• Restorative Dentistry and Endodontics
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• v.35 no.1
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• pp.30-39
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• 2010

This study evaluated the influence of the type of restoration and the amount of interdental spacing on the stress distribution in maxillary central incisors restored by means of porcelain laminate veneers and direct composite resin restorations. Three-dimensional finite element models were fabricated to represent different types of restorations. Four clinical situations were considered. Type I, closing diastema using composite resin. Labial border of composite resin was extended just enough to cover the interdental space; Type II, closing diastema using composite resin without reduction of labial surface. Labial border of composite resin was extended distally to cover the half of the total labial surface; Type III, closing diastema using composite resin with reduction of labial surface. Labial border of the preparation and restored composite resin was extended distally two-thirds of the total labial surface; Type IV, closing diastema using porcelain laminate veneer with a feathered-edge preparation technique. Four different interdental spaces (1.0, 2.0. 3.0, 4.0 mm) were applied for each type of restorations. For all types of restoration, adding the width of free extension of the porcelain laminate veneer and composite resin increased the stress occurred at the bonding layer. The maximum stress values observed at the bonding layer of Type IV were higher than that of Type I, II and III. However, the increasing rate of maximum stress value of Type IV was lower than that of Type I, II and III.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.1
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• pp.41-51
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• 2005

Statement of problem. Anatomic landmarks have been used in the orientation of occlusal plane and the determination of vertical dimension for edentulous patients. Such as labial vestibules of anterior region and hamular notches, retromolar pads of posterior region are very useful anatomic landmarks for fabrication of occlusion rim because they are to be identified on master casts. Therefore, if average distances between landmarks of maxillae and mandible in dentate subjects are measured and applied, not only occlusal plane but also vertical dimension can be established initially. Purpose. The purpose of this study is to measure vertical distances between anatomic landmarks and to present a guide to the orientation of occlusal plane and the determination of vertical dimension of edentulous patients. Material and method. Upper and lower border-molded casts were made in 93 Korean dentulous subjects, mean age 25 years. Incisal edges of central incisors, bottoms of labial vestibules, hamular notches and the half level of retromolar pads were marked on casts. Measurements of vertical distances from incisal edge of central incisor to the bottom of labial vestibule, between upper and lower bottoms of labial vestibules, from hamular notch to retromolar pad and from hamular notch to the occlusal plane established by the incisal edge of maxillary central incisor and mesiopalatal cusps of both maxillary first molars were made on each cast. Results and conclusion. 1. The mean distance from the incisal edge of central incisor to the bottom of labial vestibule was 20.8mm(SD 1.7) on upper casts and 17.3mm(SD 1.4) on lower casts. 2. The mean distance between both bottoms of labial vestibules of upper and lower casts was 35.0mm(SD 2.7). 3 The mean distance from hamular notch to the half level of retromolar pad was 5.0mm(SD 1.3). 4. The mean distance from hamular notch to occlusal plane was 7.9mm(SD 1.5). 5. Distances from incisal edge of central incisor to labial vestibule on lower casts(P<0.01) and from hamular notch to retromolar pad(P<0.0001) were greater in male than in female.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.3
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• pp.266-271
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• 2014

This study was performed to evaluate the relationship between the types of maxillary labial frenum attachment and the dental age in children. The maxillary labial frenum attachment levels were examined from the children who visited Chonbuk National University Dental Hospital between April, 2010 and December, 2013. The total number of the examined children was 320 (160 males, 160 females) between the age of 2 and 12. The types of maxillary labial frenum were categorized according to Placek's classification and each type was analyzed for its relationship with both Hellman's dental age and the eruption stage of permanent maxillary anterior teeth. The observed forms of maxillary labial frenum along with their frequency were as follows: gingival (56.3%), papillary (20.6%), mucosal (18.1%) and papillary penetrating (5.0%). The frenum form showed no significant difference due to gender (p > 0.05). From IC to IIIB in Hellman's dental age, the mucosal type increased significantly (p < 0.001). There was no significant relationship between the types of maxillary labial frenum attachment and the eruption state of permanent maxillary anterior teeth (p > 0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.694-699
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• 2001

