Twelve-month evaluation of a novel mineral-organic adhesive material used to stabilize dental implants placed in oversized osteotomies in vivo in an animal model.

OBJECTIVES: The aim of this study is to evaluate long-term in vivo stability of dental implants stabilized at time of placement in oversized osteotomies with a novel, self-setting, mineral-organic bone adhesive. MATERIALS/METHODS: Canine (26) mandibular teeth were removed, and three oversized osteotomies prepared bilaterally. Implants were placed with either adhesive, particulate xenograft, or with blood clot filling the implant/osteotomy gaps. Removal torque and histology were assessed. RESULTS: The adhesive provided significant and clinically relevant immediate implant stability of 22.2 N-cm (95% CI 5.3; 39.0), which continued throughout the early postoperative course and persisted through the nine- (155 N-cm 95% CI 113; 197) and 12-month (171 N-cm 95% CI 134.2; 209.4) time points. This is in comparison with the blood clot of 1.4 N-cm (95% CI 0.7; 2.1), 128.6 N-cm (95% CI 66.8; 190.4), and 140.7 N-cm (95% CI 78.8; 202.5) and particulate xenograft, 1.3 N-cm (95% CI 0.6; 2.0), 132.1 N-cm (95% CI 94.5; 169.7), and 101.5 (95% CI 59.5; 143.5), respectively. Histological examination shows the adhesive establishes intimate contact with the implant and bony walls and is replaced with new bone without compromising stability. Soft tissue does not penetrate the adhesive, and marginal bone/biomaterial level is maintained. Control sites filled with xenograft or blood clot heal with reduced bone levels, and in some cases, xenograft particles were encapsulated in connective tissue. CONCLUSIONS: Implants placed in oversized osteotomies and lacking primary stability can be stabilized at placement with a novel, highly osteoconductive, and resorbable adhesive. Gradual replacement of the biomaterial allows osseointegration without loss of stability through 12 months of follow-up. This novel adhesive has the potential to stabilize implants placed in sites with inadequate bony support.

Preclinical evaluation of a 3D-printed hydroxyapatite/poly(lactic-co-glycolic acid) scaffold for ridge augmentation.

BACKGROUND/PURPOSE: Supracrestal ridge augmentation (SRA) is a major challenge for clinicians. This study investigated the efficacy of a 3D-printed (3DP) hydroxyapatite/poly(lactic-co-glycolic acid) (HA/PLGA) scaffold as a potential biologic for SRA. METHODS: Scaffolds that were 5 mm in diameter and 2.5-mm thick with a 1.2-mm diameter through-and-through central hole composed of 90% HA and 10% PLGA were printed using an extrusion-based bioprinter. The HA/PLGA scaffold was fixed with a 1.2-mm titanium mini-implant on the buccal surface of rat mandible (Ti-HPS), and the outcome of SRA were compared with sites treated with a titanium mini-implant alone (control) and a titanium mini-implant covered with deproteinized bovine bone-derived matrix (Ti-DBBM) at 4 and 8 weeks by microcomputed tomography (micro-CT), back-scattered SEM, and histology assessments. RESULTS: The HA/PLGA scaffolds were 2.486 ± 0.082 mm thick with an outer diameter of 4.543 ± 0.057 mm and an inner diameter of 1.089 ± 0.045 mm, and the pore dimensions were 0.48-0.52 mm. There was significantly more mineralized tissue in the Ti-DBBM and Ti-HPS groups than in the control group at both time points. Newly formed bone (NB) was well-integrated with the DBBM and HA/PLGA scaffolds. The framework of the 3DP-HA/PLGA scaffold remained in place, and NB-implant contact (NBIC) was advanced to the middle level in the Ti-HPS group until 8 weeks, whereas dispersion of DBBM with a lower level NBIC was noted in the Ti-DBBM group at both time points. CONCLUSION: The 3DP HA/PLGA scaffold maintains supracrestal space and demonstrates osteoconductivity to facilitate SRA.

Crestal bone response to loaded zirconia and titanium implants: a radiographic and histometric analysis in canines.

