Effect of intervention using a messaging app on compliance and duration of treatment in orthodontic patients.

OBJECTIVES: This study aims to determine the effectiveness of a messaging app (WeChat) in improving patients' compliance and reducing the duration of orthodontic treatment (DOT). MATERIALS AND METHODS: A randomized controlled trial was performed in a dental hospital and a clinic from August 2012 to May 2015. Orthodontic patients were included at the beginning of treatment. Patients with multiphase treatment or braceless technique were excluded. Participants were randomized to WeChat group (received regular reminders and educational messages) or control group (received conventional management) and were followed up until the treatment was completed. Primary outcome measure was DOT. Others were late and failed attendance, bracket bond failure, and oral hygiene condition. RESULTS: One hundred twelve patients in each group participated and completed the trial. DOT in WeChat group were 7.3 weeks shorter (P = 0.007). There were less failed attendance (3.1 vs. 10.9 %, P < 0.001), late attendance (20.1 vs. 29.9 %, P < 0.001), and bracket bond failure (11.8 vs. 16.1 %, P < 0.001) in WeChat group than control. There was no difference in orthodontic plaque index nor modified gingivitis index between the two groups before and after treatment. Number of failed attendances was identified as an independent factor affecting DOT (P = 0.004; HR = 0.89, 95 % CI 0.84 to 0.95). CONCLUSIONS: The intervention with WeChat is effective in reducing the treatment duration and bracket bond failure, and improving the attendance in orthodontic patients. CLINICAL RELEVANCE: DOT can be reduced by improving patient's compliance. The messaging app is useful for outpatient education and management.

Involvement of COX-2/PGE2 signalling in hypoxia-induced angiogenic response in endothelial cells.

To evaluate the impact of hypoxia on the angiogenic capability of endothelial cells (ECs), and further investigate whether the cyclooxygenase-2 (COX-2)/prostaglandin E(2) (PGE(2)) signalling is involved in the angiogenic response of ECs to hypoxia. We explored the impact of various periods (1, 3, 6, 12, 24 hrs) of hypoxia (2% O(2)) on human umbilical vein endothelial cells (HUVECs) in vitro. We observed cell viability, migration, tube formation, analysed COX-2, vascular endothelial growth factor (VEGF), AQP1 mRNA transcription, protein expression and measured PGE(2), VEGF protein concentration in cell supernatants. Then we treated HUVECs with COX-2 selective inhibitor NS398, EP1/2 combined antagonist AH6809 and exogenous PGE(2) to investigate the role of COX-2/PGE(2) signalling in the angiogenic response of ECs to hypoxia. The results demonstrated that short-term hypoxic treatment enhanced HUVECs proliferation, migration, tube formation, significantly up-regulated COX-2, VEGF, AQP1 mRNA level, protein expression and promoted PGE(2) , VEGF release. The pharmacological inhibition study revealed that exposure of HUVEC to NS398 and AH6809 under hypoxia impaired the biological responses of ECs to hypoxia. Exogenous PGE(2) augments the effects of hypoxia on HUVECs, and partially reversed the inhibitory effects of NS398 on HUVECs proliferation and angiogenic capability. Short-term hypoxic treatment enhanced angiogenic capability of ECs, and COX-2/PGE(2) signalling may play a critical role in the biological response of ECs to hypoxia.

Effect of placement angle on the stability of loaded titanium microscrews: a microcomputed tomographic and biomechanical analysis.

INTRODUCTION: The aim of this study was to evaluate the impact of the placement angle on the stability of loaded microscrews. METHODS: Forty-eight microscrews were placed at 4 angles ( 30°, 50°, 70°, and 90°) into the tibiae of 12 beagles, loaded with a force of 2 N immediately, and maintained for 8 weeks. Microcomputed tomography and pullout tests were used for morphometric and biomechanical analyses, respectively. RESULTS: All microcomputed tomography parameters and the peak loads at extraction of the microscrews were influenced by the placement angles of the microscrews. The higher microcomputed tomography parameters and the peak load at extraction were measured at angles from 50° to 70°. Oblique and vertical placement angles resulted in reduced stability of the loaded microscrews (P <0.05). CONCLUSIONS: To achieve the best stability of microscrews, a placement angle of 50° to 70° is advisable.

