Clinician perspectives on implementation of digitally fabricated complete dentures: A national survey of prosthodontists.

STATEMENT OF PROBLEM: Research on implementation factors for digitally fabricated complete dentures is sparse. PURPOSE: The purpose of this survey of prosthodontists was to explore the current usage of conventionally and digitally fabricated complete dentures and to identify factors that may impact their use. MATERIAL AND METHODS: A confidential cross-sectional survey consisting of 20 questions was conducted in 2019 using the Qualtrics Research Suite. The survey was distributed via electronic mail to all 1820 members of the American College of Prosthodontics. Frequency distributions, chi-squared tests, and Fisher exact tests were used to analyze the data and compare subgroups (α=.05). RESULTS: The response rate was 16.8% (N=305). A total of 31.5% of respondents were implementing digitally fabricated complete dentures, 36.6% were interested in learning and/or incorporating them, 37.7% reported that they had not tried them, and 12.7% had tried them but were not interested in using them again. When asked which factors were important when considering the implementation of digitally fabricated complete dentures, 55.8% indicated laboratory costs, 72.1% total chair time spent, and 81.9% patient satisfaction. Prosthodontists who graduated from dental school after about 1991 were more interested in learning about and incorporating digitally fabricated complete dentures than earlier graduates (P=.02). CONCLUSIONS: The survey results indicate that prosthodontists are implementing digitally fabricated complete dentures in clinical practice but not at the rate that might be expected of a technology that has been available for nearly a decade. Factors reported to matter in the decision to implement this technology were decreased time, overall cost, and improved patient satisfaction.

Students' perception of digital waxing software for dental anatomy education.

The purpose of this study is to assess students' perception of digital waxing software for dental anatomy education. Dental students were introduced to digital waxing during a dental anatomy course, and were requested to finish a voluntary survey. Students strongly agreed (18.2%) or agreed (48.0%) with the statement "digital waxing contributed to my learning of dental anatomy", and strongly agreed (29.9%) and agreed (55.8%) with the statement "The digital waxing software helped develop my wax-up skills". The digital waxing software may be effective for dental anatomy education, but students do not believe digital waxing can be a replacement for conventional wax-up practice.

Linear and volumetric wear of conventional and milled denture teeth.

OBJECTIVE: The purpose of this study was to compare the linear and volumetric wear of conventional and milled double-cross-linked polymethyl methacrylate, nano-composite, and nano-ceramic infused resin posterior denture teeth. METHODS: Double-cross-linked polymethyl methacrylate (PMMA) premolar teeth were scanned and used to mill denture teeth from a double-cross-linked PMMA resin disc and a nano-composite with nano-ceramic infused resin disc. The specimens (n = 8: conventional double-cross-linked PMMA resin teeth-DCL, milled double-cross-linked PMMA resin teeth-DCL-CAM, conventional nano-composite infused resin teeth with four layers composed of composite and PMMA resin teeth-NC, and milled nano-composite and nano-ceramic infused resin teeth-NC-CAM) underwent chewing simulation in the biaxial fatigue testing machine at 1.53 Hz frequency, thermocycling between 5 and 55°C, and 49 N force against a Ø6mm steatite. After 250,000 cycles, the linear changes on the occlusal surfaces of the specimens were analyzed with pairwise comparison with Bonferroni post hoc test, and the volumetric changes of the specimens were analyzed with a one-way ANOVA with Bonferroni post hoc test (p < 0.05). RESULTS: The linear wear of the conventional and milled denture teeth was linearly correlated with the number of cycles between 50,000 and 250,000 cycles. After 250,000 cycles, NC had significantly more linear and volumetric wear (0.52 ± 0.10 mm and 4.29 ± 0.94 mm3 ) than DCL (0.18 ± 0.03 mm and 0.74 ± 0.14 mm3 ; p < 0.001) and NC-CAM (0.15 ± 0.03 mm and 0.35 ± 0.21 mm3 ; p < 0.001). DCL-CAM and NC-CAM had linearly and volumetrically equivalent wear to DCL (p > 0.05). NC-CAM had significantly less linear and volumetric wear (0.15 ± 0.03 mm and 0.35 ± 0.21 mm3 ) than DCL-CAM (0.24 ± 0.07 mm and 1.22 ± 0.61 mm3 ; p < 0.05). CONCLUSIONS: The conventional NC wore more than DCL, DCL-CAM, and NC-CAM. Both milled denture teeth wore an equivalent amount to conventional DCL. The wear between the conventional and milled DCL was equivalent. CLINICAL SIGNIFICANCE: Denture teeth selection can prolong the retreading process and decrease the occurrences of prosthetic complications. Milled denture teeth are good alternatives to conventional denture teeth with regards to their wear resistance.