The prognosis for class III patients in growing child can be made in mixed dentition and the severity of the symptom is often amenable to early intervention. Class III malocclusion can be classified as functional class lit and skeletal origin. Skeletal Class III malocclusion is usually characterized by overdeveloped mandible, underdeveloped maxilla, but the cause of pseudo class III is most dentoalveolar or functional shift of mandible. The primary goal of early intervention of malocclusion is to supply an environment that is conducive to the development of favorable occlusal relationships and avoiding of worsening of the problems. Inverted labial bow appliance is introduced as an appliance to combine the advantage of active plate and activator. It is undemanding with this appliance to initiate not only dentoalveolar expansion of upper dentition but also to orient the functional retrusion of mandible. With simple design the compliance for patients such as mouth breathing problem can be improved. For successful use of this appliance it is utmost important to make accurate and early diagnosis between pseudo- and skeletal class III malocclusion. This article will demonstrate the use of an Inverted labial bow appliance for early treatment of a functional Class III malocclusion. After 4 month treatment, anterior crossbite was treated and the results were achieved mainly dentoalveolar change of upper and lower anterior teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.103-115
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• 1991

This study was executed to analyze the stress distribution of tooth, supporting structure and overdenture by two-dimensional photoelastics when 6 types of coping were inserted. Types of coping were designed to be inclined plane, short dome, medium dome, shore square, medium square and o-p anchor attachment. Fortes were applied respectively as follows: 1) Vertical load of 10 kg on the incisal edge 2) $30^{\circ}$ diagonal load of 8 kg on the labial surface. The results were as follows: 1. In case of short dome and o-p anchor attachment, the stress is evenly distributed on teeth, supporting tissue structure under vertical and $30^{\circ}$ diagonal load, then short dome and o-p anchor attachment show better stress distribution and stabilization of overdenture than any other coping under labial diagonal load. 2. Inclined plane revealed greater tendency of displacement of overdenture than any other coping under labial diagonal load. 3. Long height of copings had greater concentration of stress than short height of copings. 4. In case of medium dome under labial diagonal load, there were high level of stress concentration on denture base contacted labioincisal angle of coping.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.31.1-31.7
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• 2019

Background: To test the hypothesis that in profile smiling view, for ideal aesthetics, a tangent to the labial face of the maxillary central incisor crowns should be approximately parallel to the true vertical line and thereby perpendicular to the true horizontal line. Methods: An idealized female image was created with computer software and manipulated using the same software to construct an "ideal" female profile image with proportions, and linear and angular soft tissue measurements, based on currently accepted criteria for idealized Caucasian profiles. The maxillary incisor labial face tangent was altered in 5° increments from 70 to 120°, creating a range of images, shown in random order to 70 observers (56 lay people and 14 clinicians), who ranked the images from the most to the least attractive. The main outcome was the preference ranks of image attractiveness given by the observers. Results: The most attractive inclination of a tangent to the labial face of the maxillary incisor crowns in profile view in relation to the true horizontal line was 85°, i.e. 5° retroclined from a perpendicular 90° inclination. The most attractive range appears to be between 80 and 90°. Excessive proclination appeared to be less desirable than retroclination. Beyond 105° most observers recommend treatment. Conclusion: In natural head position, the ideal inclination of the maxillary incisor crown labial face tangent in profile view will be approximately parallel to the true vertical line and thereby approximately perpendicular to the true horizontal line.

• The Journal of Advanced Prosthodontics
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• v.5 no.4
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• pp.409-415
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• 2013

PURPOSE. The midline fracture of maxillary complete dentures is a frequently encountered complication. The purpose of this study was to assess the effect of frenulum height on midline strains of maxillary complete dentures. MATERIALS AND METHODS. A removable maxillary complete denture was fabricated and duplicated seven times. Four different labial frenulum heights were tested for stresses occurring on the palatal cameo surface. The strains were measured with strain gauges placed on 5 different locations and the stresses were calculated. To mimic occlusal forces bilaterally 100 N of load was applied from the premolar and molar region. RESULTS. A statistically significant association between the height of the labial frenulum and the calculated stresses and strains was shown (P<.05) predominantly on the midline and especially on the incisive papilla. The results showed that stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. CONCLUSION. Within the limitations of this in vitro study, it can be concluded that the stress on the anterior midline of the maxillary complete denture increases with a higher labial frenulum. Surgical or mechanical precautions should be taken to prevent short-term failure of maxillary complete dentures due to stress concentration and low cycle fatigue tendency at the labial frenulum region.