OBJECTIVES: To evaluate the crestal bone response to a two-piece zirconia implant compared with a control titanium implant using periapical radiographs (PAs) and histometry. MATERIALS AND METHODS: Thirty zirconia and 30 titanium implants were placed in healed posterior mandibles of five canines. Full-ceramic single-tooth restorations were cemented after 6 weeks of healing. Three observers measured the distance between the implant shoulder and the crestal bone (DIB) at placement, loading, and harvesting after 4 or 16 weeks in function. The influence of implant material and loading time on DIB as well as the inter-observer agreement were analyzed. Additionally, histometric distance between implant shoulder and most coronal bone-to-implant contact (IS-cBIC) was compared with DIB. RESULTS: Mean DIB values increased between 4 and 16 weeks of loading for both zirconia (from 1.66 to 2.25 mm; P < 0.0001) and titanium (from 1.81 to 1.95 mm; P = 0.06). Zirconia yielded mean IS-cBIC values of 2.18 mm and 2.48 mm (P < 0.001) and titanium 2.23 mm and 2.34 mm (P = 0.27) after 4 and 16 weeks, respectively. The raters reached an excellent intraclass correlation coefficient. PAs underestimated the bone loss on average by 0.39 mm. CONCLUSIONS: Zirconia implants showed a greater increase of DIB during early healing and function than titanium. CLINICAL RELEVANCE: Crestal peri-implant tissue dimensions may show more pronounced changes around two-piece zirconia implants during early healing. PAs may underestimate peri-implant bone loss.

Synthesis and Characterization of Melatonin-Loaded Chitosan Microparticles Promote Differentiation and Mineralization in Preosteoblastic Cells.

In terms of a novel scaffold with well good osteoinductive and osteoconductive capacity, melatonin (Mel) possesses positive effects on chemical linkage in scaffold structures, which may allow osteogenic differentiation. The aim of this study is to fabricate Mel-loaded chitosan (CS) microparticles (MPs) as a novel bone substitute through generating a Mel sustained release system from Mel-loaded CS MPs and evaluating its effect on the osteogenic capacity of MC3T3-E1 in vitro. The physical-chemical characteristics of the prepared CS MPs were examined by both Fourier transform infrared spectroscopy and scanning electron microscopy. The released profile and kinetics of Mel from MPs were quantified, and the bioactivity of the released Mel on preosteoblastic MC3T3-E1 cells was characterized in vitro. An in vitro drug release assay has shown high encapsulation efficiency and sustained release of Mel over the investigation period. In an osteogenesis assay, Mel-loaded CS MPs have significantly enhanced alkaline phosphatase (ALP) mRNA expression and ALP activity compared with the control group. Meanwhile, the osteoblast-specific differentiation genes, including runt related transcription factor 2 (Runx2), bone morphogentic protein-2 (Bmp2), collagen I (Col I), and osteocalcin (Ocn), were also significantly upregulated. Furthermore, quantificational alizarin red-based assay demonstrated that Mel-loaded CS MPs notably enhanced the calcium deposit of MC3T3-E1 compared with controls. In essence, Mel-loaded CS MPs can control the release of Mel for a period of time to accelerate osteogenic differentiation of preosteoblast cells in vitro.

Esthetic, clinical, and radiographic outcomes of two surgical approaches for single implant in the esthetic area: 1-year results of a randomized controlled trial with parallel design.