A Retrospective, Multicenter, Cross-Sectional Case Series Study Evaluating Outcomes of CAD/CAM Abutments on Implants from Four Manufacturers: 4-Year Mean Follow-up.

PURPOSE: To evaluate the clinical, radiographic, and prosthetic outcomes of a single custom CAD/CAM abutment system on implants from four manufacturers, with a mean clinical service of 4 years in a retrospective, multicenter case series study. MATERIALS AND METHODS: Adult subjects (n = 142) previously restored with titanium or gold-shaded titanium nitride custom CAD/CAM abutments (Atlantis, Dentsply Sirona; n = 259) connected to implants from four different manufacturers (Dentsply Sirona Implants [AT], Biomet 3i [BM], Nobel Biocare [NB], Straumann [ST]), irrespective of implant-abutment interface, and replacing one or more teeth in any position were recalled for a single-visit examination by calibrated investigators at six university clinics. The primary outcomes evaluated included abutment success and survival; secondary outcomes included assessment of papillae fill, probing pocket depth (PD), bleeding on probing (BOP), marginal bone levels (MBLs), and patient-reported outcome measures (PROMs). RESULTS: Two-hundred fifty-five (98.5%) abutments supported cement-retained restorations, and four (1.5%) abutments supported screw-retained restorations. Forty-two patients had 64 AT implants (25%), 31 patients had 61 BM implants (24%), 26 patients had 50 NB implants (19%), and 43 patients had 84 ST implants (32%). The overall implant-CAD/CAM abutment success rate was 92.66% (95% CI: 88.78%, 95.53%) for all implants examined, and the survival rate was 98.84% (95% CI: 96.65%, 99.76%) for all implants evaluated. The Jemt papillae index demonstrated a minimum of at least 50% to complete fill of the interproximal papillae in 65.0% of sites. PDs had a median value of 3.0 mm, and BOP was present on 19% of abutment surfaces. Mean MBL changes from the time of placement to exam were -0.24 ± 0.99 mm (-4.9 to 2.3; P = .058) for mesial sites and -0.32 ± 0.96 mm (-4.9 to 2.1; P = .000) for distal sites. PROMs expressed 93% of patients reporting good to very good masticatory function, 97% of patients reporting being satisfied or very satisfied with their esthetic outcomes, and 94% of patients indicating that they were satisfied or very satisfied with their overall implant-restorative outcomes. CONCLUSION: This retrospective, multicenter clinical study of FDA 510k-approved titanium CAD/CAM abutments of a single manufacturer on multiple implant systems demonstrated high levels of success and survival as well as stable peri-implant tissue outcomes, reflected by overwhelmingly positive PROMs.

A Comparison of Conventionally Versus Digitally Fabricated Denture Outcomes in a University Dental Clinic.

