Sexual dimorphism in bidirectional SR-mitochondria crosstalk in ventricular cardiomyocytes.

Calcium transfer into the mitochondrial matrix during sarcoplasmic reticulum (SR) Ca2+ release is essential to boost energy production in ventricular cardiomyocytes (VCMs) and match increased metabolic demand. Mitochondria from female hearts exhibit lower mito-[Ca2+] and produce less reactive oxygen species (ROS) compared to males, without change in respiration capacity. We hypothesized that in female VCMs, more efficient electron transport chain (ETC) organization into supercomplexes offsets the deficit in mito-Ca2+ accumulation, thereby reducing ROS production and stress-induced intracellular Ca2+ mishandling. Experiments using mitochondria-targeted biosensors confirmed lower mito-ROS and mito-[Ca2+] in female rat VCMs challenged with ß-adrenergic agonist isoproterenol compared to males. Biochemical studies revealed decreased mitochondria Ca2+ uniporter expression and increased supercomplex assembly in rat and human female ventricular tissues vs male. Importantly, western blot analysis showed higher expression levels of COX7RP, an estrogen-dependent supercomplex assembly factor in female heart tissues vs males. Furthermore, COX7RP was decreased in hearts from aged and ovariectomized female rats. COX7RP overexpression in male VCMs increased mitochondrial supercomplexes, reduced mito-ROS and spontaneous SR Ca2+ release in response to ISO. Conversely, shRNA-mediated knockdown of COX7RP in female VCMs reduced supercomplexes and increased mito-ROS, promoting intracellular Ca2+ mishandling. Compared to males, mitochondria in female VCMs exhibit higher ETC subunit incorporation into supercomplexes, supporting more efficient electron transport. Such organization coupled to lower levels of mito-[Ca2+] limits mito-ROS under stress conditions and lowers propensity to pro-arrhythmic spontaneous SR Ca2+ release. We conclude that sexual dimorphism in mito-Ca2+ handling and ETC organization may contribute to cardioprotection in healthy premenopausal females.

The Long-Term Residual Effects of Low-Magnitude Mechanical Stimulation on Murine Femoral Mechanics.

As an alternative to drug treatments, low-magnitude mechanical stimulation (LMMS) may improve skeletal health without potential side effects from drugs. LMMS has been shown to increase bone health short term in both animal and clinical studies. Long-term changes to the mechanical properties of bone from LMMS are currently unknown, so the objective of this research was to establish the methodology and preliminary results for investigating the long-term effects of whole body vibration therapy on the elastic and viscoelastic properties of bone. In this study, 10-week-old female BALB/cByJ mice were given LMMS (15 min/day, 5 days/week, 0.3 g, 90 Hz) for 8 weeks; SHAM did not receive LMMS. Two sets of groups remained on study for an additional 8 or 16 weeks post-LMMS (N = 17). Micro-CT and fluorochrome histomorphology of these femurs were studied and results were published by Bodnyk et al. (2020, "The Long-Term Residual Effects of Low-Magnitude Mechanical Stimulation Therapy on Skeletal Health," J. Biol. Eng., 14, Article No. 9.). Femoral quasi-static bending stiffness trended 4.2% increase in stiffness after 8 weeks of LMMS and 1.3% increase 8 weeks post-LMMS compared to SHAM. Damping, tan delta, and loss stiffness significantly increased by 17.6%, 16.3%, and 16.6%, respectively, at 8 weeks LMMS compared to SHAM. Finite element models of applied LMMS signal showed decreased stress in the mid-diaphyseal region at both 8-week LMMS and 8-week post-LMMS compared to SHAM. Residual mechanical changes in bone during and post-LMMS indicate that LMMS could be used to increase long-term mechanical integrity of bone.

Compression generated by cortical screws in an artificial bone model of an equine medial femoral condylar cyst.

