Morphologic changes of the incisive canal and its proximity to maxillary incisor roots after anterior tooth movement.

INTRODUCTION: The objectives were to evaluate the morphologic changes of the incisive canal (IC) and the influence of IC proximity to apical root resorption of maxillary central incisors after anterior tooth movement. METHODS: Pretreatment and posttreatment cone-beam computed tomography images of adults (aged 18-47 years) were retrospectively evaluated. Subjects were divided into control group with minimal incisor movement (n = 32; maxillary incisor tip movement <2 mm) and maximum retraction group (n = 35; maxillary incisor tip movement >4 mm). The shape, direction, morphologic changes of the IC, the proximity of the central incisor root to IC, and the amount of apical root resorption associated with the proximity after orthodontic treatment were compared. RESULTS: Changes in the shape of the IC were not observed in both control and retraction groups. However, 11.4% (4 of 35 subjects) in the retraction group indicated changes in the direction of the IC from slanted-straight to slanted-curved type after the direction of anterior retraction. The thickness of the cortical bone surrounding the IC and the distance between the incisor root and IC significantly decreased after orthodontic treatment in both groups (P <0.05). However, these changes were significantly greater in the retraction group than in control (P <0.0001). Contact or invasion of the incisor root to the IC was more prominent in the retraction group (42.8%-54.3%) than the control (10.9%-12.5%) (P <0.0001). The amount of root resorption indicated a tendency to increase in the order of separation, approximation, contact, and invasion in relation to IC. CONCLUSIONS: Although remodeling of IC was evident in some patients, contact or invasion of the maxillary central incisor roots to IC was fairly high after maximum anterior retraction.

Nonsurgical treatment of an adult with a skeletal Class III malocclusion combined with a functional anterior shift, severely overclosed vertical dimension, and a reverse smile.

This case report illustrates the successful nonsurgical treatment of an adult with a skeletal Class III malocclusion exacerbated by a functional anterior shift that resulted in a severe overclosure of the mandible and a reverse smile line. To maximize the soft tissue and smile esthetics while idealizing the occlusion, active clockwise rotation of the mandible was induced along with mandibular molar uprighting and sequential leveling. In the maxilla, full arch distalization was achieved after second molar extraction. The treatment provided a satisfying esthetic and functional outcome and has remained stable.

Posterior dental compensation and occlusal function in adults with different sagittal skeletal malocclusions.

OBJECTIVE: The aim of this study was to compare posterior tooth inclinations, occlusal force, and contact area of adults with different sagittal malocclusions. METHODS: Transverse skeletal parameters and posterior tooth inclinations were evaluated using cone beam computed tomography images, and occlusal force as well as contact area were assessed using pressure-sensitive films in 124 normodivergent adults. A linear mixed model was used to cluster posterior teeth into maxillary premolar, maxillary molar, mandibular premolar, and mandibular molar groups. Differences among Class I, II, and III groups were compared using an analysis of variance test and least significant difference post-hoc test. Correlations of posterior dental inclinations to occlusal function were analyzed using Pearson's correlation analysis. RESULTS: In male subjects, maxillary premolars and molars had the smallest inclinations in the Class II group while maxillary molars had the greatest inclinations in the Class III group. In female subjects, maxillary molars had the smallest inclinations in the Class II group, while maxillary premolars and molars had the greatest inclinations in the Class III group. Occlusal force and contact area were not significantly different among Class I, II, and III groups. CONCLUSIONS: Premolar and molar inclinations showed compensatory inclinations to overcome anteroposterior skeletal discrepancy in the Class II and III groups; however, their occlusal force and contact area were similar to those of Class I group. In subjects with normodivergent facial patterns, although posterior tooth inclinations may vary, difference in occlusal function may be clinically insignificant in adults with Class I, II, and III malocclusions.

The effect of cetirizine, a histamine 1 receptor antagonist, on bone remodeling after calvarial suture expansion.

