signs or symptoms of any discomfort. Therefore, guidedendodontics is indicated for severe calcified root canals.KEYWORDSGuided endodontics; Calcified root canals; Access cavity.

Mouth opening range for Jordanian population and its relation to gender, age, height, and weight

Aim: Maximum mouth opening (MMO) is an important parameter in the assessment of several clinical situations, and its measured value is documented to have gender, age, and anthropometric variation. Background: This study measures the average value of MMO in a sample of the Jordanian population. MMO might be different for different regions of the world and is important for all dental disciplines. We attempt to find correlations between MMO and body characteristics such as gender, age, body weight, and height. Materials and Methods: A total of 565 Jordanian patients (191 males and 374 females; aged 3–70 years) were randomly selected for this cross-sectional study. Mouth opening was measured using a calibrated ruler between the incisal edges of the upper and lower central incisors (interincisal length), and weight and height were measured using a medical scale. In addition, age and gender were recorded. Patients were informed of the study and agreed to participate. Statistical differences of MMO between male and female patients in each age group were assessed using the t-test, the correlation between the MMO and body weight and height was assessed using a Pearson correlation coefficient and simple linear regression using the SPSS program. Results and Conclusions: The mean MMO across the sample was 45 ± 4.78 mm with a range of 36–61 mm. The mean MMO in males was 45.7 ± 5.2 mm, varied from females, which was 44.65 ± 4.4 mm in all age groups with the level of significance of (P = 0.013). No significant relation was found between age and MMO with a P of (>0.05), but a significant correlation was found between MMO and body weight and height with a P of (<0.01).

P6 - Deterioration of composite restorations in tooth wear patients: translational approach

This study investigated the clinical deterioration of anterior resin composite restorations placed in tooth wear patients after 36 months and later compared the ability of two chewing simulation devices in emulating in vitro the clinical deterioration observed in those restorations. For the clinical observation, 270 anterior maxillary resin composite restorations in 47 patients were evaluated after 36 months of clinical service by using intraoral photographs and 3D scans to rate modified FDI scores and investigate the presence of degradation features. Multivariable logistic regression models were used to analyze the clinical data (p<0.05). For the in vitro approach, tooth wear was simulated in bovine incisors, which were restored with materials and techniques similar to those in the clinical observation. Incisal edges of the restorations were subjected to 960,000 cycles of either compressive loading (Biocycle-V2; 125 N; 2 Hz) or wear and mechanical loading (Rub&Roll; 30 N; 20 rpm). Surface degradation was rated using the modified FDI scores to compare the chewing devices (Fisher’s test, ?=0.05). In the clinical observation, early degradation signs were present at 1 month: irregularities (41.5%) and ditching (7.4%) were observed at the surface and adhesive interfaces. The frequency of irregularities decreased in the 36-month follow up (37%), but ditching (12.2%) and fractures (10.7%) were more common. After 36 months, the most frequent esthetic deterioration was noticeable for staining (44%) and loss of luster (31%). For functional deterioration, in the 3D scans, wear (25%), marginal adaptation (24%), and surface irregularities (19%) were the most frequent forms. The simulation devices produced distinct degradation patterns: Biocycle-V2 generated deterioration not comparable to the clinical situation, including contact damage, minor wear, and localized roughening. The degradation caused by Rub&Roll was more similar to the in vivo situation, including wear facets, chipping, delamination, staining, and marginal ditching. The FDI scores differed between the chewing devices for staining, material/retention, and marginal adaptation (p?0.003). The clinical observation revealed a continuous deterioration process in tooth wear patients with a progression of the deterioration until 36 months. The laboratory simulation of the deterioration showed that the Rub&Roll chewing device could emulate the clinical deterioration observed in anterior restorations in tooth wear patients and could be used as a mouth simulation method, contributing to translational research.

