Effect of industrial scanner and framework material interaction on the marginal gaps of CAD-CAM complete arch implant frameworks.

STATEMENT OF PROBLEM: Structured-light and computed tomography industrial scanners have been used as reference scanners to measure marginal gaps between implants and superstructures. However, the effect of framework material on the scanners' ability to detect gaps and on precision has not yet been evaluated. PURPOSE: The purpose of this in vitro study was to investigate the interaction between the industrial scanner and framework material on measured marginal gaps of implant-supported fixed complete arch frameworks made from titanium and polymethylmethacrylate and on the precision of scans. MATERIAL AND METHODS: A completely edentulous maxillary model with 4 implants and multiunit abutments at the first molar and canine sites was digitized by using a laboratory scanner. Implant-supported frameworks were milled from titanium and polymethylmethacrylate (n=5). Each framework was secured on the left molar site abutment. The marginal gaps between the frameworks and abutment sites without a screw were measured by using an industrial structured-light scanner and an industrial computed tomography scanner. The effect of the scanner, the framework material, and their interaction on measured gaps was analyzed by applying linear regressions and weighted least square methods. The F-statistics was used with Bonferroni corrections for precision analysis (α=.05). RESULTS: No significant effect of scanner, material, or their interaction was found on the marginal gaps at the canine sites. The titanium framework gaps detected by using the computed tomography scanner were greater than those detected by using the structured-light scanner at the right molar site (estimated difference in means=0.054 mm; P=.003) and overall (estimated difference in means=0.023 mm; P=.033). The structured-light scanner's precision was higher than that of the computed tomography scanner when titanium frameworks were scanned (P=.001). The computed tomography scanner's precision was higher when scanning polymethylmethacrylate frameworks than when scanning titanium frameworks (P=.03). CONCLUSIONS: Framework material and industrial scanner interaction affected the measured gaps. The computed tomography scanner detected greater marginal gaps with low precision when scanning titanium frameworks than the structured-light scanner. The sample size, the use of only 2 types of materials, and a laboratory scanner to obtain the computer-aided design file should be considered when interpreting the results.

Effect of guide sleeve material, region, diameter, and number of times drills were used on the material loss from sleeves and drills used for surgical guides: An in vitro study.

STATEMENT OF PROBLEM: How material loss from sleeves and drills is affected when different guide sleeve materials and different sizes of implant drills are used for different regions of surgical guides is unclear. PURPOSE: The purpose of this in vitro study was to compare the amount of material loss from different guide sleeves (zirconia and cobalt-chromium) and drills of different diameters during osteotomy preparation in different regions. MATERIAL AND METHODS: Three tooth-supported surgical guides with sleeve holes positioned in the first premolar and second molar sites were prepared. Guide sleeves (Ø 2.20 mm, 3.40 mm, and 4.05 mm) were milled from zirconia (n=60) and cobalt-chromium (n=60) blocks. A total of 12 titanium nitride-coated stainless steel twisted drills (n=6 per sleeve material) of different diameters (Ø 2.00, 3.20, 3.85 mm) were used with corresponding sleeves during the drilling. The weight loss from the drills and the volume loss from the guide sleeves after drilling were analyzed by using multiple linear mixed effect models (α=.05). RESULTS: According to the 4-way ANOVA for volume loss from sleeves, no significant interaction was found among the 4 main effects (number of times a drill was used, region, diameter, and material), but interactions between the number of times a drill was used and diameter (P=.001) and between the number of times the drill was used and material were significant (P<.001). For weight loss from the drills, a significant interaction was detected between the number of times the drill was used and diameter (P=.024). CONCLUSIONS: Less sleeve material was lost when zirconia sleeves were used. All sleeves had more material loss in the molar region than in the premolar region. The diameter had varying effects on the amount of material loss from drills and sleeves. The sleeve material and the region did not affect the material loss from drills.

Fabrication and characterization of Pickering emulsions stabilized by desalted duck egg white nanogels and sodium alginate.

