Developing a three-dimensional statistical shape model of normal dentition using an automated algorithm and normal samples.

OBJECTIVES: The statistical shape model (SSM) is a model of geometric properties of a set of shapes based on statistical shape analysis. The SSM develops an average model of several objects using an automated algorithm that excludes the operator's subjectivity. The aim of this study was to develop a three-dimensional (3D) SSM of normal dentition to provide virtual templates for efficient treatment. MATERIALS AND METHODS: Dental casts were obtained from participants with normal dentition. After acquiring the 3D models, the SSMs of the individual teeth and whole dental arch were generated by an iterative closest point (ICP)-based rigid registration and point correspondences, respectively. Then, the individual tooth SSM was aligned to the whole dental arch SSM using ICP-based registration to generate an average model of normal dentition. RESULTS: The generated 3D SSM showed specific morphological features of normal dentition similar to those previously reported. Moreover, on measuring the arch dimensions, all values in this study were similar to those previously reported using normal dentition. CONCLUSIONS: The 3D SSM of normal dentition may increase the diagnostic efficiency of orthodontic treatments by providing a visual objective. It can be also used as a 3D template in various fields of dentistry. CLINICAL RELEVANCE: Our SSM of normal dentition provides both quantitative and qualitative information on the 3D morphology of teeth and dental arches, which may provide valuable information on 3D virtual-setup, bracket fabrication, and aligner treatment.

Effects of intravenous immunoglobulin therapy and Fc gamma receptor polymorphisms on BK virus nephropathy in kidney transplant recipients.

BACKGROUND: BK virus nephropathy (BKVN) is a major complication in kidney transplant patients. This study aimed to investigate the efficacy of intravenous immunoglobulin (IVIG) therapy against persistent BKVN and to evaluate the association between persistent BKVN and Fc gamma receptor (FcγR) single nucleotide polymorphisms (SNPs). METHODS: A total of 86 patients out of 279 kidney recipients with BKVN were investigated in a single-center retrospective study. The majority of 86 patients were Hispanic and Asian (69.8% and 17.4%). Patients were treated with adjunctive IVIG or standard therapy (controls). Subgroup analysis was performed between IVIG responders and non-responders. BK virus copy number and serum creatinine (SCr) were measured to evaluate the impact of IVIG. We analyzed the association between the response to IVIG and genotype at FcγR3A (rs396991) and FcγR2A (rs1801274) SNPs. RESULTS: Viral load in IVIG non-responders was significantly higher than in responders at the time of diagnosis (219 271.8 vs 29 816.3 copies/mL, P = .015) and after 6 months of IVIG use (12 789.5 vs 1369.5 copies/mL, P < .001). However, analyses SNP of FcγR2A (OR = 0.807, CI = 0.435-1.496 P = .495) and FcγR3A (OR = 0.997, CI = 0.505-1.970, P = .993) SNPs showed no significant differences between the 2 groups. CONCLUSION: IVIG appears to lower BK DNA viral load significantly in patients with persistent BKVN. However, no associations were identified between BKVN and FcγR2A or FcγR3A SNPs.

Analysis of genetic and clinical risk factors of post-transplant thrombocytopenia in kidney allograft recipients.

BACKGROUND: Hematological abnormalities after transplantation are complications that may arise after renal transplantation, of which thrombocytopenia is associated with increased risk of bleeding and other complications. The development of thrombocytopenia is affected by various clinical conditions, and the stromal-derived factor 1 (SDF1) and platelet factor 4 (PF4) genes are known to be involved in the production or destruction of platelets. The purpose of this study was to investigate the prevalence of posttransplant thrombocytopenia and its association with other clinical conditions and genetic polymorphisms of SDF1 and PF4 genes a long time after transplantation. METHODS: This is a retrospective study that includes a total of 305 kidney transplant (KT) recipients between 2008 and 2012 at St. Vincent Medical Center, Los Angeles, CA. In this study, posttransplant thrombocytopenia was defined as a 30% reduction in platelet count from the baseline in the first week or a decrease of <100 (×103/µL) within 1 year after KT. The subjects were divided into posttransplant thrombocytopenia and control groups. The chi-square test, t-test, and logistic regression were used for the analyses. RESULTS: In the first week, 65 patients had a 30% reduction in platelet count (21.3%). Gender, simultaneous kidney-pancreas transplantation, induction therapy (IT), and only alleles of rs2297630 of SDF1, among the SDF1 and PF4 genes, showed statistically significant differences. The rs2297630 alleles were consistently significant risk factors (non G vs. G: odds ratio = 0.445; 95% confidence interval, 0.224-0.884; p = .021) in the multiple logistic regression. In the 1-year study, 61 patients (20.0%) had platelet counts of <100 × 103/µL and had statistically significant differences in patients who had delayed graft function and induction therapy. CONCLUSIONS: In this study, non-G group of rs2297630 in SDF1 significantly increased the risk of post-transplant thrombocytopenia in the first week of kidney transplantation.