Determination of Maxillary Incisal Edge Position using Canine Visibility as a Guide – An In vivo Study

Purpose: To evaluate the reliability of the visibility of the central incisor &amp; the canine for the cervico incisal positioning of anterior maxillary teeth related to age &amp; sex while the upper lip was in repose in dentate patients &amp; the development of rehabilitation recommendations for edentulous individuals with regard to the location of the maxillary incisal edge&#x0D; Methodology: 308 subjects [152 Males &amp; 156 Females] belonging to the age of 30 to 59 years were selected using a simple stratified random technique. There were three age and sex groups: Group I was 30 to 39 years old, Group II was 40 to 49 years old, and Group III was 50 to 59 years old. The vertical distances (in mm) between the lower border of the upper lip and the right maxillary central incisal edge and canine tip were measured and recorded using adhesive tape marked with millimetres. A single examiner recorded all the measurements and the values were tabulated and subjected to statistical analysis.&#x0D; Results: Men in Groups I and II had maxillary central incisor exposure ranging from +6 to -1mm, whereas males in Group III had exposure ranging from +5 to -2mm. There was an exposure range of +6 to -2 mm in females in Group I, +7 to -2 mm in Group II, and +5 to -2 mm in Group III for the central incisors. While the canine exposure in Group I and II and Group III ranged from +2 to -4mm in females, the exposure ranged from +3 to -3mm in men of all ages. In all groups, females had statistically significant (P0.05) more central incisor and canine exposure than men.&#x0D; Conclusions: The canine visibility was less variable in all the age groups and in both males and females in comparison to the central incisor. When restoring edentulous individuals, the average canine exposure dimension can be employed for cervico-incisal location of the anterior maxillary teeth.

Effect of intracanal diode laser irradiation on fracture resistance of roots restored with CAD/CAM posts

Aim: To evaluate the fracture resistance of roots restored with CAD/CAM-fabricated posts, receiving or not intracanal laser treatment, compared with glass fiber posts under mechanical cycling. Methods: Twenty-seven endodontically treated, single-rooted teeth were divided into 3 groups: group 1 (control), prefabricated glass fiber posts relined with resin composite; group 2, CAD/CAM-fabricated intraradicular posts using Resin Nano Ceramic (RNC) blocks; and group 3, CAD/CAM-fabricated intraradicular posts using RNC blocks in canals irradiated with a 940-nm diode laser (100 mJ, 300-um optic fiber, coronal-apical and apical-coronal helical movements, speed of 2 mm/second, 4 times each canal). After cementation of the coping, cyclic loading was applied at an angle of 135° to the long axis of the root, with a pulse load of 130 N, frequency of 2.2 Hz, and 150,000 pulses on the crown at a point located 2 mm below the incisal edge on the lingual aspect of the specimen. Every 50,000 cycles, the specimens were evaluated for root fracture occurring below or above the simulated bone crest. Results were analyzed by one-way ANOVA followed by Tukey’s test (p&lt;0.05). Results: Group 1 was the least resistant, while groups 2 and 3 were the most resistant. Group 1 differed significantly from groups 2 and 3 (p&lt;0.01), but there was no difference between groups 2 and 3 (p&lt;0.01). Conclusion: Treatment of the intracanal surface with diode laser had no influence on fracture resistance of roots restored with CAD/CAM-fabricated posts, but a longer cycling time is required to evaluate the real benefits of diode laser irradiation.

Influence of the Inclination of the Incisal Edge of Planas Direct Tracks on Deciduous Dentition with Anterior Crossbite: Finite-Elements Study.

Objective This study aimed to evaluate the influence of three different inclinations of the incisal edge of Planas direct tracks (PDTs) on the upper deciduous incisors (15, 30, and 45 degrees) through simulations using the finite-elements method. Materials and Methods A three-dimensional virtual model of tooth 51 was elaborated by using the Rhinoceros computer-aided design (CAD) software. A mesh was constructed by using the Patran software, and the evaluations were processed by using the ANSYS 15.0 software. The geometry of the elements used consisted of a triangular-base tetrahedron composed of 2,167,386 elements and 3,012,995 nodal points. Results Progressive alterations of proportional intensity and distribution were seen in the areas of tension on the dentoalveolar structures, with increasing inclination of the edge of the PDT. The tractive contact tensions were seen to be concentrated in the vestibular apical thirds and palatine cervical thirds, while the compressive contact tensions were in the palatine apical thirds and vestibular cervical thirds. Conclusion It was concluded that a 30-degree inclination for the PDT was most appropriate for the cases of anterior crossbite in the deciduous dentition. Nevertheless, because this was a laboratory evaluation, clinical criteria and complementary examinations for each case need to be taken into consideration in making therapeutic decisions.