BACKGROUND: The waste of salted egg white resources has always been a serious problem in the food industry. In this current study, we report on a kind of Pickering emulsion system, which was stabilized by duck egg white nanogels (DEWNs) and sodium alginate (SA), followed by which this system was crosslinked by calcium carbonate (CaCO3 ) via controlling the gluconolactone (GDL) concentrations, aiming to open up a promising route for making full use of these protein resources. RESULTS: The droplet size of the emulsion exhibited a reduction with an increase in SA concentrations, indicating that higher negative charges and steric hindrance was useful for a stable emulsion system. Meanwhile, the result of rheology measurement showed that storage modulus (G') values were higher than loss modulus (G″) values of the samples at higher GDL concentration, revealing the formation of elastic gel-like networks in the system, which was fabricated by SA and Ca2+ released by the CaCO3 particles. The gel-like network structure in the continuous phase improved both the freeze-thaw and thermal stability of the obtained Pickering emulsion system. Encouragingly, the Pickering high internal phase emulsions (HIPEs, φ = 0.75) stabilized by DEWN/SA3 -GDL3 were prepared, which could be stored at 4 °C for at least 30 days without oiling-off and creaming. CONCLUSION: These findings not only develop a green ultra-stable Pickering emulsion system but also extend the potential commercial applications of duck egg white proteins in the food, cosmetics, and pharmaceutical industries. © 2021 Society of Chemical Industry.

Comparison of clinical outcomes between Invisalign and conventional fixed appliance therapies in adult patients with severe deep overbite treated with nonextraction.

INTRODUCTION: The use of aligner therapy for orthodontic treatment has increased substantially in the past decade. However, no study has compared treatment outcomes between the conventional fixed appliance and Invisalign therapies in patients with a severe deep overbite. METHODS: This study included 50 consecutive adult patients who underwent treatment with either Invisalign (n = 25; mean age, 23.3 ± 8.5 years) or a conventional fixed appliance (n = 25; mean age, 23.1 ± 6.5 years) to correct overbite >5 mm and >60% deep overbite. Cephalometric analysis and peer assessment rating was used to compare the clinical outcome between groups. RESULTS: Cephalometric analysis showed significant differences in N-Me (P = 0.0005) and Mp-L6 (P = 0.0001) between Invisalign and fixed appliance treatment groups. No significant differences were observed in the peer assessment rating analysis or total treatment duration between the 2 groups. CONCLUSIONS: Both Invisalign and conventional fixed appliances were effective in treating patients with a severe deep overbite. Invisalign therapy may be preferable over conventional fixed appliance therapy in patients with high angle and deep overbite. However, because this study had a retrospective design, the results should be viewed with caution.

Aesthetic crown lengthening and lip repositioning surgery: Pre- and post-operative assessment of smile attractiveness.

AIM: To assess the effect of aesthetic crown lengthening (ACL) and lip repositioning surgery (LRS) on perception of smile attractiveness. MATERIALS AND METHODS: Preoperative and 6-month postoperative smile photographs of ACL- or LRS-treated patients were evaluated by 100 raters (five gender-balanced groups of ten per procedure) of diverse background (dental students, general dentists, periodontists and laypersons with and without any aesthetic concerns about their own smile). Smile attractiveness was rated by visual analogue scale (VAS). Multivariate mixed-effect models were applied to determine the effect of procedure, rater (age, gender and group) and case (gingival display and GD) on smile attractiveness rating. RESULTS: Average preoperative and postoperative VAS scores for ACL patients were 3.8 ± 2.0 and 6.2 ± 1.9, respectively. Corresponding LRS patient values were 4.8 ± 2.0 and 6.4 ± 1.9. Treatment, baseline GD and rater age were significant determinants (p < .001) of smile attractiveness for both procedures. Rater gender was not significant. Rater group was significant (p < .032) only for ACL. Procedure (p < .001), baseline VAS (p < .001), change in GD (p ≤ .002) and rater age (p ≤ .017) were significant determinants of smile attractiveness change from preoperative to postoperative. CONCLUSIONS: ACL and LRS are two periodontal plastic surgery procedures that deliver significant smile attractiveness improvements, in the eyes of both laypersons and dental professionals.