Association of genetic polymorphisms of macrophage inhibitory factor (MIF) and B-cell activating factor (BAFF) with the detection of donor specific antibodies in kidney allograft recipients.

The posttransplant development of donor specific antibodies (DSA) initiates the antibody mediated rejection (AMR), which is associated with the increased rate of graft loss. One of the characteristics of AMR is the infiltration of innate immune system including macrophages, monocytes, neutrophils or NK cells. Macrophage inhibitory factor (MIF) and B-cell activating factor (BAFF) are well known cytokines that are associated with the activation of the innate immune system which can damage kidney allograft. In this article, the association of the genetic polymorphisms of MIF and BAFF with the development of DSA including Class I and II in kidney transplant patients is investigated. A total of 231 renal transplant patients between 2008 and 2012 at St. Vincent Medical Center, CA were studied in a retrospective study design. DSA were determined by Luminex technology, and single nucleotide polymorphisms (SNP) of MIF and BAFF were determined by the real time PCR based on 5' nuclease allelic discrimination assay. The genetic polymorphisms of MIF rs1007888 (C/T) was associated with increased risk of positive DSA detection (p=0.04) after transplantation, and consistently significant after 1year (p=0.016). Furthermore, the presence of C allele were associated with the increased risk of Class I DSA detection (OR 1.816, CI 1.141-2.889, p=0.011). Also, genetic polymorphisms of BAFF rs12583006 were associated with the increased risk of Class II DSA detection (p=0.033). In conclusion, the genetic polymorphisms of MIF and BAFF may increase the risk of posttransplant development of DSA. This result suggests the association between the development of posttransplant DSA and the activation of innate immune system.

Renal Transplant Patients Biopsied for Cause and Tested for C4d, DSA, and IgG Subclasses and C1q: Which Humoral Markers Improve Diagnosis and Outcomes?

The association between donor specific antibodies (DSA) and renal transplant rejection has been generally established, but there are cases when a DSA is present without rejection. We examined 73 renal transplant recipients biopsied for transplant dysfunction with DSA test results available: 23 patients diffusely positive for C4d (C4d+), 25 patients focally positive for C4d, and 25 patients negative for C4d (C4d-). We performed C1q and IgG subclass testing in our DSA+ and C4d+ patient group. Graft outcomes were determined for the C4d+ group. All 23 C4d+ patients had IgG DSA with an average of 12,500 MFI (cumulative DSA MFI). The C4d- patients had average DSA less than 500 MFI. Among the patients with C4d+ biopsies, 100% had IgG DSA, 70% had C1q+ DSA, and 83% had complement fixing IgG subclass antibodies. Interestingly, IgG4 was seen in 10 of the 23 recipients' sera, but always along with complement fixing IgG1, and we have previously seen excellent function in patients when IgG4 DSA exists alone. Cumulative DSA above 10,000 MFI were associated with C4d deposition and complement fixation. There was no significant correlation between graft loss and C1q positivity, and IgG subclass analysis seemed to be a better correlate for complement fixing antibodies in the C4d+ patient group.

Association of genetic polymorphisms of angiopoietin-like 4 with severity of posttransplant proteinuria in kidney allograft recipients.

