Peri-implant Bone Level Research Articles

Macrophage polarization in aseptic bone resorption around dental implants induced by Ti particles in a murine model.

Titanium particles/ions detected in peri-implant tissues have been considered as a potential etiologic factor for crestal bone loss around oral implants. However, the definite impact of titanium wear particles on the health of surrounding structures remains undetermined. The purpose of this study was to investigate the effects of titanium particles-induced foreign body reaction on peri-implant bone level and the related mechanism by using clodronate liposomes to deplete macrophages. Sprague Dawley rats with custom-made titanium screw implanted in bilateral maxillary first molar area for 4weeks to obtain osseointegration were randomly divided into four groups. Twenty microgram titanium particles were introduced into the peri-implant tissue to induce aseptic foreign body reaction, and macrophages were depleted by the local injection of 100μL clodronate liposome immediately and re-injection every 3days until the sacrifice of the rats (Ti + LipClod group). Titanium-injected rats also treated with phosphate buffer solution (Ti + PBS) or empty liposome (Ti + Lip) as well as rats injected with PBS alone (Control) were included as controls. Eight weeks later, animals were sacrificed and samples containing implants were collected. Half of the samples were analyzed radiologically to measure bone level change, and macrophage markers (CD68, CCR7, CD163) was also characterized by immunofluorescence to evaluate macrophage number, density, and phenotype distribution (CCR7+M1/CD163+M2). The rest of the samples were used to determine the relative mRNA expression levels of TNF-α, IL-1β, IL-6, and RANKL with real-time PCR analysis. No obvious bacterial contamination was found in all titanium-injected areas, and the implant survival rate was 100% with no implant loss. Compared with Ti+PBS and Ti+Lip group, macrophage density (1.64±0.86%) infiltrated into peri-implant tissue and bone loss (0.17±0.03mm) around implant decreased significantly in the Ti+LipClod group. Immunofluorescence analysis showed that more macrophage infiltrated into peri-implant tissue in the Ti+PBS and Ti + Lip groups, predominantly with M1 phenotype. In contrast, the macrophage density was lower and M2 phenotype was dominant in the Control group, while macrophages density was significantly reduced and the M1 type macrophages were slightly more than M2 type in the Ti + LipClod group. Accordingly, TNF-α, IL-1β, IL6, and RANKL mRNA expression increased significantly in the Ti+PBS and Ti+Lip groups compared with Control and Ti+LipClod groups. Titanium particles had a negative effect on peri-implant tissue by activating macrophages which induced an M1 macrophage phenotype promoting local secretion of inflammatory cytokines. It was found that clodronate liposome treatment attenuated the severity of inflammation and bone loss by depletion of macrophages. Therefore, the present study revealed the marked impact of macrophage polarization with respect to peri-implant bone loss caused by titanium particles.

Influence of implant-abutment connection structure on peri-implant bone level in a second molar: A 1-year randomized controlled trial.

PURPOSEThis study aimed to evaluate the effect of two different implant-abutment connection structures with identical implant design on peri-implant bone level.MATERIALS AND METHODSThis clinical study was a patient-blind randomized controlled trial following the CONSORT 2010 checklists. This trial was conducted in 24 patients recruited between March 2013 and July 2015. Implants with internal friction connection were compared to those with external hex connection. One implant for each patient was installed, replacing the second molar. Implant-supported crowns were delivered at four months after implant insertion. Standardized periapical radiographs were taken at prosthesis delivery (baseline), and one year after delivery. On the radiographs, distance from implant shoulder to first bone-to-implant contact (DIB) and peri-implant area were measured, which were the primary and secondary outcome, respectively.RESULTSEleven external and eleven internal implants were analyzed. Mean changes of DIB from baseline to 1-year postloading were 0.59 (0.95) mm for the external and 0.01 (0.68) mm for the internal connection. Although no significant differences were found between the two groups, medium effect size was found in DIB between the connections (Cohen's d = 0.67).CONCLUSIONConsidering the effect size in DIB, this study suggested the possibility of the internal friction connection structure for more effective preservation of marginal bone.