OBJECTIVE: Determine compression generated by lag and neutral screws over 12 h using two bone analogs. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Bone analogs were made of composite synthetic bone (CSB) or three-dimensional printed polylactic acid (PLA). Analogs had a 2 mm exterior shell with a 10 mm thick internal layer of open-cell material. METHODS: Bone analogs were opposed, making a 4-sided box with open ends. A central channel contained the sensor and the screws passed through it to engage both paired analogs. Four screw/analog conditions were tested: neutral and lag screw with bicortical engagement, neutral and lag screw with unicortical engagement. All screws were tightened to 2 Nm torque and compression values recorded at 0, 0.5, 1, 2, 6, and 12 h (six trials per condition). Medians were compared across groups for statistical significance. RESULTS: There was no difference in median compression between lag and neutral bicortical screws. For PLA, greater median compression was generated by neutral (median 437 N) and lag (median 379 N) bicortical screws compared to neutral unicortical screws (median 208 N, p < .001); lag bicortical screws generated greater median compression than lag unicortical screws (median 265 N, p = .012). For CSB, lag bicortical screws (median 293 N) generated greater median compression than neutral unicortical screws (median 228 N, p = .008). CONCLUSION: Lag and neutral screws generated similar compression. Bicortical screws had higher median compression than unicortical screws in bone analogs. CLINICAL SIGNIFICANCE: Neutral screws generate compression in cancellous bone analogs that can be increased with bicortical bone engagement.

Prospective cohort study to evaluate narrow diameter implants for restoration of a missing lateral incisor in patients with a cleft palate: One-year results.

STATEMENT OF PROBLEM: Patients diagnosed with a cleft palate often have a congenitally missing maxillary lateral incisor. The congenital cleft presents the practitioner with challenges including the quantity and quality of bone, a surgically managed cleft correction, and limited clinical space. PURPOSE: The purpose of the present prospective investigation was to report preliminary results at the 1-year follow-up for this planned 5-year investigation of narrow diameter implants used to restore a missing lateral incisor in patients with a cleft palate. MATERIAL AND METHODS: Fourteen study participants with a cleft palate and a missing maxillary lateral incisor were enrolled based on established criteria. Narrow diameter implants (AstraTech OsseoSpeed TX 3.0S and 3.5 mm) were placed by using a 2-stage protocol and restored. All study participants received an Atlantis abutment and a cement-retained crown. Four probing depth measurements and bleeding on probing were measured at baseline and at 1 year. Probing depth measurements were evaluated using a 2-way repeated measures ANOVA with Tukey-Kramer multiple comparisons tests. Radiographic marginal bone loss was measured at 1-year by using a digital subtraction technique and evaluated by using a repeated measures ANOVA. Pretreatment cone beam computed tomography (CBCT) images were used to measure a mean gray level that was proportional to bone mineral density (BMD) in the implant site. One-way mixed ANOVA was used to compare the mean gray level and average implant stability quotient (ISQ) loading. A Pearson correlation was also tested between those parameters (α=.05) for each statistical analysis. RESULTS: The mean marginal bone loss at 1 year was 0.601 ±0.48 mm. Regarding probing depth measurements, a 2-way repeated measures ANOVA found both the location (P=.012) and time (P=.009) were significant. The Tukey-Kramer multiple comparisons test showed a significant difference between the buccal and distal site (P=.006) from baseline to 1-year follow-up. CONCLUSIONS: Narrow diameter implants are a reliable treatment for replacing a missing lateral incisor in patients with a cleft palate at 1 year, with an implant survival rate of 100% and implant success rate of 94% using the established criteria. A negative association was found between the bone mineral density and the implant stability in the alveolar cleft site of a patient with a cleft palate. The peri-implant soft tissue probe depths exhibited significant change during the first year.

Evaluation of clinical parameters for the stability of 2 types of miniscrews.