• Journal of Periodontal and Implant Science
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• v.50 no.4
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• pp.226-237
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• 2020

Purpose: This study was conducted to assess the efficacy of prophylactic gingival grafting in the mandibular anterior labial area for preventing orthodontically induced gingival recession. Methods: Eight mongrel dogs received gingival graft surgery at the first (I1) and third (I3) mandibular incisors on both sides based on the following group allocation: AT group (autogenous connective tissue graft on I1), AT-control group (contralateral side in the AT group), CM group (xenogeneic cross-linked collagen matrix graft on I3) and CM-control group (contralateral side in the CM group). At 4 weeks after surgery, 6 incisors were splinted and proclined for 4 weeks, followed by 16 weeks of retention. At 24 weeks after surgery, casts were made and compared with those made before surgery, and radiographic and histomorphometric analyses were performed. Results: Despite the proclination of the incisal tip (by approximately 3 mm), labial gingival recession did not occur. The labial gingiva was thicker in the AT group (1.85±0.50 mm vs. 1.76±0.45 mm, P>0.05) and CM group (1.90±0.33 mm vs. 1.79±0.20 mm, P>0.05) than in their respective control groups. Conclusions: The level of the labial gingival margin did not change following labial proclination of incisors in dogs. Both the AT and CM groups showed enhanced gingival thickness.

• Imaging Science in Dentistry
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• v.36 no.3
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• pp.145-149
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• 2006

Purpose : To assess the width of the labial alveolar bone of the incisive canal and the width of the incisive canal on spiral computed tomographic images of the anterior portion of the maxilla. Materials and Methods : Study materials included 38 CT scans taken for preoperative planning of implant placement. Axial cross-sectioned image entirely showing the incisive canal was selected and scanned with 600 DPI resolution. The width of the labial alveolar bone of the incisive canal at an orifice to the oral cavity, middle portion, and an orifice to the nasal cavity and the diameter of the incisive canal at the middle portion were determined by two specialist using Digora for Windows 2.1 The statistical analyses were carried out using SPSS 12.0.1. Results : When the maxillary central incisors remained, the mean labial alveolar bone width were $6.81{\pm}1.41mm,\;6.46{\pm}1.33mm$, and $7.91{\pm}1.33mm$. When the maxillary central incisors were missed the mean width were $5.42{\pm}2.20mm,\;6.23{\pm}2.29mm$, and $7.89{\pm}2.13mm$. Conclusions : The labial alveolar bone width at middle portion and an orifice to the nasal cavity were of no statistical significant difference according to presence of the maxillary central incisors (P>0.05). The width between oral cavity and nasal cavity, middle portion and to nasal cavity revealed statistically significant difference (P<0.05).

• The korean journal of orthodontics
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• v.49 no.6
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• pp.381-392
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• 2019

Objective: The objective of this two-arm parallel trial was to compare the type of tooth movement during en masse retraction of the maxillary anterior teeth using labial versus lingual biocreative therapy. Methods: Twenty-eight subjects were randomized in a 1 : 1 ratio to either the labial or lingual group. En masse anterior retraction was performed using labial biocreative therapy in group A and lingual biocreative therapy in group B. Cone beam computed tomography scans were taken before and after retraction and the primary outcome was the type of tooth movement during anterior retraction. Data were analyzed using paired t-tests for comparisons within each group and independent-sample t-test for comparison of the mean treatment changes between the two groups. Results: Significant differences were found between the two groups in relation to the type of tooth movement (labiolingual inclination of the central incisor; mean difference, $5.85{\pm}1.85^{\circ}$). The canine showed significant distal tipping in the lingual group (mean difference, $6.98{\pm}1.25^{\circ}$). The canine was significantly more intruded in the lingual group (mean difference, $1.67{\pm}0.49mm$). Good anchorage control and significant soft tissue changes occurred in both groups. No serious adverse effects were detected. Conclusions: With a 10-mm retraction hook, the labial biocreative technique with the reverse curve overlay provided anterior retraction with good torque control, while in the lingual group, anterior retraction occurred with controlled tipping movement with significant distal tipping and intrusion of the canine (trial registration: The trial was registered at ClinicalTrials.gov [NCT03239275]).