Influence of Microtextured Implant Surfaces on Peri-implantitis and Its Treatment: A Preclinical Trial.

PURPOSE: The prevalence of peri-implantitis has increased significantly, forcing clinicians to search for ways to prevent it. Laser-microtextured surfaces promote soft tissue attachment and provide a tight seal around implants. Hence, the aim of this study was to examine the clinical, radiographic, and histologic features of ligature-induced peri-implantitis, as well as the effect of surgical treatment of these induced peri-implantitis lesions on laser-microtextured implants in a controlled animal model. MATERIALS AND METHODS: Six mini-pigs (three males/three females) received 6 implants each (3 resorbable blast textured [RBT] implants and 3 laser-microtextured [LM] implants) in mandibular premolar sites, for a total of 36 implants. Two groups were identified based on the time point of sample analysis. After osseointegration was achieved, metal wire ligatures were placed and left for 12 weeks. Group 1 samples were then obtained, and group 2 samples received rescue therapy following a guided bone regeneration (GBR) protocol. Sample collection in group 2 was completed 12 weeks after the samples were submerged and treated. All samples were analyzed histologically and measurements were taken. RESULTS: Four implants (three RBT, one LM) were lost at early time points because of implant instability. Interimplant distances and soft tissue thicknesses varied subtly between groups. More notable was the mean (± standard error of the mean) crestal bone loss (group 1: 1.860 ± 1.618 mm [LM] and 2.440 ± 2.691 mm [RBT]; group 2: 2.04 ± 1.613 mm [LM] and 3.00 ± 2.196 mm [RBT]) (P < .05), as demonstrated by a paired t test. Histologic pocket depth was also greater at RBT sites than at LM sites (4.448 ± 2.839 mm and 4.121 ± 2.251 mm, respectively, in group 1; and 3.537 ± 2.719 mm and 2.339 ± 1.852 mm, respectively [P < .005] in group 2). CONCLUSION: LM implants had less crestal bone loss and shallower histologic pocket depth compared with their RBT counterparts. Also, LM implants had higher bone fill when a rescue therapy (GBR) was performed.

Titanium Activates the DNA Damage Response Pathway in Oral Epithelial Cells: A Pilot Study.

PURPOSE: To evaluate the effect of titanium (Ti) particles on oral epithelial cell homeostasis and the potential of dental implants to release Ti debris upon insertion. MATERIALS AND METHODS: Dental implants with varying surface treatments were employed to determine the feasibility of particle release during implant placement as well as the impact of free Ti debris on oral epithelial cells. Ti particles derived from implant surfaces were isolated and cultured in direct contact with normal oral epithelial cells for 48 hours. Further, cells were fixed and processed for immunofluorescence assay to detect the activation of the DNA damage response (DDR) using CHK2 and BRCA1 molecular markers. Positive cells demonstrating DNA damage were quantified and statistically analyzed. RESULTS: Ti particles derived from implants containing phosphate-enriched titanium oxide (PETO), fluoride-modified (FM), and grit-blasted (GB) surface treatments were able to activate CHK2 and trigger the recruitment of BRCA1 in oral epithelial cells. Also, implants with GB surfaces were able to release Ti particles upon implant placement. CONCLUSION: The results indicate that Ti debris may be detached from the implant surface upon placement. Also, free Ti particles can trigger DDR signaling in oral epithelial cells. These findings suggest that Ti particles/debris released into a surgical wound may contribute to the disruption of epithelial homeostasis, and potentially compromise the oral epithelial barrier.

In-office fabrication of dental implant surgical guides using desktop stereolithographic printing and implant treatment planning software: A clinical report.

Guided surgery is accepted as the most accurate way to place an implant and predictably relate the implant to its definitive prosthesis, although few clinicians use it. However, recent developments in high-quality desktop 3-dimensional stereolithographic printers have led to the in-office fabrication of stereolithographic surgical guides at reduced cost. This clinical report demonstrates a protocol for using a cost-effective, in-office rapid prototyping technique to fabricate a surgical guide for dental implant placement.