PURPOSE: The purpose of this retrospective, cross-sectional study is to evaluate if there is a difference in number of visits (including fabrication and postoperative) and remake rate when comparing conventionally fabricated and digitally fabricated complete dentures by dental students in a predoctoral student dental clinic. MATERIALS AND METHODS: This two-year retrospective cross-sectional study consisted of a chart review for patients receiving maxillary and/or mandibular complete dentures between 2017 and 2019 (n = 314) at the UNC Adams School of Dentistry predoctoral student clinic. No control group was determined for this study. Data were extracted for 242 conventional dentures and 39 digital dentures. Objective treatment outcomes were obtained for each included denture: the number of patient appointments from preliminary impressions to denture placement, the number of postoperative visits, any complications noted, and any need for remakes. Fisher's Exact Test and Cochran-Mantel-Haenszel analysis were completed with statistical significance set at p < 0.05. RESULTS: For the number of visits from preliminary impression to placement, 50% of conventionally fabricated dentures had 6 or more visits, while only 5% of digitally fabricated dentures had 6 or more visits. This difference for the number of patient visits was statistically significant (p < 0.05). Additionally, conventionally fabricated dentures required an average of 2-3 postoperative visits, whereas digitally fabricated dentures required 1-2 postoperative visits. This difference was also statistically significant (p < 0.05). For the number of dentures requiring remake, there was no statistical difference (p = 0.1904). CONCLUSIONS: When comparing conventionally fabricated and digitally fabricated dentures in the predoctoral clinic, the digitally fabricated dentures required fewer patient appointments from start to finish, and fewer postoperative appointments than conventionally fabricated dentures. Fewer visits may be an important consideration for patients, especially those with limited access to care.

Laboratory Trends for Removable Prosthodontics: A Comparison of Two Surveys.

PURPOSE:  The purpose of this survey was to assess dental laboratory technicians' perceptions of the quality of communication and techniques used when receiving removable prosthodontic cases. Additionally, responses were compared to a 2009 survey and changes in trends were evaluated. MATERIALS AND METHODS:    An eleven-question anonymous response survey was developed based on a 2009 survey that assessed dental laboratory technicians' perceptions.  The survey was distributed via Qualtrics to members of the National Association of Dental Laboratories (NADL) The survey included questions related to detail of instruction, quality of work received, design of the prosthesis, and type of articulator used.  Responses were compared to those received in 2009. RESULTS:  Fifty-two survey responses were received from dental laboratory technicians. Of these, 12 did not provide removable prosthodontics services and were excluded. The remaining 40 responses were analyzed. Of these, only 3.7% of the responding laboratory technicians reported receiving work authorizations from dentists that were complete enough to do their best work. While roughly half of the respondents (48.49%) expected a dentist to send a design for a cast partial denture framework, most respondents (72.5%) answered that they designed the majority of the partial denture frameworks they fabricated. The majority of respondents reported that complete denture impressions were not border molded in custom trays, and that most dentists did not rearrange or modify a wax setup for complete or partial dentures. These findings were consistent with the trends reported in the 2009 survey. CONCLUSIONS:  Most dental laboratory technicians answered that based on their selected techniques, dentists tend to complete clinical procedures that minimize patient chair time. While the surveyed technicians appeared satisfied with the quality of work they received, there was a consistent message that communication was frequently inadequate, limiting the technicians ability to fabricate their best work.

A Randomized Controlled Trial Evaluating Grafting the Facial Gap at Immediately Placed Implants.

Immediate implant placement in extraction sockets requires management of postextraction alveolar resorption. This randomized controlled trial evaluated the facial alveolar bone dimension 10 months following immediate implant placement with or without the addition of anorganic xenograft at the time of flapless, one-stage placement of a sloped-platform implant. The primary outcome of facial crestal alveolar bone thickness revealed no difference in the mean dimension (no graft: 1.47 ± 0.85 mm; graft: 1.63 ± 0.71 mm; P = .950). Secondary outcomes, including pink esthetic score, were not different between the two groups. This study suggests that bone formation does occur along the facial surface of implants placed into extraction sockets.

Retrospective cohort analysis of maxillary overdentures retained by unsplinted implants.