INTRODUCTION: The purpose of this research was to compare insertion techniques and effects on mechanical and clinical parameters between 2 types of miniscrews. METHODS: Forty-four consecutive patients whose orthodontic treatment involved the use of miniscrews (miniscrew A [MA] and miniscrew B [MB]) for anchorage were included in this study. Miniscrews were placed with predrilling or self-drilling; peak maximum insertion torque (MIT) and Periotest values were measured. Cone-beam computed tomography was performed after the insertion of miniscrews and root proximity determination; cortical bone thickness was also analyzed. Periotest values were measured after the application of orthodontic force. RESULTS: Self-drilling produced higher Periotest values (P <0.01) for MA and higher MIT (P <0.01) for MB with closer root proximity (P <0.05). MB had higher MIT and Periotest values with drilling compared with MA (P <0.05); MB also showed closer root proximity (P <0.05). Successful miniscrews had lower MIT (P <0.05) for MB and lower Periotest values (P <0.01) for both MA and MB, with significantly more distant root proximity (P <0.01). Self-drilling produced higher Periotest values at the time of placement (P <0.01) and after 4 weeks (P <0.05) in MA. Drilling produced higher Periotest values for MB at the time of placement (P <0.05). MIT had positive correlations with Periotest values for MB with self-drilling (P <0.01) and with root proximity for MA with drilling (P <0.01). Periotest values had negative correlations with root proximity for MA and the MB group with drilling (P <0.01). CONCLUSIONS: For miniscrews with larger diameters, higher MIT may result in more mobility (higher Periotest values). Drilling can avoid root contact and enhance primary stability, thus producing lower Periotest values.

Comparison of Post Space Volume Changes Following Fiber Post Removal Using Er,Cr:YSGG Laser Versus Ultrasonic Instrument.

PURPOSE: The purpose of this in vitro study was to compare the post space volume changes following removal of glass fiber posts in endodontically treated teeth by using erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser to the conventional ultrasonic method. MATERIALS AND METHODS: Twelve single-root human extracted teeth were cut into 13 mm near cementoenamel junction (CEJ), and then underwent endodontic treatment. The post spaces were prepared to 8 mm in length. Glass fiber posts were inserted with self-curing resin cement. Specimens were randomly assigned to laser or ultrasonic methods for their post removal. Post space volumes were measured using microcomputed tomography (micro-CT) before post cementation and after post removal. Dentin thickness was measured after post removal at coronal, middle, and apical third of the root canal space. Paired t-test and t-test were used to compare space volumes between before post cementation and after post removal, and between laser and ultrasonic groups, respectively. RESULTS: Six specimens were tested for each group. The average volume change was 6.499 mm3 in laser and 7.418 mm3 in ultrasonic method. There was not a significant difference between laser and ultrasonic group in respect of post space volume changes (p = 0.71). Both methods showed significant volume increase following post removal (p < 0.05). Significantly less dentin was lost when laser was used for post removal in the coronal portion of the post space (p = 0.002). CONCLUSIONS: Er,Cr:YSGG laser can be used as effective option, comparable to the conventional ultrasonic method when removing posts in endodontically treated teeth. Laser has the potential to provide conservative post removal.

Alendronate-induced Perturbation of the Bone Proteome and Microenvironmental Pathophysiology.

Objectives: Bisphosphonates (BPs) are powerful inhibitors of osteoclastogenesis and are used to prevent osteoporotic bone loss and reduce the risk of osteoporotic fracture in patients suffering from postmenopausal osteoporosis. Patients with breast cancer or gynecological malignancies being treated with BPs or those receiving bone-targeted therapy for metastatic prostate cancer are at increased risk of bisphosphonate-related osteonecrosis of the jaw (BRONJ). Although BPs markedly ameliorate osteoporosis, their adverse effects largely limit the clinical application of these drugs. This study focused on providing a deeper understanding of one of the most popular BPs, the alendronate (ALN)-induced perturbation of the bone proteome and microenvironmental pathophysiology. Methods: To understand the molecular mechanisms underlying ALN-induced side-effects, an unbiased and global proteomics approach combined with big data bioinformatics was applied. This was followed by biochemical and functional analyses to determine the clinicopathological mechanisms affected by ALN. Results: The findings from this proteomics study suggest that the RIPK3/Wnt/GSK3/ß-catenin signaling pathway is significantly perturbed upon ALN treatment, resulting in abnormal angiogenesis, inflammation, anabolism, remodeling, and mineralization in bone cells in an in vitro cell culture system. Conclusion: Our investigation into potential key signaling mechanisms in response to ALN provides a rational basis for suppressing BP-induced adverse effect and presents various therapeutic strategies.