Lip repositioning surgery for gummy smile: 6-month clinical and radiographic lip dimensional changes.

OBJECTIVES: The present case series aimed to examine lip repositioning surgery (LRS) outcomes related to changes in external and internal upper lip (UL) dimensions, utilizing both conventional clinical and novel radiographic approaches. MATERIALS AND METHODS: Patients (n = 13) diagnosed with hypermobile UL (>8-mm mobility during smile) and excessive gingival display (≥4-mm) were included and assessed at baseline and 6 months postoperatively. Clinical parameters at rest included total lip and internal lip length (vestibular depth). At maximum smile included total lip, philtrum (ergotrid), and vermilion lengths. Cephalometric parameters included anterior maxillary height; lip length; nasolabial angle; anteroposterior lip thickness; internal lip length (vestibular depth); and vestibular fornix position (using novel approach employing radiopaque marker). Linear mixed-effect models, Pearson's correlation, and linear regression were used for statistical analyses. RESULTS: LRS did not affect total UL length at rest (p = 0.418). It resulted in significant internal UL length decrease (-3.8 ± 2.1 mm, p < 0.001) and significant increases of vermilion length (1.9 ± 1.0 mm, p < 0.001) and anteroposterior lip thickness (0.7 ± 0.7 mm, p = 0.002). The clinical and radiographic measurements of total UL length at rest (r ≥ 0.734) and of internal UL length (r ≥ 0.737), and the two radiographic assessments of vestibular depth (r = 0.842), were strongly correlated. CONCLUSIONS: LRS resulted in significant decrease of vestibular depth/internal UL length and in significant increases of UL vertical vermilion length and UL anteroposterior thickness, without affecting total UL length at rest. CLINICAL RELEVANCE: The documented lip dimensional outcomes should help practitioners when treatment-planning LRS and counseling patients seeking treatment for hypermobile UL.

Reversal of Multidrug Resistance by Apolipoprotein A1-Modified Doxorubicin Liposome for Breast Cancer Treatment.

Multidrug resistance (MDR) remains a major problem in cancer therapy and is characterized by the overexpression of p-glycoprotein (P-gp) efflux pump, upregulation of anti-apoptotic proteins or downregulation of pro-apoptotic proteins. In this study, an Apolipoprotein A1 (ApoA1)-modified cationic liposome containing a synthetic cationic lipid and cholesterol was developed for the delivery of a small-molecule chemotherapeutic drug, doxorubicin (Dox) to treat MDR tumor. The liposome-modified by ApoA1 was found to promote drug uptake and elicit better therapeutic effects than free Dox and liposome in MCF-7/ADR cells. Further, loading Dox into the present ApoA1-liposome systems enabled a burst release at the tumor location, resulting in enhanced anti-tumor effects and reduced off-target effects. More importantly, ApoA1-lip/Dox caused fewer adverse effects on cardiac function and other organs in 4T1 subcutaneous xenograft models. These features indicate that the designed liposomes represent a promising strategy for the reversal of MDR in cancer treatment.

Comparison of 2 Invisalign tray generations using the Peer Assessment Rating index.

