Dentoskeletal and soft tissue changes associated with miniscrew anchorage in customized lingual orthodontics.

OBJECTIVES: The goal of this study was to analyze skeletal, dental, and soft tissue changes of patients treated with customized lingual systems and to evaluate the clinical effectiveness of miniscrew anchorage. METHODS: Nine upper first premolar extraction patients who were treated with customized lingual appliances were included in this study. Miniscrews were used for reinforcement of molar anchorage. Cephalometric films and study models were obtained before treatment (T1), after alignment (T2), and after treatment (T3). Treatment effects were analyzed by cephalometric radiographs and study models. RESULTS: The upper anterior teeth were retracted significantly at T2 and T3 (4.41 ± 4.14 mm and 5.51 ± 2.48 mm, respectively). During space closure, the upper first molars showed slight mesial movement (1.50 ± 1.97 mm). The intercanine width of the upper arch increased at T2 (1.59 ± 1.81 mm), but decreased at T3 (0.11 ± 1.00 mm). The sella-nasion-A, A-nasion-B, and mandibular plane angles were not significantly changed at T3. The upper lip showed continuous retraction at both T2 and T3 (1.40 ± 1.46 mm and 2.32 ± 2.48 mm, respectively). CONCLUSIONS: By using miniscrew anchorage for lingual orthodontics, patients' dental and soft tissue changes considerably improved and molar anchorage was reinforced.

Litsea japonica Leaf Extract Suppresses Proinflammatory Cytokine Production in Periodontal Ligament Fibroblasts Stimulated with Oral Pathogenic Bacteria or Interleukin-1ß.

Periodontal disease, a chronic disease caused by bacterial infection, eventually progresses to severe inflammation and bone loss. Regulating excessive inflammation of inflamed periodontal tissues is critical in treating periodontal diseases. The periodontal ligament (PDL) is primarily a connective tissue attachment between the root and alveolar bone. PDL fibroblasts (PDLFs) produce pro-inflammatory cytokines in response to bacterial infection, which could further adversely affect the tissue and cause bone loss. In this study, we determined the ability of Litsea japonica leaf extract (LJLE) to inhibit pro-inflammatory cytokine production in PDLFs in response to various stimulants. First, we found that LJLE treatment reduced lipopolysaccharide (LPS)-induced pro-inflammatory cytokine (interleukin-6 and interleukin-8) mRNA and protein expression in PDLFs without cytotoxicity. Next, we observed the anti-inflammatory effect of LJLE in PDLFs after infection with various oral bacteria, including Fusobacterium nucleatum, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia. These anti-inflammatory effects of LJLE were dose-dependent, and the extract was effective following both pretreatment and posttreatment. Moreover, we found that LJLE suppressed the effect of interleukin-1 beta-induced pro-inflammatory cytokine production in PDLFs. Taken together, these results indicate that LJLE has anti-inflammatory activity that could be exploited to prevent and treat human periodontitis by controlling inflammation.

Dexmedetomidine as an Additive to Local Anesthesia: A Step to Development in Dentistry.

