The effects of facial bone from facial tipping of incisors in monkeys

Combined distalization and lingual cortex remodeling during mandibular growth for facial profile improvement: a case report

Borderline crowding poses a challenge in deciding whether or not to prescribe premolar extraction. This case report describes the two-phase nonextraction orthodontic treatment of an 11-year-old girl with a hyperdivergent skeletal Class I pattern exhibiting anterior crowding and moderate lip protrusion. The initial phase of treatment included maxillary and mandibular expansion to correct the transverse discrepancy as an early intervention. Subsequently, comprehensive treatment was initiated at the age of 13 years, with fully erupted permanent second molars and growth potential remaining. Phase II treatment involved a second round of maxillary expansion, followed by simultaneous bimaxillary total arch intrusive distalization, using interradicular, temporary skeletal anchorage devices to correct dental crowding and improve the facial profile. Although the limited retromolar space posed a challenge to mandibular tooth distalization, gradual bone remodeling was observed in the lingual cortex of the mandibular body, enabling sufficient orthodontic tooth movement without noticeable side effects. After 4 years 3 months of treatment, her dental crowding was relieved, with significant improvement in the facial profile and proper occlusion. The treatment outcomes remained stable 2 years 4 months after retention.

Age-related osteogenesis on lateral force application to rat incisor – Part III: Periodontal and periosteal bone remodeling

Objectives:

This study was aimed to compare the histological pattern of bone modeling on either periodontal or periosteal side induced by lateral orthodontic tooth movement in different age groups.

Material and Methods:

A total of 50 male Sprague-Dawley rats (25 rats in the adult group – 52 weeks and 25 rats in the young group – 10 weeks) were utilized in this study. Each age group was classified into the control, 3 days, 7 days, 14 days, and 21 days groups (five rats in each) by the duration of experimental device application. A double-helical spring was produced using 0.014” stainless steel wire to provide 40 g lateral force to the left and right incisors. Hematoxylin-eosin staining, proliferating cell nuclear antigen (PCNA) immunohistochemical staining, fibroblast growth factor receptor 2 (FGFR2) immunohistochemical staining, and Masson trichrome staining were performed; and the slides were subject to histological examination.

Results:

In 7 days, active bone modeling represented by the scalloped surface was observed on the periosteal side of the crestal and middle alveolus at the pressure side in the young group, while similar changes were observed only on the crestal area in the adult group. In the young group, the number of PCNA-positive cells increased significantly on the crestal area and middle alveolus on the 3, 7, and 14 day groups, with subsequent decrease at 21 days. In the adult group, PCNA-positive cells were localized on the crestal area throughout the period. In the young group, FGFR2-positive cells were observed mainly on the crestal and middle alveolus at 3, 7, and 14 days than the control group. In the adult group, these cells appeared on the crestal and middle alveolus in the 3 days group, but mainly on the crestal area at 14 days. In the young group, FGFR2-positive cells were observed on the crestal and middle alveolus on the 3, 7, and 14 days groups more than on the control group. In the adult group, these cells appeared on the crestal and middle alveolus in the 3 days group, but mainly on the crestal area in the 14 days group. In Masson trichrome stain, an increased number of type I collagen fibers were observed after helical spring activation in both age groups. Large resorption lacunae indicating undermining bone resorption were progressively present in both young and adult groups.

Conclusion:

According to these results, orthodontic tooth movement may stimulate cell proliferation and differentiation primarily on the periosteal side according to progressive undermining bone resorption on the periodontal side. This response may lead to prominent bone modeling during tooth movement in the young group, compared to the relatively delayed response in the adult group.

Bone changes in the mandibular incisors after orthodontic correction of dental crowding without extraction: A cone-beam computed tomographic evaluation

Purpose

This study aimed to evaluate changes of the alveolar bone and interdental bone septum of the mandibular incisors through cone-beam computed tomography (CBCT) after orthodontic treatment of mandibular dental crowding without dental extraction.

Materials and Methods

The sample consisted of 64 CBCT images (32 pre-treatment and 32 post-treatment) from 32 adult patients with class I malocclusion and an average age of 23.0±3.9 years. The width and height of the alveolar bone and interdental septum, the distance between the cementoenamel junction (CEJ) and the facial and lingual bone crests, and the inclination of the mandibular incisors were measured.

