Surface Of Maxillary Central Incisor Research Articles

Evaluation of thickness of 3D printed versus thermoformed aligners: A prospective invivo ageing experiment.

To compare and investigate the effects of intraoral ageing on the thickness of one group of directly printed and two groups of thermoformed aligners on the labial surface of maxillary central incisors. Six groups (12 samples per group) were included in this prospective invivo experiment. Groups DP-Clin, INV-Clin and CA-Clin consisted of directly printed (Tera Harz TC-85 DAC resin), thermoformed (Invisalign, PU based polymer) and in house thermoformed (CA-Pro, PET-G based polymer) aligners, retrieved after 1 week of intraoral service. Groups DP-Ctr, INV-Ctr and CA-Ctr included unused aligners samples. Thickness measurements were conducted using confocal laser scanning microscopy (CLSM). Data that underwent log-10 transformation was analysed by multiple linear regression analysis (p < .05). Statistically significant differences were found between the materials in both Clin and Ctr categories (p < .001). Group DP had the highest thickness among the groups and the least thickness was observed in the CA group (p < .001). However, intraoral ageing did not significantly affect the aligner thickness of any groups. Both thermoforming and direct printing of clear aligners led to thickness deviations in terms of increase for printed aligners and decrease for thermoformed aligners. Intraoral ageing did not affect the aligner thickness in any of the groups.

Three-dimensional measurement of periodontal support during surgical orthodontic treatment of high-angle skeletal Class III malocclusion: A retrospective study

This study aimed to quantify the periodontal health of incisors during surgical orthodontic treatment in patients with high-angle Class III malocclusion using a cone-beam computed tomography (CBCT) 3-dimensional (3D) reconstruction technique. The sample consisted of 30 patients with high-angle Class III malocclusion (mean age, 20.53 ± 2.86 years). CBCT images were taken before treatment (T0), after presurgical orthodontic treatment, and after treatment (T2). In addition, 3D tooth and alveolar bone models were generated. The root surface area, periodontal ligament (PDL)_Area, and vertical bone level (VBL) around the maxillary and mandibular central incisors were measured. The root surface area and PDL_Area of maxillary and mandibular central incisors decreased continuously between T0 and T2 (P<0.01). At T2, mandibular central incisors showed 38.64 ± 13.39% PDL_Area loss, and maxillary central incisors exhibited 21.13 ± 16.48% PDL_Area loss. For mandibular central incisors, the PDL_Area loss caused by VBL loss was significantly greater than that for maxillary central incisors (P<0.01) and significantly greater than the PDL_Area loss caused by root resorption (P<0.01). From T0 to T2, the lingual surface of maxillary central incisors exhibited greater VBL loss than the other 3 surfaces (P<0.01), and the labial and lingual surfaces ofmandibular central incisors demonstrated greater VBL loss than proximal surfaces (P<0.01). The 3D CBCT reconstruction method provides useful information regarding the periodontal defects of incisors in patients with high-angle skeletal Class III malocclusion. The PDL_Area of maxillary and mandibular central incisors decreased continuously during the treatment. Vertical alveolar bone levels at proximal surfaces appeared to be relatively stable.

Distance Between the Most Prominent Labial Surface of Maxillary Central Incisors to the Posterior Limit of Incisive Papilla in Various Arch Forms