STATEMENT OF PROBLEM: Implant therapy involving an unsplinted 2-implant-retained overdenture is well defined as a successful treatment for a patient with an edentulous mandible. However, a similar unsplinted implant therapy supporting a maxillary overdenture is not well characterized. PURPOSE: The purpose of this retrospective study was to evaluate maxillary overdentures retained by 4 unsplinted implants measuring implant survival, overdenture survival, and patient-reported outcomes. MATERIAL AND METHODS: Participants who had received an unsplinted implant-retained maxillary overdenture were included in the study. Participants presented for one denture recall appointment, during which comprehensive examination, including radiographs, was performed and clinical findings were recorded. Participants also completed the Oral Health Impact Profile-49 (OHIP-49) and a 20-item visual analog scale (VAS) satisfaction questionnaire. Nonparametric statistical tests were used to compare OHIP-49 and VAS scores across age, sex, time since overdenture insertion, mandibular dental status, smoking status, maxillary mucosal health, and overdenture hygiene. RESULTS: For the 44 participants, 3 of 4 implants failed in 1 individual. The cumulative implant survival rate was 98% (97.7% patient level). No prosthetic failures (that is, overdenture replacement) occurred, indicating a 100% prosthesis survival rate. The mean ±standard deviation OHIP-49 severity score was 23.6 ±26.0, and the mean ±standard deviation total VAS score was 179.2 ±29.4. Increased age was associated with lower OHIP-49 severity score (P=.036), and participants with unhealthy oral mucosa or denture stomatitis demonstrated significantly higher OHIP-49 severity scores (P=.003). CONCLUSIONS: In this retrospective evaluation, unsplinted implant-retained maxillary overdenture therapy was associated with high implant and prosthetic survival, as well as high patient satisfaction and quality of life. Age, sex, maxillary mucosal health, and mandibular dental status resulted in significant differences with respect to oral health-related quality of life and patient satisfaction, indicating that this treatment option may be ideal for certain patients.

Prosthodontic Management of Implant Therapy: Esthetic Complications.

The essential promise of implant dentistry is the ability to imperceptibly replace missing teeth. To achieve this, careful planning, execution, and maintenance is required by the dentist and patient to maintain a long-term esthetic and functional result. Unfortunately, as a result of biological, prosthetic, and iatrogenic factors, unesthetic results can occur. This article explores the potential causes for the unesthetic dental implant and the possible solutions that may improve the clinical situation. Whereas relatively simple errors may be corrected through prosthetic means, greater complications may require surgical intervention to achieve the desired result.

Management of Implant/Prosthodontic Complications.

Dental implants continue to grow in popularity because they are a predictable treatment to replace missing teeth. They have a high success rate; however, they are still associated with some clinical complications. This article discusses a diverse range of complications related to the restorative and mechanical aspects of dental implants and the management of such complications, as well as potential factors contributing to them.

The Role of Implant-Tooth Distance on Marginal Bone Levels and Esthetics.

PURPOSE: The peri-implant bone and mucosa architecture contribute to the health and esthetics of single-tooth dental implants. The implant-tooth distance (ITD) has been regarded as a key determinant of their outcomes. This study was conducted to determine the relationship between ITD and peri-implant bone, mucosa, and pink esthetic scores (PES) for anterior single-tooth implants. MATERIALS AND METHODS: For 44 dental implants with a microthread conical abutment interface design placed in 38 participants, periapical radiographs and photographs were evaluated at 1 and 4 years to assess interproximal bone levels and PES. RESULTS: Mean mesial and distal marginal bone level change over 4 years was 0.20 ± 1.00 mm and 0.20 ± 0.74 mm, respectively. In this cohort there was no relationship between ITD and interproximal bone changes or papilla fill at 4 years; however, marginal bone changes influenced PES score-the smaller the ITD, the lower the PES (P < .001). Alone, ITD did not influence marginal bone levels or papilla in this cohort. CONCLUSION: These results imply a complex relationship between ITD, marginal bone levels, and PES scores for single-tooth implants.

Molecular Assessment of Human Peri-implant Mucosal Healing at Laser-Modified and Machined Titanium Abutments.