INTRODUCTION: This study aimed to establish if there is a significant difference in effectiveness between 2 generations of Invisalign trays in terms of Peer Assessment Rating (PAR) score reduction for finished patients from a graduate orthodontic clinic. METHODS: Forty-five pretreatment and posttreatment patients treated with the previous Invisalign material and 49 pretreatment and posttreatment patients treated with SmartTrack material were scored using the Peer Assessment Rating (PAR) index. Both groups were controlled for initial weighted PAR score, age, gender, and treatment time. The 2 generations were compared in regard to absolute reduction, percent reduction, and great improvement in PAR score. RESULTS: The mean absolute reduction in weighted PAR score between the groups was not statistically significant (P = 0.526). The mean percent reduction in weighted PAR score between the groups was not statistically significant (P = 0.210). The proportion of great improvement between the groups was not significant (P = 0.526). Only 6 of the 8 components of occlusion had enough variation to be modeled. An absolute reduction in unweighted PAR score was not significantly different between the groups for maxillary anterior alignment, overjet, or mandibular anterior alignment (P = 0.996, 1.000, and 0.114, respectively). Percent reduction in unweighted PAR score was not significantly different between the 2 groups for an anteroposterior, overbite, or transverse (P = 1.000, 1.000, and 1.000, respectively) relationships. CONCLUSIONS: Our study indicates that both generations of Invisalign aligners improved the malocclusion to a similar degree according to the PAR index. Patient-centric benefits of SmartTrack aligner should also be considered by the provider.

Upper lip characteristics and associated excessive gingival display etiologies in adults: Race and sex differences.

BACKGROUND: This cross-sectional study aimed to examine upper lip (UL) and smile characteristics and soft tissue excessive gingival display (EGD) etiologies (hypermobile upper lip [HUL], altered passive eruption [APE], and short upper lip [SUL]) in a nondental adult population and to analyze interracial (Black and White) and intersex differences. METHODS: Community participants, non-Hispanic Blacks (NHB) and non-Hispanic Whites (NHW), were recruited and examined for UL vertical dimensions at rest and maximum smile and for HUL, APE, and SUL. Associations between gingival display (GD) or EGD and UL anatomical characteristics, HUL, APE, and SUL were analyzed. RESULTS: Participants included 66 NHB and 65 NHW adults. Ergotrid height (greater among NHW; p = 0.019) averaged 14.0 mm. Upper lip vermilion length (ULVL), total UL length, internal lip length, total UL length during smile, and UL mobility averaged 8.6, 22.5, 23.1, 16.6, and 5.9 mm, respectively (all significantly greater in NHB; p ≤ 0.012). SUL prevalence was 4.6%, found only among NHW. Lip length change from rest to smile (LLC) averaged 26.2% (significantly greater in females; p = 0.003). HUL prevalence was 10.7% (NHB 13.1%, NHW 3.5%; p = 0.024). NHB had significantly greater GD (p ≤ 0.017). EGD and APE prevalence (6.9% for both) showed significant interracial and intersex differences (p ≤ 0.014). Multivariate logistic regression analyses indicated that LLC and HUL were the most consistently significant EGD determinants. CONCLUSIONS: UL anatomical and functional characteristics and soft tissue-related EGD etiologies exhibit significant interracial and intersex differences, with UL mobility/hypermobility being the most consistently significant determinant of GD.

Enhanced chemoimmunotherapy of breast cancer in mice by apolipoprotein A1-modified doxorubicin liposomes combined with interleukin-21.

Backgroud: Breast cancer is a prevalent malignancy among women, with triple-negative breast cancer (TNBC) comprising approximately 15-20% of all cases, possessing high invasiveness, drug resistance and poor prognosis. Chemotherapy, the main treatment for TNBC, is limited by toxicity and drug resistance. Apolipoprotein A1 modified doxorubicin liposome (ApoA1-lip/Dox) was constructed in our previous study, with promising anti-tumour effect and improved safety been proved. However, during long-term administration, the problem of cumulative toxicity and insufficient tumour inhibition is still inevitable. Interleukin-21 is a small molecule protein secreted by T cells with various immune regulatory functions. IL-21 has significantly curative effects in numerous solid tumours, but it has the disadvantages of low response rate and short half-life. The combination of chemotherapy and immunotherapy has received increasing attention.Purpose: In this study, ApoA1 drug loading system and long-acting IL-21 are innovatively combined for tumour treatment.Methods: We combined ApoA1-lip/Dox and IL-21 for treatment and evaluated their impact on tumor-infiltrating lymphocytes and CD8+ T and NK cell cytotoxicity.Results: Combined administration significantly improved the tumour-infiltrating lymphocytes and enhanced the cytotoxicity of CD8+ T and NK cells. The combination of ApoA1-lip/Dox and IL-21 exhibits significantly enhanced anti-tumour efficacy with lower toxicity of ApoA1-lip/Dox, providing a new strategy for TNBC treatment with enhanced anti-tumour response and reduced toxicity.

