Bacillus Calmette-Guérin vaccination as defense against SARS-CoV-2 (BADAS): a randomized controlled trial to protect healthcare workers in the USA by enhanced trained immune responses.

BACKGROUND: A large epidemic, such as that observed with SARS-CoV-2, seriously challenges available hospital capacity, and this would be augmented by infection of healthcare workers (HCW). Bacillus Calmette-Guérin (BCG) is a vaccine against tuberculosis, with protective non-specific effects against other respiratory tract infections in vitro and in vivo. Preliminary analyses suggest that regions of the world with existing BCG vaccination programs have lower incidence and mortality from COVID-19. We hypothesize that BCG vaccination can reduce SARS-CoV-2 infection and disease severity. METHODS: This will be a placebo-controlled adaptive multi-center randomized controlled trial. A total of 1800 individuals considered to be at high risk, including those with comorbidities (hypertension, diabetes, obesity, reactive airway disease, smokers), racial and ethnic minorities, elderly, teachers, police, restaurant wait-staff, delivery personnel, health care workers who are defined as personnel working in a healthcare setting, at a hospital, medical center or clinic (veterinary, dental, ophthalmology), and first responders (paramedics, firefighters, or law enforcement), will be randomly assigned to two treatment groups. The treatment groups will receive intradermal administration of BCG vaccine or placebo (saline) with groups at a 1:1 ratio. Individuals will be tracked for evidence of SARS-CoV-2 infection and severity as well as obtaining whole blood to track immunological markers, and a sub-study will include cognitive function and brain imaging. The majority of individuals will be followed for 6 months, with an option to extend for another 6 months, and the cognitive sub-study duration is 2 years. We will plot Kaplan-Meier curves that will be plotted comparing groups and hazard ratios and p-values reported using Cox proportional hazard models. DISCUSSION: It is expected this trial will allow evaluation of the effects of BCG vaccination at a population level in high-risk healthcare individuals through a mitigated clinical course of SARS-CoV-2 infection and inform policy making during the ongoing epidemic. TRIAL REGISTRATION: ClinicalTrials.gov NCT04348370. Registered on April 16, 2020.

Oral health assessment of independent elders in Texas.

BACKGROUND: The oral health status of older adults in North Texas is largely unknown. METHODS: This cross-sectional, pilot study used the Basic Screening Survey for older adults involving a self-administered questionnaire and oral screening examination of 155 adults aged 65 years and older, in four Dallas, TX settings, stratified socioeconomically. Recruitment occurred from July 2012 through March 2014. RESULTS: Participants were between 65 and 90 years of age. The sample was predominantly female (64%), reflecting Texas population diversity with 49.7% White, 34.2% Hispanic, 14.2% Black, and 1.8% others. Missing teeth number (P < .019), functional contacts, untreated decay, root decay (P < .05), tooth mobility, root fragments and need for emergency treatment (P < .021) differed significantly regarding site and ethnicity. Participants at the least affluent sites (two) evidenced significant unmet dental needs and suboptimal access to care. In contrast, those at the most affluent sites (also oldest participants) had good oral health and access to care. CONCLUSIONS: There are profound oral health disparities in urban North Texas based on socioeconomic status. These findings suggest that poor oral health is not inevitable in the elderly, as long as there is access to care. Larger-scale studies are required to broadly address oral health disparities among elderly Texans.

Localizing the osseous boundaries of micro-osteoperforations.