Results

The distance between the CEJ and the marginal bone crest on the facial side increased significantly (P<0.05). An increased distance between the CEJ and the bone crest on the facial and lingual sides showed a correlation with the irregularity index (P<0.05); however, no significant association was observed with increasing mandibular incisor inclination (P>0.05). The change in the distance between the CEJ and the marginal bone crest on the facial side was correlated significantly with bone septum height (P<0.05).

Conclusion

Bone dehiscence developed during the treatment of crowding without extraction only on the incisors' facial side. Increasing proclination of the mandibular incisor was not correlated with bone dehiscence. The degree of dental crowding assessed through the irregularity index was associated with the risk of developing bone dehiscence. The interdental septum reflected facial marginal bone loss in the mandibular incisors.

Treatment of Class II malocclusion with tooth movement through the maxillary sinus

This case report describes the successful extraction treatment of a Class II malocclusion with excessive maxillary sinus pneumatization. A 20-year-old man sought treatment with the major complaint of protrusive mouth and anterior teeth. He was diagnosed with a skeletal Class II relationship and protrusion of the maxilla. The clinical examination showed a severe Class II molar relationship with excessive overjet and deep overbite. Panoramic radiograph showed obvious maxillary sinus pneumatization bilaterally. Three premolars and one deciduous molar were extracted, and spaces were used to correct molar relationship and retract maxillary incisors. Light forces and low speed movement were applied to overcome the challenge of moving teeth through the maxillary sinus wall. Balanced facial esthetic and stable occlusion were obtained posttreatment with a notable bone formation of the maxillary sinus wall. This result highlights the possibility of tooth movement through cortical floor with bone remodeling and no obvious complications.

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.

Knowledge of orthodontic tooth movement through the maxillary sinus: a systematic review

Background

To investigate the feasibility, safety and stability of current interventions for moving teeth through the maxillary sinus (MTTMS) by performing a systematic review of the literature.

Methods

The electronic databases PubMed, Embase, CENTRAL, Web of Science, CBM, CNKI and SIGLE were searched without a language restriction. The primary outcomes were parameters related to orthodontic treatment, including orthodontic protocols, magnitude of forces, type of tooth movement, duration and rate of tooth movement, and remolding of alveolar bone and the maxillary sinus floor. The secondary outcomes were safety and stability, including root resorption, perforation of the sinus floor, loss of pulp vitality and periodontal health and relapse.

Results

Nine case reports with 25 teeth were included and systematically analyzed. Fifty to two hundred g of force was applied to move teeth through the maxillary sinus. Bodily movement was accomplished, but initial tipping was observed in 7 cases. The rate was 0.6–0.7 mm/month for molar intrusion and 0.16–1.17 and 0.05–0.16 mm/month for mesial-distal movement of premolars and molars, respectively. Bone formation and remolding of the sinus floor occurred in 7 cases. Root resorption within 6 to 30 months was observed in 3 cases, while no cases of perforation of the sinus floor, loss of pulp vitality, periodontal health impairment or relapse were reported.

Conclusions

At the present stage, no evidence-based protocol could be recommended to guide MTTMS. The empirical application of constant and light to moderate forces (by TAD, segment and multibrackets) to slowly move teeth through or into the maxillary sinus in adults appears to be practical and secure. Bodily movement was accomplished, but teeth appear to be easily tipped initially, potentially resulting in root resorption. However, this conclusion should be interpreted with caution as the currently available evidence is based on only a few case reports or case series and longitudinal or controlled studies are lacking in this area.

[Orthodontic tooth movement through the maxillary sinus in an adult with multiple missing teeth]

This case report describes the successful orthodontic tooth movement through the maxillary sinus in an adult patient. A 41-year-old Asian woman had severe lip protrusion and multiple missing posterior teeth. Her orthodontic treatment included the extraction of two teeth, maximum retraction of the incisors using the extraction spaces and the existing spaces from the missing molars, and closure of all remaining spaces. Even though the treatment time was extended because of the anatomic and biologic challenges associated with moving posterior teeth over a long distance through the maxillary sinus, a successful outcome was obtained, with significant bone modeling of the maxillary sinus. The results demonstrate that a carefully selected force system can overcome the anatomic limitations of moving tooth against the cortical bone of the maxillary sinus wall in adult patients.