Understanding Early-Stage Posttraumatic Osteoarthritis for Future Prospects of Diagnosis: from Knee to Temporomandibular Joint.

PURPOSE OF REVIEW: Many mechanical load-bearing joints of the body are prone to posttraumatic osteoarthritis (PTOA), including the knee joint and temporomandibular joint (TMJ). Early detection of PTOA can be beneficial in prevention or alleviating further progression of the disease. RECENT FINDINGS: Various mouse models, similar to those used in development of novel diagnosis strategies for early stages of OA, have been proposed to study early PTOA. While many studies have focused on OA and PTOA in the knee joint, early diagnostic methods for OA and PTOA of the TMJ are still not well established. Previously, we showed that fluorescent near-infrared imaging can diagnose inflammation and cartilage damage in mouse models of knee PTOA. Here we propose that the same approach can be used for early diagnosis of TMJ-PTOA. In this review, we present a brief overview of PTOA, application of relevant mouse models, current imaging methods available to examine TMJ-PTOA, and the prospects of near-infrared optical imaging to diagnose early-stage TMJ-OA.

Factors Associated with Mutations: Their Matching Rates to Cardiovascular and Neurological Diseases.

Monogenic hypertension is rare and caused by genetic mutations, but whether factors associated with mutations are disease-specific remains uncertain. Given two factors associated with high mutation rates, we tested how many previously known genes match with (i) proximity to telomeres or (ii) high adenine and thymine content in cardiovascular diseases (CVDs) related to vascular stiffening. We extracted genomic information using a genome data viewer. In human chromosomes, 64 of 79 genetic loci involving >25 rare mutations and single nucleotide polymorphisms satisfied (i) or (ii), resulting in an 81% matching rate. However, this high matching rate was no longer observed as we checked the two factors in genes associated with essential hypertension (EH), thoracic aortic aneurysm (TAA), and congenital heart disease (CHD), resulting in matching rates of 53%, 70%, and 75%, respectively. A matching of telomere proximity or high adenine and thymine content projects the list of loci involving rare mutations of monogenic hypertension better than those of other CVDs, likely due to adoption of rigorous criteria for true-positive signals. Our data suggest that the factor-disease matching rate is an accurate tool that can explain deleterious mutations of monogenic hypertension at a >80% match-unlike the relatively lower matching rates found in human genes of EH, TAA, CHD, and familial Parkinson's disease.

Reliability and accuracy of assessing temporary anchorage device-tooth root contact with cone-beam computed tomography.

INTRODUCTION: This study was aimed at investigating the reliability and accuracy of cone-beam computed tomography (CBCT) diagnosis of contact between a temporary anchorage device (TAD) and tooth root and assessing any effect produced by metal brackets, imaging software program, and image segmentation or color enhancement tools. METHODS: Eighteen fresh pig mandibles were used. TADs (Vector, 1.4 × 8 mm) were placed at the buccal intermolar alveolar bone on both sides of the mandibles. With soft tissue kept intact, each mandible underwent CBCT scans (voxel size, 400 µm) before and after placing TADs, and after placing metal brackets on involved molars. Alveolar bone specimens containing the TADs were then exposed to microcomputed tomography (microCT) scans (voxel size, 27 µm) after TAD removal. Two independent raters, blinded of image identity, diagnosed TAD-root contact using ImageJ (National Institutes of Health and the Laboratory for Optical and Computational Instrumentation, University of Wisconsin, Madison, Wis) for microCT; Dolphin (Dolphin Imaging and Management Solutions, Chatsworth, Calif) and Anatomage software programs (Anatomage, Santa Clara, Calif) for CBCT images. Intrarater and interrater reliability and diagnostic accuracy were statistically assessed using Cohen kappa and McNemar tests. RESULTS: Intrarater and interrater reliability of TAD-root contact diagnoses were perfect for microCT diagnoses (κ = 1), generally moderate to good (κ >0.5) for CBCT diagnoses except for the use of color enhancement tools (κ <0.25). For diagnostic accuracy, there was generally a low agreement (κ <0.45) between CBCT and microCT (gold standard). The percent accuracy ranged from 68.1% to 79.2% and was not different among raters, bracket presence/absence, or software choices (chi-square tests, P >0.05). Overall, diagnostic sensitivity was above 80%, whereas specificity was below 55%. CONCLUSIONS: Despite good reliability, diagnoses of TAD-root contact using 400 µm voxel size CBCT imaging tend to be inaccurate, with a likelihood of high false-positive diagnoses.