Analysis of the effect magnitude of different parameters on smile attractiveness.

To evaluate the effect magnitude of different parameters on smile attractiveness. A reference and 13 images were produced by manipulating 13 parameters. Image rating was performed with a 4-point Likert scale from least attractive (1) to most attractive (4). Image raters included laypeople, dental students, dentists, and dental specialists. Friedman and Wilcoxon image were used for estimate of effect size. Parameters were classified into small (0.10- < 0.30), medium (0.30- < 0.5), or large (≥0.50). A total of 1040 people participated with good consistency (α=0.861), and moderate reliability (0.64-0.7). The reference image had the highest rank (laypeople:11.79, dental background: 12.55). For effect size; gingival margin level (-0.11, -0.01), teeth width proportion (-0.09, -0.10), inverted smile arch (-0.09, -0.21), commissure line cant (-0.15, -0.17) and low smile (-0.24, -0.23) had small effect size; occlusal plane cant (-0.36, -0.49), midline cant (-0.36, -0.48), and midline shift (-0.37, -0.49) had medium effect size; diastema (-0.55, -0.54) and color (-0.56, -0.56) had large effect size for the laypeople and dental groups. High smile (-0.42, -0.51), incisor edge symmetry (-0.46, -0.54) had medium effect size in laypeople group and large effect size in the dental group. Width to length tooth proportion (-0.26, -0.39) had small effect size in the laypeople group and medium effect size in the dental group. Smile parameters had different effect magnitude on smile attractiveness and were classified into small, medium, or large parameters. Neither laypeople nor professionals have a collective judgment on what constitutes a beautiful smile. This study investigated the effect magnitudes of 13 smile parameters and presented a small, medium, and large smile parameters classification. It should provide the clinician with an insight into the expected effect each parameter has on the smile.

Comparison of commercially available Nickel Titanium preformed archwires with the common archform found in Indian population – An experimental study

Objective: To evaluate most suitable preformed Nickel Titanium Archwires for ovoid archform which is commonly observed in the population. Material and Methods: Sixty casts of mandibular arches with ovoid arch form were included of the patients visiting Department of Orthodontics. The buccal and incisal edges of all teeth on the cast were marked by HB pencil on the mandibular study models and were transferred on a sheet of paper. Nickel Titanium archwires of ovoid form of four different companies were compared by matching them with the arch forms obtained from the patients. Results: There is significant difference in the preformed archwires obtained from 4 different companies when compared to the ovoid archform. The archwires used are wider than the normal arch form observed. Conclusion: Variation in available preformed arch wires does not entirely cover the range of diversity of the common dental arch form of our population. Keywords: NiTi, Archform, Retention.

Investigating the Effect of Nonrigid Connectors on the Success of Tooth-and-Implant-Supported Fixed Partial Prostheses in Maxillary Anterior Region: A Finite Element Analysis (FEA).

Objective This study was designed to assess the effect of nonrigid connectors (NRCs) and their location in the success of tooth-and-implant-supported fixed prostheses in the maxillary anterior region by finite element analysis (FEA). Materials and Methods Three 3D FEA models were designed, presuming maxillary lateral incisor and canine to be extracted. Implant (replacing canine), abutment, bone (spongious and cortical), central incisor (containing dentin, root cement, gutta-percha, and casting post and core), periodontal ligament, and three three-unit cemented PFM prostheses (a rigid one and two nonrigid) were modeled. The NRC was once in the tooth side and once in the implant side. The prostheses were loaded twice: 250N to the incisal edges (0° to the long axis) and 200 N to the cingula (45° to the long axis). The von-Mises stress and vertical displacement were analyzed. Results Under both vertical and oblique loadings, the rigid model presented the highest stress. Under vertical loading, the NRC caused a significant decrease in the applied stress to the prosthesis, bone, implant, and tooth. Locating the NRC in the tooth side decreased the applied stress to the prosthesis and NRC. Under oblique loading, prosthesis and implant tolerated less stress in the presence of an NRC. Placing the NRC in the tooth side resulted in the least stress in all of the components except for porcelain and patrix. Vertical displacement of the tooth apex was approximately equal in all models. Conclusion Using an NRC on the tooth side is the most efficient method in reducing the applied stress to prosthesis, implant, tooth, and bone. The amount of intrusion is not dependent on using an NRC or not.