Alveolar bone thickness around maxillary central incisors of different inclination assessed with cone-beam computed tomography

OBJECTIVE

To assess the labial and lingual alveolar bone thickness in adults with maxillary central incisors of different inclination by cone-beam computed tomography (CBCT).

METHODS

Ninety maxillary central incisors from 45 patients were divided into three groups based on the maxillary central incisors to palatal plane angle; lingual-inclined, normal, and labial-inclined. Reformatted CBCT images were used to measure the labial and lingual alveolar bone thickness (ABT) at intervals corresponding to every 1/10 of the root length. The sum of labial ABT and lingual ABT at the level of the root apex was used to calculate the total ABT (TABT). The number of teeth exhibiting alveolar fenestration and dehiscence in each group was also tallied. One-way analysis of variance and Tukey's honestly significant difference test were applied for statistical analysis.

RESULTS

The labial ABT and TABT values at the root apex in the lingual-inclined group were significantly lower than in the other groups (p < 0.05). Lingual and labial ABT values were very low at the cervical level in the lingual-inclined and normal groups. There was a higher prevalence of alveolar fenestration in the lingual-inclined group.

CONCLUSIONS

Lingual-inclined maxillary central incisors have less bone support at the level of the root apex and a greater frequency of alveolar bone defects than normal maxillary central incisors. The bone plate at the marginal level is also very thin.

Are there bone dehiscences in maxillary canines orthodontically moved into the grafted alveolar cleft?

INTRODUCTION

The aim of this study was to assess the bone morphology of teeth mesialized into the grafted region in patients with unilateral alveolar cleft.

METHODS

The sample comprised 30 patients with unilateral cleft lip and palate with a mean age of 20.5 years. High-resolution cone-beam computed tomography images of the maxilla were obtained 6 months to 2 years after comprehensive orthodontic treatment. The contralateral canines and lateral incisors were used as controls. Axial section was used to measure the bone thickness, and cross section was used to measure the alveolar crest height using the cementoenamel junction as a reference. Paired t tests and Wilcoxon tests were used to compare the cleft and noncleft sides (P <0.05).

RESULTS

High individual variability was found. In general, the canines in the cleft side had statistically thinner buccal bone plates than the contralateral teeth. No differences between the cleft and noncleft sides were found for the lingual bone plate thickness. The canine on the cleft side showed a slightly greater distance between the lingual alveolar crest and the cementoenamel junction than the lateral incisor in the noncleft side.

CONCLUSIONS

In patients with unilateral cleft lip and palate, mesial orthodontic movement of the maxillary canines into the grafted alveolar cleft results in acceptable buccal and lingual periodontal morphology.

Orthodontic tooth movement through the maxillary sinus in an adult with multiple missing teeth

This case report describes the successful orthodontic tooth movement through the maxillary sinus in an adult patient. A 41-year-old Asian woman had severe lip protrusion and multiple missing posterior teeth. Her orthodontic treatment included the extraction of 2 teeth, maximum retraction of the incisors using the extraction spaces and the existing spaces from the missing molars, and closure of all remaining spaces. Even though the treatment time was extended because of the anatomic and biologic challenges associated with moving posterior teeth over a long distance through the maxillary sinus, a successful outcome was obtained, with significant bone modeling of the maxillary sinus. The results demonstrate that a carefully selected force system can overcome the anatomic limitations of moving tooth against the cortical bone of the maxillary sinus wall in adult patients.

Periodontal responses to augmented corticotomy with collagen membrane application during orthodontic buccal tipping in dogs

This prospective randomized split-mouth study was performed to examine the effects of absorbable collagen membrane (ACM) application in augmented corticotomy using deproteinized bovine bone mineral (DBBM), during orthodontic buccal tipping movement in the dog. After buccal circumscribing corticotomy and DBBM grafting into the decorticated area, flaps were repositioned and sutured on control sides. ACM was overlaid and secured with membrane tacks, on test sides only, and the flaps were repositioned and sutured. Closed coil springs were used to apply 200 g orthodontic force in the buccolingual direction on the second and third premolars, immediately after primary flap closure. The buccal tipping angles were 31.19 ± 14.60° and 28.12 ± 11.48° on the control and test sides, respectively. A mean of 79.5 ± 16.0% of the buccal bone wall was replaced by new bone on the control side, and on the test side 78.9 ± 19.5% was replaced. ACM application promoted an even bone surface. In conclusion, ACM application in augmented corticotomy using DBBM might stimulate periodontal tissue reestablishment, which is useful for rapid orthodontic treatment or guided bone regeneration. In particular, ACM could control the formation of mesenchymal matrix, facilitating an even bone surface.

