The association between sleep bruxism and awake bruxism: Polysomnographic and electromyographic recordings in women with and without myofascial pain.

BACKGROUND: Sleep bruxism (SB) and awake bruxism (AB) are masticatory muscle activities that are rarely assessed in the same individuals and are thought to be associated with different behaviours. OBJECTIVES: To investigate whether individuals engaging in SB also engage in AB, that occurs during rest and during stress-related activity, and to investigate whether SB and AB are associated with different characteristics. METHODS: Females with myofascial pain (N = 122) and non-myofascial pain controls (N = 46) were evaluated for SB events and for AB events at rest and AB during stress-related activity, using electromyographic (EMG) recordings and a standardised scoring of bruxism events. The joint distributions between SB and AB events and EMG activity were evaluated, and the characteristic qualities of SB and AB were assessed. RESULTS: Neither SB event rates nor the EMG activity associated with those events was associated with AB events rates or EMG activity, either at rest or during stress-related activity. On the contrary, event rates and EMG activity when awake and at rest were positively associated with events and activity during stress-related activity. SB was characterised mainly by grinding, while AB was characterised mainly by clenching. CONCLUSION: Sleep bruxism and awake bruxism do not tend to occur in the same individuals.

In vitro comparison of physical characteristics of milled versus printed zirconia discs.

PURPOSE: The purpose of this study was to compare the dimensional accuracy, translucency, and biaxial flexural strength of milled zirconia (MZ) versus 3D-printed zirconia (PZ) discs. MATERIALS & METHODS: A circular disc measuring 14.0 mm in diameter and 1.20 mm in thickness was designed using computer-aided design (CAD) software. The resulting standard tessellation language (STL) file was used both as a control and to fabricate 36 zirconia (3Y-TZP) disc specimens (n = 36): 18 were milled (group MZ) and 18 were 3D-printed (group PZ). The diameter and thickness of each disc were measured using a digital caliper. Translucency was evaluated using a calibrated dental colorimeter. The flexural strength was determined using the piston-on-three-ball biaxial flexure test. All measurements were done by one blinded examiner. The statistical significance level was set to α = 0.05. RESULTS: The MZ discs had significantly more accurate dimensions than the PZ discs in both diameter and thickness when compared to the control CAD software-designed disc. The MZ discs exhibited significantly higher translucency (translucency parameter (TP) = 16.95 ±0.36 vs. 9.24 ±1.98) and biaxial flexural strength (996.16 ±137.37 MPa vs. 845.75 ±266.16 MPa) than the PZ discs. Finally, MZ possessed a significantly higher Weibull modulus relative to PZ. CONCLUSIONS: The results showed that the milled specimens achieved better dimensional accuracy and were more translucent, stronger, and less prone to failure than printed specimens.

Effects of LED curing light on silver diamine fluoride penetration into dentin.

This ex-vivo study investigated the effect of a light-emitting diode (LED) curing light on the depth of penetration of Silver Diamine Fluoride (SDF) into carious lesions. Twenty-four primary teeth with untreated caries lesions were allocated into groups and treated within 5 min after extraction: (1) n = 6 treated for 1 min with one drop of SDF followed by 10 sec rinse with tap water, (2) n = 6 treated for 10 sec with one drop of SDF and exposed to LED light for 20 sec (30 sec total SDF exposure) followed by 10 sec rinse with tap water, (3) n = 6 treated for 10 sec with one drop of SDF followed by a 10 sec rinse with tap water, (4) n = 3 untreated, and (5) n = 3 untreated but exposed to LED light for 20 sec. Samples were prepared, embedded, sectioned and silver penetration was measured using backscattered electron imaging in the scanning electron microscope and energy-dispersive X-ray spectroscopy analysis. Results were expressed as the average relative depth of penetration (%) = Ag depth/lesion depth × 100 from 5 sites in each lesion. Group means were compared using mixed model analysis. Mean ± standard deviation (SD) penetration was: 86.4 ± 20.7% in Group 1, 94.3 ± 13.7% in Group 2, and 26.7 ± 13.9% in Group 3. Groups 1 and 2 were statistically similar and different from Group 3 (p < 0.001). Groups 4 and 5 had no silver present. Use of LED light for 20 sec after 10 sec SDF application appears to facilitate silver penetration, similar to a 1 min SDF application. Clinical studies are needed to define the role of silver penetration in sustained caries arrest.