PURPOSE: The study aimed to compare the effect of dexmedetomidine added to lidocaine against epinephrine added to lidocaine on local anesthetic potency and to look for future prospects of dexmedetomidine as an additive to local anesthesia in dentistry. MATERIALS AND METHODS: The study included 25 healthy volunteers in whom extraction of all first premolars was scheduled as part of their orthodontic treatment plan. In this split-mouth, double-blind, crossover, randomized controlled trial, patients were randomized into 2 groups: Group 1 received injection lidocaine plus dexmedetomidine, and group 2 was administered lidocaine plus epinephrine. Patients were assessed for the onset of action of anesthesia, duration of analgesia, pain perception, and vital signs. RESULTS: The mean values (±standard deviations) for the onset of anesthetic action in groups 1 and 2 were 113 ± 24.9 and 141 ± 34.8 seconds, respectively, for the mandible. For the maxilla, the mean values were 113 ± 24.9 seconds for group 1 and 165 ± 43.8 seconds for group 2. The duration of anesthesia was longer in group 1 (lidocaine plus dexmedetomidine), in which the requirement for the first analgesic on request was seen after a longer time interval, when compared with group 2 (lidocaine plus epinephrine). Pain perception elicited statistically significant results with less perception of pain in group 1 (lidocaine plus dexmedetomidine). The vital parameters remained stable, and the results were not statistically significant. CONCLUSIONS: In this study, we observed that the addition of dexmedetomidine to lidocaine for maxillary and mandibular nerve blocks significantly prolonged the block duration and shortened the onset of action, as well as improved postoperative analgesia in terms of the need for fewer analgesics in the postoperative period. Furthermore, the vital parameters remained stable and no complications were encountered. The findings were supportive of the use of dexmedetomidine as an adjunct to local anesthetics in dental procedures.

Extraction of mandibular premolars and molars: comparison between local infiltration via pressure syringe and inferior alveolar nerve block anesthesia.

OBJECTIVES: The purpose of this study was to evaluate the anesthetic efficiency of local infiltration anesthesia administered with a pressure syringe (P-INF) via a special technique versus direct block anesthesia of the inferior alveolar nerve (IANB) for tooth extraction in the posterior mandible. MATERIALS AND METHODS: In a prospective randomized study, 101 teeth in 101 patients were extracted in the posterior mandible under local anesthesia whereby two different administration techniques were used (P-INF n = 48; IANB n = 53). Primary objectives were comparisons of anesthetic success rate (yes/no) and efficacy (full/sufficient vs. insufficient). Secondary objectives were patients' pain perception during treatment, pain of injection (numerical rating scale), need for second injections (always IANB), time until onset of anesthetic action (min), and duration of local numbness (min). RESULTS: IANB was successful in all cases, whereas initial P-INF achieved 35% of success only. Furthermore, IANB reached significant higher values of anesthetic efficacy compared to P-INF (P < 0.001). Concerning pain of injection, patients rated IANB to be more painful (P = 0.039). Second injections were significantly more often necessary for P-INF (P = 0.006) whereas duration until onset of action as well as the duration of local numbness were found to be equal. CONCLUSIONS: For anesthetic efficacy as well as anesthetic success, block anesthesia of the inferior alveolar nerve (IANB) turned out to be more proficient to local infiltration via special delivering system with a special technique. CLINICAL RELEVANCE: Infiltration, even when performed with 4% articaine and a pressure syringe system, is not a suitable method of anesthesia in the posterior mandible.

Wide Linear Corticotomy and Anterior Segmental Osteotomy Under Local Anesthesia Combined Corticision for Correcting Severe Anterior Protrusion With Insufficient Alveolar Housing.

BACKGROUNDS: This article presents an alternate surgical treatment method to correct a severe anterior protrusion in an adult patient with an extremely thin alveolus. To accomplish an effective and efficient anterior segmental retraction without periodontal complications, the authors performed, under local anesthesia, a wide linear corticotomy and corticision in the maxilla and an anterior segmental osteotomy in mandible. METHODS: In the maxilla, a wide linear corticotomy was performed under local anesthesia. In the maxillary first premolar area, a wide section of cortical bone was removed. Retraction forces were applied buccolingually with the aid of temporary skeletal anchorage devices. Corticision was later performed to close residual extraction space. In the mandible, an anterior segmental osteotomy was performed and the first premolars were extracted under local anesthesia. RESULTS: In the maxilla, a wide linear corticotomy facilitated a bony block movement with temporary skeletal anchorage devices, without complications. The remaining extraction space after the bony block movement was closed effectively, accelerated by corticision. In the mandible, anterior segmental retraction was facilitated by an anterior segmental osteotomy performed under local anesthesia. Corticision was later employed to accelerate individual tooth movements. CONCLUSIONS: A wide linear corticotomy and an anterior segmental osteotomy combined with corticision can be an effective and efficient alternative to conventional orthodontic treatment in the bialveolar protrusion patient with an extremely thin alveolar housing.