BACKGROUND: Proteinuria is a hallmark of glomerular injury, and persistent proteinuria is associated with graft failure in kidney transplant patients. Recently, it is known that the level of circulating angiopoietin-like 4 (ANGPTL4) is elevated in the patients with human nephrotic syndrome, in which ANGPTL4 is responsible for relieving proteinuria. PURPOSE: The purpose of this study is to determine effects of clinical factors and genetic polymorphism of ANGPTL4 on proteinuria after kidney transplantation. METHODS: A total of 282 patients out of 400 renal transplant patients between 2008 and 2012 at St. Vincent Medical Center, CA were studied in a retrospective study design. The level of proteinuria was measured by random urine protein to creatinine ratio, and divided into two groups (Group 1: UPC<500mg/day, Group 2: ≥500mg/day). Single nucleotide polymorphisms of ANGPTL4 genes (rs1044250, rs2278236, rs116843064, rs11672433, rs4076317) were determined by real time PCR with sequence specific primers. RESULTS: Among various clinical factors, only delayed graft function, mTOR inhibitor use and fish oil use were significantly associated with posttransplant proteinuria. Statistical differences were found in genetic polymorphisms of ANGPTL4 (rs1044250, rs2278236) in regards to proteinuria among tested patients. rs1044250 (C/T, T228M, missense mutation) alleles showed multiple significant differences (Group 1 vs. Group 2: C vs. T: OR=1.893, CI=1.322-2.710, p<0.001). Similar trends were found in rs2278236 (A/G) alleles with statistical significances (Group 1 vs. Group 2: A vs. G: OR=0.620, CI=0.443-0.867, p=0.005). With multiple logistic regression, rs1044250 was still a significant risk factor of moderate/severe proteinuria (p=0.021). CONCLUSIONS: This study suggests that the presence of C allele of rs1044250 and G allele of rs2278236 in ANGPTL4 gene is associated with higher risk of moderate/severe proteinuria in renal transplant patients.

Clinical risk factors associated with the post-transplant anemia in kidney transplant patients.

BACKGROUND: Anemia is a very common occurrence in post-renal transplant patients. Post-transplantation anemia (PTA) is associated with significant graft loss or cardiovascular morbidity. The objective of this study is to identify clinical risk factors associated with anemia after kidney transplantation. METHODS: Our retrospective cohort study included a total of 570 renal transplant recipients. For the definition of anemia, we adopted "the lower limit of normal for Hgb concentration of blood" proposed by Beutler E and Waalen J [14], which has adjustments for age, gender and ethnicity. Post-transplant anemia (PTA) was defined as anemia that arose between 30 and 180days after transplantation. Based on this definition, of the 570 renal transplant recipients, 344 patients (62.1%) experienced PTA. The patients were divided into anemic and non-anemic groups, and a total of 20 clinical factors were compared between the two groups. RESULTS: In the univariate analysis, age, race, multiple transplants, delayed graft function (DGF), and use of tacrolimus, sirolimus, thymoglobulin, ganciclovir, ACE inhibitors, and ARBs were associated with PTA. In the multivariate analysis, age (>60years old, OR=2.62, p=0.001), race (OR=2.54, p=0.001), and use of sirolimus (OR=2.01, p=0.019), antiviral agents (OR=1.96, p=0.015), thymoglobulin (OR=1.86, p=0.011), and DGF (OR=2.78, p=0.001) remained significant. CONCLUSION: The current results show that undergoing a transplant at age 60 or older, use of sirolimus, antiviral agents, and thymoglobulin are independent clinical risk factors associated with PTA. In terms of ethnicity, AA, MEA, or PI is higher risk for PTA and Hispanic is significantly lower risk for PTA compared to Caucasians.

Simplified proteomics approach to discover protein-ligand interactions.