Ridge Preservation Using an Innovative Enzyme-deantigenic Equine Bone Paste: A Case Report with 36-month Follow-up

This study aimed to report a successful clinical, histological, and histomorphometric outcome of a novel equine-derived bone paste for a ridge preservation surgery involving a single post-extractive socket. After tooth avulsion, unless the implant position is not carried out straightforwardly, the alveolar process undergoes resorption: to limit it, post-extractive sockets may be grafted according to the ridge preservation principles. Grafting materials should display proper biological properties and optimal handling characteristics. Bone pastes may facilitate grafting operations, avoid granules' dispersion, and maximize the contact of the graft with the surrounding bone. An innovative equine-derived bone paste has been recently introduced on the market, but its use has never been documented in the medical literature. This report describes the treatment of a patient who received the equine-derived bone paste in a post-extractive socket to allow the preservation of the alveolar ridge and was later rehabilitated with a crown supported by a single implant. The handling properties of the equine-derived bone paste were excellent. At the 36-month follow-up, the peri-implant bone levels had been maintained, with the implant being successful according to the Albrektsson and Zarb criteria. Histologic outcome showed that the bone paste was fully biocompatible; histomorphometric analysis showed that a significant amount of newly formed bone could be observed in the grafted socket. Alveolar ridge preservation using bone grafts is a well-known approach, yet there is still no agreement about which bone graft might be considered the most suitable for this indication. The novel equine-derived bone paste used in the present study appears a promising option for effective socket preservation and may promote secondary intention healing. How to cite this article: Di Stefano DA, Arosio P, Cinci L, et al. Ridge Preservation Using an Innovative Enzyme-deantigenic Equine Bone Paste: A Case Report with 36-month Follow-up. J Contemp Dent Pract 2019;20(10):1229-1234.

Does traumatic occlusal forces lead to peri-implant bone loss? A systematic review.

Observational studies have indicated that crestal bone level changes at implants are typically associated with clinical signs of inflammation, but still mechanical overload has been described as possible factor leading to hard-tissue deficiencies at implant sites without mucosal inflammation. The aim of this paper was systematically review the literature regarding the possible effect of traumatic occlusal forces on the peri-implant bone levels. Literature search was conducted using PubMed, Scielo and Lilacs, including the following terms: oral OR dental AND implant$ AND (load OR overload OR excessive load OR force$ OR bruxism) AND (bone loss OR bone resorption OR implant failure$). Databases were searched for the past 10 years of publications, including: clinical human studies, either randomized or not, cohort studies, case control studies, case series and animal research. Exclusion criteria were review articles, guidelines and in vitro and in silico (finite element analysis) research, as well as retrospective studies. The PICO questions formulated was: "does traumatic occlusal forces lead to peri-implant bone loss?" The database searches as well as additional hand searching, resulted in 807 potentially relevant titles. After inclusion/exclusion criteria assessment 2 clinical and 4 animal studies were considered relevant to the topic. The included animal studies did not reveal an association between overload and peri-implant bone loss when lower overloads were applied, whereas in the presence of excessive overload it seemed to generate peri-implant bone loss, even in the absence of inflammation. The effect of traumatic occlusal forces in peri-implant bone loss is poorly reported and provides little evidence to support a cause-and-effect relationship in humans, considering the strength of a clinically relevant traumatic occlusal force.

A Radiographic Evaluation of Peri-implant Bone Level in Immediate and Conventionally Loaded Implants Using Flap and Flapless Techniques

The purpose of this research is to compare peri-implant bone level in immediate and conventionally loaded implants using flap and flapless techniques. Forty patients were selected and were subjected into four groups. Group A: 10 patients with immediate loading (IL) by raising the flap. Group B: 10 patients with IL without raising the flap. Group C: 10 patients with conventional loading by raising the flap. Group D: 10 patients with conventional loading without raising the flap. It was observed that for most of the flapless techniques with IL cases, the bone loss settled at first thread or just below the implant collar after 6 months. It was seen that the crestal bone height was reduced in both flap and flapless techniques by immediate and conventional loading, respectively. On comparing the bone loss, the flapless approach by IL showed statistically significant lesser reduction as determined by radiovisiography. Postoperative pain was less in the flapless technique as compared to the traditional flap technique. IL minimizes invasiveness, complexity, and also improves acceptance by patients.