AIM: The objectives of this study were to compare (a) esthetic, (b) clinical, (c) radiographic, and (d) patient-centered outcomes following immediate (Type 1) and early implant placement (Type 2). MATERIAL AND METHODS: Forty-six subjects needing a single extraction (premolar to premolar) were randomly allocated to Type 1 or Type 2 implant placement. One year following permanent restoration, evaluation of (a) Esthetics using soft tissue positions, and the pink and white esthetic scores (PES/WES), (b) Clinical performance using probing depth, modified plaque index, and sulcus bleeding index (c) Radiographic bone level, and (d) Patient satisfaction by means of visual analogue scales (VAS) was recorded. RESULTS: Thirty-five patients completed the one-year examination (Type 1, n = 20; Type 2, n = 15). Type 1 implants lost 1.03 ± 0.24 mm (mean ± SE) of mid-facial soft tissue height while Type 2 implants lost 1.37 ± 0.28 mm (p = 0.17). The papillae height on the mesial and distal was reduced about 1 mm following both procedures. Frequency of clinical acceptability as defined by PES ≥ 6 (Type 1: 55% vs. Type 2 40%), WES ≥ 6 (Type 1: 45% vs. Type 2 27%) was not significantly different between groups (p > 0.05). Clinical and radiographic were indicative of peri-implant health. Patient-centered outcomes failed to demonstrate significant differences between the two cohorts. CONCLUSION: One year after final restoration, there were no significant differences in esthetic, clinical, radiographic, and patient-centered outcomes following Type 1 and Type 2 implant placement. At one year, patient satisfaction may be achieved irrespective of the two placement protocols.

Bone response to functionally loaded, two-piece zirconia implants: A preclinical histometric study.

OBJECTIVE: To evaluate the bone response to a two-piece zirconia implant in comparison with a control titanium implant in the canine mandible 4 and 16 weeks after restoration. MATERIAL AND METHODS: Zirconia and titanium implants were alternately placed bilaterally in healed mandibular molar and premolar sites of five canines. Full-ceramic single-tooth restorations were cemented after 6 weeks of transmucosal healing, allowing for full functional loading of the implants. Histologic and histometric analyses were performed on orofacial and mesiodistal undecalcified sections of the specimens obtained upon sacrifice after 4 and 16 weeks of functional loading. Bone-to-implant contact (BIC), multinucleated giant cells-to-implant contact (MIC), crestal bone level, and peri-implant bone density were histometrically assessed. RESULTS: All 60 implants and 60 restorations were still in function after 4 and 16 weeks of loading in both test and control groups. No implant loss, no implant or abutment fracture, and no chipping of the restorations could be detected. Histometric analysis showed no statistically significant differences between zirconia and titanium implants in BIC, crestal bone level, and peri-implant bone density at both time points. Between 4 and 16 weeks, the crestal bone level around zirconia implants showed a small but statistically significant increase in its distance from the implant shoulder. MIC was very low on both implant types and both time points and decreased statistically significantly overtime. CONCLUSION: The present two-piece zirconia implant showed a similar bone integration compared to the titanium implant with similar surface morphology after 4 and 16 weeks of loading.

Injectable, compression-resistant polymer/ceramic composite bone grafts promote lateral ridge augmentation without protective mesh in a canine model.

OBJECTIVE: The objective of this study was to test the hypothesis that a compression-resistant bone graft augmented with recombinant human morphogenetic protein-2 (rhBMP-2) will promote lateral ridge augmentation without the use of protective mesh in a canine model. MATERIALS & METHODS: Compression-resistant (CR) bone grafts were evaluated in a canine model of lateral ridge augmentation. Bilateral, right trapezoidal prism-shaped defects (13-14 mm long × 8-9 mm wide × 3-4 mm deep at the base) in 13 hounds (two defects per hound) were treated with one of four groups: (i) absorbable collagen sponge + 400 µg rhBMP-2/ml (ACS, clinical control) protected by titanium mesh, (ii) CR without rhBMP-2 (CR, negative control), (iii) CR + 200 µg rhBMP-2 (CR-L), or (iv) CR + 400 µg rhBMP-2 (CR-H). All animals were euthanized after 16 weeks. Ridge height and width and new bone formation were assessed by µCT, histology, and histomorphometry. The release kinetics of rhBMP-2 from CR bone grafts in vitro and in vivo in a femoral condyle defect model in rabbits was also evaluated. RESULTS: All four bone grafts promoted new bone formation (11-31.6 volume%) in the lateral ridge defects. For CR grafts, ridge height and width increased in a dose-responsive manner with increasing rhBMP-2 concentration. Ridge height and width measured for CR-H without the use of protective mesh was comparable to that measured for ACS with a protective mesh. CONCLUSIONS: At the same dose of rhBMP-2, an injectable, compression-resistant bone graft resulted in a comparable volume of new bone formation with the clinical control (ACS). These findings highlight the potential of compression-resistant bone grafts without the use of protective mesh for lateral ridge augmentation.