Influence of facial type on attractiveness of vertical canine position from the perspective of orthodontists and laypeople.

To evaluate the attractiveness of changes in vertical position of maxillary canines in frontal smiles of different facial types, and to evaluate the esthetic perceptions of orthodontists and laypeople, and the influence of facial type on these perceptions. Three adult female volunteers were selected as individuals with normal, vertical, and horizontal growth patterns. Frontal posed smile photographs were digitally altered by adjusting vertical positions of the maxillary canines above, below, or coincident with the incisal line in increments of 0.5 mm within a range of 1 mm of extrusion and intrusion. For assessment, a web-based survey was formed with 18 images (six images for each model). A scale was present underneath each image, graded from 0 to 10 (0: unattractive; 10: the most attractive). Images were rated by 233 participants (105 orthodontists; 128 laypeople). Orthodontists scored 0-mm images significantly as the highest in all groups. Laypeople scored significantly higher for -0.5 mm images regardless of facial type. The lowest scored images were -1 mm (except for horizontal pattern) and +1 mm images. Mean values of scores given by men were higher (P < .05). Orthodontists favored ideal dental alignment and preferred the incisal edges of central and canine teeth to be at the same level. Laypeople preferred a smoother smile arc than orthodontists and found harmony with the soft tissue more attractive. Facial type affected perceptions of the vertical changes of maxillary canines.

885 Surgical Removal of Unerupted Ectopic Maxillary Central Incisors - A Case Report

Abstract Introduction Maxillary incisors have a significant role on the facial aesthetics of an individual. Following trauma to the primary dentition, the maxillary incisors are vulnerable to eruption failure and occasionally root dilaceration. These teeth can be challenging to treat. Discussion This case report demonstrates the complex management of a 10-year-old male who presented with severely displaced and unerupted maxillary central incisors, following a history of dental trauma when he was 4 years old. Cone beam computed tomography revealed the upper maxillary central incisors to be lying transversely across the maxillary arch with the crowns directed superiorly and significantly close to the floor of the nose. The incisal edges of both crowns perforated the labial cortex of the maxilla. The roots of the maxillary central incisors were dilacerated with the apices directed superiorly. A multi-disciplinary approach was taken, with involvement from both maxillofacial surgery and orthodontic teams. Maxillofacial surgeons completed the surgical removal of the ectopic maxillary central incisors, rather than the more common approach of surgical exposure and orthodontic repositioning. In this case, full alignment of these teeth would most likely have led to perforation of the labial cortical plate of bone. Conclusions Although surgery was complex and technique sensitive, both teeth were successfully removed under general anaesthesia with no iatrogenic damage. The patient underwent fixed orthodontics to align the maxillary lateral incisors as central incisors. A multidisciplinary approach along with careful surgical planning and effective communication with the patient and his mother helped to achieve a satisfactory outcome.

Andy’s Facial Growth Indicator

Facial growth indicator line was originally developed by Dr John RC Mew. Dr Mew discloses a facial growth indicator in his textbook, Bioblock Therapy published in Great Britain by Dr Mew. The indicator line—this is defined as the distance from the tip of the nose to the incisal edge of the lowest upper central incisor. Andy’s facial growth indicator is a modification of facial growth indicator, which was originally developed by Dr Mew.

Correlation of the Iris Diameter with the Mesiodistal Width of Maxillary Central Incisor using Digital Image Analyzer