The Effect of Inital-Phase Bone Remodeling on Implant Wound Healing.

This case series aimed to investigate the initial-phase bone remodeling during implant wound healing and to discuss the possible contributing factors. A total of 11 implants with polished collars were placed in premaxillary regions via flapless approach with the aid of computer technology. After 15 months of follow-up, the results suggested that the presence of polished collars triggered bone resorption via a bone remodeling mechanism. The overall vertical crestal resorption was 0.78 ± 0.46 mm on average. This initial-phase bone remodeling primarily occurred within the first 3 months postoperatively. The slightly exposed polished collar may not worsen crestal bone level.

Comparison of Clinical and Radiographic Outcomes of Platform-Switched Implants with a Rough Collar and Platform-Matched Implants with a Smooth Collar: A 1-Year Randomized Clinical Trial.

PURPOSE: The aim of this study was to evaluate and compare the clinical and radiographic outcomes of single implants with a platform-switched rough collar (PSRC) and a platform-matched smooth collar (PMSC). MATERIALS AND METHODS: Twenty-six patients missing a tooth in the anterior maxilla (through the premolars) were randomly assigned to the PSRC or the PMSC group. All implants were placed in a flapless approach and restored with an early loading protocol. Clinical measurements were performed at surgery, loading, and at 3, 6, and 12 months after loading. In addition, radiographic evaluations were carried out using standardized periapical radiographs and cone beam computed tomography. Patient satisfaction surveys were completed, and microbial analysis with DNA probes was performed. RESULTS: The implant survival rate was 100% for both groups. The mean marginal bone level (MBL) was significantly higher in the PSRC group compared to the PMSC group at all time points. From the 2-week postoperative visit to 1 year postloading, the mean MBL change in the PSRC group was 0.21 ± 0.56 mm and in the PMSC group it was 0.74 ± 0.47 mm. Soft tissue profiles were stable over time, with no significant differences between groups. There were no significant differences between groups in the number of microbial species seen. Patients in both groups were highly satisfied with postoperative and postprosthetic experiences. CONCLUSION: In this study, the PSRC method preserved marginal bone by a mean of 0.53 mm more than the standard PMSC protocol. Within the limitations of the present study, it can be concluded that the PSRC protocol may be beneficial in marginal bone preservation. Longitudinal studies are needed to verify the long-term effects of this approach.

Bone Engineering of Maxillary Sinus Bone Deficiencies Using Enriched CD90+ Stem Cell Therapy: A Randomized Clinical Trial.

Bone engineering of localized craniofacial osseous defects or deficiencies by stem cell therapy offers strong prospects to improve treatment predictability for patient care. The aim of this phase 1/2 randomized, controlled clinical trial was to evaluate reconstruction of bone deficiencies of the maxillary sinus with transplantation of autologous cells enriched with CD90+ stem cells and CD14+ monocytes. Thirty human participants requiring bone augmentation of the maxillary sinus were enrolled. Patients presenting with 50% to 80% bone deficiencies of the maxillary sinus were randomized to receive either stem cells delivered onto a ß-tricalcium phosphate scaffold or scaffold alone. Four months after treatment, clinical, radiographic, and histologic analyses were performed to evaluate de novo engineered bone. At the time of alveolar bone core harvest, oral implants were installed in the engineered bone and later functionally restored with dental tooth prostheses. Radiographic analyses showed no difference in the total bone volume gained between treatment groups; however, density of the engineered bone was higher in patients receiving stem cells. Bone core biopsies showed that stem cell therapy provided the greatest benefit in the most severe deficiencies, yielding better bone quality than control patients, as evidenced by higher bone volume fraction (BVF; 0.5 versus 0.4; p = 0.04). Assessment of the relation between degree of CD90+ stem cell enrichment and BVF showed that the higher the CD90 composition of transplanted cells, the greater the BVF of regenerated bone (r = 0.56; p = 0.05). Oral implants were placed and restored with functionally loaded dental restorations in all patients and no treatment-related adverse events were reported at the 1-year follow-up. These results provide evidence that cell-based therapy using enriched CD90+ stem cell populations is safe for maxillary sinus floor reconstruction and offers potential to accelerate and enhance tissue engineered bone quality in other craniofacial bone defects and deficiencies (Clinicaltrials.gov NCT00980278).