OBJECTIVE: The objective of this study was to evaluate the effects of cetirizine, a histamine 1 receptor antagonist, on bone remodeling after calvarial suture expansion. METHODS: Sixty male Sprague-Dawley rats were divided into 4 groups; the phosphate-buffered saline (PBS)-injected no expansion group, cetirizine-injected no expansion group, PBS-injected expansion group, and cetirizine-injected expansion group, and were observed at 7, 14, and 28 days. Five rats per group were examined at each observation day. Daily injections of cetirizine or PBS were administered to the relevant groups starting 2 weeks prior to expander insertion. A rapid expander was inserted in the calvarial bone to deliver 100 cN of force to the parietal suture. The specimens were prepared for hematoxylin and eosin and tartrate-resistant acid phosphatase (TRAP) staining. Suture opening and bone regeneration were evaluated using microcomputed tomography and bone histomorphometric analysis. Serum blood levels of osteocalcin and carboxy-terminal collagen crosslinks (CTX) were also evaluated. RESULTS: TRAP-positive cell counts and CTX levels decreased while osteocalcin levels increased in the cetirizine-injected expansion group at observation day 28. In the expansion groups, the mineralized area gradually increased throughout the observation period. At day 28, the cetirizine-injected expansion group showed greater bone volume density, greater mineralized area, and narrower average suture width than did the PBS-injected expansion group. CONCLUSIONS: Cetirizine injection facilitated bone formation after suture expansion, mostly by suppressing osteoclastic activity. Histamine 1 receptor antagonists may aid in bone formation after calvarial suture expansion in the rat model.

A longitudinal comparison of body height growth of orthodontically treated Class I and Class III adolescents compared with the general population.

INTRODUCTION: The aim of this study was to evaluate the height growth of Class I and III orthodontic patients according to the Fishman skeletal maturation index (SMI) and to compare it with that of a general population. METHODS: The study sample included 81 Class I and 71 Class III adolescents who had height measurements and hand-wrist radiographs taken annually and categorized according to SMI. Height completion rate, residual height, height increase per sequential SMI stage, and height velocity were analyzed. Sex differences were evaluated and comparisons between Class I and Class III groups were made. In addition, the height of orthodontic patients was indirectly compared with that of the general population. RESULTS: In boys and girls, height completion rate was >90% at SMI 6, residual height was fewer than 10 cm at SMI 7, and height increase per sequential SMI stage was greatest from SMI 6 to SMI 7. Height velocity was greatest from SMI 5 to SMI 6 in boys and from SMI 4 to SMI 5 in girls. CONCLUSIONS: There was no significant difference in body height parameters for all SMI stages between Class I and Class III adolescents. Adolescents who had orthodontic treatment were not shorter in stature at growth completion compared with the general population.

Periodontal and root changes after orthodontic treatment in middle-aged adults are similar to those in young adults.

INTRODUCTION: The goal of this study was to compare the outcomes and amount of change in periodontal health of anterior teeth in young versus middle-aged adults, who were treated to improve anterior alignment and occlusion. METHODS: Pre- and posttreatment records including orthodontic casts, cephalograms, and standardized periapical radiographs were retrospectively collected from young adults (aged 19-30 years; n = 12) and middle-aged adults (aged ≥40 years; n = 27). Following the American Board of Orthodontics criteria, discrepancy index (DI), cast-radiograph evaluation (CRE), treatment duration (TD), marginal bone loss (MBL), and tooth length (TL) were measured, and with the use of periapical radiographs, changes in the level of marginal bone (MBC) and the amount of root resorption (RR) after orthodontic treatment were calculated. RESULTS: DI, MBL, and TD were significantly higher in the middle-aged adults than in the young adults (P < 0.05). However, CRE and MBC after treatment were similar between the 2 groups (P > 0.05). The mean amount of RR following treatment was -0.6 ± 0.44 mm and -1.0 ± 0.61 mm in young and middle-aged adults, respectively. The degree of RR after compensating for treatment complexity and TD was similar between the 2 groups (P > 0.05). CONCLUSIONS: Although the initial malocclusion and periodontal conditions were unfavorable for the middle-aged adults, the overall treatment and periodontal outcomes after orthodontic treatment of the anterior teeth were similar to those for young adults. It appears that older adults tolerate orthodontics to improve the appearance of the anterior teeth as well as younger adults, with no additional burden because of their increased age.

Differential alveolar bone modeling after orthodontic retraction.