Enterococcus faecalis sir2-like gene enhances aerobic metabolism of themselves and mitochondrial respiration of mammal cells to bring about improving metabolic syndrome through the PGC-1α pathway.

Recent studies showed that probiotics could improve metabolic syndrome, making the identification of factors affecting metabolic control more important than ever. The mammalian sirtuin protein family has received much attention for its regulatory role, especially in various mitochondrial ATP, glucose, and lipid metabolic pathways. However, compared with the mammalian sirtuin protein family, the function of prokaryotic sir2 protein is much less known. We studied the effects of probiotics sir2 protein on cell energy metabolize pathway, which showed that deletion of Enterococcus faecalis sir2 inhibited the aerobic oxidation of bacteria and increased the bacterial fermentation. The study of EF-sir2 (sir2 protein of E. faecalis) role of molecular targets demonstrated that deacetylation of EF-sir2 was via Rho upregulating in E. faecalis. When transfected into HEK293T cells, EF-sir2 could significantly facilitate aerobic oxidation of glucose, enhance the respiration to generate more ATP, and cause upregulation of NRF1 target gene. Then, we found EF-sir2 could increase activity of PGC-1α by deacetylation and PGC-1α inhibition decreased the expression of NRF1 target gene. Finally, we demonstrated that EF-sir2 could significantly improve the metabolic index of mammalian cells through insulin resistanced model in vitro and metabolic syndrome rat model in vivo. Our results first revealed that prokaryotic sir2 genes affect the molecular mechanism of cellular metabolism and the regulatory of cell homeostasis in prokaryotic and mammalian cells, suggesting that EF-sir2 has a positive regulatory effect on metabolic disturbance and may be used for the prevention and treatment of pathological processes related to metabolic syndrome.

Oral engineered Bifidobacterium longum expressing rhMnSOD to suppress experimental colitis.

In recent years, using genetic engineering and bioengineering techniques, Bifidobacterium as a carrier to express specific functions of the protein or polypeptide, has become a new treatment for disease. Ulcerative colitis (UC) is a type of inflammatory bowel diseases (IBD). Although the cause of this inflammatory disorder is still unknown, a large amount of evidence suggests that ulcerative colitis is associated with increased activity of reactive oxygen species (ROS), manganese superoxide dismutase (MnSOD) is a kind of superoxide dismutase (SOD) has been demonstrated to play a key role in the pathophysiology of colitis. Here, we explored the Bifidobacterium as a drug delivery system to orally deliver a potent anti-inflammatory but poor penetration and stability antioxidant enzymes human MnSOD, transported into cells by a penetratin PEP-1. We constructed an expression vector expressing PEP-1-hMnSOD fusion protein, and successfully expressed hMnSOD fusion protein in engineered Bifidobacterium. Then we identified the bioactivity of engineered Bifidobacterium in LPS-induced inflammatory cell model. Finally, we used Bifidobacterium expressing PEP-1-hMnSOD fusion protein against DSS-induced ulcerative colitis mice. B. longum-PEP-1-rhMnSOD can successfully express rhMnSOD in the colon. We found that levels of inflammatory cytokines TNF-α, IL-1ß, IL-6 and IL-8 as well as histological damage in colonic tissues showed that engineered Bifidobacterium effectively reduced dextran sulfate sodium(DSS)-induced ulcerative colitis, we also tested the MPO, verified the above conclusions. These results suggest that oral Bifidobacterium expressing PEP-1-hMnSOD fusion protein can be treated as a new method of UC treatment.