Legumain Induces Oral Cancer Pain by Biased Agonism of Protease-Activated Receptor-2.

Oral squamous cell carcinoma (OSCC) is one of the most painful cancers, which interferes with orofacial function including talking and eating. We report that legumain (Lgmn) cleaves protease-activated receptor-2 (PAR2) in the acidic OSCC microenvironment to cause pain. Lgmn is a cysteine protease of late endosomes and lysosomes that can be secreted; it exhibits maximal activity in acidic environments. The role of Lgmn in PAR2-dependent cancer pain is unknown. We studied Lgmn activation in human oral cancers and oral cancer mouse models. Lgmn was activated in OSCC patient tumors, compared with matched normal oral tissue. After intraplantar, facial or lingual injection, Lgmn evoked nociception in wild-type (WT) female mice but not in female mice lacking PAR2 in NaV1.8-positive neurons (Par2Nav1.8), nor in female mice treated with a Lgmn inhibitor, LI-1. Inoculation of an OSCC cell line caused mechanical and thermal hyperalgesia that was reversed by LI-1. Par2Nav1.8 and Lgmn deletion attenuated mechanical allodynia in female mice with carcinogen-induced OSCC. Lgmn caused PAR2-dependent hyperexcitability of trigeminal neurons from WT female mice. Par2 deletion, LI-1, and inhibitors of adenylyl cyclase or protein kinase A (PKA) prevented the effects of Lgmn. Under acidified conditions, Lgmn cleaved within the extracellular N terminus of PAR2 at Asn30↓Arg31, proximal to the canonical trypsin activation site. Lgmn activated PAR2 by biased mechanisms in HEK293 cells to induce Ca2+ mobilization, cAMP formation, and PKA/protein kinase D (PKD) activation, but not ß-arrestin recruitment or PAR2 endocytosis. Thus, in the acidified OSCC microenvironment, Lgmn activates PAR2 by biased mechanisms that evoke cancer pain.SIGNIFICANCE STATEMENT Oral squamous cell carcinoma (OSCC) is one of the most painful cancers. We report that legumain (Lgmn), which exhibits maximal activity in acidic environments, cleaves protease-activated receptor-2 (PAR2) on neurons to produce OSCC pain. Active Lgmn was elevated in OSCC patient tumors, compared with matched normal oral tissue. Lgmn evokes pain-like behavior through PAR2 Exposure of pain-sensing neurons to Lgmn decreased the current required to generate an action potential through PAR2 Inhibitors of adenylyl cyclase and protein kinase A (PKA) prevented the effects of Lgmn. Lgmn activated PAR2 to induce calcium mobilization, cAMP formation, and activation of protein kinase D (PKD) and PKA, but not ß-arrestin recruitment or PAR2 endocytosis. Thus, Lgmn is a biased agonist of PAR2 that evokes cancer pain.

Oral cancer patients experience mechanical and chemical sensitivity at the site of the cancer.

INTRODUCTION: Oral cancer patients suffer severe chronic and mechanically-induced pain at the site of the cancer. Our clinical experience is that oral cancer patients report new sensitivity to spicy foods. We hypothesized that in cancer patients, mechanical and chemical sensitivity would be greater when measured at the cancer site compared to a contralateral matched normal site. METHODS: We determined mechanical pain thresholds (MPT) on the right and left sides of the tongue of 11 healthy subjects, and at the cancer and contralateral matched normal site in 11 oral cancer patients in response to von Frey filaments in the range of 0.008 to 300 g (normally not reported as painful). We evaluated chemical sensitivity in 13 healthy subjects and seven cancer patients, who rated spiciness/pain on a visual analog scale in response to exposure to six paper strips impregnated with capsaicin (0-10 mM). RESULTS: Mechanical detection thresholds (MDT) were recorded for healthy subjects, but not MPTs. By contrast, MPTs were measured at the site of the cancer in oral cancer patients (7/11 patients). No MPTs were measured at the cancer patients' contralateral matched normal sites. Measured MPTs were correlated with patients' responses to the University of California Oral Cancer Pain Questionnaire. Capsaicin sensitivity at the site of the cancer was evident in cancer patients by a leftward shift of the cancer site capsaicin dose-response curve compared to that of the patient's contralateral matched normal site. We detected no difference in capsaicin sensitivity on the right and left sides of tongues of healthy subjects. CONCLUSIONS: Mechanical and chemical sensitivity testing was well tolerated by the majority of oral cancer patients. Sensitivity is greater at the site of the cancer than at a contralateral matched normal site.

