Three-D imaging of dental alveolar bone change after fixed orthodontic treatment in patients with periodontitis.

OBJECTIVES: The objective of this study was to radiographically quantify bone height and bone density in patients with periodontitis after fixed orthodontic treatment using cone beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 81 patients including 40 patients with chronic periodontitis (group 1) and 41 patients with normal periodontal tissues (group 2) were selected. CBCT scanning for anterior teeth were taken before and after orthodontic treatment. Measurements of bone height and bone density were performed using CBCT software. RESULTS: The group 1 presented a statistically lesser bone density and bone height when compared to group 2 before treatment. There was a significant loss of bone density for both groups after orthodontic treatment, but bone density loss was significantly greater in the group 1. There was no statistically significant bone height change in two groups after treatment. CONCLUSIONS: This study demonstrated that orthodontic treatment can preserve bone height but not capable of maintaining bone density, especially for patients with periodontitis. It is indicated that the change of bone density may be more susceptible than that of bone height when radiographically evaluating bone status under this combined periodontal and orthodontic therapy.

[Inter-relationship between mandibular rotation center and maxillary Le Fort I impaction osteotomies].

PURPOSE: The purpose of the present investigation was to locate the instantaneous rotation center of the mandible during maxillary surgical impaction, and explore the relationship between automatic rotation center of the mandible and maxillary elevation amount, the length of the mandible and mandibular plane angle. METHODS: Twenty-five patients who underwent maxillary Le Fort I impaction without concomitant major mandibular ramus split osteotomies were included. The preoperative and postoperative lateral cephalograms were used to evaluate the surgical changes and locate the mandibular autorotation center with Reuleaux method. The automatic rotation center of the mandible was compared to the maxillary elevation amount, the length of the mandible and mandibular plane angle with Pearson correlation and linear regression analysis. The data was analyzed by SPSS 13.0 software package. RESULTS: The mandibular automatic rotation center was located in average 15.64 mm below and 0.82 mm behind the center of the condylar head in these 25 patients. The correlation analysis demonstrated a positive correlation between maxillary elevation amount, the length of the mandible and the position of the rotation center of the mandible. Similar positive correlation was presented between the mandibular plane angle and the vertical position of the rotation center of the mandible. CONCLUSIONS: The rotation center in 25 cases were located outside the condylar head. The maxillary elevation amount, the length of the mandible and the mandibular plane angle was positively correlated to the position of the rotation center of the mandible.

[Research on periodontal changes on the compression side during rapid tooth movement into newly distracted bone].

PURPOSE: To investigate periodontal remodeling mechanism on the compression side during early tooth movement into newly distracted bone. METHODS: Ten male Beagle dogs were selected. Distraction osteogenesis was performed on randomized side as experimental group, while the fourth premolars were extracted on the other side as control group. Then the third premolars were distalized with 30g orthodontic force instantly after the cessation of distraction or extraction. The distance of the tooth movement was measured with a sliding caliper every week. Each distance was measured 3 times and the mean value was recorded. The measurement data were analysed with paired t test by SPSS 18.0 software package. Beagle dogs were killed in the first, second, fourth week after tooth movement. Slices were obtained for HE staining and TRAP staining to observe the periodontal tissue on the compression side. RESULTS: The average moving velocity of the teeth in the distracted bone was (1.055±0.054)mm per week, which was significantly faster than that in the control group(P<0.05).There was no apparent lag period in the experimental group. In addition, there was no hyalinization observed on the compression side of the periodontal tissue in the experimental group, while the amount and area of distribution of the TRAP-positive cells on the compression side was significantly larger and strongly expressed. CONCLUSIONS: The moving velocity of the teeth in the newly distracted bone was significantly faster, and no apparent lag period, which may be related to no hyalinization and more early-appeared, vigorous and wide-distributed osteoclasts on the compression side of the periodontal tissue.

Mia-assisted orthodontic treatment for dental malocclusion secondary to periodontal disease.