Mechanical and clinical evaluation of the effect of microscrew on root proximity and cortical bone thickness.

BACKGROUND/OBJECTIVES: Primary stability is required for successful use of microscrew. This study investigated correlations among biomechanical, morphological, and clinical values in relationship to root contact and different placement locations. MATERIALS/METHODS: Thirty-three microscrews were placed between the molars (n = 18) or in the body of the mandible (n = 15) in three pigs. Insertion torque, Periotest, resonance frequency analysis (RFA), and static and dynamic stiffness were measured. Cone beam computed tomography was performed before and after the insertion of microscrews. Interproximal microscrews were divided into root contacted microscrews (n = 9) and non-root contact microscrews (n = 9). Factorial analysis of variance was conducted, with significance set at P < 0.05. RESULTS: A significant difference was observed between bodily and root contacted microscrews in Periotest, RFA, static and dynamic stiffness, Tanδ, and bone density (RFA, P = 0.045; all others, P < 0.001). A significant difference was observed between bodily and non-root contact microscrews in Periotest, RFA, and bone density (RFA, P = 0.025; all others, P < 0.001). A significant difference was observed in static (P = 0.01) and dynamic (P = 0.038) stiffness between microscrews with and without contact. Dynamic stiffness (P = 0.02) and Tanδ (P = 0.03) showed significant correlations with Periotest results only in bodily microscrews. LIMITATIONS: Since a pig bone was used, some differences in the quality and quantity of the bone might be observed between humans. CONCLUSIONS/IMPLICATIONS: Stiffness values distinguished between microscrews with and without contact. Periotest and RFA results indicated that bodily microscrews were more stable than interproximal microscrews. Periotest and RFA may be useful with large, microscrews and/or in thick cortical bone, but further investigation is required to determine the stability of interproximal microscrews.

The Effect of Parathyroid Hormone Analogues When Added to Mineralized Bone Xenografts.

Implants can be a treatment option when there is sufficient quantity and quality of bone to provide support for long-term success. In the reconstruction of defects, autogenous bone remains the gold standard for its osteogenic and compatibility properties. However, the disadvantage of secondary surgery and the associated donor site morbidity prompts researchers to develop the ideal bone substitute for optimum bone reconstruction. Parathyroid hormone (PTH1-34) has provided a new option for improvement in bone regeneration. This study used a pig model to evaluate the effectiveness of parathyroid hormone when added to a xenograft, Bio-Oss, in reconstructing mandible defects. Six domestic pigs were used to create 3 posterior mandibular defects measuring 2 × 1-cm bilaterally with a total of 36 defects to simulate tooth extraction sites in humans. The defects were grafted in random order and divided into 3 groups as follows: control (no graft), Bio-Oss without PTH, and Bio-Oss with PTH. Defects were assessed with cone beam computerized tomography (CBCT), micro computerized tomography (microCT), nanoindentation, and histology. Results showed that adding PTH1-34 significantly enhanced the graft construct. CBCT showed a significant increase in the degree of bone mineralization. Nanoindentation showed increased hardness of regenerated bone and accelerated bone mineralization with PTH. MicroCT analysis revealed a trend toward higher bone regeneration and mineralization. The histological analysis showed a positive trend of the increase in cortical bone thickness and mineral apposition rate. In conclusion, the local addition of PTH1-34 to a xenograft has shown promising results to enhance bone regeneration in the reconstruction of mandibular defects.