The influence of collagen membrane and autogenous bone chips on bone augmentation in the anterior maxilla: a preclinical study.

OBJECTIVES: To evaluate the effect of a resorbable collagen membrane and autogenous bone chips combined with deproteinized bovine bone mineral (DBBM) on the healing of buccal dehiscence-type defects. MATERIAL AND METHODS: The second incisors and the first premolars were extracted in the maxilla of eight mongrels. Reduced diameter, bone-level implants were placed 5 weeks later. Standardized buccal dehiscence-type defects were created and grafted at implant surgery. According to an allocation algorithm, the graft composition of each of the four maxillary sites was DBBM + membrane (group D + M), autogenous bone chips + DBBM + membrane (group A + D + M), DBBM alone (group D) or autogenous bone chips + DBBM (group A + D). Four animals were sacrificed after 3 weeks of healing and four animals after 12 weeks. Histological and histomorphometric analyses were performed on oro-facial sections. RESULTS: The pattern of bone formation and resorption within the grafted area showed high variability among the same group and healing time. The histomorphometric analysis of the 3-week specimens showed a positive effect of autogenous bone chips on both implant osseointegration and bone formation into the grafted region (P < 0.05). The presence of the collagen membrane correlated with greater bone formation around the DBBM particles and greater bone formation in the grafted region after 12 weeks of healing (P < 0.05). The oro-facial width of the augmented region at the level of the implant shoulder was significantly reduced in cases where damage of the protection splints occurred in the first week of healing (P < 0.05). CONCLUSIONS: The addition of autogenous bone chips and the presence of the collagen membrane increased bone formation around DBBM particles. Wound protection from mechanical noxa during early healing may be critical for bone formation within the grafted area.

Twenty years of enamel matrix derivative: the past, the present and the future.

BACGROUND: On June 5th, 2015 at Europerio 8, a group of leading experts were gathered to discuss what has now been 20 years of documented evidence supporting the clinical use of enamel matrix derivative (EMD). Original experiments led by Lars Hammarström demonstrated that enamel matrix proteins could serve as key regenerative proteins capable of promoting periodontal regeneration including new cementum, with functionally oriented inserting new periodontal ligament fibres, and new alveolar bone formation. This pioneering work and vision by Lars Hammarström has paved the way to an enormous amount of publications related to its biological basis and clinical use. Twenty years later, it is clear that all these studies have greatly contributed to our understanding of how biologics can act as mediators for periodontal regeneration and have provided additional clinical means to support tissue regeneration of the periodontium. AIMS: This review article aims to: (1) provide the biological background necessary to understand the rational for the use of EMD for periodontal regeneration, (2) present animal and human histological evidence of periodontal regeneration following EMD application, (3) provide clinically relevant indications for the use of EMD and (4) discuss future avenues of research including key early findings leading to the development of Osteogain, a new carrier system for EMD specifically developed with better protein adsorption to bone grafting materials.

A lateral ridge augmentation study to evaluate a synthetic membrane for guided bone regeneration: an experiment in the canine mandible.