Ring-tailed lemurs (Lemur catta) use olfaction to locate distant fruit.

OBJECTIVES: As many primates live in forests where visibility is limited, the ability to detect the aroma of distant fruit and navigate odor plumes would be highly adaptive. Our study is the first to investigate this ability with strepsirrhine primates. MATERIALS AND METHODS: We tested the ability of a group of ring-tailed lemurs to detect hidden fruit from afar using scent alone. We hid containers in the underbrush of a semi-natural forest, some baited with real cantaloupe and some with sham cantaloupe, 4-17 m from a path routinely used by the lemurs. Crucially, the containers were not visible from the path. Therefore, the lemurs had to use olfactory cues, but did not have to prioritize them to locate the bait. RESULTS: The lemurs found the real cantaloupe on days that the wind blew the scent of the fruit toward the trail. They did not find the sham cantaloupe. Upon detecting the odor of the bait, the lemurs sniffed the air at one or more locations as they moved toward the bait, a process of navigation known as klinotaxis. DISCUSSION: The traditional belief is that primates are unable to track odor plumes. The untrained lemurs in this study were able to detect the odor of the cantaloupe among the complex odors of the forest and navigate the odor plume to the fruit. The results indicate that olfaction may be used to respond to cues from distant sources. The ability to track odor plumes may be a critical foraging skill for strepsirrhines.

Stress-evoked muscle activity in women with and without chronic myofascial face pain.

BACKGROUND: Amplified muscle activity in reaction to daily life stressors might explain chronic pain in temporomandibular disorder (TMD). OBJECTIVES: To assess whether patients with myofascial TMD pain (MFP) react to standardised stressors with greater masticatory muscle activity than demographically matched controls. METHODS: A total of 124 female MFP patients and 46 demographically matched and pain-free controls rated distress while performing a series of standardised stress-reactivity tasks (viz., cold pressor test, mental arithmetic test, speech stressor test and reaction time/startle response test) as well as a vanilla baseline control task. Blood pressure was measured before and after each task, and electromyographic (EMG) activity was continuously recorded over the jaw-closing muscles and several non-masticatory muscles during each task. Linear mixed model analyses were used to test the hypothesis that case status, stress-reactivity task and muscle recording site influenced EMG activity. RESULTS: Stress induction was successful, as evidenced by distress ratings and blood pressure measurements that were significantly elevated during performance of the stress tasks. Participants reported that some of the tasks were stressful in a way that resembled stressors experienced in their daily lives. Elevated muscle activity could be confirmed only for the reaction time/startle response task, where mean EMG activity was elevated more in cases than in controls, specifically in the jaw-closing muscles. CONCLUSION: These data could not provide clear support for the theory that psychological stressors produce a differential increase in masticatory muscle activity in MFP patients than pain-free controls.

Effect of multiple injections of botulinum toxin into painful masticatory muscles on bone density in the temporomandibular complex.

BACKGROUND: Adverse effects of masticatory muscle injections of Botulinum Toxin (Btx) have been noted in animal and, less dramatically, human studies. OBJECTIVE: Among women treated in multiple community-based private practices, to compare TMJ bone density and mandibular condylar volume between patients with myofascial TMJD receiving multiple masticatory muscle Btx treatments and similarly diagnosed women not receiving such treatment. METHODS: Cohorts consisted of women whose treatment charts indicated a diagnosis of myofascial TMJD: 35 received at least 2 Btx treatment cycles; 44 received none. Bone density at pre-specified regions of interest (ROI) was defined by grey scale values from Cone Beam CT, adjusting for a fixed density phantom included in each scan. Mean bone density and mandibular condyle volume were compared between groups. Dose-response effects were tested within the Btx-exposed group. RESULTS: The mean density of primary and secondary ROIs was similar between exposure groups, as was condylar volume. Among Btx-exposed women, increasing dose of Btx to the temporalis muscle was inversely proportional to the density of the trabecular area of the mandible body. Many Btx-exposed women received smaller doses of Btx to the masseter muscles than in most TMJD Btx clinical trials. CONCLUSION: Masticatory muscle injections of Btx failed to produce clinically significant TMJ bone-related changes. Should Btx receive regulatory approval for treatment of myofascial TMJD, a phase IV study is recommended to evaluate potential adverse effects of Btx on bone and muscle when administered at higher doses and/or for more treatment cycles.