Oral Bifidobacterium longum expressing GLP-2 improves nutrient assimilation and nutritional homeostasis in mice.

Bifidobacterium has been developed for the oral delivery of peptides and has the added beneficial effect on our bodies through its probiotic properties. Here, we utilize Bifidobacterium as a delivery system to orally deliver Glucagon like peptide-2 (GLP-2). We constructed vector derived from pET-31b(+) to construct a Bifidobacterium longum expressing GLP-2. We then determined the bioactivity of recombinant Bifidobacterium in Caco-2 cells. Finally, we quantified newly synthesized ApoB48 and chylomicron production in mice infused with exogenous GLP-2 or Bifidobacterium expressing GLP-2. Results based on secretion of the triglyceride (TG)-rich lipoprotein (TRL)-ApoB48 and secretion of chylomicron revealed that recombinant Bifidobacterium was efficient in treating intestinal dysfunction,suggesting an alternative way to use Bifidobacterium as a delivery system to deliver GLP-2 for gastrointestinal nutrition coordination.

The NAD+-dependent deacetylase, Bifidobacterium longum Sir2 in response to oxidative stress by deacetylating SigH (σH) and FOXO3a in Bifidobacterium longum and HEK293T cell respectively.

Silent information regulator 2 (Sir2) enzymes which catalyze NAD+-dependent protein/histone deacetylation. The mammalian sirtuin family SIRT1, SIRT2, SIRT3 and SIRT6 can regulate oxidative stress. The probiotics (Bifidobacterium longum(B.longum) and Lactobacillus acidophilus(L. acidophilus)) have Sir2 gene family and have antioxidant activity in human body. it remains unknown whether probiotics Sir2 has a direct role in regulating oxidative stress. To this end, we knockout BL-sir2(sir2 B. longum) and LA-sir2(sir2 L.acidophilus) in low oxygen level. The antioxidant activities of two sir2 deficient strains was decreased, while when reintroduction of BL-sir2 and LA-sir2, the antioxidant activities were recoveried. In order to understand the regulation mechanism of probiotics Sir2 oxidation response. Then, we screened 65 acetylated protein, and found that SigH (σH) was a substrate of BL-Sir2. In addition, the acetylation level of σH decreased with the increase of BL-Sir2 level in B. longum. Thus, BL-Sir2 deacetylated σH in response to oxidative stress. Next, we transfected BL-Sir2 into H2O2-induced oxidative damage of 293T cells, BL-Sir2 increased the activity of manganese superoxide dismutase (MnSOD/SOD2) and catalase (CAT) and reduced reactive oxygen species(ROS). Then, we analyzed the differential gene by RNA sequencing and Gene ontology (GO) and found that BL-Sir2 regulated forkhead transcription factor (FOXO3a) mediated antioxidant genes in overexpressed BL-Sir2 HEK293T cells. Our study is the first to link probiotics Sir2 with oxidative stress and uncover the antioxidant mechanism of BL-Sir2 in B. longum itself and human body.

Anti-inflammatory properties of Bifidobacterium longum expressing human manganese superoxide dismutase using the TNBS-induced rats model of colitis.

The chronic enteritis disease ulcerative colitis (UC) is a formidable opponent, and its etiology remains unclear. Current studies have shown that oxidative stress is closely related to the pathogenesis of inflammatory bowel disease. Antioxidant enzymes, such as manganese superoxide dismutase (MnSOD)，have been deemed to exert an anti-inflammatory function. Normally, oral administration of MnSOD directly leads to an incapacitation because of poor penetration and stability. To address this problem, the probiotic Bifidobacterium longum (B. longum), which naturally occurs in the intestinal flora, was engineered to secrete a biologically active human MnSOD. Then this engineered bacterium was utilized against a rat model harboring UC induced through trinitrobenzene sulfonic acid. The data showed the engineered B. longum successfully secreted a penetratin-hMn-SOD fusion protein. The bioactivity assay demonstrated that this fusion protein was delivered into Caco-2 cells and significantly decreased TNF-α (P<0.01) and IL-6 (P<0.01) expression, as well as, ROS level (P<0.001) in LPS-induced Caco-2 cells. The rat UC model experiment indicated that the B. longum harboring rhMn-SOD (penetratin-hMn-SOD) successfully inhibited the release of cytokines like TNF-a, IL-6, IL-1ß and IL-8, and reduce MPO activity and MDA levels. The histological analysis of the colon tissue section revealed that the engineered B. longum was efficient in attenuating UC damage. These results suggested that preventing UC by the use of B. longum harboring rhMn-SOD could be an alternative choice.