OBJECTIVES: To evaluate guided bone regeneration outcomes in defects protected with an in situ formed polyethylene glycol (PEG) hydrogel membrane as compared to a non-cross-linked collagen membrane (CM). MATERIAL AND METHODS: Four mandibular alveolar ridge defects were created in eight hound dogs. Regenerative procedures were randomly allocated to one of four groups consisting of freeze-dried bone allograft, which is referred to in this study as freeze-dried bone xenograft (FDBX) + PEG, autogenous bone (AB) + PEG, AB + CM, and AB alone. After 8 weeks, titanium dental implants were placed into augmented sites. After 8 weeks of allowed time for osseointegration, the animals were sacrificed to harvest block specimens for bone-to-implant contact (BIC) and ridge width histomorphometric analysis. RESULTS: Polyethylene glycol membranes had an exposure rate of 50% as compared to 12.5% for sites grafted with CM. Regenerative outcomes with respect to implant placement were least favorable for FDBX + PEG which had implants placed in 37.5% of augmented sites compared to 100% implant placement for all other groups. No statistically significant differences were noted between groups for ridge width measurements in implant and non-implant histologic sections (P > 0.05). Buccal BIC (%) values between treatment groups also failed to reach statistical significant difference (FDBX + PEG [60.2 ± 9.4]; AB + PEG [58.8 ± 8.5]; AB + CM [57.9 ± 12.8]; AB [61.0 ± 10.2]). CONCLUSION: When used in conjunction with FDBX, PEG had unpredictable bone formation and in most cases negatively impacted future implant placement.

Esthetic, clinical and patient-centered outcomes of immediately placed implants (Type 1) and early placed implants (Type 2): preliminary 3-month results of an ongoing randomized controlled clinical trial.

AIM: The objective of the study was to compare (i) esthetic, (ii) clinical and (iii) patient-centered outcomes following immediate (Type 1) and early implant placement (Type 2). MATERIAL AND METHODS: Thirty-eight subjects needing a single extraction (premolar to premolar) were randomly allocated to Type 1 or Type 2 implant placement. Three months following permanent crown insertion, evaluation of (i) esthetic outcomes using soft tissue positions, and the pink and white esthetic scores (PES/WES), (ii) clinical performance using probing pocket depth (PPD), modified plaque index (mPI) and modified sulcus bleeding index (mSBI) around each implant and (iii) patient satisfaction by means of a questionnaire using a visual analogue scale (VAS) was performed. RESULTS: Thirty-two patients completed the 3-month follow-up examination (Type 1, n = 17; Type 2, n = 15) with a 100% implant survival rate. Type 1 implants lost 0.54 ± 0.18 mm of mid-facial soft tissue height, while Type 2 implants lost 0.47 ± 0.31 mm (P > 0.05). The papillae height on the mesial and distal was reduced about 1 mm following both procedures. The PES/WES following Type 1 implant placement amounted to 13.7 ± 0.6 and 12.5 ± 0.7 in the Type 2 group (P > 0.05). PPD, mPI and mSBI were low in both groups (P > 0.05). Patient-centered outcomes failed to demonstrate any statistical difference between the two cohorts. CONCLUSION: Three months following final crown delivery, there were no significant differences in esthetic, clinical and patient-centered outcomes following Type 1 and Type 2 implant placement. On the short term, one may achieve good optimal esthetic and clinical results irrespective of these two placement protocols. These results need to be confirmed on the long term.

Bone-Level Tapered Implants for Single Tooth Replacement: Immediate vs Delayed Placement-A Multicenter Randomized Controlled, 1-Year, Non-inferiority Clinical Study.

PURPOSE: To compare the outcomes of immediate and delayed implant placement with bone-level tapered implants. MATERIALS AND METHODS: In this post-market, multicenter prospective randomized controlled study with a primary endpoint of 1 year, 53 patients were randomized to receive either immediate implant placement (test group) or delayed implant placement (control group). The mean crestal bone level changes from implant loading to 12 months postloading were measured using standardized digital periapical radiographs. Changes in facial plate thickness (as measured on CBCT images), implant success and survival, implant stability, soft tissue changes, patient-centered outcomes, and adverse events were measured to assess outcomes between the test and control treatments at 12 months postloading. RESULTS: Of the original 53 patients, 46 patients completed the study (23 in each group). Mean bone changes from loading to the 12-month follow-up were recorded with no statistically significant difference (P = .950) between the groups. The hypothesis was confirmed that immediate implant placement (test) in extraction sockets produces in similar outcomes as delayed placement (control). The test group was found to be similar to the control group (P = .022) in terms of mean changes in facial plate thickness. Implant survival and success were 95.8% in the test group and 92% in the control group. Stability in the control group was superior at the time of surgery, but there was no difference between the groups at implant loading, producing a nonsignificant P value of .563). CONCLUSIONS: This randomized controlled multicenter study showed comparable outcomes 1 year after prosthetic loading in the immediate and delayed implant placement groups.