Identifying targets of biologically active small molecules is an essential but still challenging task in drug research and chemical genetics. Energetics-based target identification is an approach that utilizes the change in the conformational stabilities of proteins upon ligand binding in order to identify target proteins. Different from traditional affinity-based capture approaches, energetics-based methods do not require any labeling or immobilization of the test molecule. Here, we report a surprisingly simple version of energetics-based target identification, which only requires ion exchange chromatography, SDS PAGE, and minimal use of mass spectrometry. The complexity of a proteome is reduced through fractionation by ion exchange chromatography. Urea-induced unfolding of proteins in each fraction is then monitored by the significant increase in proteolytic susceptibility upon unfolding in the presence and the absence of a ligand. Proteins showing a different degree of unfolding with the ligand are identified by SDS PAGE followed by mass spectrometry. Using this approach, we identified ATP-binding proteins in the Escherichia coli proteome. In addition to known ATP-binding proteins, we also identified a number of proteins that were not previously known to interact with ATP. To validate one such finding, we cloned and purified phosphoglyceromutase, which was not previously known to bind ATP, and confirmed that ATP indeed stabilizes this protein. The combination of fractionation and pulse proteolysis offers an opportunity to investigate protein-drug or protein-metabolite interactions on a proteomic scale with minimal instrumentation and without modification of a molecule of interest.

In vitro and in vivo mechanical stability of orthodontic mini-implants.

OBJECTIVE: To compare in vivo and in vitro mechanical stability of orthodontic mini-implants (OMIs) treated with a sandblasted, large-grit, and anodic-oxidation (SLAO) method vs those treated with a sandblasted, large-grit, and acid-etching (SLA) method. MATERIALS AND METHODS: Fifty-four titanium OMIs (cylindrical shape, drill-free type; diameter  =  1.45 mm, length  =  8 mm, Biomaterials Korea Inc, Seoul, Korea) were allocated into control, SLA, and SLAO groups (N  =  12 for in vivo and N  =  6 for in vitro studies per group). In vitro study was carried out on a polyurethane foam bone block (Sawbones, Pacific Research Laboratories Inc, Vashon, Wash). In vivo study was performed in the tibias of Beagles (6 males, age  =  1 year, weight  =  10 to 13 kg; OMIs were removed at 8 weeks after installation). For insertion and removal of OMIs, the speed and maximum torque of the surgical engine were set to 30 rpm and 40 Ncm, respectively. Maximum torque (MT), total energy (TE), and near peak energy (NPE) during the insertion and removal procedures were statistically analyzed. RESULTS: In the in vitro study, although the control group had a higher insertion MT value than the SLA and SLAO groups (P < .01), no differences in insertion TE and NPE or in any of the removal variables were noted among the three groups. In the in vivo study, the control group exhibited higher values for all insertion variables compared with the SLA and SLAO groups (MT, P < .001; TE, P < .01; NPE, P < .001). Although no difference in removal TE and removal NPE was noted among the three groups, the SLAO group presented with a higher removal MT than the SLA and control groups (P < .001). CONCLUSIONS: SLAO treatment may be an effective tool in reducing insertion damage to surrounding tissue and improving the mechanical stability of OMIs.

Effects of cleft type, facemask anchorage method, and alveolar bone graft on maxillary protraction: a three-dimensional finite element analysis.

OBJECTIVE: To investigate biomechanical effects of cleft type (unilateral/bilateral cleft lip and palate), facemask anchorage method (tooth-borne and miniplate anchorage), and alveolar bone graft on maxillary protraction. DESIGN: Three-dimensional finite element analysis with application of orthopedic force (30° downward and forward to the occlusal plane, 500 g per side). MODEL: Computed tomography data from a 13.5-year-old girl with maxillary hypoplasia. INTERVENTION: Eight three-dimensional finite element models were fabricated according to cleft type, facemask anchorage method, and alveolar bone graft. MAIN OUTCOME MEASURE(S): Initial stress distribution and displacement after force application were analyzed. RESULTS: Unilateral cleft lip and palate showed an asymmetric pattern in stress distribution and displacement before alveolar bone graft and demonstrated a symmetric pattern after alveolar bone graft. However, bilateral cleft lip and palate showed symmetric patterns in stress distribution and displacement before and after alveolar bone graft. In both cleft types, the graft extended the stress distribution area laterally beyond the infraorbital foramen. For both unilateral and bilateral cleft lip and palate, a facemask with a tooth-borne anchorage showed a dentoalveolar effect with prominent stress distribution and displacement on the upper canine point. In contrast, a facemask with miniplate anchorage exhibited an orthopedic effect with more favorable stress distribution and displacement on the middle maxilla point. In addition, the facemask with a miniplate anchorage showed a larger stress distribution area and sutural stress values than did the facemask with a tooth-borne anchorage. The pterygopalatine and zygomatico-maxillary sutures showed the largest sutural stress values with a facemask with a miniplate anchorage and after alveolar bone grafting, respectively. CONCLUSION: In this three-dimensional finite element analysis, it would be more advantageous to perform maxillary protraction using a facemask with a miniplate anchorage than a facemask with a tooth-borne anchorage and after alveolar bone graft rather than before alveolar bone graft, regardless of cleft type.