Titanium as a Possible Modifier of Inflammation Around Dental Implants.

PURPOSE: The exact etiopathogenesis of peri-implant diseases remains unclear. While significant information on molecular markers is available, studies on biomarkers related to possible biocorrosion are sparse. This study aimed to evaluate periimplant crevicular fluid (PICF) for possible titanium (Ti) contamination and explore associations between clinical findings, inflammatory mediators, and Ti levels. MATERIALS AND METHODS: Patients with implant-supported restoration (≥ 1 year in function) were recruited for this cross-sectional study. Demographics, systemic, and periodontal health history were recorded. Clinical evaluations were conducted to reach peri-implant/periodontal diagnoses and grade severity of peri-implant soft tissue inflammation. Crevicular fluid (CF) was collected from both implants and adjacent teeth (PICF, gingival crevicular fluid [GCF]) and analyzed for Ti (inductively coupled plasma mass spectrometry) and inflammatory mediators (V-plex assays). Multiple regression analysis with a linear mixed effect model was used to analyze possible associations between clinical diagnosis, PICF/GCF cytokine, and Ti concentrations. RESULTS: Seventy-seven patients (aged 62 ± 2 years; 39 male) with 117 implants (9 ± 1 years in function) were recruited. Diabetes, positive periodontitis history, and current/former smoking were reported by 8%, 39%, and 39% of subjects, respectively. Seventy-nine implant sites (63 patients) were included in CF cytokine analysis, and 45 of these sites (42 patients) were paired with Ti analysis. Statistically significant increases from health to disease were noted in log-transformed PICF concentrations of IL-1ß, IL-6, IL-10, and INF-γ (P ≤ .05). Also, statistically significant increases from health to severe clinical inflammation were detected in log-transformed PICF concentrations of IL-8, IL-13, and TNF-α (P ≤ .05). Ti was detected in the majority (82%) of PICF and GCF samples. There was no statistically significant difference in log-transformed Ti concentration based on disease status. However, log-transformed Ti concentration was positively correlated to IL-1ß, IL-2, IL-4, IL-8, IL-13, and INF-γ concentrations when data were adjusted for site-specific health (P ≤ .05). CONCLUSION: Ti was detectable in PICF and adjacent GCF, even in health. Specific inflammatory mediator concentrations were increased in peri-implant disease and significantly associated with Ti concentrations, even when data were adjusted for peri-implant health status. Increased GCF inflammatory mediator concentrations were also associated with increased Ti concentrations. Ti effects on peri-implant as well as periodontal tissues require additional longitudinal investigations.

Quantitative evaluation of training method in placing miniscrews in orthodontic graduate program.

BACKGROUND: The purpose of this study was to assess the effectiveness of training residents in an orthodontic program in the placement of miniscrews by using cone beam computed tomography (CBCT) images. A total of 90 miniscrews were placed in 15 pig mandibles over a 3-year period by 15 first-year orthodontic residents. Miniscrews were divided into three groups (Control group: no radiographs; 2D group: placement with 2D radiographs; CBCT group: placement with CBCT). Proximity of the miniscrew to the neighboring root was measured. The miniscrew success rate was examined in the graduate clinic from 2015 to 2021. RESULTS: The percentage of root contact for each group was: 36.7% (11/30), 20.0% (6/30), 0% (0/30), for the Control, 2D, and CBCT groups, respectively. The CBCT group was significantly different from the Control and 2D groups (p < 0.05). For root proximity, the miniscrews were significantly closer to the roots in the Control (p < 0.001) and 2D (p < 0.001) groups compared with the CBCT group. No significant difference was observed between the Control and 2D groups (p = 0.80). There was no significant difference among the years in the miniscrew success rate. CONCLUSIONS: Training the residents in an orthodontic graduate program using CBCT may be helpful to avoid root damage and to decrease the miniscrew failure rate.