INTRODUCTION: The aim of this work was to determine how far the effects of micro-osteoperforations (MOPs) extend within bone by quantifying the damage caused and the short-term bony adaptations that occur in and around the injury site. METHODS: With the use of a split-mouth design, 34 MOPs (Propel) were randomly placed in the mandibular furcal bone of 13 beagle dogs either 2 or 4 weeks before killing them. The control side received no treatment. Vickers hardness microindentation, microscopic computed tomography, and histologic analyses were performed to evaluate the bone surrounding the MOPs. RESULTS: Microfractures produced during insertion extended ∼0.6 mm from the MOP sites. Cortical and trabecular bone were significantly less dense on the experimental than on the control side up to 4.2 mm from the edge of the MOP, but side differences were small (<5%) beyond 1.5 mm from the MOP. Experimental cortical bone was significantly softer than the control bone up to 0.8 mm from the MOP after 2 weeks of healing, and up to 0.5 mm from the MOP after 4 weeks of healing. Hematoxylin and eosin stained sections of cortical and trabecular bone showed small areas of woven bone within the MOP sites after 2 weeks, and acellular areas of bone extending ∼0.5 mm from the MOP. After 4 weeks of healing, there were greater amounts of woven bone, as well as early signs of lamellar bone, in and around the MOP sites. Markedly increased TRAP activity extending up to 2.5 mm from the MOP was evident after 2 weeks, but not after 4 weeks. Vital fluorescence staining showed diffuse bone deposition on the experimental side up to 1.5 mm from the MOP margin. CONCLUSIONS: When MOPs are performed in beagle dogs, demineralization is transient and healing of the injured area, as well as remineralization of bone affected by MOP placement, begins during the first 2 weeks. Although the transient effects extend farther, the principal effects extend only ∼1.5 mm from the MOP site.

Effects of micro-osteoperforations on tooth movement and bone in the beagle maxilla.

PURPOSE: The purpose of this study was to determine how micro-osteoperforations (MOPs) affect tooth movements, bone turnover, bone density, and bone volume. METHODS: A split-mouth experimental design with 7 beagle dogs was used to evaluate bone surrounding maxillary second premolars that had been retracted for 7 weeks. One month after the maxillary third premolars were extracted, 8 MOPs (1.5 mm wide and 7 mm deep) were created without flaps with the use of the Propel device (6 were placed 3 mm distal to the second premolar and 2 were placed in the premolar furcation) on one randomly chosen side. The maxillary second premolars were retracted bilaterally with the use of 200 g nickel-titanium closed coil springs. Tooth movements were measured intraorally and radiographically. Microscopic computed tomography was used to evaluate the material density and volume fraction of bone distal to the premolars. Hematoxylin and eosin-stained and fluorescent sections were used to examine the bone remodeling. RESULTS: Neither the intraoral (P = 0.866) nor radiographic (P = 0.528) measures showed statistically significant side differences in tooth movements. There also were no statistically significant differences in the density (P = 0.237) or volume fraction (P = 0.398) of bone through which the premolars were being moved. Fluorescent and histologic evaluations showed no apparent differences in osteoblasts, osteoclasts, or mineralization of bone near the teeth being moved. Bone healing was evident in and near the MOP sites, which had nearly but not completely healed after 7 weeks. Regions of acellular bone were evident extending ∼0.8 mm from the MOP sites. CONCLUSIONS: MOPs placed 3 mm away from teeth do not increase tooth movements and have limited and transitory effect on bone.

Histology of NeoMTA Plus and Quick-Set2 in Contact with Pulp and Periradicular Tissues in a Canine Model.

INTRODUCTION: NeoMTA Plus (Avalon Biomed Inc, Bradenton, FL) is a tricalcium silicate material similar to the first mineral trioxide aggregate product, ProRoot MTA (Dentsply Sirona, York, PA), but with improvements such as decreased setting time, increased ion release, increased water sorption, and nonstaining radiopacifiers. Quick-Set2 (Avalon Biomed Inc) is a newly formulated calcium aluminosilicate material that has a faster setting time and increased acid resistance and is nonstaining. The purpose of this study was to compare the healing of pulpal and periapical tissues in dogs after exposure to NeoMTA Plus and Quick-Set2 after pulpotomy and root-end surgery procedures. METHODS: Seventy-two teeth (36 for each procedure) in 6 beagle dogs received pulpotomy or root-end surgery using either NeoMTA Plus or Quick-Set2. The dogs were sacrificed at 90 days, and the teeth and surrounding tissues were prepared for histologic evaluation. Sixty teeth were evaluated and scored histologically (29 with pulpotomies and 31 with root-end resections). Specimens were scored for inflammation, quality and thickness of dentin bridging, pulp tissue response, cementum and periodontal ligament formation, and apical bone healing. RESULTS: Both materials displayed favorable healing at 90 days. The only significant difference was the quality of dentin bridge formation in pulpotomies using NeoMTA Plus compared with Quick-Set2. CONCLUSIONS: Quick-Set2 and NeoMTA Plus had similar effects on inflammation, pulp response, periodontal ligament and cementum formation, and apical tissue healing in dogs. NeoMTA Plus had superior dentin bridge quality compared with Quick-Set2.