Associations of pretreatment parameters with changes during orthodontic treatment.

OBJECTIVES: To examine whether pretreatment conditions of a patient can determine alveolar bone changes after orthodontic treatment. SETTING AND SAMPLE POPULATION: Cone beam computed tomography (CBCT) images were obtained from 44 patients (17 male and 27 female, 14.02 ± 1.29 years). MATERIAL AND METHODS: Buccal bone height (BBH), buccal bone thickness (BBT), and molar angulation (MA) of right and left maxillary molars and intermolar distance (ID) were measured using the CBCT images obtained before and after orthodontic treatment using conventional brackets and self-ligating conventional brackets. RESULTS: There was a significant change only in BBH after treatment. All posttreatment parameters had significant positive correlations with the corresponding pretreatment parameters (r2  = 0.376-0.719, P < 0.001). Most of the changes had significant negative correlations with the corresponding pretreatment parameter (r2  = 0.054-0.249, P < 0.03). The results were not significantly influenced by the different bracket types. CONCLUSION: The current findings suggest that the CBCT-based morphological information about dentition and oral bone conditions of patients can provide a better pretreatment plan to estimate the results of orthodontic treatment.

Diagnostic testing of cervical vertebral maturation staging: An independent assessment.

INTRODUCTION: The reliability of the cervical vertebral maturation (CVM) method has been questioned. The objective of this research was to evaluate the diagnostic reliability of the CVM method to diagnose the mandibular growth spurt using longitudinal records from an alternative database (Iowa Facial Growth Study [IFGS]) using established diagnostic testing methods. METHODS: Cephalometric films from 43 subjects (males = 20, females = 23) with Class I or Class II skeletal pattern from the IFGS were scanned, digitized, and adjusted for magnification. At least 5 consecutive, annual films were digitized. For each subject, mandibular length (Co-Gn) was measured for each film, and the growth increment between films was calculated. The largest growth increment was the growth spurt. For each subject, the film displaying CVM stage 3 was identified by a blinded examiner viewing the films in random order. Interrater and intrarater repeatability for Co-Gn (intraclass correlation) and CVM staging (weighted kappa) were calculated. Diagnostic tests, including sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) were carried out. The present data were compared with data previously derived from samples of the University of Michigan, Oregon, and Burlington Growth studies (UMGS, OGS, and BGS, respectively). A multilevel logistic regression analysis was also run with the mandibular growth peak as the response variable. RESULTS: Interrater repeatability for mandibular measurements (intraclass correlation coefficient [ICC] = 0.91) and CVM staging (k = 0.88) were excellent. Intrarater repeatability for mandibular measurements (ICC = 0.98) and CVM staging (kw = 0.55) were excellent to moderate. The UMGS data demonstrated higher sensitivity with comparable specificity. Accuracy was largely similar. Their PPV and NPV had larger ranges. The OGS and BGS data, compared with the IFGS data, showed that our sensitivity and PPVs were higher, that their specificity was higher, and that the NPV and accuracy were very similar. The regression analysis was applied to age groups 10-11 years through 13-14 years. Only chronological age was significant (P = 0.04). CONCLUSIONS: Agreement between CVM stage 3 and the maximum mandibular growth spurt is inconsistent. The diagnostic capability of CVM for the mandibular growth spurt is questionable.

Positional accuracy of a prosthetic treatment plan incorporated into a cone beam computed tomography scan using surface scan registration.