Introduction: Arranging artificial teeth has always been a challenging work since edentulous alveolar ridges are in a constant verge of physiological resorptive changes. Incisive papilla is a reliable biometric guide which can be used as a reference for arrangement of anterior teeth, since it is a stable intraoral anatomical landmark unless surgically modified.&#x0D; Objective: This study was conducted to determine the mean distance between the most prominent labial surface of maxillary central incisors to the posterior limit of incisive papilla in various arch forms.&#x0D; Materials and Methods: The study was carried out among 170 undergraduate students of BPKIHS, after obtaining ethical clearance from Institutional Review Committee, BPKIHS. Maxillary impressions were made with alginate impression materials and casts were poured with dental stone. Distance from the posterior limit of incisive papilla to maximum convexity of central incisor (Papillo-Incisal Distance, PID) was measured with a Digital Vernier caliper with a precision of 0.01mm. The arch forms were analyzed and classified into ovoid, tapering and squarish arch, subjectively based on morphological parameters. The intra-examiner reliability of the measurement was tested in 17 casts calculating Cronbach’s Alpha. Pearson Chi-square test was applied to explore the relation of the arch forms with age and gender. One-way ANOVA was used to check the association between the mean PID between with different arch forms.(p value = 0.05)&#x0D; Results: The mean distance from the labial surface of maxillary central incisors to the posterior limit of incisive papilla was 11.58±1.32 mm. The mean papillo-incisal distance varied with respect to different arch forms which was statistically significant (P&lt;0.05). The mean PID of oval, squarish and tapering arch forms were 11.86 mm, 10.82 mm and 11.93 mm respectively.&#x0D; Conclusion: Incisive papilla is a valuable starting point in the preliminary location of maxillary incisors during fabrication of dentures. The suggested mean PID for arranging central incisors is 11.58 mm.

Tooth wear patterns in subjects with class II division 1 and class II division 2 malocclusion

There is an increasing trend of malocclusion among children, so it is necessary to identify the cause of the tooth wear so that the orthodontist can treat the patient accordingly. It is necessary to determine the wear patterns of different malocclusions. Therefore, the aim of our study was to compare the patterns of tooth wear among two categories of Angle's class II malocclusions, i.e. class II division 1 and class II division 2. The sample consisted of 100 pretreatment orthodontic patients in the age group of 15-25 years with Angle's class II malocclusion and were divided into following two groups: (a) Group 1: 50 subjects with full cusp Angle's class II division 1 malocclusion. (b) Group 2: 50 subjects with full cusp Angle's class II division 2 malocclusion. Clinical examination of the patients for tooth wear was done supplemented with dental casts, intraoral photographs and intraoral radiographs. Then each group was assessed for severity of tooth wear according to modified tooth wear index (TWI) given by de Carvalo Sales-Peres et al. Scores were subjected to statistical analysis and the pattern of tooth wear among the two groups of class II malocclusion was compared. A correlation between the gender of the patient and the tooth wear was also determined. The level of statistical significance (p-value) was less than 0.05. The class II division 1 subjects showed statistically greater wear on the occlusal surfaces of the maxillary canines, first, second premolar and first molar, and the occlusal surfaces of the mandibular first molars. The class II division 2 subjects showed statistically greater tooth wear on the labial surfaces of the mandibular central and lateral incisors, the incisal surface of maxillary and mandibular incisors, the palatal surfaces of the maxillary second premolars, first and second molars. In class II division 1 subjects, the tooth wear was significant on the buccal surface of maxillary canines, occlusal surface of mandibular first premolars and second molars in males. In class II division 2 subjects, the tooth wear was significant on the buccal surface of mandibular canines, palatal surface of maxillary central incisors in females and palatal surface of maxillary first premolars in males. The results of this study suggested that the two categories of Angle's class II malocclusion have different tooth-wear patterns. The wear patterns were different in both the sexes. Men showed higher occlusal wear scores than did women. The findings also suggest that tooth wear in relation to malocclusion is physiologic and is due to dissimilar interocclusal arrangement.

Minimum size and positioning of imaging field for CBCT scans of impacted maxillary canines