BACKGROUND: Distinct, irregular, and hard nodular protuberances similar to the morphologic features of exostoses can occasionally be noted on the labial surface of the alveolar bone after orthodontic retraction of anterior teeth in adults. These have long been believed to be exostoses developed in response to loading. However, specific characterization of this phenomenon has not been documented. CASE DESCRIPTIONS: Three cases of patients displaying multiple irregular labial bony protuberances after retraction of anterior teeth are reported. These protuberances appeared during retraction and became more prominent with additional retraction. Serial clinical photographs, lateral cephalograms, digital models, and cone-beam computed tomography scans were evaluated. On the basis of 3-dimensional superimpositions of digital models and cone-beam computed tomographic scans, the irregular protuberances appear to be the result of differential alveolar bone modeling, with more resorption of bone covering the tooth root than that of interdental bone, and not of true bone overgrowth or deposition (that is, exostoses). CONCLUSION AND PRACTICAL IMPLICATIONS: Orthodontic patients often seek treatment to improve occlusion as well as esthetics. Although this study shows that these protuberances are the result of differential modeling, they may still be perceived by patients as "outgrowths," which may cause concerns related to esthetics or comfort. Clinicians should note that these protuberances are a possible outcome when large amounts of bodily retraction and root movement of anterior teeth are planned. Patients who experience psychosocial problems with this phenomenon may be candidates for alveoloplasty.

Anchorage loss assessment of the indirect anchor tooth during adjunctive orthodontic treatment.

INTRODUCTION: This study quantitatively assessed movement of anchor teeth connected to a miniscrew (indirect anchor tooth) and investigated factors affecting movement during adjunctive orthodontic treatment. METHODS: Dental plaster models of 28 patients whose treatment included an indirect anchor tooth on one side were collected before and after treatment. The casts were digitally scanned, and 2 groups were constituted: the indirect anchor teeth (experimental group; n = 52) and the untreated teeth (control group; the first and second premolars opposing the indirect anchor tooth to which no orthodontic force was applied; n = 55). Pretreatment and posttreatment models were superimposed and the amount and direction of indirect anchor tooth movement were evaluated with the use of a univariate linear mixed model. Possible factors affecting movement of the indirect anchor tooth and its significance were also evaluated with the use of a multiple linear mixed model. RESULTS: The indirect anchor tooth moved 0.91 ± 0.50 mm and did not exhibit significant differences in the transverse, vertical, or sagittal directions. The location of the indirect anchor tooth affected movement and the tooth moved significantly more in the mandible than in the maxilla. CONCLUSIONS: The indirect anchor tooth can move during adjunctive orthodontic treatment and thus requires careful monitoring for occlusal changes.

Dynamics of alveolar bone healing after the removal of orthodontic temporary anchorage devices.

OBJECTIVE: The aim of this study was to investigate the dynamics of alveolar bone formation and healing pattern after the removal of orthodontic temporary anchorage devices (TADs). METHODS: Miniscrews (N = 32) were inserted into the buccal inter-radicular alveolar bone in beagle dogs. Afterward, miniscrews were removed at different time points during a 13-week period and six different in vivo fluorescent markers were injected at 1, 2, 6, 8, 10, and 12 weeks. Serial changes in bone apposition at the removal and intact control sites were evaluated using µCT, histology, and bone histomorphometry. RESULTS: Gradual bone apposition at the TAD removal site was noted with bone volume/tissue volume (BV/TV) reaching the level of the control alveolar bone by 7 weeks. Histologically, newly formed woven bone was detected within the removal site which was distinct from the surrounding pre-existing alveolar bone at 13 weeks. Accelerated mineral apposition rate (MAR) and bone formation rate (BFR) were noted between 2 and 6 weeks in the removal site (P < 0.05). Although MAR and BFR gradually decreased after its peak at 2-4 weeks, BFR in the removal site was still higher than the control site at 10-12 weeks (P < 0.05). CONCLUSIONS: Spontaneous bone healing was noted after TAD removal with regional acceleration of MAR and BFR within 2-6 weeks. However, the removal site was mainly filled with woven bone even after 13 weeks, suggesting a longer healing period is required for the quality of the alveolar bone to reach levels comparable to the surrounding alveolar bone.

A 15-year follow up of an orthodontic treatment including a lower incisor extraction and keeping the maxillary canine-premolar transposition.

Lower incisor extraction is an effective option for treating lower anterior crowding in patients with a good facial profile, Class I molar occlusion, and narrow upper incisors. This report describes the successful treatment of an adolescent patient with lower anterior crowding and a transposed maxillary canine and premolar treated by extracting a lower incisor and keeping the transposed positions of the teeth. With the use of retainers, treatment results were stable up to the 2-year postretention visit. However, upon a 15-year postretention appointment, the fixed retainer had been removed and the removable retainer was no longer in use, which resulted in relapse of lower anterior alignment. Moreover, the transposed canine had extruded during this period, causing occlusal interference and gingival recession, as well as loss of tooth vitality, which indicates the importance of maintaining orthodontic retainers for long-term stable occlusion.