Periodontal disease, peri-implant disease and levels of salivary biomarkers IL-1β, IL-10, RANK, OPG, MMP-2, TGF-β and TNF-α: follow-up over 5 years.

Objective The aim of this study was to evaluate the levels of salivary biomarkers IL-1β, IL-10, RANK, OPG, MMP-2, TG-β and TNF-α in individuals with diagnosis of peri-implant mucositis in the absence or presence of periodontal and peri-implant maintenance therapy (TMPP) over 5 years.Material and Methods Eighty individuals diagnosed with peri-implant mucositis were divided into two groups: one group that underwent periodontal and peri-implant regularly maintenance therapy, called GTP (n=39), and a second group that received no regular maintenance GNTP (n=41). Each participant underwent a complete periodontal and peri-implant clinical examination. Collection of saliva samples and radiographic examination to evaluate peri-implant bone levels were conducted at two times: initial examination (T1) and after 5 years (T2). The salivary samples were evaluated through ELISA for the following markers: IL-1β, IL-10, RANK, OPG, MMP-2, TGF and TNF-α.Results A higher incidence of peri-implantitis was observed in the GNTP group (43.9%) than in the GTP group (18%) (p=0.000). All individuals (n=12) who presented peri-implant mucositis and had resolution at T2 were in the GTP group. After 5 years, there was an increase in the incidence of periodontitis in the GNTP group compared to the GTP group (p=0.001). The results of the study revealed an increase in the salivary concentration of TNF-α in the GNTP group compared to the GTP group. The other salivary biomarkers that were evaluated did not show statistically significant differences between the two groups.Conclusions The salivary concentration of TNF-α was increased in individuals with worse periodontal and peri-implant clinical condition and in those with a higher incidence of peri-implantitis, especially in the GNTP group. Longitudinal studies in larger populations are needed to confirm these findings and elucidate the role of this biomarker in peri-implant disease.

The Implant stability and bone height changes for immediately loaded single implant-retained mandibular overdentures with locator attachments

Aim: The aim was to evaluate the efficacy of attachment placement on initial stability and bone height changes for immediately loaded single-implants retaining mandibular overdentures.
 Methodology: Twenty edentulous patients were recruited for this study; 9 females (45.0%) and, 11 males (55.0%) (age ranged from 59.0 to 70.0 year). Single endoosseos implant was inserted in the mandibular midline region. Immediately after surgery; Locator abutment was secured on the implant and the male housing was connected intraorally using direct pick-up procedure. Marginal bone height measurements and implant stability values were assessed at the time of implant placement (baseline), 2,4,6,8, 12, 24 weeks then every 6-month interval up to 18 months post-implant placement. 
 Results: The implant stability values decreased markedly from the baseline, during 4 weeks and, then increased gradually until reaching the initial values after 12 weeks followed by continuous increase to study’s end (p<0.05). The peri-implant marginal bone level revealed an acceptable range of bone loss with a statistically significant differences between different follow-up times and it continued to the end of the study (p<0.05).
 Conclusion: Retaining an overdenture by immediately loaded single implant could be a successful treatment option for mandibular edentulous arches, especially in people with limited financial resources. The use of Locator attachment seemed to have a favorable effect on implant stability and marginal bone around immediately loaded single implant mandibular overdenture after 18-months of function.

Outcome of early dental implant placement versus other dental implant placement protocols: A systematic review and meta-analysis.

The aim of this systematic review and meta-analysis was to compare the clinical efficacy of the early dental implant placement protocol with immediate and delayed dental implant placement protocols. An electronic and manual search of literature was made to identify clinical studies comparing early implant placement with immediate or delayed placement. Data from the included studies were pooled and quantitative analyses were performed for the implant outcomes reported as the number of failed implants (primary outcome variable) and for changes in peri-implant marginal bone level, peri-implant probing depth, and peri-implant soft tissue level (secondary outcome variables). Twelve studies met the inclusion criteria. Significant difference in risk of implant failure was found neither between the early and immediate placement protocols (risk difference=-0.018; 95% confidence interval [CI]=-0.06, 0.025; P=0.416) nor between early and delayed placement protocols (risk difference=-0.008; 95% CI=-0.044, 0.028; P=0.670). Pooled data of changes in peri-implant marginal bone level demonstrated significantly less marginal bone loss for implants placed using the early placement protocol compared with those placed in fresh extraction sockets (P=0.001; weighted mean difference=-0.14mm; 95% CI=-0.22, -0.05). No significant differences were found between the protocols for the other variables. The available evidence supports the clinical efficacy of the early implant placement protocol. Present findings indicate that the early implant placement protocol results in implant outcomes similar to immediate and delayed placement protocols and a superior stability of peri-implant hard tissue compared with immediate implant placement.