Bioactive endodontic materials for everyday use: a review.

Bioceramic materials are at the forefront of modern dentistry. Bioactive bioceramic endodontic materials promote pulpal and periapical tissue healing and are easy to use. Dentists can choose among many endodontic materials, depending on their needs. This article highlights the major differences among commercially available bioactive tricalcium silicate bioceramics, commonly known as mineral trioxide aggregate materials, to enable dentists to make appropriate decisions in the selection of these materials.

Preclinical Evaluation of a Crown-Splinted Custom Root-Shaped Implant.

OBJECTIVE: To test whether a Maryland bridge-type splint provides adequate stability for a custom root-shaped implant to osseointegrate in a manner substantially equivalent to that of a threaded implant. METHODS: Six beagle dogs were subjected to intraoral impressions and cone beam scans that were used to fabricate custom root-shaped implants (RTIs) and crowns. Premolars in the mandible (P4) and in the maxilla (P3) were extracted, and 24 RTIs were immediately placed in extraction sockets. Splint extensions of the crowns were bonded to mesial and distal teeth. Twelve mandibular molars (M2) were extracted, and threaded implants (DXI), serving as controls, were placed immediately. Animals were placed on a soft diet after surgery. Weekly intraoral photographs and radiographs were taken, and animals were sacrificed at 4 months. Fluorescent labels were injected 35, 21, and 7 days before sacrifice. Clinical implant stability and vertical pullout forces were tested, and loss of vertical bone height was measured on radiographs. Histomorphometric measurements of percent bone-to-implant contact (BIC) and mineral apposition rates were made from undecalcified sections. RESULTS: Three RTI splints broke or debonded, and the implants were removed. No loss of DXI implants was noted. All remaining implants were clinically stable. Mean pullout forces were 366.7 ± 182.8 N for RTI (no pullout data for the threaded DXI). Mean vertical bone loss was 0.4 ± 0.6 mm mesially and 0.2 ± 0.7 mm distally for RTI and 0.8 ± 1.1 mm mesially and 0.8 ± 1.0 mm distally for DXI, with no significant differences between groups. BIC values were 70.8% ± 12.7% for mandibular RTI, 68.3% ± 11.6% for maxillary RTI, and 78.8% ± 5.5% for DXI. Mineral apposition rates within local osteons were 1.9 ± 0.5 µm for RTI and 1.7 ± 0.3 µm for DXI; at the implant surface, they were 2.5 ± 1.2 µm for RTI and 3.3 ± 1.8 µm for DXI, with no significant differences between groups. CONCLUSION: All RTIs with intact splints exhibited clinically successful integration, similar to that of control threaded implants. The RTI may be a viable option for single-tooth replacement.

Elastic Properties of Chimpanzee Craniofacial Cortical Bone.

Relatively few assessments of cranial biomechanics formally take into account variation in the material properties of cranial cortical bone. Our aim was to characterize the elastic properties of chimpanzee craniofacial cortical bone and compare these to the elastic properties of dentate human craniofacial cortical bone. From seven cranial regions, 27 cylindrical samples were harvested from each of five chimpanzee crania. Assuming orthotropy, axes of maximum stiffness in the plane of the cortical plate were derived using modified equations of Hooke's law in a Mathcad program. Consistent orientations among individuals were observed in the zygomatic arch and alveolus. The density of cortical bone showed significant regional variation (P < 0.001). The elastic moduli demonstrated significant differences between sites, and a distinct pattern where E3 > E2 > E1 . Shear moduli were significantly different among regions (P < 0.001). The pattern by which chimpanzee cranial cortical bone varies in elastic properties resembled that seen in humans, perhaps suggesting that the elastic properties of craniofacial bone in fossil hominins can be estimated with at least some degree of confidence. Anat Rec, 299:1718-1733, 2016. © 2016 Wiley Periodicals, Inc.