Tooth movement out of the bony wall using augmented corticotomy with nonautogenous graft materials for bone regeneration

This prospective randomized split-mouth study was performed to compare the effects of augmented corticotomy with those of different nonautogenous bone graft materials combined with orthodontic tooth movement in dogs. Decortication was performed on the buccal bone surface of 6 male beagle dogs that were randomly assigned to receive grafts of deproteinized bovine bone mineral, irradiated cortical bone, or synthetic bone. Immediate orthodontic force was applied to the second and third premolars for buccal tipping for 6 weeks. The pocket depth and width of keratinized tissue (WKT) were measured. Histologic and histomorphometric analyses were performed. The probing depth, WKT, and ratio of the area of new bone to that of total bone on the buccal side were not significantly different between groups. All groups had considerable new bone formation on the pressure side. New bone formation on the buccal side and buccal plate formation in the coronal direction along the root surfaces were induced by the bone-derived and PDL-derived mesenchymal matrix, respectively. The angular change between groups was significantly different (P < 0.001). Augmented corticotomy using nonautogenous graft materials facilitated tooth movement without fenestrations and accelerated new bone formation on the pressure side.

Gingival recession and adult orthodontics: a clinical evidence-based treatment proposal

The presence of a gingival recession prior to orthodontic treatment is a real problem. Patients are concerned about losing their teeth but may also complain of their unpleasant appearance or root sensitivity in the exposed area. The orthodontist is not sure whether orthodontic treatment can be performed or whether the tooth movement will not aggravate the recession and whether periodontal surgery needs to be done before or after orthodontic treatment. The aim of this paper is to present recent data from the literature and several clinical situations in adults in order to submit a treatment sequence and clarify the role of different periodontal plastic surgery root coverage procedures.

An update on periodontic-orthodontic interrelationships

Talking about periodontic-orthodontic interrelationships is related primarily to the 1960s, where a generalized increase in salivary bacterial counts, especially Lactobacillus, had been shown after orthodontic band placement. The purpose of this article is to provide the dental practitioner with basic understanding of the interrelationship between periodontics and orthodontics by means of representing classical studies, and, to give an update on this topic by demonstrating the most recent opinions concerning periodontic-orthodontic interrelationships. Specific areas reviewed are the ability of orthodontic treatment to afford some degree of protection against periodontal breakdown, short-term and long-term effects of orthodontic treatment on the periodontium, and some mucogingival considerations. Topics considering orthodontic treatment in periodontally compromised patients were not included in this review. While past studies have shown that orthodontic treatment can positively affect the periodontal health, recent reviews indicate an absence of reliable evidence for the positive effects of orthodontic therapy on patients’ periodontal status. Periodontic-orthodontic interrelationships are still controversial issues. However, a standard language between the periodontist and the orthodontist must always be established to eliminate the existing communications barrier, and to improve the outcomes of the whole treatment.

Periodontal status of mandibular central incisors after orthodontic proclination in adults

INTRODUCTION

Some animal and human studies showed that periodontal recession occurs after incisor proclination, but other authors disagree. The purpose of this study was to assess the periodontal status of mandibular central incisors that were proclined during orthodontic treatment.

METHODS

The sample comprised 34 adults who had completed treatment over periods of 7 months to 3 years 11 months. The proclination and vertical movement of these teeth were analyzed by 6 measurements from lateral cephalometric radiographs taken before and after treatment. The thickness and height of the symphysis were recorded from pretreatment lateral cephalometric films. Crowding was determined based on the irregularity index from the initial cast. The following periodontal clinical parameters were assessed: plaque and gingival bleeding indexes, probing pocket depth, clinical levels of attachment, and recession of selected teeth and of the mandibular central incisors. The height of the keratinized tissue and the thickness of the facial gingival margin of these incisors were also measured. The Pearson and Spearman correlation analyses, the Fisher exact test, and the Kruskal-Wallis test were applied.