Peri-implantitis induction and resolution around zirconia versus titanium implants.

BACKGROUND: This study compared titanium and zirconia implant ligature-induced peri-implant defect progression and response to regenerative surgical intervention. METHODS: Eight tissue-level endosseous implants were placed in 6 mixed-breed foxhounds, with 2 zirconia and 2 titanium alternating in each hemimandible. Cotton ligatures were placed subgingivally for 16 weeks followed by 8 weeks of spontaneous progression. Standardized radiographs were captured every 2 weeks to evaluate the rate of bone loss. Regenerative surgery was performed utilizing water-jet decontamination, enamel matrix derivative, and locally harvested autogenous bone. After 16 weeks of healing, final radiographic bone levels as well as probing depths, recession, and clinical attachment levels were assessed. RESULTS: All 48 implants integrated successfully. The final average post-ligature radiographic defects were 2.88 and 3.05 mm for titanium and zirconia implants, respectively. There was no significant difference between materials in the rate of radiographic bone loss (p = 0.09). Following regenerative surgery, the total average amount of radiographic bone gain was 1.41 and 1.20 mm for titanium and zirconia, respectively. The percentage of defect fill was 51.56% and 37.98% (p = 0.03) for titanium and zirconia, respectively. Inter-group differences were minimal for clinical parameters at the time of sacrifice including periodontal pocket depths (p = 0.81), recession (p = 0.98), or clinical attachment levels (p = 0.51). CONCLUSIONS: No significant difference was found in the rate of peri-implant defect development between titanium and zirconia implants. Both materials gained significant radiographic bone following regenerative surgery with significantly greater defect percentage fill in titanium implants. The final clinical parameters were similar in both groups.

Recruitment strategies and retention rates for five National Dental PBRN studies.

Background: We describe a retrospective assessment of practitioner and patient recruitment strategies, patient retention strategies, and rates for five clinical studies conducted in the National Dental Practice-Based Research Network between 2012 and 2019, and practitioner and patient characteristics associated with retention. Methods: Similar recruitment strategies were adopted in the studies. The characteristics of the practitioners and patients are described. The proportion of patients who either attended a follow-up (FU) assessment or completed an online assessment was calculated. For studies with multiple FU visits or questionnaire assessments, rates for completing each FU were calculated, as were the rates for completing any and for completing all FU assessments. The associations of practitioner and patient characteristics with all clinic FU visits, and with the completion of all assessments for a study were ascertained. Results: Overall, 591 practitioners and 12,159 patients were included. FU rates by patients for any assessment varied from 91% to 96.5%, and rates for participating in all assessments ranged from 68% to 87%. The mean total number of patients each practitioner recruited was 21 (sd = 15); the mean number per study was 13 (sd = 7). For practitioners, practice type and patient enrollment were associated with greater clinic retention, while only race was associated with their patients completing post-visit online assessments. For patients, age was associated with clinic retention, while female gender, age, race, and education were all associated with greater completion of post-visit online assessments. Conclusion: The Network efficiently recruited practitioners and patients and achieved high patient retention rates for the five studies.

Characteristics of dentists in the National Dental Practice-Based Research Network.