STATEMENT OF PROBLEM: The registration of surface scans onto cone beam computed tomography (CBCT) scans has been proposed as a method of visualizing different anatomic structures and the prosthetic treatment plan simultaneously. This method also overcomes some of the problems associated with conventional radiographic templates. However, it has not been thoroughly investigated or validated for use in implant dentistry. PURPOSE: The purpose of this in vitro study was to evaluate the accuracy of a prosthetic treatment plan surface scan incorporated into a CBCT scan and to compare it to conventional radiographic templates for single tooth replacement. MATERIAL AND METHODS: Direct surface scans of a completely dentate master model with removable radiopaque teeth were made using an intraoral scanner, and indirect surface scans of a stone duplicate of the master model were made using a laboratory scanner. To simulate a clinical scenario, the mandibular left first molar was removed. A CBCT scan of the clinical scenario was made. The surface scans were registered onto the CBCT scans. Radiographic templates for the clinical scenario were fabricated, and the master model was subsequently scanned using the same CBCT scanner with each radiographic template seated. Metrology software was used to assess the accuracy of each method by measuring the 3-dimensional deviation on standard tessellation language (STL) files generated from the CBCT scans against an STL file of the completely dentate master model generated from a CBCT scan. One-way ANOVA and the Tukey HSD test were used for statistical analysis (α=.05). RESULTS: The incorporation technique had a significant effect on deviation from the master model (P=.004). The overall mean 3-dimensional deviation was 0.04 mm for direct surface scan registrations, 0.03 mm for indirect surface scan registrations, and 0.33 mm for radiographic templates. Radiographic templates were significantly less accurate compared with both surface scan registration methods (P<.001), whereas no statistically significant difference in accuracy was found between the registration of a laboratory scan and that of an intraoral scan (P=.94). CONCLUSIONS: Intraoral and laboratory surface scan registration on CBCT scans were more accurate than radiographic templates for prosthetic treatment plan incorporation. The accuracy of the registration of an intraoral scan and a laboratory scan was comparable.

Reproduction Differentially Affects Trabecular Bone Depending on Its Mechanical Versus Metabolic Role.

During pregnancy and lactation, the maternal skeleton provides calcium for fetal/infant growth, resulting in substantial bone loss, which partially recovers after weaning. However, the amount of bone that is lost and the extent of post-weaning recovery are highly variable among different skeletal sites, and, despite persistent alterations in bone structure at some locations, reproductive history does not increase postmenopausal fracture risk. To explain this phenomenon, we hypothesized that the degree of reproductive bone loss/recovery at trabecular sites may vary depending on the extent to which the trabecular compartment is involved in the bone's load-bearing function. Using a rat model, we quantified the proportion of the load carried by the trabeculae, as well as the extent of reproductive bone loss and recovery, at two distinct skeletal sites: the tibia and lumbar vertebra. Both sites underwent significant bone loss during pregnancy and lactation, which was partially recovered post-weaning. However, the extent of the deterioration and the resumption of trabecular load-bearing capacity after weaning varied substantially. Tibial trabecular bone, which bore a low proportion of the total applied load, underwent dramatic and irreversible microstructural deterioration during reproduction. Meanwhile, vertebral trabecular bone bore a greater fraction of the load, underwent minimal deterioration in microarchitecture, and resumed its full load-bearing capacity after weaning. Because pregnancy and lactation are physiological processes, the distinctive responses to these natural events among different skeletal sites may help to elucidate the extent of the trabecular bone's structural versus metabolic functions.

Efficacy of Cone-Beam Computed Tomography in Evaluating Bone Quality for Optimum Implant Treatment Planning.

PURPOSE: This study examined (1) if cone-beam computed tomography (CBCT) can determine relative differences in bone mineral density distribution using clinical images of patients' mandibular bone and (2) if the relative differences can be used to detect the effects of sex and age on bone mineral density distribution. MATERIALS AND METHODS: Sixty-six clinical CBCT images from patients (36 females and 30 males) of 3 age groups (40, 50, and 60 years) were identified. Alveolar (AB) and basal cortical bone (CB) regions were digitally isolated. A histogram of gray levels, which are proportional to degrees of bone mineralization, was obtained from each region. Mean, variability (SD and coefficient of variation), and percentage differences of gray level parameters between AB and basal CBs were computed. RESULTS: Significant sex differences in gray level variability were observed within the postmenopausal age group (P < 0.042). CONCLUSION: These findings suggest that clinical CBCT images can be a valuable tool in providing information on bone quality, which is an important criterion for optimum planning for dental implant placement.