Histomorphometric analysis of bone regeneration using a dual layer of membranes (dPTFE placed over collagen) in fresh extraction sites: a canine model.

In untreated extraction sockets, buccal bone remodeling compromises the alveolar ridge width. The aim of this study was to histologically assess the efficacy of using a dual layer of membranes (high-density polytetrafluoroethylene [dPTFE] placed over collagen) for ridge preservation in fresh extraction sites. Eight beagle dogs were used. After endodontic treatment of mandibular bilateral second (P2), third (P3), and fourth (P4) premolars, mandibular bilateral first premolars and distal roots of P2, P3, and P4 were extracted atraumatically. Animals were randomly divided into 4 treatment groups. group 1, the control group, received no treatment; in group 2, allograft was placed in the alveolum and the socket covered with dPTFE membrane; in group 3, allograft was placed in the alveolum, the buccal plate was overbuilt with allograft, and the socket was covered with dPTFE membrane; in group 4, allograft was placed in the alveolum and covered with dual layer of membranes (dPTFE placed over collagen). No intent of primary closure was performed for all groups. After 16 weeks, the animals were sacrificed and mandibular blocks were assessed histologically for buccolingual width of alveolar ridge, percentage of bone formation and bone marrow spaces, and the remaining bone particles. The buccolingual width of the alveolar ridge was significantly higher among sockets in group 4 than in group 1 (P < .05). the amount of newly formed bone in each socket was higher in extraction sockets in group 4 than in groups 1, 2, and 3 (P < .001). A significant difference was found in the percentage of bone marrow spaces among all groups (P < .001). No significant difference was found in the number of nonresorbed bone particles among the groups. Using a dual layer of membrane was more effective in ridge preservation than conventional socket augmentation protocols.

Optimized cell survival and seeding efficiency for craniofacial tissue engineering using clinical stem cell therapy.

Traumatic injuries involving the face are very common, yet the clinical management of the resulting craniofacial deficiencies is challenging. These injuries are commonly associated with missing teeth, for which replacement is compromised due to inadequate jawbone support. Using cell therapy, we report the upper jaw reconstruction of a patient who lost teeth and 75% of the supporting jawbone following injury. A mixed population of bone marrow-derived autologous stem and progenitor cells was seeded onto ß-tricalcium phosphate (ß-TCP), which served as a scaffold to deliver cells directly to the defect. Conditions (temperature, incubation time) to achieve the highest cell survival and seeding efficiency were optimized. Four months after cell therapy, cone beam computed tomography and a bone biopsy were performed, and oral implants were placed to support an engineered dental prosthesis. Cell seeding efficiency (>81%) of the ß-TCP and survival during the seeding process (94%) were highest when cells were incubated with ß-TCP for 30 minutes, regardless of incubation temperature; however, at 1 hour, cell survival was highest when incubated at 4°C. Clinical, radiographic, and histological analyses confirmed that by 4 months, the cell therapy regenerated 80% of the original jawbone deficiency with vascularized, mineralized bone sufficient to stably place oral implants. Functional and aesthetic rehabilitation of the patient was successfully completed with installation of a dental prosthesis 6 months following implant placement. This proof-of-concept clinical report used an evidence-based approach for the cell transplantation protocol used and is the first to describe a cell therapy for craniofacial trauma reconstruction.

Effectiveness of three different alveolar ridge preservation techniques: a pilot randomized controlled trial.