A doxycycline-treated hydroxyapatite implant surface attenuates the progression of peri-implantitis: A radiographic and histological study in mice.

Oral rehabilitation with dental implants has become increasingly common; however, the increase of peri-implantitis is a great concern. Doxycycline (DOX) is a widely used antibiotic that inhibits bacteria growth, inflammation, and bone resorption. To evaluate the progression of peri-implantitis of hydroxyapatite (HA)-coated implants with (5 mg/mL, DOX group) or without (HA group) DOX treatment on the surface. The maxillary first molars of 20 male mice were extracted. Eight weeks later, small titanium screw implants coated with thin HA and treated with or without DOX were placed at the extracted sites. Four weeks after implant placement, half of the animals in both groups were sacrificed, and ligatures were placed around the implant necks in the other half. These mice were sacrificed 4 weeks later. The bone around the implants was examined radiologically and histologically. Four weeks after the ligature placement, the radiographic measurements revealed that peri-implant bone levels of palatal and mesial sites, and histological measurements showed that bone levels of mesial and distal sites in the DOX group were significantly higher than those in the HA group. The present results indicating that the DOX-treated HA implant surface attenuates the progression of peri-implantitis.

Clinical Outcome of Implants Placed in Staged Maxillary Sinus Augmentation Using Bovine Bone Mineral Mixed with Autogenous Bone at Three Different Ratios: A 5-Year Prospective Follow-up Study.

To evaluate the 5-year clinical outcomes for implants placed in a staged sinus floor elevation (SFE) procedure and to compare three patient groups with sinus grafts with three different ratios of bovine bone mineral (BBM) and autogenous bone (AB) mixture. A 5-year prospective cohort study was conducted on 81 patients with 119 staged SFEs non-randomly distributed to three groups based on the origin of the AB and the mixture ratio with BBM: group 1 (locally harvested AB [LHB] from osteotomy sites + BBM, ratio: 1:10), 31 patients, 37 SFEs; group 2: (LHB + intraorally harvested peripheral AB [IHPB] from retromolar/chin region + BBM, ratio: 1:4), 22 patients, 29 SFEs; and group 3 (LHB + extraorally harvested peripheral AB [EHPB] from iliac crest/tibia + BBM, ratio 1:1), 28 patients, 53 SFEs. After graft healing (5 to 7 months), 284 dental implants (group 1: 76, group 2: 61, group 3: 147 [overall: 2.3 implants/sinus]) were placed. After an additional healing period (5 to 7 months), all implants placed were functionally loaded and prospectively followed by clinical and radiographic evaluations assessing implant survival/success rate as well as peri-implant marginal bone level (MBL) alteration at 1, 3, and 5 years postloading. A total of 76/81 patients with 267/284 implants were followed for up to 5 years (dropouts: 5 patients/15 implants; implant loss = 2). The 5-year implant survival and implant success rate (group 1: 100%/98.6%; group 2: 98.3%/96.6%; group 3: 99.3%/95.7%) did not differ between the three graft mixture groups. The peri-implant marginal bone alteration (reduction) averaged over all 5 years was 1.40 ± 0.29 mm for group 1, 1.41 ± 0.22 mm for group 2, and 1.46 ± 0.46 mm for group 3 (P = .187). However, over time, a continual and significant MBL reduction (P = .045) was noted for all groups presenting peri-implant MBL changes between 1 year and 5 years of -0.17 mm (group 1), -0.12 mm (group 2), and -0.24 mm (group 3), respectively. According to the clinical results obtained, dental implants inserted in grafted (staged) SFE using a mixture of BBM with a minimal amount of AB harvested from local sites provide for similarly high 5-year implant/augmentation success rates as graft mixtures with AB harvested from peripheral intraoral or extraoral donor sites, confirming no need for additional bone harvesting.