PURPOSE: To compare, by gene profiling analysis, the molecular events underscoring peri-implant mucosa formation at machined vs laser-microgrooved implant healing abutments. MATERIALS AND METHODS: Forty endosseous implants were placed by a one-stage approach in 20 healthy subjects in nonadjacent sites for single-tooth restorations. In a split-mouth design, machined smooth and laser-microgrooved healing abutments were randomly assigned in each subject. Peri-implant mucosa adjacent to healing abutments was harvested by tissue punch biopsy at either 1, 2, 4, or 8 weeks following abutment placement. Total RNA was isolated from the peri-implant transmucosal soft tissues. A whole genome microarray using the Affymetrix Human Gene 2.1 ST Array was performed to describe gene expression profiles in relation to abutment topography and healing time duration. Data analysis was completed using GeneSpring software v.12.6. RESULTS: Differential gene expression was revealed at all time points and among surfaces. Five hundred one genes were differentially expressed (fold change ≥ 2.0) at machined versus laser-modified abutments, and 459 of these were statistically significant (P ≤ .05). At 1 week, unique expression of IL-24 and MMP1 was observed in tissues from laser-treated surfaces. At 2, 4, and 8 weeks, mRNAs encoding keratins and protective proteins of cornified epithelium were upregulated in tissues from laser-modified abutments. At 4 weeks, upregulation (> 2-fold) of mRNAs encoding proteins associated with collagen fibril formation and function was observed in tissue from laser-modified abutments. In both tissues of machined and laser-modified abutments, mRNAs encoding junctional epithelium-specific proteins, ostogenic ameloblast associated protein (ODAM) and follicular dendritic cell secreted protein (FDCSP) were highly upregulated throughout weeks 2 to 8. CONCLUSION: Peri-implant abutment mucosal wound healing involves selective differentiation of epithelium and induction of the junctional epithelium. Laser-mediated alterations in abutment topography enhance collagen fibril-associated gene expression and alter epithelium/junctional epithelial gene expression. Clinically, shallower probing depths are measured at laser-mediated versus machined implant abutments.

Benefits of Case-Based versus Traditional Lecture-Based Instruction in a Preclinical Removable Prosthodontics Course.

This study compared the acceptability and relative effectiveness of case-based learning (CBL) versus traditional lecture-based (LB) instruction in a preclinical removable prosthodontics course in the University of North Carolina at Chapel Hill School of Dentistry DDS curriculum. The entire second-year class (N=82) comprised this crossover study's sample. Assessments of baseline comprehension and confidence in removable partial denture (RPD) treatment planning were conducted at the beginning of the course. Near the end of the course, half of the class received CBL and LB instruction in an RPD module in alternating sequence, with students serving as their own control group. Assessments of perceived RPD treatment planning efficacy, comprehension, and instruction method preference were administered directly after students completed the RPD module and six months later. Analyses of variance accounting for period, carryover, and sequence effects were used to determine the relative effects of each approach using a p<0.05 statistical significance threshold. The results showed that the students preferred CBL (81%) over LB instruction (9%), a pattern that remained unchanged after a six-month period. Despite notable period and carryover effects, CBL was also associated with higher gains in RPD treatment planning comprehension (p=0.04) and perceived efficacy (p=0.01) compared to LB instruction. These gains diminished six months after the course-a finding based on a 49% follow-up response rate. Overall, the students overwhelmingly preferred CBL to LB instruction, and the findings suggest small albeit measurable educational benefits associated with CBL. This study's findings support the introduction and further testing of CBL in the preclinical dental curriculum, in anticipation of possible future benefits evident during clinical training.

Factors Influencing Removable Partial Denture Patient-Reported Outcomes of Quality of Life and Satisfaction: A Systematic Review.

PURPOSE: A systematic search of the literature was performed to identify and characterize articles reporting the influence of removable partial denture (RPD) therapy on satisfaction and quality of life (QoL). MATERIALS AND METHODS: The literature search for relevant articles published between January 1983 and March 30, 2013 was conducted using keyword searches of electronic databases and complimentary hand searches. The search strategy included the following keyword combinations (MeSH and free-text terms): fail, complication, surviv*, longevity, outcome, patient satisfaction or QoL, and denture or prosthes*, and partial and removable. Based on inclusion and exclusion criteria, articles focused on the effect of RPD therapy were reviewed and classified according to Strength-of-Recommendation Taxonomy (SORT) criteria. RESULTS: The combined search identified 997 publications; 198 duplicates were identified and removed, leaving 799 references for further evaluation. After abstract review, 209 articles were selected and read; 18 reports representing findings from 4002 patients were included. While two studies were prospective comparative investigations, the majority of studies represented cross-sectional and retrospective studies. Different instruments were used to measure oral health-quality of life (OHQoL) and satisfaction. Several investigations reported a significant association of satisfaction and QoL with either (a) age of the patient, (b) number of occluding dental units replaced, (c) replacement of anterior teeth, and (d) nature of the opposing arch. CONCLUSIONS: A paucity of detailed investigations concerning outcomes of RPD therapy was noted. Improvement in OHQoL or satisfaction following provision of RPDs was not consistently reported. There is little evidence supporting any association between patient-reported QoL or satisfaction with technical or biological parameters of therapy. Therapeutic success of tooth replacement using RPDs should be carefully considered and compared with alternatives.

