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Introduction: Dental aplasia is an anomaly in which the number of teeth is reduced. It is the most commonly occurring dental anomaly during tooth development. Treatment management of patients with dental aplasia is challenging., Objectives: The aim of this retrospective clinical study was to analyze the survival and success rates of dental implants placed in hypodontic patients, rated with different criteria., Methods: Forty-three patients were diagnosed with dental aplasia and treated with dental implants between November 2000 and February 2016. The variables assessed included the plaque level, bleeding on probing, probing depth, implant mobility, implant stability, and implant loss. To analyze the peri-implant bone level, a panoramic X-ray of each patient was taken. The results were compared with X-rays taken immediately after implantation., Results: Thirty-seven patients (16 males; 21 females) participated in this study. In total, 155 implants (86 maxillary; 69 mandibular) were inserted. Two of the 155 implants failed; the in situ survival rate was 98.7%. The success rate according to the criteria of Buser et al. was 96.8%, and that according to the criteria of Albrektsson et al. was 88.4%., Conclusion: The survival and success rates of dental implants in patients with congenitally absent teeth were very high and did not differ significantly from results achieved in an unaffected population. Dental implants are a reliable therapy for patients with dental aplasia.

Purpose: To evaluate the effect of misfit at implant-level fixed partial dentures (ILFPDs) and marginal bone support on the generation of implant cracks., Materials and Methods: This in vitro study included a mechanical fatigue test and finite element analysis. A mechanical cycling loading test was performed using 16 experimental models, each consisting of two parallel implants subdivided into four groups based on the misfit and the supporting bone condition. The framework, firmly seated at implants, was dynamically loaded vertically with a force of 1,600/160 N and 15 Hz for 1 × 10 6 cycles. Optical microscope, scanning electron microscope (SEM), and computed tomography three-dimensional (CT-3D) analyses were performed to detect impairments. Finite element models, representing the setups in the mechanical fatigue test, were used to represent the fatigue life., Results: None of the mechanical components presented distortion or fracture at the macroscopic level during the test. In a microscopy evaluation, the fatigue test revealed scratches visible in the inner part of the conical portion of the implants regardless of the groups. SEM and CT-3D analysis revealed one implant from the misfit/no bone loss group with a microfracture in the inner part of the conical interface. The simulated effective stress levels in the coronal body were higher in the misfit groups compared with the no misfit groups. The misfit groups presented effective stress levels, above 375 MPa, that penetrated the entire wall thickness. The no bone loss group presented an effective stress level above 375 MPa along its axial direction. In the no misfit group, the area presenting effective stress levels above 375 MPa in the conical connection was larger for the bone loss group compared with the no bone loss group., Conclusion: This study confirmed that implant fracture is an unlikely adverse event. A clear pattern of effective distribution greater than fatigue limit stresses could be noticed when the misfit was present. The dynamic load simulation demonstrated that the crack is more likely to occur when implants are fully supported by marginal bone compared with a bone loss scenario. Within the limitations of this study, it is speculated that marginal bone loss might follow the appearance of an undetected crack. Further research is needed to develop safe clinical protocols with regard to ILFPD.

To evaluate peri-implant bone loss (PIBL) and stability around submerged and non-submerged dental implants in patients with and without type 2 diabetes mellitus (T2DM). Thirty-five T2DM and non-diabetic (NT2DM) patients were included in this study. Demographic data were recorded using a questionnaire and PIBL was measured on digital radiographs. Resonance frequency analysis (RFA) was carried out for each implant at the time of fixture placement and at 3 months in both groups. P values less than 0.05 were considered statistically significant. One hundred and eighteen dental implants with a mean height of 10 to 12 mm and 3.3 to 4.1 mm in diameter were placed. The comparison of the mean RFA values at baseline and at 3 months was statistically significant (p = 0.008) in T2DM patients. The inter-group mean RFA values at baseline and at 3 months were not significant (p > 0.05). PIBL was significantly high in T2DM as compared to NT2DM patients at each follow-up (p < 0.05). At 2, 3, and 7 years, non-submerged dental implants showed significantly high PIBL in T2DM patients as compared to NT2DM individuals (p<0.05). The results of the present clinical study demonstrate increased PIBL around non-submerged single-tooth implant-supported restorations in T2DM patients, which may be due to the immune inflammatory status.