Immediate Implant Placement Into Fresh Extraction Sites Using Single-Drilling Bur and Two Loading Procedures: Follow-Up Results

Modern clinical protocols in implantology aim at shortening the treatment time and reducing duration and discomfort of the surgical phase, while maintaining optimal treatment outcomes. The purpose of this study was to evaluate clinical outcomes of implants immediately placed in extraction sites, using a single drilling step for implant site preparation. One-hundred thirty-three patients (mean age 55.3 ± 12.7 [SD] years, range 20-83 years) were treated at 2 clinical centers. Two-hundred sixty-one implants were inserted in fresh postextraction sockets. One-hundred sixty-five implants were immediately loaded (IL) and 96 underwent delayed loading (DL). Implant survival, peri-implant bone level change and patients' satisfaction were assessed after at least 3 years of function. No patient dropout occurred. The mean follow-up was 63.61 ± 11.52 months (range 39.71-85.71 months) from prosthesis delivery. Two IL and 1 DL implant failed in 3 patients. Implant survival was 98.8% and 99% for IL and DL group, respectively. The mean marginal bone loss after 1 year was 0.48 ± 0.40 mm and 0.52 ± 0.34 mm for IL and DL group. No biological nor mechanical complications occurred. All patients demonstrated full satisfaction. The present protocol with single burs for site preparation produced satisfactory clinical outcomes independent of the loading timing. Further long-term comparative studies are needed to confirm the present findings.

The conometric concept‐ immediate definitive full arch rehabilitation of the edentulous maxilla supported by cone‐in‐cone abutments and guided implants‐ a preliminary report

Background The use of a cone in cone Morse taper connection between the abutment and the crown to retain an implant-supported definitive fixed dental prosthesis (FDPs) has been recently proposed in the literature. This prosthetic approach, named Conometric Concept, was used to retain both lithium disilicate and zirconia structures. Aim/Hypothesis The aim of this study was to evaluate the rehabilitation of fully edentulous maxillae with immediate full arch zirconia restorations supported by implants placed using guided surgery and cone in cone connection abutments. Material and Methods A maxillary surgical guide was manufactured using CBCT and six implants were placed in the planned sites. The fixtures were inserted in both healed sites or fresh extraction sockets. The definitive planned abutments and the respective conical caps were placed in the planned position and the full-arch zirconia restoration cemented to the caps intra-orally. The restoration was then removed from the oral cavity with a spring bridge remover, the excess of cement was removed, the structure was polished and reinserted. Peri-implant bone levels and pocket depths were recorded for three years at each follow-up visit. Esthetic, functional and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed at the last follow-up appointment. The opposing dentition was categorization by type of restoration and supporting structure at the time of placement of the full-arch restoration and at the three-year follow-up. Results A total of 12 full-arch restorations supported by 72 implants reached the three-year follow-up. None of the prostheses broke, became loose or detached. No significant difference involving peri-implant bone and probing levels between the experimental times were found. Conclusions and Clinical Implications The results of this preliminary report demonstrated that the edentulous maxilla can be restored with an immediate full-arch zirconia restoration placed the day of the surgery supported by implants placed using guided surgery and cone in cone connection abutments.

The effect of antiresorptive drugs on implant therapy: Systematic review and meta-analysis.