ObjectivesIn children and adolescents, cone-beam computed tomography (CBCT) is frequently used for localization of unerupted or impacted teeth in the anterior maxilla. CBCT causes a higher radiation dose than conventional intraoral and panoramic imaging. The objective was to analyze the location of impacted canines in a three-dimensional coordinate and thereby optimize the CBCT field-of-view (FOV), for radiation dose reduction.Materials and methodsLocation of 50 impacted maxillary canines of children under 17 years was retrospectively evaluated from CBCT scans. The minimum and maximum distances of any part of the right- and left-side canines to three anatomic reference planes were measured to assess the adequate size and position of a cylindrical image volume.ResultsA cylinder sized 39.0 (diameter)×33.2 (height) mm, with its top situated 13.8 mm above the hard palate, its medial edge 8.4 mm across the midline, and anterior edge 2.5 mm in front of the labial surface of maxillary central incisors fitted all the analyzed canines.ConclusionsIn this sample, the FOV required for imaging maxillary impacted canines was smaller than the smallest FOV offered by common CBCT devices. We encourage development of indication-specific CBCT imaging programs and aids to facilitate optimum patient positioning.Clinical relevanceAn impacted maxillary canine is a common dental problem and a frequent indication for 3D imaging particularly in growing individuals. This article focuses on the optimization of CBCT of impacted canines. Our recommendation of a reduced FOV promotes radiation safety.

The correlation between upper lip length, amount of free way space and visible portion of anterior teeth at rest position.

The aims of this study were to investigate the degree of visibility of maxillary and mandibular anterior teeth surfaces when the lips are at rest. And to evaluated its correlation with age and sex. As well as to determine the correlation of the upper lip length with the amount of clinical free way space.Two hundred adults (100 males and 100 females) were examined. All the subjects had maxillary and mandibular anterior teeth present with bilateral molar support. The measurement was taken at the midpoint of the each anterior tooth when the lips and lower jaw were at rest position. The length of upper lip was measured from the base of the columella to the tip of the philtrum at the midline of the face. Artificial landmarks (adhesive tape) were placed on the more prominent parts of the nose and chin of each subject. The clinical free way space value was obtained by subtracting measured vertical dimension of occlusion from postural vertical dimension.Females showed more of the maxillary central and lateral incisors than males. With increasing age, the amount of maxillary anterior teeth that was visible at rest position decreased. Statistically the amount of visible surface of maxillary central incisor showed significant differences with increasing age of subjects. The subjects with shorter upper lips displayed more of maxillary central and lateral incisors than those with longer upper lips. Significant differences were founded between the visible amount of maxillary central and lateral incisors and lip length. It was founded that the more increased in the length of upper lip, the more decreased in the vertical dimension as increased in the amount of clinical free way space which is founded within the recommended range (2-4mm). High significant differences were founded between the amount of clinical free way space and length of upper lip. Females showed shorter upper lip than males and high significant differences were founded between sexes and upper lip length.

Lateral pedicle graft for repair of residual gingival defect following complete surgical excision of a pyogenic granuloma

The pyogenic granuloma, one of the gingival lesions, has recurrence rate of 16%. To minimize the recurrence rate, it must be completely excised. Complete surgical excision can result in residual gingival defect. McCrea repaired residual gingival defect by subepithelial connective tissue graft with lateral mucogingival pedicle flap, and Choudhary et al. managed residual gingival defect by subepithelial connective tissue graft only. The aim of this case report was to use lateral pedicle graft for repair of residual gingival defect following complete surgical excision of a pyogenic granuloma. A patient with pyogenic granuloma on labial surface of maxillary central incisors was treated by complete surgical excision, and residual gingival defect was repaired by lateral pedicle graft. A lateral pedicle graft was raised as full-thickness up to mucogingival line and partial-thickness apical to mucogingival line from the left side of residual gingival defect. After 6 months, no recurrence was noticed. Thus, lateral pedicle graft can be potentially used for repair of residual gingival defect following complete surgical excision of a pyogenic granuloma.

Relationship of Incisive Papilla to Maxillary Incisors and Canines

The study was carried to find a relationship between the postextraction stable landmark, the incisive papilla, and the most labial position of the maxillary central incisor teeth, which occurred in Nepalese population. Casts of the subjects selected by nonprobability random sampling meeting the inclusion criteria were obtained. Each casts were standardized with respect to the occlusal plane and a photographic technique was used to measure the distance from the tangent of the labial surface of the central incisors to the posterior border of the incisive papilla. The measurements were made using Adobe Photoshop and results were analyzed by using appropriate statistical methods. Most appropriate software (SPSS) for the purpose was used to generate all desired values. The data obtained suggested that the distance from the labial surface of maxillary central incisors to the posterior border of the incisive papilla ranged from 9 to 15.9 mm with a mean of 11.59 mm (SD 1.3). Various other results were also found after evaluation of the arch forms in relation to sex and race. Within the limitations of the study, these results suggested that there is a relationship between the maxillary central incisors and the incisive papilla aiding in the anteroposterior positioning of the anterior tooth. The clinical relevance of the study lies in application of the incisive papilla as a starting point in the preliminary location of maxillary incisors and canines during construction of the denture in absence of preextraction records.