The aim of this pilot study was to obtain preliminary data regarding the effectiveness of three different alveolar ridge preservation modalities as compared with a control. Subjects in need of single-rooted tooth extraction were recruited and randomly allocated to one of four treatment groups: group 1 (control)--collagen plug; group 2--socket grafting and polytetrafluoroethylene (PTFE) barrier; group 3--socket grafting, buccal overbuilding, and PTFE barrier; group 4--socket grafting, collagen barrier, and PTFE barrier. The grafting material used in all groups was an allograft. At 16 weeks, surgical reentry was performed, and a bone core biopsy was harvested for histomorphometric analysis. A cone beam computed tomography scan was obtained at baseline and before surgical reentry. Clinical (keratinized mucosa [KM] and buccolingual ridge width [RW] changes) and volumetric outcomes were statistically analyzed. A total of 20 patients were recruited (5 patients per group). KM and buccolingual RW changes were minimal during the 16-week healing period for all groups, with no statistically significant differences. Volumetric analyses revealed comparable alveolar ridge resorption values for groups 1, 2, and 4 (3%, 7%, and 5%, respectively), while group 3 exhibited more reduction (16%). Histomorphometric analysis revealed the presence of adequate average values of mineralized tissue (group 1, 46.4%; group 2, 28.88%; group 3, 48.81%; group 4, 41.13%). Based on the clinical and volumetric outcomes, none of the ridge preservation modalities was superior to the control. The combination allograft (freeze-dried bone allograft and demineralized freeze-dried bone allograft) employed in this study appears to be a safe and adequate biomaterial for intraoral grafting.

A randomized clinical trial evaluating the efficacy of the sandwich bone augmentation technique in increasing buccal bone thickness during implant placement surgery: I. Clinical and radiographic parameters.

OBJECTIVES: Sandwich bone augmentation (SBA) has been proposed to augment the width of edentulous ridges for implant placement. This study aimed to investigate the effect of a membrane on SBA for the regeneration of buccal implant dehiscence defects. MATERIAL AND METHODS: Twenty-six healthy patients, each with a single defect, were randomly assigned into two groups. Both groups received an inner and outer layer of mineralized human cancellous and cortical particulate allograft. In the test group, a bovine pericardium membrane covered the bone grafts, while no membrane was placed in the control group. Cone beam computed tomography (CBCT) scans were taken before and immediately after implant placement and at 6 months post-surgery. RESULTS: All implants placed were successfully osseointegrated at 6 months. Clinical re-entry measurements showed significant buccal bone gain in the test group compared with the control group (P < 0.05). The test group had 1.12, 2.21 and 2.44 mm more buccal bone thickness at 2, 4 and 6 mm below the bone crest. There were no significant differences in the mid-buccal vertical bone height, defect height and width reductions and bone fill between the two groups (P > 0.05). Cone beam computed tomography analysis demonstrated significant buccal bone gain of 1.22 mm in the test group. Radiographic vertical bone loss at 1-year post-surgery showed no significant differences between the groups. CONCLUSION: Sandwich bone augmentation is a predictable technique for regenerating buccal bone on implant dehiscence defects. Addition of a barrier membrane prevented significant horizontal buccal bone resorption as space was maintained more effectively when compared with sites treated without a membrane.

Effect of flapless surgery on single-tooth implants in the esthetic zone: a randomized clinical trial.