A considerable portion of the adult population has received and/or is receiving treatment with antiresorptive drugs (ARDs). It is thus relevant to assess possible side effects of ARD intake in connection to various aspects of implant therapy. The aim of this study was to answer the focused question "In patients with systemic intake of ARDs, what is the outcome and complication rate of implant therapy including associated bone grafting procedures comparing to patients without systemic intake of ARDs?" Original studies fulfilled predefined inclusion criteria (e.g., case series, cohort studies, case-control studies, and controlled and/or randomized controlled clinical trials; retro- or prospective design; and ≥10 patients with systemic intake of ARDs). Various patient-, medication-, and intervention-related parameters [i.e., implant loss, grafting procedure complication/failure, peri-implant marginal bone levels/loss, medication-related osteonecrosis of the jaws (MRONJ), and peri-implantitis] were extracted, and meta-analyses and quality assessment were performed. Twenty-four studies with bisphosphonate (BP) intake (mainly low dose for osteoporosis treatment) and seven studies on hormone replacement therapy (HRT), including ≥10 patients, and controls not taking the medication were identified. Furthermore, seven studies on MRONJ associated with implants were included. Meta-analyses based on four studies reporting on patient level and eight studies reporting on implant level showed no significant differences in terms of implant loss between patients on BPs (mainly low dose for osteoporosis treatment) and controls. Furthermore, low-dose BP intake did not compromise peri-implant marginal bone levels. Based on two studies, no negative effect of HRT was observed on the implant level, while HRT appeared to exert a marginally significant negative effect regarding implant survival on the patient level and regarding peri-implant marginal bone levels. Based on six studies reporting single-patient data, MRONJ in patients on BP for osteoporosis appeared in 70% of the cases >36months after start of drug intake, while in patients with cancer, MRONJ appeared in 64% of the cases ≤36months after first BP intake. Low-dose oral BP intake for osteoporosis treatment, in general, does not compromise implant therapy, that is, patients on ARDs do not lose more implants nor get more implant-related complications/failures comparing to implant patients without BP intake. There is almost no information available on the possible effect on implant therapy of high-dose BPs or other widely used ARDs (e.g., denosumab), or on the success or safety of bone grafting procedures. Patients with high-dose ARD intake for management of malignancies, patients on oral BP over a longer period of time, and patients with comorbidities should be considered as high-risk patients for MRONJ.

Clinical outcomes of peri-implantitis treatment and supportive care: A systematic review.

To report the clinical outcomes for patients with implants treated for peri-implantitis who subsequently received supportive care (supportive peri-implant/periodontal therapy) for at least 3years. A systematic search of multiple electronic databases, grey literature and hand searching, without language restriction, to identify studies including ≥10 patients was constructed. Data and risk of bias were explored qualitatively. Estimated cumulative survival at the implant- and patient-level was pooled with random-effects meta-analysis and explored for publication bias (funnel plot) at different time intervals. The search identified 5,761 studies. Of 83 records selected during screening, 65 were excluded through independent review (kappa=0.94), with 18 retained for qualitative and 13 of those for quantitative assessments. On average, studies included 26 patients (median, IQR 21-32), with 36 implants (median, IQR 26-45). Study designs (case definitions of peri-implantitis, peri-implantitis treatment, supportive care) and population characteristics (patient, implant and prosthesis characteristics) varied markedly. Data extraction was affected by reduced reporting quality, but over 75% of studies had low risk of bias. Implant survival was 81.73%-100% at 3years (seven studies), 74.09%-100% at 4years (three studies), 76.03%-100% at 5years (four studies) and 69.63%-98.72%at 7years (two studies). Success and recurrence definitions were reported in five and two studies respectively, were heterogeneous, and those outcomes were unable to be explored quantitatively. Therapy of peri-implantitis followed by regular supportive care resulted in high patient- and implant-level survival in the medium to long term. Favourable results were reported, with clinical improvements and stable peri-implant bone levels in the majority of patients.

Clinical and radiographic outcomes of a surgical reconstructive approach in the treatment of peri-implantitis lesions: A 5-year prospective case series.

The aim of this study was to evaluate the 5-year clinical and radiographic outcomes following reconstructive therapy of peri-implantitis lesions using mineralized dehydrated bone allograft and resorbable membrane in the nonsubmerged mode of wound healing. Thirty-four patients with at least one implant diagnosed with peri-implantitis were treated by mechanical debridement; chemical decontamination using hydrogen peroxide (3%), chlorhexidine (0.2%), and a tetracycline hydrochloride solution; and bone defect filling with mineralized dehydrated bone allograft and resorbable membrane. Clinical and radiographic assessments were obtained during 5-year follow-up. The primary outcome was the absence of additional marginal peri-implant bone loss ≥1.0mm after surgery, and the composite outcome included the additional marginal peri-implant bone loss, absence of probing depth (PD) ≥5mm, and absence of bleeding on probing (BoP)/suppuration. According to the primary and composite outcomes, the success rate of 34 implants included in the study was 100% and 91% (N=31), at 1year after surgery, and decreased progressively to 77% (N=26) and to 59% (N=20) at 5-year follow-up, respectively. Five years following treatment, only the BoP reduction was statistically significant compared to baseline (p<0.001), and no difference was found in PD (p=0.318) and in marginal peri-implant bone level (p=0.064). At 1-year follow-up, the surgical reconstructive therapy showed clinical improvement and radiographic defect filling. However, the results appeared to be unpredictable over time, due to a progressive decrease in the bone filling of the peri-implant defects and an increase in the mean PD.