Xenografts Supplemented with Pamindronate placed in postextraction sockets to avoid crestal bone resorption. Experimental study in Fox hound dogs.

OBJECTIVES: The aim of the study was to compare the effects of porcine xenografts (MP3(®)) with or without pamindronate for the healing of small and large defects of postextraction sockets. MATERIALS AND METHODS: Six beagle dogs were used in the study; second premolars and first molars of the mandible were extracted, small defects (SD) and large defects (LD) were identified. Each defect was measured and randomly filled as follows: SC (small control defects filled with MP3(®) alone), ST (small test defects filled with MP3(®) modified with pamindronate), LC (large control defects filled with MP3(®) alone), LT (large test defects filled with MP3(®) modified with pamindronate). After 4 and 8 weeks, the animals were euthanized and the percentages of new bone formation (NB), residual graft (RG) and connective tissue (CT) were analysed by histology and histomorphometry of undecalcified samples. RESULTS: After 4 weeks, NB formation was higher for ST compared to all groups and for LT compared to LC (P < 0.05); RG was significantly higher in both control groups compared to tests (P < 0.05); and CT was higher in large defects (LC and LT) compared to small defects. After 8 weeks, NB formation was higher for test groups (ST and LT) compared to controls (P < 0.05); RG was significantly higher in both control groups compared to tests (P < 0.05); and CT was higher in large defects (LC and LT) compared to small defects (P < 0.05). CONCLUSIONS: Within the limitations of this experimental study, the findings suggest that porcine xenografts modified with pamindronate favours the new bone formation and increased the porcine xenograft substitution/replacement after 4 and 8 weeks of healing.

Effect of Er:YAG and Nd:YAG lasers on the mineral content of root canal dentin.

The aim of this study was to assess the effect of two different laser systems on the mineral content of root canal dentin. Thirty-six single canal-extracted mandibular premolars were used in this study. The teeth were randomly divided into two groups of 18 teeth each and prepared with a master apical file #50. Dentin chips were obtained by Gates-Glidden burs and saved in Eppendorf tubes to serve as a control. Then, root canals were treated with a erbium:yttrium-aluminum-garnet or neodymium:yttrium-aluminum-garnet laser. Dentin chips were again obtained using Gates-Glidden. The levels of calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), and potassium (K) in each specimen were measured by inductively coupled plasma-atomic emission spectrometry. Data were statistically analyzed by a Mann-Whitney U test. The changes in Ca, P, Mg, Ca, and K levels and the Ca/P ratio after laser irradiations were minimal and statistically not significant (p > 0.05). It was determined that the laser systems used in this study did not affect the mineral content of root canal dentin.

Connective tissue graft associated or not with low laser therapy to treat gingival recession: randomized clinical trial.

BACKGROUND: To evaluate the treatment of gingival recession with a connective tissue graft (CTG) alone or in combination with low-level laser therapy (CTG + L). METHODS: Forty patients presenting 40 Miller Class I and II gingival recessions were included. The defects were randomly assigned to receive either CTG (n = 20) or CTG + L (n = 20). A diode laser (660 nm) was applied to the test sites immediately after surgery and every other day for 7 days (eight applications). RESULTS: The mean percentage of root coverage was 91.9% for the test group and 89.48% for the control group after 6 months (p > 0.05). The test group presented more complete root coverage (n = 13, 65%) than the control group (n = 7, 35%) (p = 0.04). Dentine sensitivity decreased significantly after 6 months in both groups (p < 0.001). The two groups showed improvement in aesthetics at the end of treatment. CONCLUSIONS: Low-level laser therapy may increase the percentage of complete root coverage when associated with CTG.

Efficacy of solution form of ethylenediaminetetraacetic acid on removing smear layer of root canal at different exposure time In Vitro.