Internal Bone Architecture in the Zygoma of Human and Pan.

The internal and external anatomy of the primate zygoma is central to orofacial function, health, and disease. The importance of variation in its gross morphology across extinct and extant primate forms has been established using finite element analysis, but its internal structure has yet to be explored. In this study, µCT is used to characterize trabecular bone morphometry in two separate regions of the zygoma of humans and Pan. Trabecular anisotropy and orientation are compared with strain orientations observed in trabecular regions of finite element models of four Pan crania. The results of this study show that trabecular bone morphometry, anisotropy, and orientation are highly compatible with strain orientation and magnitude in the finite element models. Trabecular bone in the zygoma is largely orthotropic (with bone orientation differing in three mutually orthogonal directions), with its primary orientation lying in the mediolateral direction. Trabecular bone in the zygomatic region appears to be highly influenced by the local strain environment, and thus may be closely linked to orofacial function. Anat Rec, 299:1704-1717, 2016. © 2016 Wiley Periodicals, Inc.

Miniscrew-assisted slow expansion of mature rabbit sutures.

INTRODUCTION: In this study, we experimentally evaluated whether complex, mature sutures can be separated using skeletal anchorage and light, continuous forces. METHODS: Twelve adult, 8- to 9-month-old female New Zealand white rabbits were randomly assigned to 1 control group and 2 experimental groups. Open-coil nickel-titanium springs delivered constant forces of 100 g across the sagittal suture to miniscrew implants placed bilaterally in the frontal bone. Sutural separation was measured biweekly. Separation was also measured with microcomputed tomography. Bone formation (mineral apposition) was measured with fluorescent labels. Qualitative histologic analyses of the suture tissues were performed using hematoxylin and eosin staining; osteoclasts were evaluated with tartrate resistant acid phosphatase staining. RESULTS: All 24 miniscrew implants remained stable throughout the experiment. There was no statistically significant sutural separation in the control group. In the experimental groups, sutural separation was significant (P <0.05) at all time points after the initial records were taken. The rate of separation was linear during the first 42 days. There were moderate correlations (R = 0.59-0.89; P <0.05) between miniscrew implant separation and bone marker separation. Mineral apposition rate, which was not measureable in the control group, was significant in the experimental group. The mineral apposition rate was greater between 14 and 28 days than between 28 and 38 days, and it was greater on the ectocranial than on the endocranial surface. Based on the microcomputed tomography analysis, 3-dimensional sutural volume of the experimental group increased significantly (P = 0.02), but surface area did not (P = 0.26). CONCLUSIONS: It is possible to separate the sagittal suture of mature rabbits. Sutural separation is limited, indicating involvement of other articulations.

Dentinal Tubule Penetration of Tricalcium Silicate Sealers.

INTRODUCTION: The treatments for which mineral trioxide aggregate (MTA)-based materials can be used in dentistry are expanding. Smaller particle size and easier handling properties have allowed the advent of tricalcium silicate sealers including EndoSequence BC Sealer (Brasseler USA, Savannah, GA), QuickSet2 (Avalon Biomed, Bradenton, FL), NeoMTA Plus (Avalon Biomed), and MTA Fillapex (Angelus, Londrina, Brazil). The objective of this study was to measure the tubule penetration with these sealers using continuous wave (CW) and single-cone (SC) obturation techniques. METHODS: Eighty single-rooted teeth were randomly divided into 8 groups of 10 and obturated with 1 of the previously mentioned sealers mixed with trace amounts of rhodamine using either the CW or SC technique. Teeth were sectioned at 1 mm and 5 mm from the apex and examined under a confocal laser microscope. The percentage of sealer penetration and the maximum sealer penetration were measured. RESULTS: The tricalcium silicate sealers penetrated tubules as deep as 2000 µm (2 mm). The percentage of sealer penetration was much higher 5 mm from the apex, with many specimens having 100% penetration for both SC and warm vertical techniques. MTA Fillapex, a resin-based sealer with less than 20% MTA particles, had significantly greater tubule penetration with a warm vertical technique versus the SC technique at the 1-mm level. CONCLUSIONS: Within the limitations of this study, the CW and SC techniques produced similar tubule penetration at both the 1-mm and the 5-mm level with the tricalcium silicate sealers BC Sealer, QuickSet2, and NeoMTA Plus.