OBJECTIVES: Our aims are to describe the characteristics of dentists, members of the US National Dental practice-based research network (PBRN) in the United States, and determine how often these dentists provide specific dental procedures. METHODS: Dentists completed a questionnaire when they enrolled in the Network about their demographic and training characteristics and characteristics of their practices and patients. Dentists also reported the frequency of providing specific dental procedures. Data were analyzed using descriptive statistics. RESULTS: Of 4,483 dentists in active clinical practice, 34% identified as females, 70% as white, and 73% as general dentists. Most dentists practiced in large metropolitan areas (87%) and in solo or small practices (72%). On average, they reported about one-half of their patients were children or older adults, a third were from historically underrepresented racial and ethnic groups, and one-quarter were covered by public insurance. Most dentists routinely performed restorations and fixed prosthetics (78%), extractions (59%), removable (44%) and implant (40%) prosthetics, and endodontics on incisor and premolar teeth (44%). CONCLUSIONS: Dentists participating in the National Dental PBRN have much in common with dentists at large. The network has a broad representation of dentists, practice types, patient populations, and treatments offered, including diversity regarding race/ethnicity, gender, insurance, and geography of its practitioners and patients. CLINICAL SIGNIFICANCE: Characteristics of National Dental PBRN dentists suggest that a broad range of dentists is interested in participating in national-level research studies, thereby enabling an array of clinical study settings and topics that can optimize the generalizability of study findings.

Tissue integration of collagen-based matrices: an experimental study in mice.

OBJECTIVES: To test whether or not tissue integration, biodegradation, and new blood vessel formation in two collagen-based matrices depend on the level of chemical cross-linking. MATERIAL AND METHODS: Two collagen matrices with high (CM1) and low (CM2) levels of chemical cross-linking were randomly implanted in two pouches in 14 athymic nude mice. Three and 6 weeks later, the animals were euthanized. Histologic and histomorphometric measurements were performed on paraffin-embedded sections. RESULTS: Both collagen matrices integrated well into the surrounding soft tissues. The level of cross-linking and duration of implantation had an effect on the formation of new blood vessels. More blood vessels (n = in absolute numbers) were found in outer compartments compared to the central compartments of the matrices, reaching 5.6 (CM2) vs. 4.3 (CM1) at 3 weeks, and 5.3 (CM2) vs. 7.3 (CM1) at 6 weeks. Similarly, connective tissue formation increased for both matrices between 3 and 6 weeks, whereas the amount of remaining collagen network gradually decreased over time being more pronounced for CM1 (-50%) compared to CM2 (-15%). CONCLUSIONS: The degree of cross-linking was negatively correlated for all outcome measures resulting in improved tissue integration, superior matrix stability and enhanced angiogenic patterns for the less cross-linked collagen matrix (CM2) in this experimental study in mice.

Radiographic evaluation of a novel bone adhesive for maintenance of crestal bone around implants in canine oversized osteotomies.

BACKGROUND: A novel bone adhesive (tetracalcium phosphate and O-phospho-L-serine) has been developed as an osteoconductive, biodegradable bone-adherent material. The purpose of this study was to evaluate the maintenance of crestal bone/material level by standardized radiographs. METHODS: This was a randomized, controlled, three arm, prospective study. Twenty-six mixed breed hound dogs were included in this study. Three implants were placed on either side of the mandible with either bone adhesive (BA), bovine bone mineral (BBM), or no biomaterial (negative control [NC]). Standardized periapical radiographs were taken immediately after implant placement and at every month up to 1 year. The vertical distance between the implant platform to the first radiopaque material on both the mesial and distal surfaces were measured and crestal bone/material level changes were analyzed. RESULTS: The crestal bone/material level adjacent to BA was stable and maintained throughout the study. There were statistically significant differences found between BA and NC in terms of maintenance of crestal bone levels at any given timepoint. CONCLUSION: This study demonstrated that BA maintained crestal bone levels and had a similar ability to maintain that level over 1 year compared with BBM.

Implications of considering peri-implant bone loss a disease, a narrative review.