RESULTS

Statistical analyses showed no correlation between recession and the plaque and gingival bleeding indexes, probing pocket depth, and total quantity of labial movement (P >.05). Recession was negatively correlated with keratinized gingival height and thickness of the facial gingival margin on the mandibular central incisors.

CONCLUSIONS

Final inclination (>95 degrees ) and free gingival-margin thickness (>0.5 mm) showed greater and more severe recession on the mandibular central incisors. Nevertheless, when comparing thickness to the final inclination, thickness had greater relevance to recession.

Comparative radiographic evaluation of the alveolar bone crest after orthodontic treatment

This study evaluated and compared the heights of the alveolar bone crests (AC) among orthodontic patients treated with either the simplified standard edgewise technique (group 1, n = 30), the edgewise straight-wire system (group 2, n = 30), or bioefficient therapy (group 3, n = 26). These 3 groups were compared with an untreated control group (group 4, n = 30). A comparison by sex of AC height was also conducted. The first premolars were extracted in every treated patient, and measurements were performed on bitewing radiographs taken after a mean posttreatment period of 2.17 years. The distances from the AC to the cementoenamel junction (CEJ) on the mesial and distal surfaces of the first molars and second premolars and on the distal surface of the canines were measured; the larger the distance, the greater the alveolar bone loss. The data were analyzed by 1-way analysis of variance and the Newman-Keuls test (P <.05) for comparison among the groups. Sex differences of the AC height were evaluated with the t test. All treated groups had larger, statistically significant CEJ-AC distances than the untreated group, primarily at the extraction areas. There were no consistent statistically significant differences in the areas among the treated groups. Mean distances of the CEJ-AC in boys were larger than or similar to those in girls. The patients in the treated groups showed a greater number of proximal surfaces with statistically significant differences between sexes, compared with the control subjects.

Changes in alveolar bone thickness due to retraction of anterior teeth

In cases of bimaxillary protrusion, extraction of 4 premolars and orthodontic treatment with retraction of the anterior teeth is a widely used approach. However, there is controversy over whether the changes that occur in the anterior alveolar bone always follow the direction and quantity of tooth movement. Nineteen patients with dentoalveolar bimaxillary protrusion treated by extracting the 4 first premolars were evaluated with lateral cephalograms and computed tomography (CT). Cephalograms and CT scans were made before treatment and 3 months after retraction of the incisors. The measurements of the cephalograms showed that maxillary and mandibular incisors were retracted primarily by controlled tipping of the teeth. For all maxillary and mandibular incisors, we assessed the labial and the lingual alveolar plates at crest level (S1), midroot level (S2), and apical level (S3) for bone-thickness changes during retraction of the maxillary and mandibular anterior segments. In the mandibular arch, the labial bone maintained its original thickness, except the S1 measurements, which showed a significant decrease in bone thickness (P <.001). In the maxillary arch, the labial bone thickness remained unchanged. There were statistically significant decreases in lingual bone width in both arches after retracting the incisors. Some of the patients demonstrated bone dehiscence that was not visible macroscopically or cephalometrically. When tooth movement is limited, forcing the tooth against the cortical bone may cause adverse sequelae. This type of approach must be carefully monitored to avoid negative iatrogenic effects.

Periodontal status of mandibular incisors after pronounced orthodontic advancement during adolescence: a follow-up evaluation