Family with sequence similarity member 20C is the primary but not the only kinase for the small-integrin-binding ligand N-linked glycoproteins in bone.

Recent studies have identified family with sequence similarity member 20C (FAM20C) as a kinase that phosphorylates the Ser in Ser-X-Glu/phospho-Ser (pSer) motifs in the small-integrin-binding ligand N-linked glycoproteins (SIBLINGs). There is no in vivo evidence that validates this finding, and it is unclear whether FAM20C is the only kinase for SIBLINGs. We extracted bone noncollagenous proteins (NCPs) from Fam20C-knockout (KO) mice and analyzed the phosphorylation levels. The total NCPs were separated into osteopontin-, bone sialoprotein-, and dentin matrix protein-1-enriched fractions by anion-exchange chromatography and analyzed by SDS-PAGE, native PAGE, and Western immunoblot analysis. The NCP phosphorylation level in the KO mice was lower than that in the wild-type (WT). On the native gel, the SIBLINGs from KO mice showed a lower migration rate (Mr) than those from the WT. Calf intestine phosphatase treatment shifted SIBLINGs from the WT mice to the level adjacent to the KO, but failed to shift the latter, suggesting a phosphorylation loss of SIBLINGs in the KO mice. Mass spectrometry identified less pSers in the SIBLINGs from the KO mice [including the region of the acidic Ser- and aspartate-rich motif (ASARM) peptides]. In an intriguing finding, several pSers in the Ser-X-Glu motifs in the KO mice maintained their phosphorylation, whereas several others in non-Ser-X-Glu motifs did not. Phospho-Tyrs and phospho-Thrs in the SIBLINGs did not appear to be associated with FAM20C. Our results indicate that FAM20C is the primary, but not the only, kinase for the SIBLINGs.-Yang, X., Yan, W., Tian, Y., Ma, P., Opperman, L. A., Wang, X. Family with sequence similarity member 20C is the primary but not the only kinase for the small-integrin-binding ligand N-linked glycoproteins in bone.

Histologic Assessment of Quick-Set and Mineral Trioxide Aggregate Pulpotomies in a Canine Model.

INTRODUCTION: Quick-Set (Primus Consulting, Bradenton, FL) is a calcium aluminosilicate cement that is a potential alternative to mineral trioxide aggregate (MTA) with greater acid resistance and faster setting. The purpose of this study was to compare the effects of Quick-Set and MTA on pulpal tissues in response to pulpotomy procedures. METHODS: The pulp chambers of 42 maxillary teeth in 7 beagle dogs were accessed, and the coronal pulpal tissue was removed. Pulpotomy procedures were performed, placing the experimental materials directly over the radicular pulp tissues. The dogs were sacrificed at 70 days, and the teeth and surrounding tissues were removed and prepared for histologic analysis. The sections of the pulpotomy areas were scored for inflammation, pulp tissue organization, reactionary dentin formation, and quality of dentinogenesis. RESULTS: The Quick-Set group exhibited significantly more pulpal inflammation (P = .002) and significantly less pulp tissue organization (P = .004). No significant difference was noted for reactionary dentin formation (P = .526) and quality of dentinogenesis (P = .436). CONCLUSIONS: Compared with ProRoot White MTA (Dentsply Tulsa Dental Specialties, Tulsa, OK), Quick-Set exhibited more pulpal inflammation and decreased pulp tissue organization. No significant differences were noted for reactionary dentin formation and quality of dentinogenesis.

Dentate transport discs can be used to reconstruct large segmental mandibular defects.