Factors Affecting the Clinical Success Rate of Miniscrew Implants for Orthodontic Treatment.

PURPOSE: The purpose of this study was to evaluate the various factors that influence the success rate of miniscrew implants used as orthodontic anchorage. MATERIALS AND METHODS: Potential confounding variables examined were sex, age, vertical (FMA) and sagittal (ANB) skeletal facial pattern, site of placement (labial and buccal, palatal, and retromandibular triangle), arch of placement (maxilla and mandible), placement soft tissue type, oral hygiene, diameter and length of miniscrew implants, insertion method (predrilled or drill-free), angle of placement, onset and strength of force application, and clinical purpose. The correlations between success rate and overall variables were investigated by logistic regression analysis, and the effect of each variable on the success rate was utilized by variance analysis. RESULTS: One hundred fourteen patients were included with a total of 253 miniscrew implants. The overall success rate was 88.54% with an average loading period of 9.5 months in successful cases. Age, oral hygiene, vertical skeletal facial pattern (FMA), and general placement sites (maxillary and mandibular) presented significant differences in success rates both by logistic regression analysis and variance analysis (P < .05). CONCLUSION: To minimize the failure of miniscrew implants, proper oral hygiene instruction and effective supervision should be given for patients, especially young (< 12 years) high-angle patients with miniscrew implants placed in the mandible.

Orthodontic mini-implant stability under continuous or intermittent loading: a histomorphometric and biomechanical analysis.

BACKGROUND: Both continuous and intermittent loadings are commonly applied in orthodontics. Clinical experiences and some studies believed that longer duration of force produce more effect (tooth movement, suture expansion, bone remodeling) than transient forces applied with the same magnitude. Alternatively, others indicated that interruption or recovery periods of various periods between loadings cause more bone remodeling and less root resorption. Therefore, which force is more favorable for osseointegration and stability of orthodontic mini-implant remains to be elucidated. PURPOSE: To evaluate the influence of continuous or intermittent loading on stability of titanium mini-implants. MATERIALS AND METHODS: One hundred ninety-two mini-implants were implanted bilaterally in intraradicular zones of mandibular M1 and P2 in 48 beagles. Loadings were delivered consecutively in continuous group, pauses were given for the last 3 or 7 days of each 2-week reactivation period for intermittent group A and B, respectively. The group unloaded was set as control. After 2, 4, 6 and 8 weeks, the animals were sacrificed and microscopic computerized tomography (µCT), histomorphological observation and pull-out test were applied. RESULTS: The µCT parameters of mini-implants in four groups were gradually increased with loading time prolonged, while the value of peak load at extraction (F(max)) increased and reached summit at week 6, but dropped slightly at week 8. In continuous group, all measurements were lower than those in intermittent groups at all time points (p < .05), and all values in intermittent group B were higher than those in intermittent group A. Histomorphology observation revealed different degrees of bone remodeling with new bone formation in the peri-implants region in different groups. CONCLUSIONS: Intermittent loading regimen is more favorable for obtaining stability than continuous force.

Histomorphometric and biomechanical analyses of the osseointegration of loaded orthodontic microscrews inserted at different cortical bone thickness sites.