A study on the validity of reference points for edentulous patient

Purpose: The purpose of this study was to evaluate the validity of reference points for edentulous patient by examining the correlation of teeth and face, and intraoral anatomic land- marks. Materials and methods: We examined a facial outline, length, bizygomatic width, nasion - gnathion length, glabella - nasion distance in 270 men and 280 women satisfied with inclusion criteria from Seoul National School of Dentistry. The shape of maxillary central incisor, mesiodistal crown width and length of maxillary 6 incisors, distance from incisive papilla to labial surface of maxillary central incisor, and perpendicular distance from incisive papilla to intercanine line were measured in the stone mod- el. We analyzed the ratio and relevant relation statistically. Results: The probability on having the same shape of face and the relative same shape maxillary incisor was 55.56% and 46.43% for men and women. The facial length proved to be a more valuable measurement in women in the tooth selection. The ratio of bizygomatic width to mesiodis- tal width of maxillary central incisor, and the ratio of bizygomatic width to width of maxillary 6 incisors were 16.8 : 1 and 3.0 : 1 and were positively correlated with each other. The distance of the canines from the maxillary incisal papilla was 1.33±1.28 mm. The distance between the center of the incisal papilla and the labial surface of their maxillary central incisor was 9.23±1.20 mm. Conclusion: It was showed that anatomical reference points in tooth selection and arrangement for edentulous patient are use- ful and have validity in our limited study. (J Korean Acad Prosthodont 2015;53:310-7)

Prevention of orthodontic enamel demineralization with Duraphat

The clinical data was collected from 26 orthodontics patients at our hospital. All of them received straight wire appliance. The observed teeth were randomly classified into experiment and comparison groups. After the mounting of orthodontic bracket, Duraphat was smeared on the surface of maxillary central incisor, maxillary lateral incisor, maxillary canine, maxillary first premolar and maxillary first premolar in the experiment group while no Duraphat was applied in the comparison group. After wearing orthodontic appliance for 1, 3, 6 and 9 months, enamel demineralization of each tooth was observed. And the enamel decalcification index (EDI) of different areas of each tooth at different timepoints was recorded. More demineralization areas existed in the comparison group than the experiment group (P<0.01). In addition, no Ⅲ degree enamel demineralization was observed in the experiment group after Duraphat applying for 1 month. EDI were 0.20, 0.24, 0.21 and 0.16 in the experiment group after Duraphat applying for 1, 3, 6 and 9 months versus 0.37, 0.44, 0.44 and 0.34 in the comparison group during the same time periods. Therefore EDI and demineralization areas were significantly smaller in the experiment group than those in the comparison group (P<0.01). Key words: Orthodontics; Sodium fluoride

PAPILLO-INCISAL DISTANCE

Objectives: To compare the influence of various arch forms on papillo-incisal distance PID (distance between posterior limit of the incisive papilla and the most prominent contour of the labial surface of maxillary central incisors). Study design: Descriptive study. Place and duration of study: Department of Prosthodontics, Lahore Medical and Dental College, Lahore, Pakistan, from October 2004-December 2005 &amp; May2010-September2010. Methodology: A total of 250 subjects, 125 male and 125 female were included. Theme of evaluation was incisive papilla maxillary central incisor distance and arch form. Normal healthy subjects with symmetrical arches and all teeth present except third molars were included. Subjects with malformed teeth, periodontal problems, orthodontic treatment or restorations on the labial tooth surfaces were excluded. Data was analyzed in SPSS 16 package by applying t test and ANOVA, with p≤0.05 as cut off point for statistical significance. Results: The mean PID was 12.02mm SD±1.5. Among the subjects 82% had ovoid, 7% had tapering and 11% had squarish arches. Conclusions: Mean PID 12.02mm SD±1.5is suggested for artificial central incisors replacement. There is higher presentation of ovoid arches with a strong influence of arch forms (p-value &lt;0.02) and a weak influence of gender (p-value &lt;0.489) on PID.