This study was aimed to evaluate the effectiveness of solution form of 17% ethylenediaminetetraacetic acid (EDTA) on removing smear layer of root canals at different exposure time periods and to provide scientific basis for EDTA as a choice of root canal irrigation in clinical practice. Twenty-five single-rooted teeth were randomly divided into 5 groups: control group (group A) was given 2.5% NaOCl, and 4 experimental groups were given 2.5% NaOCl and 17% EDTA, including groups B, C, D and E with exposure time of 1, 3, 5 and 7 min, respectively. After preparation of the root canals, the teeth were split along their longitudinal axis, and the root sections were examined under scanning electron microscope for evaluation of smear layer removal and erosion on the surface of the root canal walls. The specimens in group B showed presence of smear layer on the walls of the root canal with no statistical difference from that in group A (P>0.05). In groups C and D, partial removal of smear layer was obtained, and there was no significant difference between the two groups (P>0.05), but there was significant difference in removal of smear layer between group C and group B (P<0.05). Root canal walls in group E specimens showed almost complete removal of smear layer, and the removal of smear layer was significantly different from that in group D (P<0.01). There was no significant change in the structure of the surface of root canal for each sample. It was concluded that combined irrigation with 17% EDTA and 2.5% NaOCl could remove the smear layer with no significant alteration in dentinal structure when the chelating agent was applied for 7 min. At 3 and 5 min of application, partial removal of smear layer was observed and at 1 min negligible removal of smear layer was achieved.

Effect of frequent application of low-level laser therapy on corticotomized tooth movement in dogs: a pilot study.

PURPOSE: The purposes of the present study were to evaluate the effects of frequent applications of low-level laser therapy (LLLT) on corticotomy-assisted tooth movement in a beagle dog model and to compare the effects in the mandible and maxilla. MATERIALS AND METHODS: In 4 male beagles, the maxillary and mandibular second premolars were extracted. The third premolars were corticotomized and then protracted from the canines with a continuous force of 200 g. Daily LLLT (using an aluminum gallium indium phosphide [AlGaInP] diode) was applied at the buccal mucosa of the corticotomized premolars on 1 side only. The tooth movement was measured for 8 weeks. Fluorochromes were injected intravenously at the start of the experiment (T0) and after 2 (T2), 4 (T4), and 8 (T8) weeks to evaluate new bone formation on the tension sides. Histomorphometric and immunohistologic evaluations were performed. RESULTS: In the mandible, the movement of the corticotomized premolars in the LLLT plus corticotomy group was less than that in the corticotomy-only group, although the difference was not statistically significant. In the maxilla, no significant differences between the 2 groups were found. Osteoclastic and proliferating cell activities and the amount of new bone formation were greater in the mandibular LLLT plus corticotomy group than in the corticotomy-only group. CONCLUSIONS: The frequent application of LLLT showed no significant effect on the corticotomized tooth movement.

Efficacy of low-intensity laser therapy in reducing treatment time and orthodontic pain: a clinical investigation.

INTRODUCTION: The long duration of orthodontic treatment is a major concern for patients. A noninvasive method of accelerating tooth movement in a physiologic manner is needed. The aim of this study was to evaluate of the efficacy of low-intensity laser therapy in reducing orthodontic treatment duration and pain. METHODS: Twenty patients requiring extraction of first premolars were selected for this study. We used a randomly assigned incomplete block split-mouth design. Individual canine retraction by a nickel-titanium closed-coil spring was studied. The experimental side received infrared radiation from a semiconductor (aluminium gallium arsenide) diode laser with a wavelength of 810 nm. The laser regimen was applied on days 0, 3, 7, and 14 in the first month, and thereafter on every 15th day until complete canine retraction was achieved on the experimental side. Tooth movement was measured on progress models. Each patient's pain response was ranked according to a visual analog scale. RESULTS: An average increase of 30% in the rate of tooth movement was observed with the low-intensity laser therapy. Pain scores on the experimental sides were significantly lower compared with the control sides. CONCLUSIONS: Low-intensity laser therapy is a good option to reduce treatment duration and pain.