Nonsurgical and nonprosthetic camouflage treatment of skeletal Class II open bite with bilaterally missing lower first molars.

This report illustrates the successful nonsurgical and nonprosthetic camouflage treatment of a skeletal Class II open bite malocclusion combined with missing mandibular first molars bilaterally. In the mandible, the second and third molars were uprighted and protracted, substituting for the missing first molars. In the maxilla, anterior bodily retraction and full-arch intrusion were achieved following premolar and second molar extraction, which also induced autorotation of the mandible. The treatment outcome and prognosis were confirmed with three-dimensional superimposition techniques, along with long-term stability.

Assessment of lower incisor alveolar bone width using cone-beam computed tomography images in skeletal Class III adults of different vertical patterns.

OBJECTIVE: This study was performed to investigate the alveolar bone of lower incisors in skeletal Class III adults of different vertical facial patterns and to compare it with that of Class I adults using cone-beam computed tomography (CBCT) images. METHODS: CBCT images of 90 skeletal Class III and 29 Class I patients were evaluated. Class III subjects were divided by mandibular plane angle: high (SN-MP > 38.0°), normal (30.0° < SN-MP < 37.0°), and low (SN-MP < 28.0°) groups. Buccolingual alveolar bone thickness was measured using CBCT images of mandibular incisors at alveolar crest and 3, 6, and 9 mm apical levels. Linear mixed model, Bonferroni post-hoc test, and Pearson correlation analysis were used for statistical significance. RESULTS: Buccolingual alveolar bone in Class III high, normal and low angle subjects was not significantly different at alveolar crest and 3 mm apical level while lingual bone was thicker at 6 and 9 mm apical levels than on buccal side. Class III high angle group had thinner alveolar bone at all levels except at buccal alveolar crest and 9 mm apical level on lingual side compared to the Class I group. Class III high angle group showed thinner alveolar bone than the Class III normal or low angle groups in most regions. Mandibular plane angle showed negative correlations with mandibular anterior alveolar bone thickness. CONCLUSIONS: Skeletal Class III subjects with high mandibular plane angles showed thinner mandibular alveolar bone in most areas compared to normal or low angle subjects. Mandibular plane angle was negatively correlated with buccolingual alveolar bone thickness.

Three-dimensional evaluation of dentofacial transverse widths in adults with different sagittal facial patterns.

INTRODUCTION: The aim of this study was to evaluate the dentofacial transverse dimensions of subjects with different sagittal facial patterns using 3-dimensional cone-beam computed tomography images. METHODS: Cone-beam computed tomography images of 63 men and 80 women were divided into skeletal Class I, Class II, and Class III groups. Skeletal and dental evaluations were made on frontal views and coronal cross-sections of the images. Independent 2-sample t tests and 1-way analysis of variance followed by post hoc Tukey tests were used for sex and group differences. Pearson correlation analysis was used to identify factors related to changes in ANB angle. RESULTS: The Class II subjects did not show differences in maxillomandibular width and maxillary width compared with Class I subjects; however, their maxillary molars were more lingually tipped. The Class III subjects showed greater maxillomandibular width differences and smaller maxillary widths and maxillary buccolingual alveolar widths at midroot level compared with Class I subjects. The maxillary molars were buccally inclined, and the mandibular molars were lingually compensated in Class III subjects. The ANB angle showed positive correlations with jugal process width, maxillary width, and maxillary buccolingual alveolar width at midroot level as well as mandibular molar buccal inclination; negative correlations were found in maxillomandibular width difference, mandibular width at midroot level, and maxillary molar buccal inclination. CONCLUSIONS: A relative comparison of Class I, Class II, and Class III subjects showed that dental compensation had occurred to overcome the transverse skeletal discrepancies in the maxillary posterior segments of Class II and Class III subjects. This could escalate unidentified periodontal and functional problems in the long term. Future studies of transverse dentofacial dimensions, including periodontal evaluations and occlusal forces, would be useful for delivering proper orthodontic treatment for skeletal Class II and Class III subjects.

Treatment satisfaction and its influencing factors among adult orthodontic patients.