The purpose of this study was to analyze whether pronounced orthodontic advancement of the mandibular incisors during Class II correction in the mixed dentition results in gingival recession. Through mandibular superimposition of the pretreatment and posttreatment cephalograms of 67 Class II patients who were treated with reverse headgear to the mandibular dentition, 45 patients with a minimum of a 1-mm advancement of the cementoenamel junction (CEJ; mean, 2.18 +/- 0.87) and a minimum of a 2-mm advancement of the incisal edge (mean, 3.87 +/- 1.34) were identified. Using the same protocol in Class II patients, 30 individuals who finished treatment at a similar time and age, but without reverse headgear and with no advancement of the CEJ (mean -0.43, SD 0.53) and a maximum of 1-mm advancement of the incisal edge (mean -0.26, SD 1.15) were identified. Before treatment, the mandibular incisors were more retruded, relative to the line from point A to pogonion and relative to the mandibular plane in the patients with pronounced advancement than in those with no advancement of the mandibular incisors; no differences were found at the time of appliance removal. A total of 30 patients with pronounced advancement and 21 patients with no advancement could meet for a follow-up examination a mean period of 7.83 years (SD, 4.44) and 9.38 years (SD, 4.39) after treatment, respectively. Clinical examinations at the time of follow-up revealed no differences in the amount of recession, the width of attached gingiva, the length of supracrestal connective tissue attachment, the probing pocket depth, and gingival bleeding index or visible plaque index of the mandibular incisors between the patients in the 2 groups. An examination of color slides demonstrated no differences in the number of mandibular incisors that developed recession from before treatment to after treatment and from after treatment to follow-up. Measurement of mandibular incisor crown height on the study models demonstrated no difference in the increase in clinical crown height from after treatment to follow-up between the patients in the 2 groups. It was concluded that pronounced advancement of the mandibular incisors may be performed in adolescent patients with dentoalveolar retrusion without increasing the risk of recession.

Evaluation of labio-lingual bony support of lower incisors in orthodontically untreated adults with the help of computed tomography

The aim of the present study was to assess bone volume and bone density in orthodontically untreated adults using a CT analyzing method, with reference data in the clinically essential area of the lower incisors being obtained. For quantitative and qualitative assessment of the labial and lingual bony support of the lower incisors, existing CT-images of 20 adult men with a near-to-normal occlusion and a clinically healthy periodontal situation were evaluated. With the help of a special program (SIM/Plant) and on the basis of axial scans, sagittal scans were constructed, permitting the individual imaging of the lower incisors and their alveolar process. The bony support of each tooth was registered labially and lingually perpendicular to the tooth axis at intervals corresponding to 10% of the root length. At the various root levels, especially at the upper parts of the roots, only small amounts of bony support, if any, were frequently observed. Labially, bony fenestrations and dehiscences were frequently seen, but lingually mostly dehiscences. No clinically relevant association was found between labial bony support and cephalometrically registered inclination of the lower incisors. Bone density, which was registered in Hounsfield units at the gingival, middle and apical thirds of the root levels, increased from the gingival to the apical thirds of the roots, generally with lower lingual than labial values. Before initiating orthodontic treatment a thorough clinical assessment of the anatomical situation in the lower incisor segment should be carried out. At present bone volume in this area can be reliably assessed only with computed tomography; however, this has to be weighed up against increased radiation risks. Therefore, the form of the symphysis should initially be roughly assessed by means of conventional cephalometry, with additional CT-based analysis of individual teeth being confined to special indications.

Interrelationship between periodontics and adult orthodontics

The purpose of this review article is to provide the dental practitioner with an understanding of the interrelationship between periodontics and orthodontics in adults. Specific areas reviewed are how periodontal tissue reacts to orthodontic forces, influence of tooth movement on the periodontium, effect of circumferential supracrestal fiberotomy in preventing orthodontic relapse, effect of orthodontic bands on the periodontium, specific microbiology associated with orthodontic bands, mucogingival considerations and time relationship between orthodontic and periodontal therapy. In addition, the relationship between orthodontics and implant restorations (e.g., using dental implants as orthodontic anchorage) will be discussed.

Mandibular incisors, alveolar bone, and symphysis after orthodontic treatment. A retrospective study

The mandible of a deceased 19-year-old young woman who had been treated with an edgewise appliance was removed during autopsy. The overall tooth movements during the 19 months of treatment were reconstructed (treatment documents) and compared with the macroscopic, radiologic, and micromorphologic findings of the incisor/alveolar bone/symphysis complex of the dry mandible. The initial lateral cephalogram revealed an extremely narrow and high symphysis, with an incisor position straight above the thin bone. During treatment, the incisors had been moved to lingual (lingual root torque) and derotated. Morphologic evaluation of the dry mandible revealed lingual (oral) aspects of the roots reaching some millimeters out of the lingual alveolar bone and largely without cortical plate covering. Lateral dental contact radiographs of any bone/incisor segment showed the sagittal alveolar bone width to be smaller than the labiolingual (orobuccal) diameter of the incisor roots. A comparison of the approximate pretherapeutic alveolar bone height, which was assessed by measuring the distance from the cementoenamel junction to the most coronal margin of any root resorption in scanning electron microscopy, with that of the specimen showed a calculated bone loss on the lingual aspect extending from 2.3 to 6.9 mm. On the labial (buccal) aspect, bone loss was far less pronounced. These results suggest that in the case of a narrow and high symphysis, pronounced sagittal incisor movements and derotation during routine orthodontic treatment with a fixed appliance may be critical and lead to progressive bone loss of lingual and labial cortical plates.

