Faculty Bibliography

This study sought to qualitatively and quantitatively evaluate the effect of osteotomy preparation by conventional (control group) or OD (OD group) instrumentation on osteotomy healing. An incision of 10 cm was made in the anteroposterior direction over the hip in five sheep, and 15 osteotomies were prepared in the left ilium of the sheep (n = 3/sheep). Three different instrumentation techniques were utilized: (1) conventional/regular drilling (R [recommended by manufacturer]) in a 3-step series of a 2-mm pilot, 3.2-mm, and 3.8-mm twist drills; (2) OD clockwise (OD-CW) drilling with Densah Bur (Versah) 2.0-mm pilot, 2.8-mm, and 3.8-mm multi-fluted tapered burs; and (3) OD counterclockwise (OD-CCW) drilling with Densah Bur 2.0-mm pilot, 2.8-mm, and 3.8-mm multi-fluted tapered burs. Drilling was performed at 1,100 rpm with saline irrigation. Qualitative histomorphometric analysis of the osteotomies after 6 weeks did not show any healing impairment due to the instrumentation. Histologic analysis shows bone remodeling and growth in all samples, irrespective of osteotomy preparation technique, with the presence of bone chips observed along the length of the osteotomy wall in sites subjected to osseodensification drilling.

This study evaluates the influence of two surface physicochemical modifications on osseointegration parameters of a healing chamber implant design. We examine dental implants with internal and external trapezoidal threads that have the following surface modifications: dual acid etching (DAE) and nano-hydroxyapatite (HA) coating over DAE surface (Nano). We installed implants in the right ilium of sheep and conducted histologic/metric analyses after 3 and 12 wk in vivo. We quantified the percentage of bone-to-implant contact (%BIC) and bone area fraction occupancy (%BAFO) within implant threads. Histologic micrographs indicate early bone formation within the healing chambers of implants with Nano surface relative to DAE surface. Histomorphometric analysis demonstrates there to be no significant differences in %BIC between 3 and 12 wk (p = 0.298). Compared to DAE, Nano shows more bone formation in contact with implant, regardless of time (p < 0.025). We observe > %BAFO at 12 wk relative to 3 wk, which differs significantly for Nano (p < 0.038). Implant surface treatment affects the amounts of bone formation within healing chambers, with Nano significantly outperforming DAE at 12 wk (p < 0.025). Nano presents a synergistic effect with implant design, improving osseointegration parameters.

PURPOSE/OBJECTIVE:To evaluate Ti-Base abutment height and cement type on the retentiveness of zirconia-based restorations. MATERIAL AND METHODS/METHODS:Four millimeter (tall) and 2.5-mm-height (short) abutments along with temporary (provisional), glass ionomer (Meron), self-adhesive (U200), and conventional resin cement (Ultimate) were evaluated using pull-out testing (n = 10 crowns/group). RESULTS:Tall and short abutments demonstrated similar retention for all within cement comparisons, except U200 (P = 0.032). Resin cements exhibited superior retentiveness than others (P < 0.01). Although no significant difference was evidenced between resin cements for short abutments, Ultimate evidenced higher retention than U200 for tall abutments (P = 0.043). CONCLUSIONS:Although Ti-Base abutment height has not influenced zirconia superstructures' retentiveness, resin-based cements significantly evidenced higher retention than glass ionomer and temporary cements.

Osseointegration, the direct functional and structural connection between device and bone is influenced by multiple factors such as implant macrogeometry and surgical technique. This study investigated the effects of osseodensification drilling techniques on implant stability and osseointegration using trabecular metal (TM) and tapered-screw vent (TSV) implants in a low-density bone. Six skeletally mature sheep were used where six osteotomy sites were prepared in each of the ilia, (n = 2/technique: regular [R] (subtractive), clockwise [CW], and counterclockwise [CCW]). One TM and one TSV implant was subsequently placed with R osteotomy sites prepared using a conventional (subtractive) drilling protocol as recommended by the implant manufacturer for low density bone. CW and CCW drilling sites were subjected to osseodensification (OD) (additive) drilling. Evaluation of insertion torque as a function of drilling technique showed implants subjected to R drilling yielded a significant lower insertion torque relative to samples implanted in OD (CW/CCW) sites (p < 0.05). Histomorphometric analysis shows that the osseodensification demonstrates significantly greater values for bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). Histological analysis shows the presence of bone remnants, which acted as nucleating surfaces for osteoblastic bone deposition, facilitating the bridging of bone between the surrounding native bone and implant surface, as well as within the open spaces of the trabecular network in the TM implants. Devices that were implanted via OD demonstrated atemporal biomechanical stability and osseointegration.

STATEMENT OF PURPOSE/OBJECTIVE:Injuries to the extremities often require resection of necrotic hard tissue. For large bone defects, autogenous bone grafting is ideal, but similar to all grafting procedures, is subject to limitations. Synthetic biomaterial driven engineered healing offers an alternative approach. This work focuses on three-dimensional (3D) printing technology of solid-free form fabrication (SFF), more specifically robocasting/direct write. The research hypothesizes that a bioactive calcium-phosphate scaffold may successfully regenerate extensive bony defects in vivo and that newly regenerated bone will demonstrate mechanical properties similar to native bone as healing time elapses. METHODS:) and hardness (H) using nanoindentation. RESULTS:) data for the newly regenerated bone presented statistically homogenous values analogous to native bone at the three-time points, while hardness (H) values were equivalent to the native radial bone at 24 weeks. The negative control samples showed limited healing at 8 weeks. CONCLUSIONS:Custom engineered β-TCP scaffolds are biocompatible, resorbable, and can directionally regenerate and remodel bone in a segmental long bone defect in a rabbit model. Custom designs and fabrication of β-TCP scaffolds for use in other bone defect models warrant further investigation.

Craniomaxillofacial congenital anomalies comprise approximately one third of all congenital birth defects and include deformities such as alveolar clefts, craniosynostosis, and microtia. Current surgical treatments commonly require the use of autogenous graft material which are difficult to shape, limited in supply, associated with donor site morbidity and cannot grow with a maturing skeleton. Our group has demonstrated that 3D printed bio-ceramic scaffolds can generate vascularized bone within large, critical-sized defects (defects too large to heal spontaneously) of the craniomaxillofacial skeleton. Furthermore, these scaffolds are also able to function as a delivery vehicle for a new osteogenic agent with a well-established safety profile. The same 3D printers and imaging software platforms have been leveraged by our team to create sterilizable patient-specific intraoperative models for craniofacial reconstruction. For microtia repair, the current standard of care surgical guide is a two-dimensional drawing taken from the contralateral ear. Our laboratory has used 3D printers and open source software platforms to design personalized microtia surgical models. In this review, we report on the advancements in tissue engineering principles, digital imaging software platforms and 3D printing that have culminated in the application of this technology to repair large bone defects in skeletally immature transitional models and provide in-house manufactured, sterilizable patient-specific models for craniofacial reconstruction.