INTRODUCTION: The aim of this study was to investigate the level of satisfaction for orthodontic treatment among adult patients. In addition, the influencing host factors were monitored for their associations with satisfaction. METHODS: A questionnaire was designed to measure the level of satisfaction in 10 items; overall satisfaction, tooth alignment, facial appearance, eating and chewing, confident smile and self-image, retention state, treatment duration, treatment costs, intention to recommend, and relief of previous concerns, using a 5-point Likert scale. Total satisfaction was calculated by averaging the Likert scores from the 10 items. The survey was conducted, and the results from 298 adults were evaluated. RESULTS: For the overall satisfaction item, 45.0% were very satisfied, and 39.9% were satisfied, resulting in a satisfaction ratio of 84.9%. Total satisfaction score was 3.9. The level of satisfaction for tooth alignment and confident smile and self-image were significantly higher than facial appearance and eating and chewing (P <0.001). Patients aged 50 and above were more satisfied than the younger ones, and men were more satisfied than women (P <0.05). CONCLUSIONS: Overall, adult patients were highly satisfied with orthodontic treatment. Age, sex, motivation, expected concern, and discomfort influenced the level of satisfaction.

Three-dimensional evaluation of dentofacial transverse widths of adults with various vertical facial patterns.

INTRODUCTION: The purpose of this study was to investigate maxillomandibular transverse widths and molar inclinations of adults with hypodivergent, normodivergent, and hyperdivergent facial patterns using cone-beam computed tomography. METHODS: We evaluated Class I subjects (55 men, 66 women) who were divided into hypodivergent (<27°), normodivergent (28°-37°), and hyperdivergent (>38°) groups by their mandibular plane angles. Frontal and coronal views of the images were analyzed. Sex differences, vertical facial pattern differences, and related factors were assessed with independent 2-sample t tests, 1-way analysis of variance followed by post hoc Tukey tests, and Pearson correlation analysis. RESULTS: The hypodivergent group had greater maxillary alveolar widths 7 mm apically from the alveolar crest. The intermolar widths and molar inclinations showed no significant differences among the groups. As the mandibular plane angles increased, interjugular widths, transverse mandibular widths, and buccolingual maxillary alveolar widths at the midroot level decreased, whereas the maxillomandibular width differences and palatal heights increased im both sexes. CONCLUSIONS: An increase in the mandibular plane angle is associated with tendencies of narrow mandibular arches, thinner maxillary alveolar bones at the midroot level, and higher palatal arches in both sexes. Intermolar widths and molar inclinations were not significantly affected by vertical facial patterns.

Quantitative and perceived visual changes of the nasolabial fold following orthodontic retraction of lip protrusion.

OBJECTIVES: The objectives of this study were to evaluate the quantitative and perceived visual changes of the nasolabial fold (NLF) after maximum retraction in adults and to determine its contributing factors. MATERIALS AND METHODS: A total of 39 adult women's cone-beam computed tomography images were collected retrospectively and divided into the retraction group (age 26.9 ± 8.80) that underwent maximum retraction following 4 premolar extraction and the control group (age 24.6 ± 5.36) with minor changes of the incisors. Three-dimensional morphologic changes of hard and soft tissue including NLF were measured by pre- and posttreatment cone-beam computed tomography. In addition, perceived visual change of the NLF was monitored using the modified Global Aesthetic Improvement Scale. The influence of age, initial severity of NLF, and initial soft tissue thickness was evaluated. RESULTS: Anterior retraction induced significant changes of the facial soft tissue including the lips, perioral, and the NLF when compared with the controls ( P < .01). Perceived visual changes of the NLF was noted only in women younger than age 30 ( P < .05), with the odds ratio (95% confidence interval) of 2.44 (1.3461-4.4226), indicating greater possibility for improvement of NLF esthetics in young women of the retraction group when compared with the controls. CONCLUSIONS: Orthodontic retraction induced quantitative and perceived visual changes of the NLF. For adult women younger than age 30, the appearance of the NLF improved after maximum retraction despite the greater posterior change of the NLF.

Dentofacial transverse development in Koreans according to skeletal maturation: A cross-sectional study.