Three-dimensional interpretation of periodontal lesions and remodeling during orthodontic treatment. Part III

In a clinical study of 11 adult patients, HR-CT-examinations were performed before or during and after orthodontic treatment with fixed appliances. The treatment period between the first and second CT-scanning varied from 12 to 24 months. Comparison of the first and second CT-examination permits three-dimensional evaluation of osteoclastic and osteoblastic alveolar remodeling. The incidence of periodontal lesions such as bone dehiscences, fenestrations and root resorptions was assessed in relation to the initial periodontal situation and the orthodontic treatment concept. Anatomical risks were a small alveolar process, thin buccal or lingual bone plates, eccentric position of teeth, basally extended maxillary sinus and progressive alveolar bone loss. Therapeutic risks were uncontrolled sagittal or vertical movements of incisors and cortical or intermaxillary anchorage preparation. CT-scanning of the alveolar process during orthodontic treatment with HR-CT allows three-dimensional interpretation of the alveolar osteodynamics, especially the development and repair of orthodontically induced bone dehiscences in relation to tooth movement.

Human histologic tissue response after long-term orthodontic tooth movement

The maxilla of a deceased 19-year-old young woman who had been treated with an edgewise appliance was removed during autopsy. The specimen was prepared histologically in the horizontal plane. The type of tooth movement was reconstructed by comparing the treatment documents at outset (photograph of dental cast, radiograph) with the photograph and radiographs of the specimen. This permitted the histological findings to be correlated to the type of tooth movement.

RESULTS

the localization and extent of tissue changes at the roots depend on the type of tooth movement and the structure of the bone. In case of an atrophied alveolar bone in front of the tooth movement direction, a partial increase of osseous tissue may be induced by bone apposition in the subperiosteal layer. After tooth movement in the maxillary sinus region, however, bone resorption was found in the subperiosteal layer in front of the roots. The histologic findings are more pronounced than the radiographs would suggest. Histologically verified bony dehiscences or fenestrations in the facial or oral cortical plate could not be diagnosed by macroscopic inspection of the specimen.

Periodontal conditions after facial root tipping and palatal root torque of incisors

The maxilla of a deceased 19-year-old young woman who had been treated with a fixed appliance was removed during autopsy. The sagittal movements of the incisors could be reconstructed by using the treatment records, which were also at our disposal. The anterior segment of the specimen was prepared histologically in the sagittal plane and stained with toluidine blue.

RESULTS

The tooth movements were executed in two phases: an uncontrolled tipping (root movement to vestibular) was followed by palatinal root torque. The histologic changes, induced by the palatinal root torque were (1) root resorption with apical slope from facioapical to orocoronal, and (2) pronounced subperiosteal bone apposition (palatinal) with partial protrusion of the cortical plate thinning toward coronal. No osseous perforations occurred. The extent and the localization of root resorptions were not verified in the orthoradial x-ray film of the specimen.

Orthodontic treatment and isolated gingival recession: a review

Isolated gingival recession may occur in as many as 30 per cent of adolescents, and lead to problems of dentine hypersensitivity, root caries, and gingival inflammation in adult life. This review discusses the prevalence and aetiology of isolated recession, with particular reference to the implications for orthodontic treatment. Consideration is also given to the differing philosophies for management.

[The periodontal changes following orthodontic tooth movement--a retrospective histological study in man. 2]

The maxilla of an orthodontically treated deceased (19 years, female) could be taken in autopsy. Pretherapeutically atrophied alveolar bone and a basally exdented maxillary sinus was found. The specimen was prepared histologically in the horizontal plane. The type of tooth movement could be reconstructed by analyzing the treatment documents.

RESULTS

Dependent on the tooth movement, a partial gain of osseous tissue in the atrophied alveolar region is possible by bone apposition in the subperiosteal layer. In the maxillary sinus region, however, bone resorption could be found in the subperiosteal layer in front of the tooth. The resultant apical perforation into the sinus could not be verified by radiographic examination.