Comparison of Marginal Bone Changes with Internal Conus and External Hexagon Design Implant Systems: A Prospective, Randomized Study.

A central dental implant success criterion is the marginal bone response as measured longitudinally. Factors that influence marginal bone changes include osseous and soft tissue architecture, occlusal loading factors, implant position, implant design, and inflammatory processes. The evolution of implant design is multifactorial and includes the implant-abutment interface geometries. The primary objective of this study was to compare the proximal marginal bone changes following placement and loading of internal conus design implants (ICI) and external hex design implants (EXI) used in the treatment of posterior partial edentulism. Among 45 enrolled participants, 39 were treated with 47 ICI or 46 EXI implants using a one-stage implant protocol. Prosthetic restoration was completed after 12 weeks using stock titanium abutments and all-ceramic crowns. Follow-up visits including clinical and radiographic examinations were performed 6 months after permanent restoration and then annually for 3 years. Marginal bone level changes, papilla index scores, condition of the peri-implant mucosa, presence of complications, and participant satisfaction were evaluated. The mean marginal bone level change from implant placement to 3 years was -0.25 ± 0.60 mm and -0.5 ± 0.93 mm for ICI and EXI implants, respectively. The change recorded from permanent restoration to 3 years was a gain of 0.31 ± 0.41 mm versus 0.04 ± 0.51 mm for ICI and EXI implants, respectively (P < .05). In the evaluation of interproximal soft tissue 3 years after permanent restoration, 80% of mandibular and 66% of maxillary interproximal ICI sites received papilla scores of 2 and 3, compared with 50% of mandibular and 60% of maxillary interproximal EXI sites. No significant differences in plaque or bleeding scores were recorded. Abutment/healing abutment complications were recorded for 11 EXI versus 1 ICI participant. The vast majority (> 90%) of participants stated they were satisfied or very satisfied with their implant prosthesis and rated function and esthetics highly for both implant types after 3 years in function. Modestly greater marginal bone loss occurred at EXI implants. Further, more positive papilla scores were found between adjacent ICI implants than between adjacent EXI implants. EXI implants displayed more abutment complications than the ICI implants. The implant-abutment interface design may contribute to therapeutic outcome differences. Replacement of missing posterior teeth with unsplinted implants was successful at the implant level and as reported by the participant.

Electromyographic evaluation of masticatory muscles in dentate patients versus conventional and implant-supported fixed and removable denture wearers- a preliminary report comparing model foods.

PURPOSE: To evaluate differences in masticatory muscle function during chewing of model foods designed to differ in fracture strength between dentate subjects (n = 5, ages 59 to 68 years) versus patients treated with a maxillary conventional complete denture opposing natural dentition or one of the following types of mandibular complete dentures: conventional, implant-supported overdenture, implant-supported fixed denture (n = 20, ages 45 to 83 years). The authors hypothesized that denture wearers would differ in duration of chewing, frequency of chewing, and masticatory muscle activity while preparing a bolus for swallowing. MATERIALS AND METHODS: Surface electromyography was recorded bilaterally from the masseter, anterior temporalis, and anterior digastric. Masticatory muscle activity was evaluated using scaled values of the area under the electromyographic curve, while subjects chewed agar-based model foods with different fracture strengths. Chewing duration and frequency also were calculated from electromyographic recordings. Mixed model analysis of variance with "subject" as a random factor was used during statistical analysis. Logarithmic transformation was required to achieve normalization of residuals for the duration of chewing and the relative masticatory muscles activity, but not for the chewing frequency. RESULTS: Relative masticatory muscle activity was 2.57 times higher for the denture wearers than for the dentate subjects during chewing of model foods (P < .0001). The reduction in masticatory muscle activity from the 1st to the 10th chewing cycle was proportionally less in magnitude and occurred more gradually for denture wearers compared to dentate subjects. While chewing sequence duration increased with food fracture strength, it did not differ significantly in treatment versus dentate groups. Chewing cycle frequency did not differ between groups or with food fracture strength. CONCLUSIONS: The observed increases in relative masticatory muscle activity for denture wearers compared to the dentate subjects during oral food processing likely reflect supplemental mechanical efforts to accommodate the use of dentures for preparing a bolus for swallowing.