Evaluation of Invisalign treatment effectiveness and efficiency compared with conventional fixed appliances using the Peer Assessment Rating index.

INTRODUCTION: The purpose of this retrospective case-control study was to compare the treatment effectiveness and efficiency of the Invisalign system with conventional fixed appliances in treating orthodontic patients with mild to moderate malocclusion in a graduate orthodontic clinic. METHODS: Using the peer assessment rating (PAR) index, we evaluated pretreatment and posttreatment records of 48 Invisalign patients and 48 fixed appliances patients. The 2 groups of patients were controlled for general characteristics and initial severity of malocclusion. We analyzed treatment outcome, duration, and improvement between the Invisalign and fixed appliances groups. RESULTS: The average pretreatment PAR scores (United Kingdom weighting) were 20.81 for Invisalign and 22.79 for fixed appliances (P = 1.0000). Posttreatment weighted PAR scores between Invisalign and fixed appliances were not statistically different (P = 0.7420). On average, the Invisalign patients finished 5.7 months faster than did those with fixed appliances (P = 0.0040). The weighted PAR score reduction with treatment was not statistically different between the Invisalign and fixed appliances groups (P = 0.4573). All patients in both groups had more than a 30% reduction in the PAR scores. Logistic regression analysis indicated that the odds of achieving "great improvement" in the Invisalign group were 0.329 times the odds of achieving "great improvement" in the fixed appliances group after controlling for age (P = 0.0150). CONCLUSIONS: Our data showed that both Invisalign and fixed appliances were able to improve the malocclusion. Invisalign patients finished treatment faster than did those with fixed appliances. However, it appears that Invisalign may not be as effective as fixed appliances in achieving "great improvement" in a malocclusion. This study might help clinicians to determine appropriate patients for Invisalign treatment.

Evaluation of objective structured clinical examination for advanced orthodontic education 12 years after introduction.

INTRODUCTION: Advanced education programs in orthodontics must ensure student competency in clinical skills. An objective structure clinical examination has been used in 1 program for over a decade. The results were analyzed cross-sectionally and longitudinally to provide insights regarding the achievement of competency, student growth, question difficulty, question discrimination, and question predictive ability. METHODS: In this study, we analyzed 218 (82 first-year, 68 second-year, and 68 third-year classes) scores of each station from 85 orthodontic students. The grades originated from 13 stations and were collected anonymously for 12 consecutive years during the first 2 decades of the 2000s. The stations tested knowledge and skills regarding dental relationships, analyzing a cephalometric tracing, performing a diagnostic skill, identifying cephalometric points, bracket placement, placing first-order and second-order bends, forming a loop, placing accentuated third-order bends, identifying problems and planning mixed dentition treatment, identifying problems and planning adolescent dentition treatment, identifying problems and planning nongrowing skeletal treatment, superimposing cephalometric tracings, and interpreting cephalometric superimpositions. Results were evaluated using multivariate analysis of variance, chi-square tests, and latent growth analysis. RESULTS: The multivariate analysis of variance showed that all stations except 3 (analyzing a cephalometric tracing, forming a loop, and identifying cephalometric points) had significantly lower mean scores for the first-year student class than the second- and third-year classes (P <0.028); scores between the second- and third-year student classes were not significantly different (P >0.108). The chi-square analysis of the distribution of the number of noncompetent item responses decreased from the first to the second years (P <0.0003), from the second to the third years (P <0.0042), and from the first to the third years (P <0.00003). The latent growth analysis showed a wide range of difficulty and discrimination between questions. It also showed continuous growth for some areas and the ability of 6 questions to predict competency at greater than the 80% level. CONCLUSIONS: Objective structure clinical examinations can provide a method of evaluating student performance and curriculum impact over time, but cross-sectional and longitudinal analyses of the results may not be complementary. Significant learning appears to occur during all years of a 3-year program. Valuable questions were both easy and difficult, discriminating and not discriminating, and came from all domains: diagnostic, technical, and evaluation/synthesis.