OBJECTIVE: The aim of this study was to establish the normative data of dentofacial transverse dimensions according to the skeletal maturation stage in Korean adolescents with good occlusion, assess gender differences and determine correlations between transverse variables. METHODS: A total of 577 Korean subjects between ages 7 to 19 years and exhibiting skeletal Class I occlusion were categorized by skeletal maturation index (SMI) of Fishman using hand-wrist radiographs. Dentofacial transverse dimensions were assessed using posteroanterior cephalograms. Independent two-sample t-tests were used to analyze differences between genders. Pearson correlation coefficient was used to determine the correlation between transverse measurements. RESULTS: Dentofacial transverse norms relevant to skeletal maturation stages were established. The average maxillomandibular width difference and ratio at growth completion was 22.16 mm and 77.01% for males; 23.70 mm and 74.06% for females, respectively. Males had greater facial, maxillary and mandibular widths compared to females at every SMI stage. The maxillary and mandibular intermolar widths showed the strongest correlation for both sexes (r = 0.826 for males, r = 0.725 for females). CONCLUSIONS: Dentofacial transverse norms of Korean adolescents were established according to developmental stage. All dentofacial widths were greater in males at growth completion. Maxillary and mandibular intermolar widths were strongly correlated. This study may serve as a guideline for the assessment of dentofacial transverse growth according to skeletal maturation stage in Korean adolescents with good occlusion.

Visual attention during the evaluation of facial attractiveness is influenced by facial angles and smile.

OBJECTIVE: To examine the changes in visual attention influenced by facial angles and smile during the evaluation of facial attractiveness. MATERIALS AND METHODS: Thirty-three young adults were asked to rate the overall facial attractiveness (task 1 and 3) or to select the most attractive face (task 2) by looking at multiple panel stimuli consisting of 0°, 15°, 30°, 45°, 60°, and 90° rotated facial photos with or without a smile for three model face photos and a self-photo (self-face). Eye gaze and fixation time (FT) were monitored by the eye-tracking device during the performance. Participants were asked to fill out a subjective questionnaire asking, "Which face was primarily looked at when evaluating facial attractiveness?" RESULTS: When rating the overall facial attractiveness (task 1) for model faces, FT was highest for the 0° face and lowest for the 90° face regardless of the smile ( P < .01). However, when the most attractive face was to be selected (task 2), the FT of the 0° face decreased, while it significantly increased for the 45° face ( P < .001). When facial attractiveness was evaluated with the simplified panels combined with facial angles and smile (task 3), the FT of the 0° smiling face was the highest ( P < .01). While most participants reported that they looked mainly at the 0° smiling face when rating facial attractiveness, visual attention was broadly distributed within facial angles. CONCLUSIONS: Laterally rotated faces and presence of a smile highly influence visual attention during the evaluation of facial esthetics.

Long-term survival of retained deciduous mandibular second molars and maxillary canine incorporated into final occlusion.

Orthodontic treatment of a complex case that involves retained deciduous mandibular second molars with missing permanent successors is challenging. Usually, congenitally missing teeth are manifested with other dental anomalies that further complicate orthodontic treatment, such as retained deciduous teeth, impactions, transpositions and peg-shaped lateral incisors. Even though the long term prognosis of the retained deciduous tooth is not fully predictable, if the teeth are in good condition, the patient and clinician may incline towards a decision to preserve the deciduous teeth as long as possible. This case report demonstrates that deciduous teeth, in this case the mandibular second molars and maxillary canine, can be incorporated into final occlusion with clinically stable long-term results.

Local Injection of Hyaluronic Acid Filler Improves Open Gingival Embrasure: Validation Through a Rat Model.

BACKGROUND: The open gingival embrasure, the so-called black triangle, is one of the unsolved dilemmas in adult dentistry. Although various techniques have been introduced to improve black triangles, the lack of reproducible experimental models has prevented development of successful protocols to regenerate or to compensate loss of the interdental papilla. Therefore, the objective of this study is first to develop a reliable animal model of open gingival embrasure and then to validate a minimally invasive injection technique using hyaluronic acid (HA) filler to augment the interdental papilla. METHODS: To reproduce open gingival embrasure in rats, rapid space opening was induced between the mandibular incisors by attachment of a compression spring. Loss of interdental papilla height was morphologically evaluated and calculated using standardized serial photographs, microcomputed tomography, and histologic sections. Afterward, HA fillers or phosphate-buffered saline (PBS) was locally injected, and changes in the interdental papilla were evaluated. RESULTS: After 7 days of space opening, the margin of the interdental papilla between the mandibular incisors gradually became irregular and flat, indicating a condition similar to the open gingival embrasure (P <0.05). Local injection of HA filler induced an augmentation effect of the interdental papilla compared with injection of PBS (P <0.05). Interdental papilla became convex, and inner granules containing HA were detected within the submucosal layer after its injection. CONCLUSIONS: Open gingival embrasure was reproduced reliably in vivo. Local injection of HA filler was validated as a meaningful minimally invasive procedure to improve open gingival embrasure.