Effects of clodronate on early alveolar bone remodeling and root resorption related to orthodontic forces: a histomorphometric analysis.

INTRODUCTION: The objective of this study was to evaluate the short-term effects of clodronate, a first-generation bisphosphonate, on early alveolar bone remodeling and root resorption related to orthodontic tooth movement. METHODS: The samples consisted of 54 sex-matched Wistar rats (weight, 180-230 g) allocated to the 2.5 mmol/L clodronate, 10 mmol/L clodronate, and control groups (n = 18 for each group). After application of a nickel-titanium closed-coil spring (force, 60 g) between the maxillary central incisor and first molar, 2.5 mmol/L of clodronate, 10 mmol/L of clodronate, or saline solution was injected into the subperiosteum adjacent to the maxillary first molar every third day. All animals received tetracycline, calcein, and alizarin red by intraperitoneal injection at 1, 6, and 14 days, respectively. The amounts of tooth movement were measured at 3, 6, 9, 12, and 15 days. The animals were killed at 4, 7, and 17 days. Histomorphometric analyses of bone mineral appositional rate, labeled surface, percentage of root resorption area, and number of root resorption lacunae of the mesiobuccal root of the maxillary first molar at 4, 7, and 17 days were done. One-way analysis of variance (ANOVA) with the post-hoc test were done for statistical analyses. RESULTS: Rats in the 10 mmol/L clodronate group had significant decreases of tooth movement (12 and 15 days, P <0.05) and percentages of root resorption area and numbers of root resorption lacunae (7 day, P <0.05), and increases of labeled surface and mineral appositional rates (17 day, P <0.05) over those of the 2.5 mmol/L clodronate and control groups. CONCLUSIONS: Although clodronate might decrease root resorption related to orthodontic tooth movement, patients should be informed about a possible decrease in the amount of tooth movement and a prolonged period of orthodontic treatment.

Volumetric, planar, and linear analyses of pharyngeal airway change on computed tomography and cephalometry after mandibular setback surgery.

INTRODUCTION: The purpose of this study was to use lateral cephalometry and computed tomography (CT) to examine the volumetric, planar, and linear changes in the pharyngeal airway after mandibular setback surgery. METHODS: The pharyngeal airways of 12 subjects who underwent mandibular setback surgery at Seoul National University Dental Hospital were assessed linearly and volumetrically on lateral cephalometric radiographs and CT before surgery and 6 months after surgery. The pharynx, nasopharynx, and oropharynx were evaluated by volumetric analysis. Pharyngeal depth, airway space, pharyngeal soft-tissue thickness, and hyoid bone position were measured by linear analysis. The axial section area of the airway was measured by area analysis. RESULTS: From the linear analysis, a significant decrease in pharyngeal depth and a significant posterior movement of the hyoid bone (P <0.05) were noted. Volumetric analysis by CT showed that the oropharynx decreased after mandibular setback surgery. However, the volume and the axial section area of the airway in the CT images did not change significantly after mandibular setback surgery (P >0.05). CONCLUSIONS: Although the structures around the mandible inevitably moved backward after mandibular setback surgery on linear analysis, physiologic deformation could occur to preserve the airway capacity after sagittal compression.

Root and bone response to the proximity of a mini-implant under orthodontic loading.