Purpose: The objective of this study was to assess whether long-term implant survival rates and bone loss in patients with moderately controlled type 2 diabetes is similar to the rates reported in the nondiabetic population., Materials and Methods: This retrospective observational study utilized patient medical records from a general practitioner's dental office. The records of patients who had moderately controlled type 2 diabetes with hemoglobin A1C (HbA1c) up to 8% and glucose level below 150 mg/dL were reviewed, as patients with HbA1c up to 7% are considered to be well-controlled type 2 diabetes. Follow-up data were recorded and analyzed. Inclusion criteria were as follows: partially edentulous patients with missing teeth who were subsequently treated with implant-supported prosthetic restorations; patients were at least 18 years of age and demonstrated the ability to maintain oral hygiene. Exclusion criteria were as follows: patients did not present for annual follow-up visits; patients presented with a neglected periodontal status; patient records had incomplete surgical or restorative data or nondiagnostic radiographs; implants with external hexagonal and machined surfaces. All the restorations were cement-retained. Three different implant insertion/placement methods were used: (1) implants immediately inserted following tooth extraction; (2) implants inserted 6 to 8 weeks after tooth extraction to allow for primary healing; and (3) implants inserted 4 to 6 months after tooth extraction., Results: After review of more than 3,256 medical records, 169 patients were identified (with 1,112 implants) who met the inclusion criteria. The mean follow-up time was 8.7 years, with a minimum of 4.9 years. Sixty-seven implants failed, yielding a 94% overall implant survival rate. The overall mean bone loss around the implants was 1.98 (± 1.81) mm. Comparable to data published earlier, no statistical significance in survival rate was found between the nondiabetic and diabetic population. The delayed insertion protocol presented the least bone loss, compared with immediate insertion (P = .06), and compared with early insertion (P = .046)., Conclusion: The results show that implant survival and bone loss levels were comparable to reported outcomes in the nondiabetic population. The delayed insertion protocol presented less bone loss compared with other insertion methods. Likewise, less bone loss was found in implants placed in the posterior region.

Objective: To test whether or not the modified design of the test implant (intended to increase primary stability) has an equivalent effect on MBL compared to the control., Methods: Forty patients were randomly assigned to receive test or control implants to be installed in identically dimensioned bony beds. Implants were radiographically monitored at installation, at prosthetic delivery, and after one year. Treatments were considered equivalent if the 90% confidence interval (CI) for the mean difference (MD) in MBL was in between -0.25 and 0.25 mm. Additionally, several soft tissue parameters and patient-reported outcome measures (PROMs) were evaluated. Linear mixed models were fitted for each patient to assess time effects on response variables., Results: Thirty-three patients (21 males, 12 females; 58.2 ± 15.2 years old) with 81 implants (47 test, 34 control) were available for analysis after a mean observation period of 13.9 ± 4.5 months (3 dropouts, 3 missed appointments, and 1 missing file). The adjusted MD in MBL after one year was -0.13 mm (90% CI: -0.46-0.19; test group: -0.49; control group: -0.36; p = 0.507)., Conclusion: Both implant systems can be considered successful after one year of observation. Concerning MBL in the presented setup, equivalence of the treatments cannot be concluded., Registration: This trial is registered with the German Clinical Trials Register (ID: DRKS00007877).

Objectives: The aim of this study is to evaluate the effect of the surface modification and cervical implant design on the bone remodeling in implants installed at the crestal and subcrestal bone level., Methods: Ten American Fox Hound of approximately 1 year of age, each weighing approximately 14 to 15 kg, were used for this study. Two different dental implant macrodesign were used: cylindric-conical with 3.5 mm of diameter and 9 in length (implant A) and conical with 2.9 mm of diameter and 9 mm in length (implant B). Two surfaces were used: sandblasting and acid etching (surface 1) and sandblasting and acid etching, then maintained in an isotonic solution of 0.9% sodium chloride (surface 2). Four groups were performed (n = 20 implants): Group A1 (implant A with the surface 1), Group A2 (implant A with surface 2), Group B1 (implant B with surface 1), and Group B2 (implant B with surface 2). The mandibular premolars and molars (P1, P2, P3, M1) were removed and, after 2 months of healing, implants were inserted at the crestal and 2 mm subcrestal position related to the buccal bone level. Analysis was performed at 4 and 8 weeks. Histomorphometry with longitudinal measurements and bone implant contact, bone remodeling and implant stability quotient analysis were realized., Results: The surface 2 showed to get more close contact between implant and new bone formed after implant placement and more stability surrounding platform both at 4 and 8 weeks. Surface 2 groups and subrestally placed showed to have better results in terms of linear measurements, with less bone loss and soft tissue distance to the IS. The data showed significant differences among the groups (P < 0.001)., Conclusions: Surface modification (surface 2) has shown to be an effective alternative to conventional surface with better results in situations placed subcrestally and combined with implant design.