Topical application of melatonin and growth hormone accelerates bone healing around dental implants in dogs.

BACKGROUND: Growth hormone (GH) and melatonin belong to the group of growth factors. These substances have been proposed to improve and accelerate osseous healing using topical applications. PURPOSE: The aim of this study was to evaluate the effect of the topical administration of GH and melatonin on osseointegration of dental implants in Beagle dogs 2, 5, and 8 weeks after their insertion. MATERIALS AND METHODS: Twelve adult Beagle dogs and 48 implants were used in the study. The maxillary and mandibular premolars and molars were extracted. Each mandible received cylindrical screw implants of 3.25 mm in diameter and 10 mm in length. Prior to implanting, 4 IU of recombinant human GH and 1.2 mg of lyophilized powdered melatonin was applied to one osteotomy at each side of the mandible. None was applied at the control sites. The implants were retrieved at 2, 5, and 8 weeks for light microscopic examination, energy-dispersive x-ray microanalysis, and histomorphometric measurements in ground sections. RESULTS: At week 2, BIC was significantly higher in the melatonin-growth hormone group than in the implant control one (34.20 vs 25.05%; p = .010). The M-GH group also increased significantly the peri-implant bone area (64.72 vs 53.20%; p = .038) and interthread bone area (35.62 vs 25.08%; p = .02). At weeks 5 and 8, BIC and bone density around implants were similar to both groups. Significant differences were detected in bone neoformation at 8 weeks in ML-GH group (9.04 vs 7.53%; p = .05). Regarding the mineral composition, in ML-GH group increments in concentrations of phosphorus (10.70 vs 10.34; p = .013) were observed at 2 weeks and of magnesium (0.29 vs 0.25; p = .019) 5 weeks after implantation. CONCLUSION: The present study confirms that GH and melatonin synergistically enhance new bone formation around titanium implants in early stages of healing.

Evaluation of effects of topic melatonin on implant surface at 5 and 8 weeks in Beagle dogs.

PURPOSE: The aim of this study was to evaluate the effect of the topical application of melatonin on osteointegration of dental implants in Beagle dogs 5 and 8 weeks after their insertion. MATERIALS AND METHODS: For subsequent insertion of dental implants, upper and lower premolars and molars were extracted from 12 Beagle dogs. Each mandible received cylindrical screw implants of 3.25 mm in diameter and 10 mm in length. The implants were randomly assigned to the mesial and distal sites on each side of the mandible. Prior to implanting, 1.2 mg lyophylized powder melatonin was applied to one bone hole at each side of the mandible. None was applied at the control sites. Eight histological sections per implant were obtained for histomorphometric studies. RESULTS: After 5- and 8-week treatment periods, melatonin significantly increased the inter-thread bone (p < 0.05) and new bone formation (p < 0.05) in comparison to control implants in both weeks. There were no significant increases in the bone-to-implant contact and peri-implant bone (p > 0.05). CONCLUSION: Topical application of melatonin may act as a biomimetic agent in the placement of endo-osseous dental implants at 5 and 8 weeks after the implantation.

Application of calcium sulfate in surgical-orthodontic treatment of impacted teeth: a new procedure to control hemostasis.

PURPOSE: Calcium sulfate (CaS) is a simple, biocompatible material with a very long, safe clinical history in several different fields of medicine. CaS is a rapidly resorbing material that leaves behind a calcium phosphate lattice, which promotes bone regeneration and hemostasis. The aim of this study was to perform a clinical evaluation of a possible hemostatic effect of calcium sulfate hemihydrate (CaSO(4)), commonly known as plaster of Paris, in the surgical and orthodontic treatment of impacted teeth. MATERIALS AND METHODS: Forty-three patients with 66 impacted cuspids and premolars were enrolled in this study. The gap between teeth and bone was filled with several layers of CaS cement. Each layer was put in place and was compressed with a dry gauze. The outer layer was then hardened with a potassium sulfate solution. After hardening, the CaS excess was removed, and a bracket was applied to the surface of the tooth. RESULTS: In no case was a separation of the bracket by the surface of the tooth observed. CONCLUSIONS: These results seem to confirm the usefulness of the hemostatic effect of CaS in this procedure.