BACKGROUND: Implant therapy is a highly predictable treatment option; however, insufficient data exist to show whether flapless implant surgery provides better esthetic outcomes and less bone loss than implant surgery with a flap approach. METHODS: In this randomized, controlled study comparing the flapless and traditional flap protocol for implant placement, 24 patients received a single implant in the anterior maxillary region. A cone beam computed tomography-aided surgical guide was used for implant placement surgery for both groups. Implants were restored using a one-piece, screw-retained ceramic crown at 3 months. Radiographic and clinical measurements were assessed at baseline (implant placement) and at 3 (crown placement), 6, 9, and 15 months. Clinical parameters evaluated were plaque index, gingival index, papillary index (PPI) (0 = no papilla, 1 = less than half, 2 = more than half but not complete, 3 = complete fill, and 4 = overfill), marginal tissue levels, biotype, width of keratinized tissue, and soft tissue thickness. RESULTS: Implant success rate was 92% in both groups. Mean PPI values for the flap control group and flapless test group were 2.38 ± 0.51 versus 2.31 ± 0.48 at crown placement (P = 0.68) and 2.52 ± 0.52 versus 2.64 ± 0.54 at 15 months (P = 0.42), respectively. PPI increased over time in both groups, although the flapless group had a significantly larger change in PPI from crown placement to 6 and 9 months (P <0.01). Crestal bone levels in the flap group were more apical in relation to the implant platform than those in the flapless group for the duration of the study. No differences among groups were noted for all other measurements. CONCLUSIONS: Both flapless and flap implant placement protocols resulted in high success rates. A flapless protocol may provide a better short-term esthetic result, although there appears to be no long-term advantage.

Efficacy of using a dual layer of membrane (dPTFE placed over collagen) for ridge preservation in fresh extraction sites: a micro-computed tomographic study in dogs.

OBJECTIVE: To assess if overbuilding the buccal plate or using a dual-layer socket grafting technique prevents alveolar bone resorption and enhances final ridge width, height, and volume after tooth loss in an animal model. MATERIAL AND METHODS: In eight beagle dogs bilateral second (P2)-, third (P3)-, and fourth (P4) premolars were endodontically treated. All bilateral mandibular first premolars and distal roots of P2, P3, and P4 were hemisectioned and atraumatically extracted. Animals were randomly divided into four groups: (i) Control-Socket alone, (ii) Particulate allograft in the alveolum, socket covered with high-density polytetrafluoroethylene (dPTFE) membrane and sutured over the alveolum, (iii) Particulate allograft in the alveolum and overbuilding the buccal plate, socket covered with dPTFE membrane and sutured over the alveolum, (iv) Particulate allograft in the alveolum and covered with dual layer (dPTFE placed over collagen membrane), and sutured over the alveolum. After 16 weeks, the animals were sacrificed. Mandibular blocks of the jaws were assessed for bone volume (BV), vertical bone height (VBH), alveolar ridge thickness, and bone mineral density (BMD) using micro-computed tomography. RESULTS: The BV in groups 1, 2, 3, and 4 was 169.5, 207.57, 242.4, and 306.1 mm(3) , respectively. The VBH in groups 1, 2, 3, and 4 was 4.2, 6.4, 6.2, and 7.3 mm, respectively. Ridge widths in groups 1, 2, 3, and 4 were 5.45 ± 0.75, 5.91 ± 0.86, 6.05 ± 0.63, and 6.28 ± 1.01 mm, respectively. There was no significant difference in BMD between the groups. CONCLUSIONS: The RP using a dual layer of membrane following tooth extraction results in more BV, VBH, and alveolar ridge width as compared to when a single layer of membrane is used.

Efficacy of acellular dermal matrix and coronally advanced flaps for the treatment of induced gingival recession defects: a histomorphometric study in dogs.

BACKGROUND: Gingival recession (GR) defects can be treated by various methods, including acellular dermal matrix (ADM) or coronally advanced flaps (CAFs). The aim of this histomorphometric experiment is to compare the efficacy of ADM and CAF for treating GR defects in dogs. METHODS: In eight beagle dogs, a critical-size labial GR defect was surgically induced on bilateral maxillary cuspids under general anesthesia. Test sites received ADM and CAF, and control sites underwent CAF treatment alone. Plaque index (PI), bleeding index (BI), and gingival index (GI) were measured at 4 weeks (baseline), 8 weeks, and 16 weeks. Width of keratinized gingiva (KG) was determined at baseline and at 16 weeks. Depth of recession and width of GR below the cemento-enamel junction (CEJ) was also determined. After 4 months, animals were sacrificed, and jaw blocks were histomorphometrically assessed for tissue thickness and distance from the stent to the gingival margin (GM) and to the CEJ. RESULTS: At 4-, 8-, and 16-week intervals, there was no significant difference in the BI, GI, and PI at the test and control sites. At 16 weeks, thickness of KG was significantly higher at the control sites than test sites (P <0.01). There was no difference in the midfacial recession depth and recession width at the test and control sites at baseline and before euthanasia (16 weeks). Histomorphometrically, there was no significant difference in tissue thicknesses and distances from the stent to the GM and CEJ in the test and control sites. CONCLUSION: ADM might yield similar results to a CAF alone and could decrease the amount of KG.