Fluorine-functionalized conjugated microporous polymer as adsorbents for solid-phase extraction of nine perfluorinated alkyl substances.

Perfluorinated alkyl substances (PFASs) are persistent, toxic, ubiquitously distributed, and bioaccumulated substances, which have attracted increasing concern. To investigate the environmental effects of PFASs, there is a need to develop a sensitive, rapid, and efficient method for detecting trace level PFASs. In this study, a conjugated microporous polymer (CMP) with loading of fluorine, fabricated by Sonogashira-Hagihara cross-coupling, was exploited as a solid-phase extraction (SPE) adsorbent. The prepared fluorine-functionalized CMP (FCMP), which showed a large surface area of 1089 m2·g-1, high porosity, and good chemical stability, was used to extract PFASs from water samples. The adsorption mechanism was investigated using a sorption isotherm model, and the main interactions were fluorous and hydrophobic affinity. The FCMP-based SPE combined with high-performance liquid chromatography-tandem mass spectrometry achieved low limits of detection (0.19-0.97 ng·L-1), wide linear range (2-1600 ng·L-1), and good reproducibility (3.4%-12.9%) under the optimal conditions. Furthermore, the approach was utilized for the analysis of three water samples (snow, river water, and irrigation water) to evaluate its reliability, and satisfactory recovery (70.5%-127.5%) was obtained. Thus, FCMP was feasible SPE adsorbents for the selective extraction of PFASs.

Effect of a Combination of Nitrous Oxide and Intraligamentary Injection on the Success of the Inferior Alveolar Nerve Block in Patients with Symptomatic Irreversible Pulpitis.

INTRODUCTION: The purpose of this prospective study was to determine the effect of a combination of nitrous oxide/oxygen and 1 set of supplemental intraligamentary/periodontal ligament (PDL) injections followed by a second set of PDL injections on anesthetic success in patients with symptomatic irreversible pulpitis (SIP). METHODS: Ninety-four patients with a mandibular posterior tooth diagnosed with SIP received nitrous oxide/oxygen and an inferior alveolar nerve block (IANB) with 2% lidocaine with 1:100,000 epinephrine. Patients rated the pain of PDL injections and endodontic access on a visual analog scale. If moderate to severe pain was felt during treatment, the operator administered 1 set of supplemental PDL injections with 4% articaine with 1:100,000 epinephrine. If moderate to severe pain was felt again during treatment, the operator administered a second set of supplemental PDL injections. Anesthetic success was defined as having no to mild pain during endodontic treatment. RESULTS: The success of the IANB with nitrous oxide was 44% (95% confidence interval [CI], 34%-54%). The overall anesthetic success rate (IANB with PDL injections) was increased from 69% (95% CI, 60%-78%) with 1 set of PDL injections to 80% (95% CI, 72%-88%) with a second set of PDL injections. CONCLUSIONS: Although the second set of PDL injections increased anesthetic success, it was not sufficient to ensure complete pulpal anesthesia.

Oral Health Advocacy Education Impacts Future Engagement: Exploration at a Midwestern US Dental School.

Purpose: With the emergence of COVID-19, and the potential inclusion of dental benefits in Medicare, it is critical that dentists are able to engage in legislative advocacy to support public oral health. Dental education has an opportunity to teach advocacy skills to future dentists, although advocacy training in predoctoral dental education has been largely ignored. The purpose of this study was to evaluate fourth-year dental student's attitudes toward advocacy, identify the type and extent of advocacy experiences during dental school, and assess their future intentions to engage in advocacy. Methods: An electronic questionnaire was administered to fourth-year dental students enrolled in their final semester at Ohio State University. Results: Forty-seven students completed the survey (43% response rate). Most (84%) respondents agreed that advocacy training should be a required experience in accreditation standards for predoctoral dental education. Over half (58%) reported seldom or no exposure to legislative and regulatory processes in oral health policy development in the curriculum. Students who participated in grassroots advocacy efforts while in dental school were more likely to contact legislators regarding dental issues (p = 0.005) or public insurance (p = 0.037), and participate in future lobbying efforts (p = 0.019). Students who contributed to PAC while in dental school were more likely to express intentions to contribute in future (p = 0.005). Conclusions: There is limited exposure to legislative advocacy in predoctoral dental education. Dental students with advocacy experience are more likely to report intentions to participate in advocacy as dentists. Dental education has a critical role in preparing future dentist-advocates.