Implant rehabilitation of the edentulous jaws: Does tilting of posterior implants at an angle greater than 45° affect bone resorption and implant success?: A retrospective study.

This study aimed to (1) investigate the success of posterior implants tilted >45° when 4 immediately loaded implants were used to support full-arch prostheses, eliminating any distal cantilever and (2) examine the effect on marginal bone loss (MBL) of different combinations of anterior multi-unit abutment (MUA) angles and posterior implant tilting angles. Records of patients rehabilitated according to the Columbus Bridge Protocol were analyzed. Peri-implant bone levels (PBLs) and MBL were measured for each implant. The influence of posterior implant tilting angle on PBL, MBL, and implant and prosthetic success rate was investigated. The impact on the same endpoints of different anterior MUA angles, and different combinations of anterior MUA and tilted posterior implant angles was also examined. Records of 41 patients were analyzed, for a total of 46 complete rehabilitations, and 142 implants (52 anterior, 63 posterior tilted ≤45° [group 1], and 27 posterior tilted >45° [group 2]). No implants were lost during the follow-up (25.9 months), and no prosthetic complications were reported. Success rate for posterior implants was 100% in group 1 and 96.3% in group 2. Mean MBL differed significantly between the 2 groups (0.45 mm in group 1, 0.66 in group 2 [P = .04]), but not when the analysis was limited to implants in the same jaw. Implant tilting angle did not correlate with MBL and the MUA angle had no effect on bone resorption around posterior implants, neither in the sample as a whole nor in individual patients. Posterior implants tilted >45° to eliminate distal cantilever may be as safe as those tilted less in severely atrophic jaws rehabilitated with immediately loaded, full-arch prostheses supported on 4 implants. Further prospective studies on larger samples of patients and implants and with longer follow-up are needed to confirm these findings.

Retrospective radiographic observational study of 1692 Straumann tissue-level dental implants over 10 years. II. Marginal bone stability.

Despite accumulating evidence for the longitudinal stability of the marginal bone level around an implant, there is limited evidence of predisposing risk factors for marginal bone loss based on some implants in a relatively large patient population. The aim of this study was to retrospectively determine the marginal bone loss around Straumann tissue-level dental implants during follow-up periods among which the maximum lasts up to 10 years, as well as the predisposing risk factors for peri-implant marginal bone loss. This study analyzed 1692 Straumann tissue-level dental implants in 881 patients, and relevant data were collected. The peri-implant marginal bone level was measured on periodic radiographs, and the changes in bone level were analyzed cumulatively from surgery until up to 10 years later. The log-rank test was used to select candidate critical risk factors for marginal bone loss, and multivariate analysis using Cox regression with the shared frailty model was performed. The overall peri-implant bone loss was 0.07 ± 0.21mm, 0.09 ± 0.26mm, 0.14 ± 0.41mm, and 0.17 ± 0.45mm at 3, 5, 7, and 9 years, respectively. Only 14 implants showed pathologic marginal bone loss exceeding 2mm during the follow-up period. While 2 implants were removed with continuous progressive marginal bone loss, 5 of the 14 implants showed early bone loss exceeding 1mm within the first year but then subsequently tended to show a stable marginal bone level. In the other seven implants, bone loss started after the first year and progressed continuously. Multivariate analysis revealed that diameter of the implant affected the peri-implant marginal bone loss. Straumann tissue-level dental implants showed only slight peri-implant marginal bone loss, with a very low incidence of pathologic marginal bone loss exceeding 2mm.