OBJECTIVES: The aim of this study was to evaluate the osseointegration of loaded orthodontic microscrews at different cortical bone thickness (CBT) sites. STUDY DESIGN: Forty-eight microscrews were inserted bilaterally in the tibias of 12 beagles, and divided into thick and thin CBT group. After 1, 3, 5, and 7 weeks, the dogs were killed and bone-screw specimens prepared for polyfluorochrome sequential labeling, microscopic computerized tomography (µCT) analysis, and biomechanical pull-out testing. RESULTS: All µCT parameters were increased in the thin CBT group, and decreased in the thick CBT group with time passed. Fmax of microscrews in thick CBT sites reached a peak in week 1, but dropped to lowest levels in week 3. Remodeling, apposition, and measured deposition areas of 3 labels were significantly higher in the thin CBT group than in the thick CBT group (P < .05). CONCLUSIONS: Relatively larger CBT is of benefit for primary stability at early time points, whereas thinner CBT is more appropriate for achieving long-term stability with prolonged time.

Effect of placement angle on the stability of loaded titanium microscrews in beagle jaws.

OBJECTIVE: To evaluate the effect of insertion angle on stability of loaded titanium microscrews in beagle jaws. MATERIALS AND METHODS: Forty-eight microscrews were inserted at four different angles (30°, 50°, 70°, and 90°) into the intraradicular zones of the mandibular first molars and third premolars of 12 beagles and immediately loaded with a force of 2 N for 8 weeks. Microcomputed tomography (micro-CT) and biomechanical pull-out tests were used to assess osseointegration of the interface. RESULTS: All micro-CT parameters and maximum pull-out force (FMAX) of the microscrews were affected by insertion angles of microscrews. Higher micro-CT parameters and FMAX were seen for implants inserted at angles between 50° and 70° (P < .05). Excessive oblique and vertical insertion angles resulted in reduced stability (P < .05). CONCLUSION: An insertion angle of 50° to 70° is more favorable than excessive oblique or vertical angles to achieve stability of microscrews.

Coculture with endothelial cells enhances osteogenic differentiation of periodontal ligament stem cells via cyclooxygenase-2/prostaglandin E2/vascular endothelial growth factor signaling under hypoxia.

BACKGROUND: During periodontitis and orthodontic tooth movement, periodontal vasculature is severely impaired, leading to a hypoxic microenvironment of periodontal cells. However, the impact of hypoxia on periodontal cells is poorly defined. The present study investigates responses of cocultured endothelial cells (ECs) and periodontal ligament stem cells (PDLSCs) to hypoxia. METHODS: Osteogenic differentiation, molecular characterization, and various behaviors of PDLSCs and human umbilical venous ECs under hypoxia were assessed by quantitative real-time reverse-transcription polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay. Moreover, the effect of ECs on PDLSC osteogenic differentiation was tested using NS398 (cyclooxygenase 2 blocker), SU5416 (vascular endothelial growth factor [VEGF] receptor inhibitor), AH6809, L-798106, and L-161982 (EP1/2/3/4 antagonists). RESULTS: First, hypoxia promoted osteogenic differentiation in PDLSCs and enhanced EC migration, whereas PD98059 (extracellular signal-regulated protein kinase [ERK] inhibitor) blocked, and cocultured ECs further enhanced, hypoxia-induced osteogenic differentiation. Second, NS398 impaired EC migration and prostaglandin E2 (PGE2)/VEGF release, whereas cocultured PDLSCs and exogenous PGE2 partially reversed it. Third, NS398 (pretreated ECs) decreased PGE2/VEGF concentrations. NS398-treated ECs and AH6809/SU5416-treated PDLSCs impaired cocultured EC-induced enhancement of PDLSC osteogenic differentiation. CONCLUSIONS: Hypoxia enhances ERK-mediated osteogenic differentiation in PDLSCs. Coculture with EC further augments PDLSC osteogenic differentiation via cyclooxygenase-2/PGE2/VEGF signaling.