The effect of scanned area on the accuracy and time of anterior single implant scans: An in vitro study.

OBJECTIVES: To investigate the effect of scanned area on the accuracy and scan time of intraoral scans of an anterior implant. MATERIALS AND METHODS: Three operators experienced in intraoral scanning (at least 2-year experience) performed partial and complete-arch scans (n = 10) of a dentate resin model with an implant at left central incisor site by using an intraoral scanner (Trios3; 3Shape, Copenhagen, Denmark). Each partial- or complete-arch scan was superimposed to a reference scan from a laboratory scanner (Ceramill Map 600; Amann Girrbach AG). Mean distance (selected 7 points) and angular (mesiodistal and buccolingual) scanbody deviations in test scans (trueness) and their variance (precision) were calculated. Linear-regressions (trueness), two-sided F-tests with a Bonferroni correction (precision), and multiple linear regressions (scan time), with the operator as a covariate were applied (alpha = .05). RESULTS: Interactions were found between the scanned area and the operator for their effect on trueness of all points and angles, except for point 6 at implant-abutment connection in mesiodistal plane (p < .05). No significant difference was found between the precision of partial and complete-arch scans for all operators (p > .05). Partial-arch scan times were significantly shorter, overall, and for each operator (p < .001). No significant effect of scan time was found on the trueness of partial- and complete-arch scans (p > .05). CONCLUSIONS: Partial and complete-arch scans of anterior single implants with an intraoral scanner resulted in similar accuracies, and were not influenced by the operator or the scan time. Scan times of partial-arch scans were significantly shorter. CLINICAL SIGNIFICANCE: Partial-arch scans can be used for the fabrication of monolithic anterior single implant crowns because the scans can be completed in shorter times without compromising the accuracy.

Regional variations of jaw bone characteristics in an ovariectomized rat model.

Postmenopausal osteoporosis causes severe loss of bone quantity and quality in limb bone but has a lesser effect on jaw bone. Thus, the objective of this study was to examine whether ovariectomy (OVX) and mastication alter the regional variation of jaw bone characteristics. Sprague-Dawley female rats (6 months) were given a bilateral OVX or a sham operation (SHAM) (n = 10 for each group). After 2 months post-OVX, the hemi-mandible from each rat was dissected. A micro-computed tomography based mean, standard deviation (SD), the lower and upper 5th percentile (Low5 and High5) values of tissue mineral density (TMD) histograms were assessed for whole bone (WB), alveolar bone (AB), cortical bone (CB), and trabecular bone (TB) regions. Morphology of TB and periodontal ligament (PDL) was also obtained. Layers of AB were segmented up to 400 µm from the PDL. Mechanical properties at the tissue level were measured by nanoindentation at the same site by a single loading-unloading cycle of indentation in hydration. The AB and TB regions had significantly lower TMD Mean, Low5, and High5 but higher SD than the CB region for both sham and OVX groups (p < 0.01). TMD parameters of the OVX group rapidly increased up to 60 µm away from the PDL and were significantly higher than those of the sham group starting at 280 µm and farther in the CB region (p < 0.05). All values of morphological and nanoindentation parameters were not significantly different between sham and OVX groups (p > 0.06). Estrogen deficiency induced by OVX did not deteriorate bone characteristics including mineral density, morphology, and nanoindentation parameters in rat mandibles. Masticatory loading had an effect on the TMD parameters at the limited region of AB. These results provide insight into why osteoporosis-associated jaw bone fractures are extremely rare.