In vivo assessment of bone healing following Piezotome® ultrasonic instrumentation.

PURPOSE: This pilot study evaluated the molecular, histologic, and radiographic healing of bone to instrumentation with piezoelectric or high speed rotary (R) devices over a 3-week healing period. MATERIAL AND METHODS: Fourteen Sprague-Dawley rats (Charles River Laboratories International, Inc., Wilmington, MA, USA) underwent bilateral tibial osteotomies prepared in a randomized split-leg design using Piezotome® (P1) (Satelec Acteon, Merignac, France), Piezotome 2® (P2) (Satelec Acteon), High-speed R instrumentation, or sham surgery (S). At 1 week, an osteogenesis array was used to evaluate differences in gene expression while quantitative analysis assessed percentage bone fill (PBF) and bone mineral density (BMD) in the defect, peripheral, and distant regions at 3 weeks. Qualitative histologic evaluation of healing osteotomies was also performed at 3 weeks. RESULTS: At 1 week, expression of 11 and 18 genes involved in bone healing was significantly (p < .05) lower following P1 and P2 instrumentation, respectively, relative to S whereas 16 and 4 genes were lower relative to R. No differences in PBF or BMD were detected between groups within the osteotomy defect. However, significant differences in PBF (p = .020) and BMD (p = .008) were noted along the peripheral region between P2 and R groups, being R the group with the lowest values. Histologically, smooth osteotomy margins were present following instrumentation using P1 or P2 relative to R. CONCLUSIONS: Piezoelectric instrumentation favors preservation of bone adjacent to osteotomies while variations in gene expression suggest differences in healing rates due to surgical modality. Bone instrumented by piezoelectric surgery appears less detrimental to bone healing than high-speed R device.

Evaluation of a collagen scaffold for cell-based bone repair.

PURPOSE: To determine whether a collagen scaffold could provide an environment for mesenchymal stem cell (MSC)-related bone repair of critical-size bone defects in rat calvaria. MATERIALS AND METHODS: Craniotomy defects were created in 28 adult Sprague-Dawley rats. Two additional rats were used as MSC donors by means of femoral bone marrow lavage and culture. The rats were randomly divided into four groups: (1) empty/no graft; (2) collagen scaffold (matrix)+saline; (3) matrix+MSCs; (4) matrix+bone morphogenetic protein. The animals were euthanized 28 days after surgery. Microcomputed tomographic reconstructions were obtained to measure bone fill. The specimens were processed for histologic examination, and the total defect and bone fill areas were measured. RESULTS: Mean bone fill (± standard deviation) of 9.25%±10.82%, 19.07%±17.38%, 44.21%±3.93%, and 66.06%±15.08%, respectively, was observed for the four groups; the differences were statistically significant. Bone repair was statistically significant for groups 3 and 4. No significant difference was seen for bone repair between groups 1 and 2 or between groups 3 and 4. Bone formation differed significantly across the four groups. Statistically significant changes in radiodensity were observed between groups 1 and 3, groups 1 and 4, and groups 2 and 4. Significant differences were not observed between groups 1 and 2, groups 2 and 3, or groups 3 and 4. CONCLUSION: After grafting of adult MSCs adherent within a collagen matrix, repair of bone was significant. Expanded three-dimensional collagen represents a radiolucent, resorbable, biocompatible scaffold that is capable of supporting MSC repair of bone.