Bidimensional techniques for stronger anterior torque control in extraction cases: a combined clinical and typodont study.

OBJECTIVE: To investigate the capacity of bidimensional techniques for torque control of anterior teeth in extraction cases. MATERIALS AND METHODS: Two different bidimensional techniques were distinguished by nomenclature as bidimensional-slot (bDS) and bidimensional-wire (bDW), respectively. (1) In the clinical study, patients were randomly assigned to three groups (ie, bDS [n  =  27], bDW [n  =  24], and control [n  =  25] groups). The major inclusion criterion was mild crowding in the upper arch, with the two upper first premolars (teeth 14 and 24) to be extracted. After space closure through standardized treatment, the torque of the upper central incisors (∠TQ _U1) was calculated using the angle formed by the base of the U1 bracket and the working archwire on cephalograms. (2) In the typodont study, a standardized setup of the upper dentition with teeth 14 and 24 extracted was established. The spaces were closed through water bath followed by elastics, using the bDW or the conventional (control) technique, respectively. In six replicate experiments, after space closure, the ∠TQ _U1 was measured on the standardized lateral photographs. RESULTS: (1) In the clinical study, after space closure, the ∠TQ_U1 was 9.4° ± 3.4° (bDS), 8.3° ± 3.3° (bDW), and 5.8° ± 2.9° (control), respectively. The ∠TQ_U1 of bDS and bDW were both significantly (P < .05) larger than that of the control, but no statistical difference was found between them. (2) In the typodont study, after space closure, the ∠TQ_U1 of bDW (8.5° ± 0.9°) was significantly (P < .01) larger than that of the control (4.9° ± 1.0°). CONCLUSION: The bDS and the bDW techniques may help enhance anterior torque control in extraction cases.

Up-regulated osteogenic transcription factors during early response of human periodontal ligament stem cells to cyclic tensile strain.

INTRODUCTION: As one group of periodontal ligament (PDL) cells, human periodontal ligament stem cells (hPDLSCs) have been isolated and identified as mesenchymal adult stem cells (MSCs) since 2004. It has been well accepted that PDL sensitively mediates the transmission of stress stimuli to the alveolar bone for periodontal tissue remolding. Besides, the direction of MSCs differentiation has been verified regulated by mechanical signals. Therefore, we hypothesized that tensile strain might act on hPDLSCs differentiation, and the early response to mechanical stress should be investigated. MATERIAL AND METHODS: The hPDLSCs were cultured in vitro and isolated via a magnetic activated CD146 cell sorting system. After investigation of surface markers and other experiments for identification, hPDLSCs were subjected to cyclic tensile strain at 3,000 µstrain for 3 h, 6 h, 12 h, and 24 h, without addition of osteogenic supplements. In the control groups, the cells were cultured in similar conditions without mechanical stimulation. Then osteogenic related genes and proteins were analyzed by RT-PCR and western blot. RESULTS: Cyclic tensile strain at 3,000 µstrain of 6 h, 12 h, and 24 h durations significantly increased mRNA and protein expressions of Satb2, Runx2, and Osx, which were not affected in unloaded hPDLSCs. CONCLUSIONS: We indicate that hPDLSCs might be sensitive to cyclic tensile strain. The significant increase of Runx2, Osx and Satb2 expressions may suggest an early response toward osteogenic orientation of hPDLSCs.

Effects of cortical bone thickness at different healing times on microscrew stability.