Twice-daily red and blue light treatment for Candida albicans biofilm matrix development control.

Phototherapy has been proposed as a direct means of affecting local bacterial infections. However, the use of phototherapy to prevent fungal biofilm development has received comparatively less attention. This study aimed to determine the effects of red light treatment and blue light treatment, without a photosensitizer, on the development of Candida albicans biofilm. During the development of 48-h biofilms of C. albicans SN 425 (n = 10), the biofilms were exposed twice-daily to noncoherent blue and red light (LumaCare; 420 nm and 635 nm). The energy density applied was 72 J cm-2 for blue light and 43.8 J cm2, 87.6 J cm2, and 175.5 J cm2 for red light. Positive control (PC) and negative control (NC) groups were treated twice-daily for 1 min with 0.12% chlorhexidine (CHX) and 0.89% NaCl respectively. Biofilms were analyzed for colony forming units (CFU), dry-weight, and exopolysaccharides (EPS-soluble and EPS-insoluble). Data was analyzed by one-way ANOVA and Tukey post hoc test (α = 0.05). Dry-weight was lower than NC (p < 0.001) and approached PC levels with both red and blue light treatments. CFU were also lower in groups exposed to blue light and higher durations of red light (p < 0.05). EPS-soluble and EPS-insoluble measures were variably reduced by these light exposures. In conclusion, twice-daily exposure to both blue and red lights affect the biofilm development and physiology of polysaccharide production and are potential mechanisms for the control of C. albicans biofilm matrix development.

Migraine-provoking substances evoke periorbital allodynia in mice.

BACKGROUND: Administration of endogenous mediators or exogenous chemicals in migraine patients provoke early headaches and delayed migraine-like attacks. Although migraine provoking substances are normally vasodilators, dilation of arterial vessels does not seem to be the sole contributing factor, and the underlying mechanisms of the delayed migraine pain are mostly unknown. Sustained mechanical allodynia is a common response associated with the local administration of various proalgesic substances in experimental animals and humans. Here, we investigated the ability of a series of endogenous mediators which provoke or do not provoke migraine in patients, to cause or not cause mechanical allodynia upon their injection in the mouse periorbital area. METHODS: Mechanical allodynia was assessed with the von Frey filament assay. Stimuli were given by subcutaneous injection in the periorbital area of C57BL/6J mice; antagonists were administered by local and systemic injections. RESULTS: Calcitonin gene related peptide (CGRP), but not adrenomedullin and amylin, pituitary adenylyl cyclase activating peptide (PACAP), but not vasoactive intestinal polypeptide (VIP), histamine, prostaglandin E2 (PGE2) and prostacyclin (PGI2), but not PGF2α, evoked a dose-dependent periorbital mechanical allodynia. The painful responses were attenuated by systemic or local (periorbital) administration of antagonists for CGRP (CLR/RAMP1), PACAP (PAC-1), histamine H1, PGE2 (EP4), and PGI2 (IP) receptors, respectively. CONCLUSIONS: The correspondence between substances that provoke (CGRP; PACAP, histamine, PGE2, PGI2), or do not provoke (VIP and PGF2α), migraine-like attacks in patients and periorbital allodynia in mice suggests that the study of allodynia in mice may provide information on the proalgesic mechanisms of migraine-provoking agents in humans. Results underline the ability of migraine-provoking substances to initiate mechanical allodynia by acting on peripheral terminals of trigeminal afferents.

Caries outcome following an intensive fluoride varnish treatment regimen for children at high risk for early childhood caries.

PURPOSE: To evaluate the caries relapse rate for a cohort of 2- to 4-year-old children at high risk of early childhood caries when treated with an intensive fluoride varnish (FV) regimen. METHODS: Eighty paediatric patients were recruited. Forty of these patients were high risk and received the FV treatment (three applications within 2 weeks and additional applications at 1 and 3 months) during 2009-2010. Mutans streptococci (MS) levels in the saliva were evaluated during the treatment period. A comparative group of 40 children, selected from an electronic record search at the New York University College of Dentistry to be of similar age, gender, and ethnicity, but not at elevated risk for ECC, received the standard of care (semi-annual FV treatment). Detailed caries examination and treatment records were obtained for all patients from 2009 to 2014. RESULTS: A significant reduction (P < 0.001) in MS levels was observed in the intensive FV treatment group at the 3-month visit compared with baseline. There was no effect of the intensive FV treatment on caries outcome in the anterior teeth, and the overall caries scores were significantly increased on the posterior teeth. CONCLUSION: The intensive FV regimen appears insufficient to prevent caries relapse in children at high risk for caries.