BACKGROUND: Peri-implantitis has been suggested to cause significant increasing proportions of implant failure with increasing time. PURPOSE: To assess whether implant failure rates in long term studies are matching the supposed high prevalence of peri-implantitis. MATERIAL AND METHODS: This paper is written as a narrative review of the long-term clinical investigations available in the literature. RESULTS: Some implant systems have seen unacceptable marginal bone loss figures with time coupled to increased implant failure rates, resulting in the withdrawal of these systems. The reasons for such mishap are generally unknown, with the exception of one system failure that was found to be due to improper clinical handling. Modern, moderately rough implant systems have functioned excellently over 10-15 years of follow up with minor problems with marginal bone loss and implant failure rates within a few per cent. Machined implants have functioned adequately over 20-30 years of follow up. Implant failures occur predominantly during the first few years after implant placement. No significant increase of implant failures has been observed thereafter over 20-30 years of follow up. Over the years of our new millennium, scientific and technical advances have allowed the discovery of numerous molecular pathways and cellular interactions between the skeletal and immune system promoting the development of the interdisciplinary field called osteoimmunology. Nowadays, this knowledge has not only allowed the emergence of new etiologic paradigms for bone disease but also a new dynamic approach on the concept of osseointegration and MBL around oral implants, re-evaluating our older disease oriented outlook. This facilitates at the same time the emergence of translational applications with immunological perspectives, scientific approaches based on omics sciences, and the beginning of an era of personalized dental implant therapy to improve the prognosis of oral implant treatment. CONCLUSIONS: Oral implant systems have been found to function with very good clinical outcome over follow-up times of 20-30 years. Registered implant failures have occurred predominantly during the first few years after implantation, and there has been no significant increase in late failures due to peri-implantitis.

Structure, function, and productivity from the National Dental Practice-Based Research Network.

Introduction: Following inception in 2005 as a multiregional practice-based research network (PBRN), the "National Dental PBRN" expanded nationwide in 2012, and in 2019 implemented additional organizational changes. The objectives are to: (1) describe the new structure and function of the network; and (2) quantify its scientific productivity since 2005. Methods: A national Administrative and Resource Center is based in Alabama; regional and specialty nodes are based in Alabama, Florida, Illinois, Minnesota, Oregon, New York, and Texas. A Network Coordinating Center is based in Oregon. Studies are funded via investigator-initiated grants. Scientific productivity is assessed using specific metrics, including the Relative Citation Ratio. Results: To date, 58 studies have been completed or are in data collection or development. These studies have investigated a broad range of topics using a wide variety of study designs. Of the studies that have completed enrollment, 70,665 patients were enrolled, as were 19,827 practitioners (some participated in multiple studies), plus electronic records for 790,493 patients in two data-only studies. To date, these studies have led to 193 peer-reviewed scientific publications in 62 different journals. The mean (1.40) Relative Citation Ratio of Network publications connotes a greater-than-average influence in their fields. Conclusions: These metrics demonstrate that the PBRN research context can successfully engage practitioners and patients from diverse settings nationally with a high and sustained level of scientific productivity. This infrastructure has enabled clinical scientists in oral health and nonoral health topics and provided additional recruitment venues outside of the typical academic health center research context.

Angiogenic activity of an enamel matrix derivative (EMD) and EMD-derived proteins: an experimental study in mice.

OBJECTIVES: To determine whether all or only certain proteins in an enamel matrix derivative (EMD) are angiogenic. MATERIALS AND METHODS: The angiogenic effect was analysed using an in vivo angiogenesis assay. Silicon tubes were filled with or without potential and known angiogenic-modulating factors: (i) an EMD parent, (ii) nine pools of EMD proteins, (iii) fibroblast growth factor/vascular endothelial growth factor and (iv) amelogenin. Silicon tubes were implanted subcutaneously in mice. Dextran-fluorescein isothiocyanate (FITC) was injected via the tail vein, mice were euthanized and tubes were retrieved. Neovascularization was determined by measuring the amount of dextran-FITC within the tubes. RESULTS: The greatest angiogenic potential of the EMD parent was at a weight of 125 ng, resulting in a 4.3-fold increase compared with the negative control. Five pools of EMD proteins showed a stronger angiogenic activity than the EMD parent. Pool 5 showed the greatest angiogenic activity, when compared with the negative control (8.1-fold increase) and with 125 ng of the EMD parent (4.2-fold increase). Amelogenin demonstrated a significantly higher angiogenic activity than the negative control (increase up to 4.0-fold) and the EMD parent (increase up to 1.6-fold). CONCLUSIONS: EMD parent, recombinant porcine amelogenin and certain pools of EMD proteins induced significant angiogenesis compared with the controls using a standardized in vivo assay.