OBJECTIVE: To compare the effects of different cortical bone thicknesses on the stability of microscrews at different healing times. MATERIALS: Sixty-four microscrews were inserted into the femurs of eight beagles, with four microscrews for one femur of one beagle dog. The dogs were sacrificed at 0, 3, 6, and 9 weeks after microscrew placement, respectively. All specimens were prepared for pullout testing. Cortical bone thickness was measured. Statistical analyses were conducted with analysis of variance (ANOVA) and Student-Neuman-Keuls (SNK) tests. RESULTS: Pullout forces in thick cortical bone sites are significantly higher than those in thin sites at 0 week and 3 weeks. For both thick and thin cortical bone thickness sites, the highest pullout forces were seen in the 0 week group and the lowest in the 3 week group. In the thin cortical bone thickness sites, the pullout force of the 3 week group was statistically different from those of the 6 week group and the 9 week group; however, no such differences were noted in thick cortical bone thickness sites. CONCLUSION: Microscrews inserted into thick cortical bone thickness sites had better stability than those inserted into thin cortical bone thickness sites at early healing time. The difference diminished and became insignificant as healing time got longer. Longer healing time may be necessary if microscrews are inserted into thin cortical bone thickness sites.

The effect of varying healing times on orthodontic mini-implant stability: a microscopic computerized tomographic and biomechanical analysis.

OBJECTIVE: The aim of this study was to evaluate the effect of different healing times on the stability of titanium mini-implants used for orthodontic anchorage. STUDY DESIGN: Eight male beagles were used and randomized into 4 groups according to different healing times (1, 3, 5, and 7 weeks); each group had 2 beagles. Sixty-four mini-implants were inserted bilaterally in the maxilla and mandible of the beagles. Microscopic computerized tomography (µCT) and pull-out test were used for morphometric and biomechanical analysis, respectively. RESULTS: All µCT parameters and F(max) (maximum pull-out force) increased with the prolongation of healing time. One week after insertion, all 4 measurements, namely osseointegration, trabecular bone volume density, intersection surface, and F(max), were lower in the maxilla group than in the mandible group (P < .05). Between the span of 1 and 3 weeks after insertion, a more obvious rising tendency of the 4 values was observed in the maxilla group than in the mandible group. Five and 7 weeks after insertion, the maxilla group expressed higher values of the 4 measurements than the mandible group (P < .05). CONCLUSIONS: Although insertion in the mandible could provide higher primary stability for mini-implants, with the prolongation of healing time, insertion in the maxilla achieves higher osseointegration. The results indicated that insertion in maxilla has a more positive effect on the stability of mini-implants than insertion in the mandible.

Orthodontic mini-implant stability in different healing times before loading: a microscopic computerized tomographic and biomechanical analysis.

OBJECTIVE: The aim of this study was to evaluate the influence of different healing times before loading on the stability of implanted titanium mini-implant. STUDY DESIGN: Forty mini-implants were implanted in bilateral maxilla in 10 beagles, loaded with a force of 0.98 N after a delay of 0 day (immediately activated) and 1, 3, 5, and 7 weeks. Microscopic computerized tomography (microCT) and pullout test were used for morphometric and biomechanical analyses, respectively. RESULTS: All microCT parameters and the F(max) of mini-implants were stimulated with the prolongation of healing time before loading. Between the group of 1 week and 3 weeks, a more obvious rising tendency of both microCT parameters and the F(max) of implants was observed. After 3 weeks, the tendency of increase tapered off. CONCLUSION: The results indicated that early loading may decrease osseointegration of mini-implants.

Quantitative research using computed tomographic scanning of beagle jaws for determination of safe zones for micro-screw implantation.

OBJECTIVES: The aim of this study was to provide an anatomical map for micro-screw placement in a safe location between the posterior dental roots of the beagle jaw. STUDY DESIGN: Three dimensional (3D) reconstructed images of 12 adult male beagles and jaw ground sections of another 6 beagles were examined. We measured sagittal, vertical and horizontal parameters in the intraradicular and interradicular regions of posterior teeth. RESULTS: The data showed that the safe zones were located in the intraradicular spaces of P2, P3, P4, M1, M2 and the interradicular spaces between P4 and M1, M1 and M2 in the mandible; in the maxilla, they were located in the intraradicular spaces of P3, P2, M1 and the interradicular space between P3 and M1. CONCLUSIONS: The present study provides a map of safe areas for the application of micro-screws in beagles.