Early Healing Evaluation of Commercially Pure Titanium and Ti-6Al-4V Presenting Similar Surface Texture: An In Vivo Study.

OBJECTIVE: This study evaluated the osseointegration of commercially pure titanium (Ti) grade-2 (G2) and Ti-6Al-4V alloy (G5) implants with the same geometry and surface treatment. MATERIALS AND METHODS: Thirty-six dental implants with a grit-blasted acid-etched surface were used (n = 18, each). Two implants, one per group, were installed in each subject, in the radius diaphysis (n = 18 beagle dogs), with interchanged fixture position (proximal-distal) between animals for a balanced number of devices per group and time in vivo (1, 3, and 6 weeks). RESULTS: Similar topographical parameters between G2 and G5 were observed for average surface roughness, root mean square, developed surface ratio, maximum height of surface, and density of summits. Removal torque was significantly higher for G5 than for G2. No differences were observed for bone-to-implant contact and bone-area-fraction occupancy. Removal torque significantly increased with time for both groups. At 1 week, new bone formation in direct contact with the implant surface and osteogenic tissue migration was observed with an increase in woven bone formation at 3 weeks followed by the onset of lamellar bone formation at 6 weeks. CONCLUSION: Although both surfaces were biocompatible and osteoconductive, increased removal torque was observed for Ti-6Al-4V compared with commercially pure Ti implants.

Microcomputed Tomography Evaluation of Volumetric Shrinkage of Bulk-Fill Composites in Class II Cavities.

PURPOSE: This study aimed to quantify polymerization shrinkage of one conventional and three bulk-fill composites, under bonded and unbonded conditions, in Class II preparations using 3D microcomputed tomography (µCT) and report its location. MATERIALS AND METHODS: Preparations (2.5 mm occlusal depth × 4 mm wide × 4 mm mesial box and 1 mm beyond the CEJ distal box depth) were made in 48 human extracted molars (n = 6). Four composites were tested, one regular (Vitalescence/VIT) and three bulk-fill: SureFil SDR Flow (SDR), Tetric EvoCeram Bulk Fill (TET), and Filtek flowable Bulk Fill (FIL). Teeth were divided into four groups according to restorative material used and subdivided into two subgroups, according to the presence of an adhesive system (XP Bond) application (bonded [-B]) or its absence (unbonded [-U]). Each tooth was scanned three times: (1) after cavity preparation, (2) before and (3) after composite light-curing. Acquired µCT images were imported into 2D and 3D software for analysis. RESULTS: Significantly different volumetric shrinkage between bonded and unbonded conditions was observed only for TET group (p < 0.05), unbonded presenting significantly higher volumetric shrinkage. Among the bonded groups, TET-B presented significantly lower shrinkage than both SDR-B and FIL-B but not significantly different from VIT-B. Generally, shrinkage occurred at occlusal and distal surfaces. CONCLUSIONS: When applied to bonded Class II cavities, TET exhibited significantly lower volumetric shrinkage compared to the other bulk-fill composites. However, it also exhibited the highest difference of volumetric shrinkage values between unbonded and bonded cavities. CLINICAL SIGNIFICANCE: Volumetric polymerization shrinkage occurred with all composites tested, regardless of material type (conventional or bulk-fill) or presence or absence of bonding. However, volumetric shrinkage has been reduced or at least maintained when bulk-fill composites were used compared to a conventional composite resin, which makes them a potential time saving alternative for clinicians. (J Esthet Restor Dent 29:118-127, 2017).

A survey to determine agreement regarding the definition of centric relation.