In contemporary dental care, an increasing number of adult patients with periodontal disease are seeking orthodontic treatment. Achieving optimal results in such adult patients is difficult because decreased posterior tooth anchorage is risky. This case report demonstrates the use of miniscrew implant anchorage (MIA) in a Chinese male 21 years 5 months of age with maxillary and mandibular anterior dental spacing, bimaxillary protrusion, and severe bone loss caused by periodontal disease. Prior to orthodontic treatment, the patient underwent treatment to control his periodontitis. The patient was treated with 0.022-in straight-wire orthodontic appliances. After 17 months of active orthodontic treatment, the patient had healthier periodontal tissue with increased bone support, as well as improved facial esthetics and a functional occlusion. The results demonstrate that MIA is useful in enhancing anchorage in patients with bone loss associated with severe periodontal disease.

[Cephalometric analysis of implant anchorage-assisted retraction of anterior teeth].

PURPOSE: The purpose of this study is to compare the different effects of alveolar bone remolding due to retraction of anterior teeth by two types of anchorage mini-screw implant or regular maximum anchorage. METHODS: The sample comprised 26 orthodontic patients with upper dental alveolar bone protrusion and mild crowding. The treatment plan was to remove the four first bicuspids. 14 patients,3 males,11 females, aged 20-54 years old (mean: 25 years) were treated with implant anchorage to retract the maxillary anterior teeth. 12 patients, 1 male,11 females, aged 18-30 years old (mean: 21 years) were treated with regular maximum anchorage to retract maxillary anterior teeth. Lateral cephalograms of all patients were evaluated at two stages: pretreatment, post-treatment.The changes of the long axis of the anterior teeth and dental alveolar were measured.SPSS11.0 software package was used for statistical analysis. RESULTS: The cephalometric findings showed that the anterior teeth were retracted with implant anchorage significantly more than the maximum anchorage, there was no significant difference in the dental alveolar bone remolding between two groups. The first molars moved anteriorly slightly (less than 1mm) with implant anchorage, but significantly (3.08 mm) with regular maximum anchorage. CONCLUSIONS: The maxillary anterior teeth are significantly retraced with the implant anchorage; the molars move mesially significantly less in the implant group than the maximum group. There are no significant differences in dental alveolar bone remolding between both groups. Support by Shanghai Leading Academic Discipline Project (Grant No.Y0203) and Research Fund of Science and Technology Committee of Shanghai Municipality (Grant No. 05B224).

[Clinical evaluation of implant anchorage for molar intrusion: report of the short-term results].

PURPOSE: The purpose of this study is to evaluate the efficiency and security of self-drilling mini-screw implant anchorage for molar intrusion, to achieve the right position of the mini-screw implant. METHODS: Ten patients with overerupted maxillary molars were selected, aging from 25 to 53 years old, the average age was 33 years old. There were 2 men and 8 women. All the overerupted molars were intruded in gingival direction with mini-screw implants anchorage. RESULTS: The mean intrusive movement of the overerupted maxillary molars was 3 mm, the mean treatment time were 3.5 months.All of the missing teeth were treated by prosthetic treatment. No obvious root resorption, pulp necrosis and tooth loosen were found. CONCLUSIONS: Significant true intrusion of maxillary molars could be obtained by mini-screw implant as bony anchorage.Supported by Shanghai Leading Academic Discipline Project (Grant No.Y0203) and Research Fund of Science and Technology Committee of Shanghai Municipality (Grant No.05B224).

[Current gene study in etiological analysis of congenital craniofacial abnormalities].

The cause of congenital craniofacial abnormalities are very complicated. Understanding of the gene mechanisms of abnormalities taking place are very important for prevention and therapy.DNA sequence analysis provides the fundaments of gene study of the congenital craniofacial abnormalities. Human genome project (HGP) paved the confirmation of candidate gene of the congenital craniofacial abnormalities.Transgenic animal models and gene knockout techniques are effective methods in study of gene function. This paper reviews current gene study in etiopathogenisis analysis of the congenital craniofacial abnormalities.