PURPOSE: This study tested the use of a dentate transport segment for the reconstruction of a large U-shaped defect in the anterior segment of the canine mandible using a novel curved reconstruction plate. The quality and quantity of bone regenerate formed by dentate versus edentulous transport segments were compared. MATERIALS AND METHODS: In 5 adult foxhound dogs, a defect of 70 to 75 mm was created in the canine mandible by excising the mandible anterior to the right and left fourth premolars. Reconstruction was performed by trifocal distraction osteogenesis using a bone transport reconstruction plate (BTRP-02), with 2 transport units being activated simultaneously, one on either side of the defect, 1 dentate and 1 edentulous. Bilateral distraction proceeded at a rate of 1 mm/day until the segments docked against each other in the midline. After 39 to 44 days of consolidation, the animals were euthanized. The quantity and quality of bone regeneration on the 2 sides were compared using micro-computed tomography. RESULTS: The defect reconstruction was successful. The amount and quality of bone formed by the transport segments were similar on the 2 sides. There were no major differences in the bone volume fraction and density of the regenerate bone formed by the 2 transport segments. The bone volume fraction and density of the regenerate bone were considerably lower than those of the host bone in the distal segments, likely owing to the short consolidation period. CONCLUSIONS: Bone transport remains a viable option in reconstructing anterior segmental defects in the mandible. The use of dentate or edentulous transport segments for reconstruction provides options for the surgeon in often highly compromised patients requiring these surgeries.

Comparison of Quick-Set and mineral trioxide aggregate root-end fillings for the regeneration of apical tissues in dogs.

INTRODUCTION: Quick-Set (Avalon Biomed Inc, Bradenton, FL) is a calcium aluminosilicate cement that is a potential alternative to mineral trioxide aggregate (MTA) with greater acid resistance and faster setting. The purpose of this study was to compare the regeneration of apical tissues after root-end surgery when the apical tissues were exposed to Quick-Set or White ProRoot MTA (Dentsply Tulsa Dental Specialties, Tulsa, OK) by root-end resection. METHODS: The root canals of 42 mandibular premolars in 7 beagle dogs were accessed, cleaned and shaped, and obturated with Quick-Set or white MTA. Osteotomies and root-end resections were performed immediately. The dogs were sacrificed at 90 days, and the teeth and surrounding tissues were removed and prepared for histologic analysis. The sections of the apical areas were scored for inflammation, new cementum formation, periodontal ligament formation, and bone quality. RESULTS: At 90 days, both materials supported some degree of cementum formation on the surface of the material, periodontal ligament regeneration, and excellent bone quality. The only significant difference was greater inflammation found in the Quick-Set group. CONCLUSIONS: Quick-Set and White ProRoot MTA had a similar effect on bone quality, cementum formation, and periodontal ligament formation after root-end surgery in dogs. Quick-Set was associated with greater inflammation.

Biomechanics of the canine mandible during bone transport distraction osteogenesis.

This study compared biomechanical patterns between finite element models (FEMs) and a fresh dog mandible tested under molar and incisal physiological loads in order to clarify the effect of the bone transport distraction osteogenesis (BTDO) surgical process. Three FEMs of dog mandibles were built in order to evaluate the effects of BTDO. The first model evaluated the mandibular response under two physiological loads resembling bite processes. In the second model, a 5.0 cm bone defect was bridged with a bone transport reconstruction plate (BTRP). In the third model, new regenerated bony tissue was incorporated within the defect to mimic the surgical process without the presence of the device. Complementarily, a mandible of a male American foxhound dog was mechanically tested in the laboratory both in the presence and absence of a BTRP, and mechanical responses were measured by attaching rosettes to the bone surface of the mandible to validate the FEM predictions. The relationship between real and predicted values indicates that the stress patterns calculated using FEM are a valid predictor of the biomechanics of the BTDO procedures. The present study provides an interesting correlation between the stiffness of the device and the biomechanical response of the mandible affected for bone transport.

Capping a pulpotomy with calcium aluminosilicate cement: comparison to mineral trioxide aggregates.