STATEMENT OF PROBLEM: The definition of centric relation (CR) has been both controversial and divisive, with little consensus. PURPOSE: The purpose of this study was to determine whether agreement can be reached on a definition for CR among the Fellows of the Academy of Prosthodontics, the organization that writes the Glossary of Prosthodontic Terms. MATERIAL AND METHODS: A survey of the Fellows of the Academy of Prosthodontics was conducted at the organization's annual business meeting. RESULTS: Of the 83 eligible Fellows in attendance, 72 responded to the survey, a response rate of 86%. Of those, the 5 responders who did not indicate a preferred definition and the 2 that chose 2 definitions were censored, yielding an analyzable sample of 65 for the definitions. The most common definition received 19 votes, the next 16, and the third 13, with the other 6 definitions receiving from 2 to 5 votes. Some of the variability in definition depended on the era of training. CONCLUSIONS: Disagreement and confusion continues regarding the definition of centric relation. Some of this disagreement can be explained by training era.

Histomorphological and Histomorphometric Analyses of Grade IV Commercially Pure Titanium and Grade V Ti-6Al-4V Titanium Alloy Implant Substrates: An In Vivo Study in Dogs.

PURPOSE: To evaluate the bone response to grade IV commercially pure titanium (G4) relative to Ti-6Al-4V (G5). MATERIALS AND METHODS: Implant surface topography was characterized by optical interferometry and scanning electron microscopy (SEM). Thirty-six implants (Signo Vinces, n = 18 per group) were installed in the radius of 18 dogs. The animals were killed at 1, 3, and 6 weeks, resulting in 6 implants per group and time in vivo for bone morphology, bone-to-implant contact (BIC), and bone area fraction occupancy (BAFO) evaluation. RESULTS: SEM depicted a more uniform topography of G4 than G5. Surfaces were statistically homogeneous for Sa, Sq, and Sdr. At 1 week, new bone formation was observed within the healing connective tissue in contact with the implant surface. At 3 weeks, new bone in direct contact with the implant surface was observed at all bone regions. At 6 weeks, the healing chambers filled with woven bone depicted an onset of replacement by lamellar bone. No significant effect of substrate was detected. Time presented an effect on BIC and BAFO (P < 0.001). CONCLUSION: Both titanium substrates were biocompatible and osseoconductive at the bone tissue level.

Markers of endothelial dysfunction and inflammation predict progression of diabetic nephropathy in African Americans with type 1 diabetes.

African Americans with early-onset type 1 diabetes mellitus are at a high risk for severe diabetic nephropathy and end-stage renal disease. In order to determine whether baseline plasma levels of inflammatory markers predict incidence of overt proteinuria or renal failure in African Americans with type 1 diabetes mellitus, we re-examined data of 356 participants in our observational follow-up study of 725 New Jersey African Americans with type 1 diabetes. At baseline and 6-year follow-up, a detailed structured clinical interview was conducted to document medical history including kidney dialysis or transplant, other diabetic complications, and renal-specific mortality. Plasma levels of 28 inflammatory biomarkers were measured using a multiplex bead analysis system. After adjusting for baseline age, glycohemoglobin, and other confounders, the baseline plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) in the upper two quartiles were, respectively, associated with a three- to fivefold increase in the risk of progression from no albuminuria or microalbuminuria to overt proteinuria. Baseline plasma levels of the chemokine eotaxin in the upper quartile were significantly associated with a sevenfold increase in risk of incident renal failure. These associations were independent of traditional risk factors for progression of diabetic nephropathy. Thus, in type 1 diabetic African Americans, sICAM-1 predicted progression to overt proteinuria and eotaxin-predicted progression to renal failure.

Are insertion torque and early osseointegration proportional? A histologic evaluation.

OBJECTIVES: The objective of this histologic study was to determine the effect of three drilling protocols (oversized, intermediate, and undersized) on biologic responses to a single implant type at early healing periods (2 weeks in vivo) in a beagle dog model. MATERIALS AND METHODS: Ten beagle dogs were acquired and subjected to surgeries in the tibia 2 weeks before euthanasia. During surgery, each dog received three Unitite implants, 4 mm in diameter by 10 mm in length, in bone sites drilled to 3.5, 3.75, and 4.0 mm in final diameter. The insertion torque was recorded during surgery, and bone-to-implant contact (BIC), and bone area fraction occupied (BAFO) measured from the histology. Each outcome measure was compared between treatment conditions with the Wilcoxon signed-rank test. Bonferroni-corrected statistical significance was set to 95%. RESULTS: Insertion torque increased as an inverse function of drilling diameter, as indicated by significant differences in torque levels between each pair of conditions (P = 0.005). BIC and BAFO levels were highest and statistically similar in the recommended and undersized conditions and significantly reduced in the oversized condition (P < 0.01). CONCLUSIONS: Reduced drilling dimensions resulted in increased insertion torque (primary stability). While BIC and BAFO were maximized when drilling the recommended diameter hole, only the oversized hole resulted in evidence of statistically reduced integration.