OBJECTIVE: To determine the histological reaction of the root and bone as a mini-implant approaches the root. MATERIALS AND METHODS: Two kinds of mini-implants were inserted into the buccal alveolar bone of 4 beagles (2 males and 2 females). The specimens were classified as the near-root group, the PDL contact group, the root contact group, and the root perforation group. Cementum resorption, dentin resorption, cementum repair, cementum growth, ankylosis, root cracking, and root fracture were assessed as the implant neared the root. RESULTS: The incidence of root resorption increased when the mini-implant was less than 0.6 mm from the root in the near-root group and PDL contact group. Root cracking and root fracture occurred in the root contact group and root perforation group. Bone resorption and ankylosis were observed in some specimens. However, some specimens of the PDL contact group and root contact group had cementum growth or little root resorption despite proximity to the root. In the root perforation group, root resorption and ankylosis occurred on the side opposite the insertion. CONCLUSIONS: There is a risk of root contact and severe tissue damage from a thick mini-implant and the drilling procedure, either of which can induce root resorption or ankylosis. Use of smaller mini-implants may reduce root contact and tissue damage. However, the small mini-implant may need enhancement of its stability.

Static tensional forces increase osteogenic gene expression in three-dimensional periodontal ligament cell culture.

Orthodontic tooth movement results from the combinational process of both bone resorption and formation in the compressive and tension sides, respectively. However, the genes responsible for new bone formation in tension sides have not been determined. In this study, we used DNA microarray and real-time RT-PCR to identify genes in human periodontal ligament (PDL) cells that undergo significant changes in expression in response to static tensional forces (2 or 12 hours). The genes found were alkaline phospatase (ALP), matrix metalloproteinases (MMPs), vascular endothelial growth factor (VEGF), and several collagen genes. Furthermore, an ELISA evaluating the expression of VEGF, type IV collagen and MMP-2 found levels significantly increased after 24 and 72 hours (P 0.05). ALP activity was also increased after 24 hours (P 0.05). Collectively, we found the genes up-regulated in our study by the static tensional force are related to osteogenic processes such as matrix synthesis and angiogenesis.

Mapping transient partial unfolding by protein engineering and native-state proteolysis.

Transient partial unfolding of proteins under native conditions may have significant consequences in the biochemical and biophysical properties of proteins. Native-state proteolysis offers a facile way to investigate the thermodynamic and kinetic accessibilities of partially unfolded forms (cleavable forms) under native conditions. However, determination of the structure of the cleavable form, which is populated only transiently, remains challenging. Although in some cases partially cleaved products from proteolysis provide information on the structure of this elusive form, proteolysis of many proteins does not accumulate detectable intermediates. Here, we describe a systematic approach to determining structures of cleavable forms by protein engineering and native-state proteolysis. By devising phi(c) analysis, which is analogous to conventional phi analysis, we have determined the structure of the cleavable form of Escherichia coli maltose-binding protein (MBP), which does not accumulate any partially cleaved products. We mutated 10 buried residues in MBP to alanine and determined phi(c) values from the effects of the mutations on global stability and proteolytic susceptibility. The result of this analysis suggests that two C-terminal helices in MBP are unfolded in their cleavable form. The effect of ligand binding on proteolytic susceptibility and C-terminal deletion mutations also confirms the proposed structure. Our approach and methodology are generally applicable not only in elucidating the mechanism of proteolysis but also in investigating other important processes involving partial unfolding under native conditions such as protein misfolding and aggregation.

Effects of microgrooves on the success rate and soft tissue adaptation of orthodontic miniscrews.

OBJECTIVE: To evaluate the effect of microgrooves on orthodontic miniscrews in terms of success rate and soft tissue adaptation in animal experiments. MATERIALS AND METHODS: The sample consisted of a non-microgroove (NMG) group and a microgroove group (MG; 50 microm pitch and 10 microm depth microgroove on the upper surface of the miniscrew). Miniscrews of 1.6 mm diameter and 6.0 mm length were placed into beagle dogs. Histomorphometric analysis in each group focused on bone-to-implant contact (BIC) and the bone area (BA) of pressure and tension sides. Independent and paired t-tests were completed for statistical analysis. RESULTS: The success rate was found to be higher in the MG group than in the NMG group. The MG group showed significantly higher BIC on the pressure side when compared with the NMG group (P < .01). Although the NMG group showed significantly lower BIC on the pressure side than on the tension side at the upper side of the miniscrew (P < .01), the MG group revealed no significant differences between BIC on pressure and tension sides. The MG group generally exhibited perpendicular or circular alignment of the gingival connective tissue fiber with the miniscrew; the NMG group showed parallel alignment. CONCLUSIONS: The orthodontic load may affect bone remodeling on the pressure side of the miniscrew and may affect stability. The microgroove could exert some positive effects on soft tissue adaptation and bone healing.