INTRODUCTION: Calcium aluminate cements have shown little affinity for bacterial growth, low toxicity, and immunogenicity when used as a restoration material, but calcium aluminate cements have not been tested in vivo in pulpotomy procedures. METHODS: To address this question, a calcium aluminosilicate cement (Quick-Set) was tested along with 2 mineral trioxide aggregates, ProRoot MTA and MTA Plus. These cements were used as a capping agent after pulpotomy. Control rats had no pulpotomy, or the pulpotomy was not capped. Proinflammatory cytokines interleukin (IL)-1ß and IL-1α were measured, and histology was performed at 30 and 60 days after capping. The nociceptive response was determined by measuring the lengthening of the rat's meal duration. RESULTS: and CONCLUSIONS: IL-1ß and IL-1α concentrations were reduced in the capped teeth, but no differences were observed among the 3 cements. Dentinal bridging could be detected at both 30 and 60 days with each of the 3 cements, and the pulps were still vital 60 days after capping. Meal duration significantly shortened after placement of the 3 different cements, indicating a nociceptive response, but there were no differences among the materials. Calcium aluminosilicate cement had similar properties to mineral trioxide aggregates and is a viable option for pulpotomy procedures.

How does the amount of surgical insult affect bone around moving teeth?

INTRODUCTION: The purpose of this study was to determine how the amount of surgical insult affects the quantity and maturity of dentoalveolar bone around teeth that have been orthodontically moved. METHODS: A split-mouth design with 8 foxhound dogs was used to evaluate bone surrounding maxillary second premolars that were protracted for 15 days and retained for 7 weeks. The maxillary first premolars were extracted, and the interseptal bone was removed to within 1 mm of the second premolars; on the insult (lesser surgical insult) side, buccal and lingual vertical grooves were made in the extraction socket to undermine the mesial root of the second premolar; the insult+ (greater surgical insult) side was flapped and had modified corticotomies extending to, but not through, the lingual cortex 1 mm distal to the distal root, and 3 to 5 mm apical to both roots. Microcomputed tomography analyses were used to evaluate the material density, bone volume fraction, and trabecular characteristics of surrounding bone. Hematoxylin and eosin sections were used to determine osteoclast numbers, bone surface areas, and bone volumes. RESULTS: After 7 weeks of consolidation, there was significantly (P <0.05) less bone on the insult+ side; it was less dense and less mature than the bone on the insult side. Relative to the control bone, bone on the insult+ side was significantly less dense but showed no differences in bone volume. Preliminary histologic evaluations indicated increased numbers of osteoclasts and greater bone surface areas on the insult+ side than the insult side, but no differences in bone volume. CONCLUSIONS: Increased surgical insults produce less dense and less mature bone but have no effect on bone volume at 9 weeks after surgery.

A pilot histologic comparison of bone-to-implant contact between phosphate-coated and control titanium implants in the canine model.

PURPOSE: This study tested the null hypothesis that phosphate-treated titanium implants would perform no differently on mineral apposition rates (MARs), new bone-to-implant contact (new BIC), and total bone-to-implant contact (total BIC) compared to standard titanium implants. MATERIALS AND METHODS: Forty 3.3×8.0-mm titanium implants, either phosphate-treated or untreated, were placed in the mandibles of five foxhounds following 6 weeks of postextraction healing. The untreated implants (control) had sandblasted, acid-etched (SLA) surfaces, while the treated implants were electrolytically phosphorylated at 50 volts (T50) or 100 volts (T100). Confocal and histologic analyses were performed on all the implants after 4 weeks of healing. RESULTS: The MARs could not be analyzed due to a lack of delineation between the three bone markers. New BIC results for control implants ranged from 6.0% to 56.0% with a mean of 23.92% and standard deviation (SD) of 13.29%; T50 implants ranged from 8.0% to 43.0% with a mean of 22.29% and SD of 10.26%; and T100 implants ranged from 0.0% to 47.0% with a mean of 17.43% and SD of 11.40%. Total BIC results for control implants ranged from 8.0% to 68.0% BIC with a mean of 41.4% and SD of 19.3%; T50 implants ranged from 21.0% to 65.0% with a mean of 43.7% and SD of 15.2%; and T100 implants ranged from 5.0% to 68.0% with a mean of 38.0% and SD of 19.5%. CONCLUSION: Within the limitations of this pilot study, no significant differences in new BIC or total BIC were found between the three implant groups (C, T50, and T100). Given the very large sample size required to show clinically significant differences, phosphated surfaces do not appear to provide additional advantages to SLA surfaces.