Aim: The purpose of this clinical study was to determine the correlation between the horizontal visible iris diameters with the mesiodistal width of the central incisor respectively in the Central India population aged between 18 and 26 years. Background: Can the Iris Diameter be correlated with the mesiodistal width of maxillary central incisor. If thus results obtained, the iris diameter can be used as a tool for the selection of maxillary anterior tooth in completely edentulous patients. Materials and Methods: Seventy Five Central Indian participants aged between 18 and 26 years participated in this study. Standardized digital photographs of the face generated from the frontal aspect were made using a digital camera. The measurements of the iris diameter and the mesiodistal width of the maxillary central incisor at the incisal edge, middle third, and cervical third were assessed with photoimaging software. The data obtained have undergone the statistical analysis by using the paired-sample t-test to compare the right and left sides, and independent-sample t-tests to compare between gender, and the Pearson correlation coefficient (r) to evaluate the relationship between variables. Results: A positive correlation between the horizontal visible iris diameter and the mesiodistal width of the maxillary central incisor was found in men and women. In men, the r = 0.276, 0.373, 0.378 (right side) and 282, 158, 429 (left side) respectively were found for cervical third, middle third, and incisal third region. In women, the r = 0.329, 0.415, 0.192 (right side) and 0.053, 0.469, 0.163 (left side) were found respectively in cervical third, middle third, and incisal region were found. Conclusions: The conclusion was that the horizontal visible iris diameter can be used as a reference point to estimate the mesiodistal width of the maxillary central incisor tooth.

Proximal incisal edge length and recent clinical observation of Siewert type Ⅱ advanced esophagogastric junction adenocarcinoma

Objective: To investigate the clinical effect of the radical resection with a proximal incisal edge length of 20-25 mm and 30-35 mm in Siewert type Ⅱ advanced esophagogastric junction adenocarcinoma, to shorten the minimum safe distance of the proximal incisal edge to 20-25 mm. Methods: A retrospective cohort study method was used. The clinical data of 166 patients with Siewert type Ⅱ advanced esophagogastric junction adenocarcinoma who underwent total gastrectomy from January 2017 to August 2020 in the Department of Gastrointestinal Surgery, Heji Hospital Affiliated to Changzhi Medical College were retrospectively collected. According to the proximal incisal edge length, the patients were divided into two groups: the proximal incisal edge length of 20-25 mm group (69 cases) and 30-35 mm group (97 cases). The perioperative conditions and the 6-month follow-up after the operation were compared between the two groups. Results: There was no statistically significant difference in baseline information between the patients in the two groups (P>0.05). The operations of both groups were completed. The intraoperative operation time of the proximal incisal edge length of 20-25 mm group was shorter than that in the proximal incisal edge length of 30-35 mm group ((172±24)and(206±27)min, P<0.001). There were no significant differences in the amount of intraoperative blood loss, the treatment of the diaphragm during the operation and the positive rate of intraoperative freezing of the upper incisal edge between the patients in the two groups (all P>0.05). And there was no significant differences in the first exhaust time, gastric tube removal time, first feeding time and hospital stay after the operation of the two groups (all P>0.05). There was no significant differences in the incidence of anastomotic leakage, anastomotic stenosis, reflux esophagitis and intestinal obstruction after the operation between the patients in the two groups (all P>0.05). And there was no anastomotic leakage case among the 69 cases in the proximal incisal edge length of 20-25 mm group. Postoperative pathological treatment showed no significant differences in the vascular tumor thrombus and nerve infiltration between the two groups (both P>0.05). During the 6-month follow-up, there was no death or tumor recurrence in the two groups, and there was no significant difference in body weight loss at 6 months after the operation between the two groups (P=0.178). Conclusion: When radical resection of Siewert type Ⅱ advanced esophagogastric junction adenocarcinoma is performed, it is feasible to shorten the minimum safe distance of the proximal incisal edge to 20-25 mm under the premise of ensuring R0 resection. The operation time is shortened. Due to the shortening the incisal edge distance, the anastomotic tension is decreased, and the incidence of postoperative anastomotic leakage is also reduced.

Central incisors shape and proportions prevalence in Argentinian university students: by visual assessment and a new standardized method.