Comparison of stability between cylindrical and conical type mini-implants. Mechanical and histological properties.

OBJECTIVE: To investigate the mechanical and histologic properties of conical compared with cylindrical shaped mini-implants in terms of the success rate. MATERIALS AND METHODS: The samples consisted of cylindrical and conical groups, and commonly had 1.6 mm diameter and 6.0 mm length (Jeil Medical Corporation, Seoul, Korea) placed in beagle dogs. The mechanical study for analyzing maximum insertion torque (MIT), maximum removal torque (MRT), and torque ratio (TR; MRT/MIT) in Sawbones (Pacific Research Laboratories Inc, Vashon, Wash), and the animal study for resonance frequency analysis (RFA) and histomorphometric analysis (bone-to-implant contact and bone area) in two beagle dogs were done. All measurements were statistically evaluated using independent t-tests to determine any difference in MIT, MRT, TR, RFA, bone-to-implant contact (BIC), and bone area (BA) between the cylindrical group and conical group. A P value less than 0.05 was considered significant. RESULTS: The conical group showed significantly higher MIT and MRT than the cylindrical group in the mechanical study. However, there was no significant difference in RFA, BIC, and BA between the two groups in the animal and histomorphometric studies. CONCLUSIONS: Although the conical shaped mini-implant could induce tight contact to the adjacent bone tissue and might produce good primary stability, the conical shape may need modification of the thread structure and insertion technique to reduce the excessive insertion torque while maintaining the high resistance to removal.

Initial effect of multiloop edgewise archwire on the mandibular dentition in Class III malocclusion subjects. A three-dimensional finite element study.

The purpose of this study was to compare the effect of a multiloop edgewise archwire (MEAW) with a plain ideal archwire (IA) on distal en masse movement of the mandibular dentition. A three-dimensional finite element model (3D FEM) of the mandibular dentition, without third permanent molars, was constructed to include the periodontal membrane (PDM), alveolar bone, standard edgewise bracket (0.018 x 0.025 inch), stainless steel IA (0.016 x 0.022 inch), and MEAW (0.016 x 0.022 inch). Stress distribution and displacement of the mandibular dentition were analyzed when Class III intermaxillary elastics (300 g/side) and 5 degree tip-back bends from the first premolar to the second molar were applied to the IA and the MEAW for distal en masse movement of the mandibular dentition. Compared with the IA, the discrepancy in the amount of tooth displacement was less and individual tooth movement with the MEAW was more uniform and balanced. There was minimal vertical displacement or rotation of the teeth with the MEAW when compared with the IA. The MEAW seems to have advantages for distal en masse movement of the mandibular dentition.

Skeletodental factors affecting chin point deviation in female patients with class III malocclusion and facial asymmetry: a three-dimensional analysis using computed tomography.

OBJECTIVE: Three-dimensional computed tomography (CT) was used to investigate which skeletodental factors are related to chin point deviation of facial asymmetry in skeletal class III malocclusion (SCIII) patients. STUDY DESIGN: Forty Korean adult female patients with SCIII, who had a three-dimensional CT taken 1 month before orthognathic surgical surgery, were assigned to group 1 (symmetry) or group 2 (asymmetry) according to the amount of chin point deviation from facial midline. Midfacial, mandibular, and cranial base variables were measured with software and statistically analyzed. RESULTS: Group 2 showed higher positions of the upper canine and first molar, shorter ramus height, more superior-posterior positioning of gonion (Go) on the deviated side, and more mesial inclination of the ramus and medial positioning of Go on the opposite side. CONCLUSION: Facial asymmetry in SCIII patients occurs due to greater growth and mesial inclination of the ramus and greater maxillary vertical excess in the opposite side.