The success rate of narrow body implants used for supporting immediate provisional restorations: a pilot feasibility study.

BACKGROUND: Implants were first designed to be used in the reconstruction of edentulous mandibles. However, with the technological advancement, enormous changes were made to improve the implant design and surface characteristics leading to the wide use of implants in the replacement of missing teeth. During the transition from an edentulous span to a fixed prosthesis, narrow body implants (NBIs) have been proposed to enhance patient comfort and function. Therefore, this study was aimed at investigating the survival and success rates of NBIs used for supporting immediately nonfunctional loaded provisional fixed partial denture (PFPD). METHODS: Either 2.2- or 2.4-mm-diameter dental implants were placed transmucosally into the edentulous ridges of 10 partially edentulous patients. PFPD of self-cured bis-acryl composite material were made using either a vacuform template chairside or a relined prefabricated PFPD. Occlusal adjustments were made to ensure that there was no functional loading on the provisional restorations before they were secured onto the transitional implants. RESULTS: At 1 year, the implant success and survival rates were 38.7% and 93.5%, respectively, with a mean percentage of bone loss of 9.46% (0%-40%) and a mean bone loss of 1.19 mm (range: 0-3.5 mm). CONCLUSIONS: With a favorable implant survival rate, the use of NBIs to support provisional restorations seemed to be a feasible treatment option. In addition, there is merit for research on the long-term use of NBIs-supported final prostheses.

Influence of lateral window dimensions on vital bone formation following maxillary sinus augmentation.

PURPOSE: The aim of this study was to evaluate the influence that lateral window dimensions may have on maxillary sinus augmentation outcomes. MATERIALS AND METHODS: Patients requiring maxillary sinus augmentation by a lateral window approach and delayed implant placement were recruited in this study. Approximate window dimensions (AWD) were calculated in mm2 at the time of the surgical intervention. In all cases, a mixture of cortical and cancellous allograft particles was used as the sole grafting material. Patients were followed for 6 months. At the time of implant placement, bone core biopsies were harvested. Transversal circular samples were histomorphometrically analyzed. Proportions of vital bone (VB), remaining allograft particles (RA), and nonmineralized tissue (NMT) were quantified. Analysis of correlation of AWD with %VB, %RA, and %NMT was performed using a statistical model. RESULTS: A total of 24 maxillary sinus augmentation procedures were performed in 21 patients. One patient developed an infection after grafting and was excluded. Histomorphometric analysis showed that mean %VB was 21.69% ± 16.30%, %RA was 23.51% ± 16.33%, and %NMT was 55.08% ± 8.52%. A strong negative correlation was observed between AWD and %VB (r = -0.621; P = .0007), a marked positive correlation was found between AWD and %RA (r = 0.565; P = .002), and a minimal positive correlation, without statistical significance, was found between AWD and %NMT (r = 0.076; P = .365). CONCLUSIONS: The results of this study suggest that AWD may have an important influence on the maturation and consolidation of a mixture of cortical and cancellous allograft in the maxillary sinus.

Analysis of the influence of residual alveolar bone height on sinus augmentation outcomes.