The effect of pulsed electromagnetic fields on the acceleration of tooth movement.

AIM: Accelerating the speed of orthodontic tooth movement should contribute to the shortening of the treatment period. This study was designed to determine whether a pulsed electromagnetic field (PEMF) affects orthodontic tooth movement. METHODS: The canines of one side of 10 patients (mean age 23.0 ± 3.3 years) who needed canine retraction were exposed to a PEMF; the canines on the contralateral sides of the same patients were not similarly exposed. After extraction of the maxillary first premolars, both canines were retracted with coil springs. A circuit and a watch battery were used to generate a PEMF (1 Hz). The generator was embedded in a removable appliance. Foil was used to obstruct the contol group from PEMF exposure. Patients were instructed to use the device from the commencement of canine retraction, and it was removed when Class I canine relationship was achieved in either of the canines after 5.0 ± 0.6 months. The changes in the space between the maxillary canine and first molar were measured to indicate the amount of tooth movement. The canine retraction distances were compared by paired t test. Afterward, the treatment plan was continued. RESULTS: With exposure to a PEMF, canine retraction was 1.57 ± 0.83 mm more than the control group (P<.001). CONCLUSION: These findings suggest that application of a PEMF can accelerate orthodontic tooth movement.

Effects of low-level laser therapy after Corticision on tooth movement and paradental remodeling.

BACKGROUND AND OBJECTIVE: Both Corticision and low-level laser therapy (LLLT) are known to affect the rate of tooth movement. Our objective was to investigate the combined effects of Corticision and LLLT on the tooth movement rate and paradental remodeling in beagles. STUDY DESIGN/MATERIALS AND METHODS: The maxillary second premolars (n = 24) of 12 beagles were randomly divided into four groups (n = 6 per group) based on the treatment modality: group A, only orthodontic force (control); group B, orthodontic force plus Corticision; group C, orthodontic force plus LLLT; group D, orthodontic force plus Corticision and LLLT. RESULTS: Ratios of second premolar-to-canine movement were greater by 2.23-fold in group B and 2.08-fold in group C, but 0.52-fold lesser in group D than in group A. The peak velocity was observed at an earlier stage of tooth movement in group B but at a later stage in group C during the 8-week treatment period. At week 8, both tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts on the compression side and proliferating cell nuclear antigen (PCNA)-positive osteoblasts on the tension side increased significantly (P<.05) in group C but decreased in group D. Histomorphometric analysis revealed that the mean apposition length of newly formed mineralized bone during the 8 weeks of treatment significantly increased in both group B (2.8-fold) and group C (2.2-fold). In group D, the labeling lines on lamina dura were thin and discontinuous, but intratrabecular remodeling and lamellation were found to be active. CONCLUSION: Periodic LLLT after Corticision around a moving tooth decreased the tooth movement rate and alveolar remodeling activity.

Effects of antibacterial agents on dental pulps of monkeys mechanically exposed and contaminated.