Bone regenerative potential of modified biphasic graft materials.

PURPOSE: To investigate the bone regenerative effect of polymer and collagen incorporation to synthetic bone graft materials. MATERIALS AND METHODS: The bone ingrowth of biphasic graft materials was tested in a rabbit calvaria defect model after chemical characterization: HA/TCP (25%/75%) with collagen, HA/TCP (25%/75%) without collagen, (HA/TCP)/PLGA (85%/15%) with collagen, (HA/TCP)/PLGA (65%/35%) with collagen and a commercially available (HA/TCP)/PLGA (50%/50%) (ReOss™, Intra-Lock International, Boca Raton, FL) was used as control. After 4 and 8 weeks, the retrieved samples were subjected to histomorphometrical analysis. RESULTS: Histomorphometry presented no significant differences concerning the bone formation between the different groups at both 4 and 8 weeks. Evidently, the (HA/TCP)/PLGA (65%/35%) with collagen presented the least amount of soft tissue incorporation within the defect. The same group possessed higher amounts of bone graft material within the defect throughout the 8-week observation period, whereas the other groups seemed to decrease in volume from 4 to 8 weeks. CONCLUSION: Changing the PLGA percentage to 35% within the biphasic graft material seemed to maintain its volume and prevented soft tissue migration, which could be clinically beneficial.

Surface characterization and in vivo evaluation of dual Acid-etched and grit-blasted/acid-etched implants in sheep.

PURPOSE: Dual acid-etching is widely used to modify dental implant topography and enhance early bone healing. This study evaluated the histomorphometric, biomechanical, and histological bone response to acid-etched (AA) in comparison with grit-blasted/acid-etched (GB) and machined control (C) implants within sites of relatively low-bone remodeling rates. MATERIALS AND METHODS: Implant surface topography was evaluated by scanning electron microscopy and optical interferometry (IFM). Six adult male sheep (n = 6) received 72 Ti-6Al-4V implants (n = 24 per surface) in both ilium (n = 12 per bone bilaterally). The implants remained for 3 and 6 weeks in vivo. The histomorphometric parameters bone-implant contact (BIC) and bone area fraction occupancy (BAFO) were evaluated. Biomechanical analysis consisted of torque-to-interface failure. RESULTS: IFM analysis showed the highest average surface roughness for GB and the highest density of summits and developed surface area percentage (P < 0.01) for AA. No difference was observed in BAFO for all groups in 3 and 6 weeks. Increased BIC and torque resistance were observed for AA implants at both time points after implantation. CONCLUSIONS: Overall, improved bone-to-implant response was observed for the AA implant surface.

The effect of different surgical drilling procedures on full laser-etched microgrooves surface-treated implants: an experimental study in sheep.

OBJECTIVES: To evaluate the influence of instrumentation technique on the early osseointegration histomorphometrics and biomechanical fixation of fully laser-etched microgrooves implant surfaces in a sheep model. MATERIAL AND METHODS: Six sheep were subjected to bilateral hip surgeries 3 and 6 weeks before euthanasia. A total of 48 implants (∅4.5 mm, 8 mm in length) were distributed among four sites (8 per animal) and placed in bone sites drilled to 4.6 mm (reamer), 4.1 mm (loose), 3.7 mm (medium) and 3.2 mm (tight) in diameter. After healing, the animals were euthanized and half of the implants were biomechanically tested, while the remainder was subjected to non-decalcified histologic processing. The histomorphometric parameters assessed were bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). Statistical analysis was performed using a mixed-model analysis of variance with significance level set at P < 0.05. RESULTS: A general increasing trend is present from 3 to 6 weeks for most of the variables. The groups prepared to be press fit seemed to present higher values, which were maintained throughout the observation period. The reamer group presented the lowest BIC probably due to the drilling technique; however qualitatively, more new bone seemed to be in contact to the implant surface, at 3 weeks, whereas the implants placed in press-fit situations were mainly supported by cortical bone. CONCLUSION: The laser-etched microgrooved implant presented osteoconductive and biocompatible properties for all surgical procedures tested. However, procedures providing increasingly higher press-fit scenarios presented the strongest histomorphometric and biomechanical responses at 3 and 6 weeks.