A rare case of multiple talon cusps in three siblings

Talon cusp is an uncommon anomaly, whose etiology may be disturbances in the morphodifferentiation stage. Dens in dente is also a rare anomaly that is challenging in clinic as it may cause pulp necrosis or periapical lesions due to the communication with the oral cavity. This article reports multiple talon cusps on permanent maxillary and mandibular incisors and molars in 3 siblings. A 9-year-old boy presented with structures like nodules, shaped as cylindrical cones with a sharp point or a raindrop with deep developmental fissures on the palatal aspect of the maxillary central incisors, lingual aspect of the mandibular central incisors and labial aspect of both mandibular first molars. The buccal surface of the maxillary right central incisor was also affected. Some of them exhibited dens in dente. His 15-year-old sister had prominent talon cusps on the palatal surface of maxillary central incisors and buccal surface of the mandibular first molars and mandibular left second molar. His 7-year-old brother had only one trace talon on the maxillary left central incisor. No syndrome was identified in the patients. In conclusion, genetic inheritance may be a causative factor in talon cusp.

The effect of altering jaw position on the transmission of vibration between the skull and teeth in humans

The forces that develop in the human temporomandibular joint during function have never been directly measured, yet many patients exhibit excessive localized wear and tear of the joint, suggesting that at times these forces exceed tissue tolerance. The purpose here was to gain insight into vibration transmission between the cranium and mandible in healthy humans during variations of jaw position. In 13 normal healthy adult men (age 25–40 years) with normal dentitions, vibration (around 400 Hz, sine wave) was applied to the skull vertex and changes in the intensity of the vibration signal were measured using several small linear accelerometers cemented to the buccal surfaces of mandibular first molars and the labial surfaces of maxillary central incisors. The jaw was opened, protruded and moved laterally by the individual participant and vibration signal intensities were tested (lower first molar signal/upper incisor signal) for change at each mandibular position by ANOVA. The results showed the vibration signal changed significantly with opening and less so on protrusion and laterotrusion. The vibration signal during opening could be categorized into three types: (1) signal increased continuously with increased opening; (2) signal increased, then reached a plateau during last third of opening; (3) signal increased, then decreased when the individual moved from 40 mm to maximum opening. These findings show that as the jaw moves laterally, and especially as it opens, the magnitude of the vibration signal increases substantially compared with the near-closed position.

Distribution of Tabercle-shaped Incisors in South Pacific Populations.

The basal tubercle and its related traits on the basal part of the lingual surface of maxillary central incisors vary in developmental grades. Although a well-developed basal tubercle was observed in fossil humans, much attention to this trait has not been paid in modern humans. We compared five morphological traits on the lingual surface of maxillary incisors among seven Pacific populations. Results showed that the South-Pacific populations examined in this study especially Fijians and New Guinea Highlanders had a well-developed basal tubercle, but with a low frequency of shovel-shaped incisors. On the contrary, Japanese and Kiribatian populations of this study had a high frequency of shovel-shaped incisors, but a low frequency of tubercle-shaped incisors. It was suggested that the basal tubercle is one of the key dental traits in characterizing Pacific populations.

Incisor microwear and feeding behavior in Alouatta seniculus and Cebus olivaceus.

Dental microwear features on the labial surfaces of maxillary central incisors of wild-shot museum specimens of Cebus olivaceus (n = 11) and Alouatta seniculus (n = 7) were examined at 200 × by polarized light microscopy. While wear scratch orientation patterns do not differ between the two samples, Cebus has a significantly higher density of wear features, and displays scratches that extend further cervically. Preliminary observations (n = 50 hours) on anterior tooth use in these species at Hato Masaguaral, in the Llanos of Venezuela, provide suggestions regarding how foraging patterns reported in the literature relate to these microwear differences. Cebus uses its front teeth more frequently in the manipulation of a greater variety of objects than does Alouatta.