INTRODUCTION: Maxillary sinus augmentation is a predictable implant site development technique for posterior atrophic maxillary ridges. However, graft consolidation requires adequate angiogenesis and migration of osteogenic cells from native bone. Therefore, the amount of residual bone height (RBH) may play a role in the rate of graft maturation. The purpose of this study was to analyze the influence of RBH in the histomorphometric outcomes of maxillary sinus augmentation procedures. MATERIAL AND METHODS: Patients in need of sinus augmentation were recruited for the study. Customized radiographic guides were fabricated and a cone-beam computerized tomography scan was obtained at baseline. Two examiners measured RBH on the scans at the locations marked by the radiographic guide. Sinus grafting was performed by a lateral window approach using a particulated mineralized allograft. Patients were followed up for 6 months. At the time of implant placement, bone core biopsies were harvested using the radiographic guide, which was converted into a surgical guide. Samples were histomorphometrically analyzed. Proportion of vital bone (%VB), remaining allograft particles (%RA), and non-mineralized tissue (%NMT) were quantified. Categorical analysis of correlation of RBH (<4 or ≥4 mm) with%VB and%RA was performed using a statistical model. RESULTS: Twenty-one patients underwent sinus augmentation for a total of 21 sinuses. One patient developed an infection after grafting and was excluded. Histomorphometric analysis revealed that mean%VB was 20.47 ± 18.25, mean %RA was 29.04 ± 24.94, and average %NMT was 50.47 ± 12.76. No significant correlation between RBH and %VB (r = 0.016; P = 0.951), and RBH and % (r = 0.009; P = 0.971) was found. Similarly, categorical analysis of correlation showed no statistical significance. CONCLUSION: These findings suggest that the remaining alveolar bone height does not appear to influence the maturation and consolidation of an allograft in the maxillary sinus.

Hard and soft tissue changes after crestal and subcrestal immediate implant placement.

BACKGROUND: The purpose of this study is to assess the influence of the placement level of implants with a laser-microtextured collar design on the outcomes of crestal bone and soft tissue levels. In addition, we assessed the vertical and horizontal defect fill and identified factors that influenced clinical outcomes of immediate implant placement. METHODS: Twenty-four patients, each with a hopeless tooth (anterior or premolar region), were recruited to receive dental implants. Patients were randomly assigned to have the implant placed at the palatal crest or 1 mm subcrestally. Clinical parameters including the keratinized gingival (KG) width, KG thickness, horizontal defect depth (HDD), facial and interproximal marginal bone levels (MBLs), facial threads exposed, tissue-implant horizontal distance, gingival index (GI), and plaque index (PI) were assessed at baseline and 4 months after surgery. In addition, soft tissue profile measurements including the papilla index, papilla height (PH), and gingival level (GL) were assessed after crown placement at 6 and 12 months post-surgery. RESULTS: The overall 4-month implant success rate was 95.8% (one implant failed). A total of 20 of 24 patients completed the study. At baseline, there were no significant differences between crestal and subcrestal groups in all clinical parameters except for the facial MBL (P = 0.035). At 4 months, the subcrestal group had significantly more tissue thickness gain (keratinized tissue) than the crestal group compared to baseline. Other clinical parameters (papilla index, PH, GL, PI, and GI) showed no significant differences between groups at any time. A facial plate thickness ≤1.5 mm and HDD ≥2 mm were strongly correlated with the facial marginal bone loss. A facial plate thickness ≤2 mm and HDD ≥3 were strongly correlated with horizontal dimensional changes. CONCLUSIONS: The use of immediate implants was a predictable surgical approach (96% survival rate), and the level of placement did not influence horizontal and vertical bone and soft tissue changes. This study suggests that a thick facial plate, small gaps, and premolar sites were more favorable for successful implant clinical outcomes in immediate implant placement.

Cross-sectional analysis of the mandibular lingual concavity using cone beam computed tomography.