[Correlations of orthodontics and periodontics]

Periodontics and orthodontics are correlated with one other in many ways. For instance, periodontal conditions have to be considered in the orthodontic treatment of adults, special orthodontic measures are taken to enhance a periodontal treatment, and when periodontal surgery is performed for the prevention of relapse or the disimpaction of teeth. Dental practitioners working in the field of orthodontics should have a sound understanding of the biology and pathology of the periodontium in order to avoid causing periodontal lesions, or when lesions are present, how best to determine prognosis and differential treatment.

Periodontal status of mandibular incisors following excessive proclination. A study in adults with surgically treated mandibular prognathism

The present study was undertaken to examine whether excessive proclination of mandibular incisors results in gingival retraction. In patients with surgically treated mandibular prognathism, 29 with more than 10 degrees proclination of mandibular incisors and 33 with minimal change in incisor inclination during presurgical orthodontic phase were selected. A total of 21 and 19 patients, respectively, could meet for a clinical follow-up examination including Visible Plaque Index, Gingival Bleeding Index, probing pocket depth, and length of supracrestal connective tissue attachment. Study models and intraoral color slides were also made. The mean postoperative times at this examination were 7.8 (SD 2.5) and 8.1 (SD 2.8) years, respectively. Clinical crown height was measured on the study models taken before and after appliance therapy, at the 3-year postoperative control (check) and at the follow-up examination. The number of teeth with recession was determined from the color slides taken at the same intervals; the thickness of the symphysis was measured on the cephalograms taken before treatment. The results demonstrated significantly more increase in clinical crown height and significantly more teeth developing recession both during appliance therapy and during the period from removal of appliance to the 3-year postoperative control in the patients with excessive proclination than in the patients with minimal change in incisor inclination. The correlation coefficient between width of symphysis and increase in clinical crown height in patients with excessive proclination was statistically significant. Only minimal changes were observed from 3 years postoperatively to the follow-up examination. No differences in clinical measurements were observed between the groups and bone dehiscences were not found.

Effects of incisor repositioning on monkey periodontium after expansion through the cortical plate

The anterior teeth of five adult pigtail monkeys were moved lingually to correct a previously induced extreme labial displacement. (Roots had been moved through the labial bone to create bone dehiscence, loss of attachment, and gingival recession.) Eight months later, repositioning was performed with fixed appliances (Fig. 3). The teeth were retained in their more normal arch position for 5 months, after which clinical and histologic measurements were made of several periodontal parameters. The canines were not moved and served as reference teeth. Measurements were made to record changes in the levels of the gingival margin, the mucogingival junction, and the marginal bone relative to a fixed point on the tooth crowns, and the width of keratinized gingiva. Oxytetracycline was administered three times to label areas of osteogenesis in the periodontium. The incisors were retracted lingually a mean of 1.8 mm. The marginal bone level increased (moved coronally) a mean of 2.5 mm. and 3.1 mm. for maxillary and mandibular incisors, respectively (Table II). The tetracycline labels showed that osteogenesis occurred in the periodontium to a significant degree. The anchor canines had a loss of 1.1 mm. marginal bone (moved apically). Effects on gingival clefts and keratinized gingiva were slight. These observations demonstrate that in monkeys reapposition of labial bone can occur in a coronal direction, once teeth in extreme labial position with bone dehiscence and gingival recession are moved to a more normal environment. The effects on the periodontal soft tissues (width of keratinized gingiva, recession, attachment level) were, on the other hand, negligible in this study.

A clinical and histologic study of healing following the excisional new attachment procedure in rhesus monkeys

Experimental suprabony periodontal pockets were established around the incisors of Rhesus monkeys and subsequently were treated by the Excisional New Attachment Procedure. Healing was evaluated clinically and histologically for up to 6 months. Clinical examinations demonstrated an overall mean pocket depth reduction from 5.02 mm to 2.82 mm, of which 0.57 mm was recession and 1.59 mm (73.6%) was clinical new attachment. Histologic evaluation of experimental sites consistently revealed a long, thin junctional epithelium with a minimal amount of inflammatory infiltrate in the subjacent, densely fibered, lamina propria. Control areas demonstrated the classic histologic picture of periodontal disease and tended to be progressive in nature clinically.