歯が色沢と耐うしょく性との関係についての研究

Labial surfaces of maxillary central incisors were analyzed for the color and the acid resistance using as materials 130 teeth of dental students. Color of the teeth was measured intraorally with a fiber-colorimeter and was expressed with Adams' L, a, b. The enamel solubility in vivo was measured by applying a paper disk containing lactate buffer to the enamel surface. A weak but significant correlation between the enamel solubility and Adams' b values was found (r=0.314). This is supportive evidence for the clinical view that yellowish teeth are caries-resistant.

顎関節形態および前歯部被蓋状態が前方滑走運動に及ぼす影響

Maxillary central incisors are important as a dental factor of protrusive excursion. However, most orthodontists decide upon the relationship of maxillary central incisors without considering protrusive excursion in order to improve the function of mandibular movements and esthetics of facial profile. In the present study, to obtain data on the effects of changed incisal guidance on protrusive excursion, fifteen adult male subjects with normal occlusion and another fifteen adult male subjects with maxillary protrusion were selected, and records of the temporomandibular joint morphology and protrusive excursion were made using cephalometric laminagraph. In addition, data of protrusive excursion were collected when incisal guidance was experimentally changed on subjects with maxillary protrusion. Using this information, the effects of the temporomandibular joint morphology and incisal guidance on protrusive excursion were examined. The following results were obtained. 1. In cephalometric laminagraph, the depth of cut through the center of the condyle was a very effective method in which to examine the temporomandibular joint morphology and condyle path. 2. There was no significant difference in the temporomandibular joint morphology between the subjects with normal occlusion and those with maxillary protrusion. 3. There were significant differences in the condyle path from the intercuspal occlusal position to the edge-to-edge occlusal position between the subjects with normal occlusion and those with maxillary protrusion, and values of the angle and distance were bigger in the subjects with maxillary protrusion than in those with normal occlusion. 4. There was a correlation between the condyle path from the intercuspal occlusal position to the most anterior occlusal position and the inclination of articular eminence in the subjects with normal occlusion or with maxillary protrusion. 5. There were no correlations between the condyle path from the intercuspal occlusal position to the edge-to-edge occlusal position, and the inclinations of the articular eminence and lingual surface of maxillary central incisor, or between the inclination of the lingual surface of maxillary central incisor and the inclination of articular eminence, in the subjects with normal occlusion or with maxillary protrusion. 6. The steeper the incisal guidance was made, the steeper became the condyle path when the incisal guidance was experimentally changed. The foregoing results suggest that jaw movements alter when the incisal guidance is changed by orthodontic treatment. Therefore, orthodontists must pay attention to jaw movements and temporomandibular morphology.

A Clinical Study on the Plaque Formation and Its Propagative Process

In the present study, 12 dental students at Nihon University School of Dentistry were used. They were instructed to brush their maxillary and mandibular anteriors thoroughly for 10 minutes and, subseqently, their teeth remined unbrushed for 48 hours, in which time the formational processes of dental plaque were observed at 6 different intervals.In the initial time interval, the individual differences were particularly noted with the rate of plaque formation being anywhere form 21 to 27% after 4 hours. After the passage of 48 hours, however, the rate of plaque formation was just 4 to 10%. In terms of different teeth and surfaces, the labial surface of maxillary lateral incisors was the soonent in plaque formation in 13 to 16 hours after the brushing. followed by that of mandibular lateral incisors in 15 to 17 hours. The lingual surface of maxillary central incisors was the latest in plaque formation with the time lapse of 24 hours.Although there was no appreciable difference between the maxilla and mandible with regard to the labial surface, the mandible hed a tendency of a sooner plaque formation as regards the lingual surface.Propagative processes were not directly connected with an inadequate toothbrushing, and, in many cases, the tips of propagative plaques presented round appearances.