OBJECTIVES: To study the prevalence and the degree of lingual concavity in the edentulous first molar region from cone beam computed tomography (CBCT) scans of the mandibles. MATERIAL AND METHODS: Qualified cross-sectional images in mandibular first molar edentulous region taken from CBCT were selected. The mandible morphology 2 mm above the inferior alveolar canal (IAC) was classified into the convex (C), parallel (P) and undercut (U) type, based on the presence of lingual concavity and the shape of alveolar ridge. The prevalence of each group was determined. Subsequently, the lingual concavity characters, including the depth, the angulation and the vertical location were determined by the measurements of selected anatomic landmarks. RESULTS: One hundred and three subjects (mean age 51 with a range of 23.7-70.4 years) were studied. The U type was the most prevalent, accounting for 66% of the study population. The mean undercut depth and angulation at the level 2 mm above IAC were on average 2.4 mm and 57.7°. The mean vertical distances from the most prominent point (P) of the lingual concavity to the cemento-enamel junction of second premolar and the inferior border of the mandible were 11.7 and 14.9 mm, respectively. CONCLUSIONS: The anatomic location and the degree of the lingual concavity presented in this article add more information in implant treatment planning in the mandibular first molar edentulous region.

Risk assessment of lingual plate perforation in posterior mandibular region: a virtual implant placement study using cone-beam computed tomography.

BACKGROUND: Lingual plate perforation at the time of implant placement in posterior mandible is a potential surgical complication, and presence of a lingual concavity is considered a risk factor. Little is known about the spatial relationship between implant and lingual plate. The role of lingual concavity in the risk of lingual perforation has not yet been fully studied. This computer-simulated study investigates the incidence of lingual plate perforation in edentulous mandibular first molar region and the risk of perforation in the area of lingual concavity. METHODS: One hundred and three qualified cone-beam computed tomography scans were selected from the database. Implants of various dimensions were virtually placed into the area using computer software. The distance between implant tip and lingual plate was measured using a digital caliper. Incidence of lingual plate perforation and proximity of the implant tip to lingual plate were measured for three types of cross-sectional mandibular morphology. RESULTS: One hundred and three cone-beam computed tomography scans with 118 sites were available for analysis. The intraexaminer and interexaminer agreements were 0.93 and 0.89, respectively. The predicted incidence of lingual plate perforation was 1.1% to 1.2%. Most implants, which were within 1 mm from lingual plate, occurred in sites with lingual concavity (type-U ridge). CONCLUSIONS: This study demonstrates a novel experimental design by which the spatial relation between implant and lingual plate in mandibular first molar region is investigated. Incidence of lingual plate perforation during implant placement is predicted to be 1.1% to 1.2% and it will most likely happen in type-U ridge.

Clinical and histologic outcomes after the use of a novel allograft for maxillary sinus augmentation: a case series.

PURPOSE: To document the clinical and histologic outcomes of sinus augmentation using a novel allogenic bone substitute as a sole grafting material. MATERIALS: Patients in need of sinus augmentation before implant placement were recruited for this study. Sinus augmentation procedures were performed following a lateral approach, using a freeze-dried allograft as the only grafting material. Patients were followed up postoperatively for 6 months. Plaque score, wound healing, and patient discomfort were recorded at each follow-up visit. Implants were placed between 6 and 7 months after sinus augmentation and restored 6 months later. Bone core biopsy specimens were harvested at the time of implant placement and processed for histologic and histomorphometrical analysis. Vital bone, remaining allograft (RA) particles, and nonmineralized tissue percentages were assessed on each sample. Results were expressed as mean percentages with SD. RESULTS: Of the 23 sinus patients, 20 patients underwent sinus augmentation surgery. All patients had satisfactory postoperative healing in the absence of complications. A total of 39 implants were placed. One implant failed and was replaced 3 months later. Histologic analysis revealed the presence of well-organized lamellar bone, in direct contact with RA particles. Mean vital bone was 23.02 +/- 19.11%, mean RA was 22.25 +/- 20.30%, and average nonmineralized tissue was 54.73 +/- 13.51%. CONCLUSION: Clinical and histologic findings support the suitability of an allograft consisting of a combination of cortical and cancellous chips for sinus augmentation procedures.