OBJECTIVE: The purpose of this study was to compare the effectiveness of antibacterial agents and mineral trioxide aggregate in the healing of bacterial contaminated primate pulps. STUDY DESIGN: The experiment required four adult male primates (Cebus opella) with 48 teeth prepared with buccal penetrations into the pulpal tissues. The preparations were performed under general anesthesia and the exposed pulps were exposed to cotton pellets soaked in a bacterial mixture consisting of microorganisms normally found in human pulpal abscesses obtained from the Endodontic Clinic of UNESP. Following bacterial inoculation (30 minute exposure), the pulpal tissue was immediately treated with either sterile saline, Cipro HC Otic solution (12), diluted Buckley' formecresol solution (12) or Otosporin otic solution (12) for 5 minutes. After removal of the pellet, hemostasis was obtained and a ZOE base applied to the DFC treated pulps and the non-treated controls (12). After hemostasis, the other exposed pulps were covered with mineral trioxide aggregate (ProRoot). The pulpal bases were all covered with a RMGI (Fuji II LC). The tissue samples were collected at one day, two days, one week and over four weeks (34 days). RESULTS: Following perfusion fixation, the samples were demineralized, sectioned, stained and histologically graded. After histologic analysis, presence of neutrophilic infiltrate and areas of hemorrhage with hyperemia were observed. The depth of the neutrophilic infiltrate depended on the agent or material used. The pulpal tissue treated with Otic suspensions demonstrated significantly less inflammation (Kruskal Wallis non parametric analysis, H = 9.595 with 1 degree of freedom; P = 0.0223) than the formocresol and control groups. The hard tissue bridges formed over the exposure sites were more organized in the MTA treatment groups than in the control and ZOE groups (Kruskal Wallis non parametric analysis, H = 18.291 with 1 degree of freedom; P = 0.0004). CONCLUSIONS: Otic suspensions and MTA are effective in treating bacterial infected pulps and stimulate the production of a hard tissue bridge over the site of the exposure.

[Posttreatment stability of four first bicuspid extraction cases treated with the Alexander technique--model analysis].

OBJECTIVE: To evaluate the posttreatment stability of four first bicuspid extraction cases with the Alexander technique. METHODS: Fifteen patients, 8 males and 7 females in the permanent dentition were selected. The age range of the patients was 10.3 to 16.2 years old. Four first bicuspids of every patient were extracted and all patients were treated with the Alexander technique. The study casts were taken before (T(1)), after treatment (T(2)) and 27.8 months averagely follow-up (T(3)). Data were correlated by means of paired t tests. RESULTS: Although maxillary and mandibular intercanine widths were increased by 0.98 mm and 0.87 mm, respectively, during treatment, they were decreased by 0.37 mm and 0.72 mm, respectively, during follow-up period. Maxillary and mandibular crowding were increased by 0.53 mm and 0.98 mm, respectively, during follow-up period. No statistical significance were found. Upper and lower arch depth were decreased significantly due to retraction of anterior teeth and remained stable during follow-up period. CONCLUSIONS: According to this study, the design of the Alexander appliance and the Alexander technique are helpful for stability of extraction therapy. Follow-up is still necessary to evaluate the long-term stability.

Calcium sulphate as a bone substitute for various osseous defects in conjunction with apicectomy.

AIM: The purpose of this study was to investigate the effect of calcium sulphate on various osseous defects when used in conjunction with apicectomy. METHODOLOGY: Mandibular third and fourth premolars of 11 beagle dogs were used. After root-canal treatment and apicectomy, three types of osseous defects were prepared on both sides of the mandible as follows: type 1, osseous defect communicating with the gingival sulcus: type 2, large osseous defect including two roots; type 3, 'through and through' osseous defect. The experimental side was allocated randomly, and the osseous defects were filled with medical grade calcium sulphate. The defects on the opposite side were left unfilled as controls. The dogs were sacrificed at 8 and 16 weeks postoperatively. Undemineralized sections were obtained and examined histomorphometrically. RESULTS: In type 1 defects, bone was not observed on the buccal side of the root on either experimental or control side at 8 and 16 weeks. In both type 2 and 3 defects, bone volume/tissue volume (BV/TV) values on the experimental side were significantly higher than those on the control side (P < 0.01), and mineral apposition rate (MAR) values on the experimental side were significantly higher than those on the control side (P < 0.01). CONCLUSIONS: The use of calcium sulphate was effective in bone regeneration on both large osseous defects and 'through and through' osseous defects. It was less effective in osseous defects communicating with the gingival sulcus.