Are Intraoral Radiographs Accurate in Determining the Peri-implant Marginal Bone Level?

The primary objective of this study was to assess the accuracy of periapical radiographs in determining the peri-implant marginal bone level. The accuracy of the linear measurements on radiographs was considered as the absolute difference between the true, intraoperative or surgical marginal bone level measurements (direct bone measurements during surgical procedures) and the radiographic measured distances. The secondary aims were to identify the variables influencing the radiographic evaluation (arch: mandible/maxilla; implant location: anterior/posterior; timing of implant placement: "early delayed" and "prolonged delayed"). The influence of vestibular and palatal/lingual crestal bone levels was also investigated. STROBE guidelines were followed. As soon as the implant was inserted, the marginal bone levels were recorded using a straight periodontal probe (intraoperative or surgical measurements). At the same time, periapical radiographs were taken. To standardize the radiographic images, periapical radiographs were acquired using the long-cone parallel technique and film holding system. All radiographs were analyzed by two examiners blinded to the surgical measurements. Intraclass correlation coefficient (ICC) was employed to assess the intraobserver and interobserver variability. The descriptive statistics, t test, and multivariate statistics were used; the threshold for statistical significance was P ≤ .05. Two hundred sixty-eight implants were inserted in 142 patients. The interobserver agreement was 0.980; the intraobserver variability was 0.990 and 0.993. The mean difference between the radiographic and surgical measurements was 0.45 mm (range: 0 to 8 mm; SD: 1.76). Comparing the radiographic and surgical measurements, a statistically significant difference (P = .000) was detected. None of the variables considered (arch, implant location, and timing of implant placement) significantly influenced the accuracy. Neither the vestibular alveolar edge (P = .908) nor the lingual/palatal (P = .485) significantly influenced the accuracy. The periapical radiograph statistically significantly overestimates the level of peri-implant marginal bone compared with surgical measurements. The arch, implant location, timing of implant placement, and level of vestibular or lingual/palatal alveolar edge do not influence deviation between the intraoperative peri-implant marginal bone level measurements and the radiographically determined marginal bone levels.

A Histologic and Histomorphometric Retrospective Analysis of the Outcomes of Ridge Preservation Using Anorganic Bovine Bone Minerals and a Nonresorbable Membrane

The objective of this study was to examine wound healing in extraction sockets following ridge preservation and the outcome of implants placed in those sites. Extraction sockets (N = 31) were grafted with anorganic bovine bone mineral (ABBM) and covered with dense polytetrafluoroethylene membrane. Bone cores obtained during implant placement were examined histologically and histomorphometrically. Percentages of vital bone and residual graft were 37.5% ± 21.3% and 12.5% ± 8.9%, respectively. New vital bone showed a negative correlation with patient age. Percentage of vital bone formation in sockets was correlated with neither postgraft wound healing time nor peri-implant marginal bone level.

Are intraoral radiographs reliable in determining peri-implant marginal bone level changes? The correlation between open surgical measurements and peri-apical radiographs

This study was performed to evaluate the reliability of peri-apical radiographs in determining peri-implant marginal bone level changes. The STROBE guidelines were followed. Marginal bone levels were measured at the time of implant insertion using a straight periodontal probe and using peri-apical radiographs. These intraoperative and radiographic measurements were repeated at the time of second surgery. All radiographs were analysed by two examiners blinded to the intraoperative measurements. To standardize the radiographic images, the long-cone parallel technique and a film-holding system were used. Intra-observer agreement and inter-observer variability were assessed using the intra-class correlation coefficient (ICC). Descriptive statistics, the t-test, and the Pearson correlation coefficient were also used. A total of 268 implants were inserted in 142 patients. Inter-observer agreement was 0.950; intra-observer variability was 0.980 and 0.973. The mean difference between the radiographic and intraoperative measurements was 0.50±1.55mm (range 0–8mm); the difference was statistically significant (P=0.000). A significant linear correlation was found between the marginal bone level changes evaluated intraoperatively and radiographically (P<0.005). Radiographic analysis significantly overestimated the level of peri-implant marginal bone compared to intraoperative measurements, but peri-apical radiographs are reliable in determining the bone level changes at different follow-ups.