The aim of this study was to analyze the dimensions of the clinical crown of upper central incisors and the prevalence of tooth shapes by two different protocols. Assessment was performed on each of the 111 dental stone type V maxillae models of students of dentistry from Buenos Aires University [93 females and 18 males, mean age 23.70 (± 2.26) years] The mesial and distal-vestibular angles were defined on each right upper incisor, and the following segments were defined: AB (zenith - incisal edge), CD, EF, GH (apical, middle, and incisal thirds - vestibule - mesial and vestibule-distal angles) and their lengths were determined with a precision caliper. Then, the CD/AB, EF/AB and mean CD-EF/AB ratios were calculated. Shapes were assessed by four independent observers, three of whom evaluated digital images of the models, while the fourth had no access to the images, and determined the shapes using an algorithm developed from the dimensions of the studied segments. Rates and confidence intervals were determined, and Fleiss' Kappa was calculated to assess the agreement among the evaluators who worked with the images and among all of them. Average incisor length was 10 mm, and widths at CD and EF were 7.35 mm (0.65) and 8.27 mm (0.58), respectively. Regarding shapes, 51.58% (47.90-55.20) of the incisors were identified as square, 18.02% (14.50-21.90) as ovoid and 30.41% (30.00-30.90) as triangular. Fleiss' Kappa agreement was 0.71 (0.62-0.80). The application of the proposed algorithm provided a considerable level of agreement among the observers. Regarding tooth size, both the average segment length and the proportions were similar to those reported by various authors.

Comparison of apical resorption of endodontically treated teeth before and after orthodontic movement with clear aligner

Introduction: Patients treated with orthodontics show short root due to apical root resorption. Aim: The aim of the study was to compare the external apical root resorption (EARR) of endodontically treated teeth before and after orthodontic movements using clear aligner therapy. Materials and Methods: The study group comprised 22 class I adult healthy patients with a mean age of (28 ± 8.2) years treated with clear aligner therapy. Thirty-four endodontically treated teeth (maxillary incisors and molars) were measured for the extent of the EARR in panoramic radiographs at the beginning and at the end of clear aligner therapy. Root resorption was measured using an electrical digital caliper (Mitutoyo Manufacturing Co. Ltd., Tokyo, Japan) on the dental panoramic radiographs from the mesial cusps of the first molar tooth to the apex of the root, and from the incisal edge to the apex of the root for the central incisors. Results and Discussion: All the endodontically treated teeth demonstrated reduction in pretreatment root length. Less than one percent of EARR was found in 4 teeth, and 1%–4.9% of the EARR was observed in 23 teeth. Six teeth showed EARR of 5–7.9 while only one tooth EARR in the range of 8–10. A pretreatment versus posttreatment comparison of median root lengths of #16, #26, #36, and #46 showed a statistically significant difference (P &lt; 0.05). The mean differences of root lengths after clear aligner therapy among different teeth showed no significant difference (P = 0.981). Conclusion: All the endodontically treated teeth showed minimal external root resorption after orthodontic treatment with a clear aligner.

Finite elements analysis of stresses formed in core and spongious bone tissue by restored implanted fixed prostheses with Polyetheretherketone (PEEK) and fiber-reinforced composite

Aim: This study uses the finite element analysis method to compare the effects of different abutments and prosthetic materials on stress distribution in the rehabilitation of maxillary anterior tooth deficiencies with fixed implanted prostheses. Methodology: In our study, two titanium implant models with a diameter of 4.1 mm and a length of 10 mm were designed for the maxillary central and canine teeth regions. 3D models of the prosthetic restorations were created with PEEK and fiber-reinforced composite and two different abutment materials (titanium and zirconia). After meshing the materials used with cortical and cancellous bone, Poisson ratio and young module values were loaded into the program. Maxillary central and canine to the palatal surface of the tooth, 2 mm below the incisal edge; a 178 N force was applied in both the vertical and 45° oblique directions, and analysis was performed. The distributions of the highest compression and tensile stress values in peri-implant cortical and cancellous bone were examined, and the results were compared. Results: Material with low elastic modulus caused higher stress accumulation in the cortical and cancellous bone tissue around the implant during oblique force application. In all study groups, the maximum stress values ​​observed in the cancellous and cortical bone during oblique force application were significantly higher than those observed during vertical force application. Thus, different prosthetic materials had different effects on stress distribution in peri-implant cortical and cancellous bone tissue, and the highest stress accumulations were in the peri-implant cortical bone. Conclusion: Different prosthetic materials had different effects on stress distribution in peri-implant cortical and cancellous bone tissue. How to cite this article: Zengingul AI, Goncu Basaran E, Celik H. Finite elements analysis of stresses formed in core and spongious bone tissue by restored implanted fixed prostheses with Polyetheretherketone (PEEK) and fiber-reinforced composite. Int Dent Res 2021;11(Suppl.1):250-8. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.37 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.