The benefits and feasibility of platform switching have been discussed in several studies, reporting lesser crestal bone loss in platform-switched implants than in platform-matched implants. Objective. The aim of the present study was to observe the changes in vertical and horizontal marginal bone levels in platform-switched and platform-matched dental implants. Materials and Methods. 51 patients received 60 dental implants in the present study over a 1-year period. Measurement was performed between the implant shoulder and the most apical and horizontal marginal defect by periapical radiographs to examine the changes of peri-implant alveolar bone before and 12 months after prosthodontic restoration delivery. Results . These marginal bone measurements showed a bone gain of 0.23 ± 0.58 mm in the vertical gap and 0.22 ± 0.53 mm in the horizontal gap of platform matching, while in platform switching a bone gain of 0.93 ± 1 mm ( P < 0.05) in the vertical gap and 0.50 ± 0.56 mm in the horizontal gap was found. The average vertical gap reduction from the baseline until 12 months was 0.92 ± 1.11 mm in platform switching and 0.29 ± 0.85 mm in platform matching ( P < 0.05). Conclusions. Within the limitations of the present study, platform switching seemed to be more effective for a better peri-implant alveolar bone vertical and horizontal gap reduction at 1 year.

More studies evaluating the outcome of dental implant restorations in diabetics are needed. To investigate the outcome of immediate function implant rehabilitations in diabetic patients. This retrospective cohort study included 70 diabetic patients (type 1 = six patients; type 2 = 64 patients; 33 females and 37 males, mean age=59 years), rehabilitated with 352 implants. Primary outcome measure was implant survival estimated at 5 years through the Kaplan-Meier product limit estimator using the patient as unit of analysis (first implant failure as reference); secondary outcome measures were marginal bone loss and biological complications. Risk indicators associated with bone loss >2·0 mm were tested in a multivariate logistic regression model. The level of significance considered was 5%. Seven patients were lost to follow-up (10%). Seven patients lost ten implants rendering a global implant cumulative survival rate for diabetic patients of 89·8% (type 1 = 80·0%; type 2 = 90·5%). The average (95% confidence interval) marginal bone loss at 1 and 5 years was 1·64 mm (0·00;3·32) and 2·55 mm (1·38;3·72) for type 1 diabetic patients, 0·79 mm (0·59;1·00) and 1·45 mm (1·09;1·82) for type 2 diabetic patients and 0·88 mm (0·65;1·10) and 1·56 mm (1·21;1·91) overall. Biological complications occurred in seven patients. Female gender (OR = 28·1) and smoking habits (OR = 10·3) were risk indicators for marginal bone loss >2·0 mm at 5 years when controlled for other variables of interest. Implant rehabilitations represent a valid treatment for diabetic patients, with a good risk/benefit ratio. Female gender and smoking habits were risk indicators for a higher marginal bone resorption at 5 years., (© 2016 John Wiley & Sons Ltd.)

Purpose . To investigate peri-implant alveolar bone changes using periapical radiographs before and after prosthetic delivery in submerged and nonsubmerged dental implants. Methods . Digital periapical films of 60 ITI Straumann nonsubmerged dental implants and 60 Xive Dentsply submerged dental implants were taken before, immediately after, and 12 and 24 weeks after the prosthetic restoration was delivered. Results . The 60-nonsubmerged dental implant group showed mean marginal bone resorption at baseline of 0.10 ± 0.23 mm and 24 weeks later, marginal bone resorption was 0.16 ± 0.25 mm. The submerged dental implant group showed a significantly higher distal marginal bone resorption over the mesial side. Mean marginal bone resorption at baseline was 0.16 ± 0.32 on the mesial and 0.41 ± 0.56 on the distal side. Twenty-four weeks later, it was 0.69 ± 0.69 mm on the mesial and 0.99 ± 0.90 mm on the distal side. Conclusion . First, it was possible to determine that submerged implants had a higher mean marginal bone resorption and less bone-to-implant contact than nonsubmerged implants. And second, the distal side of submerged dental implants presented higher marginal bone loss than the mesial side., Competing Interests: The authors claim to have no financial interests, either directly or indirectly, in the products or information listed in the article.

Objectives: Bone formation and maintenance around implants placed immediately after tooth extraction may be affected by implant surface treatment and compromise long-term esthetic results. This study morphometrically evaluated buccal bone loss and bone-to-implant contact (BIC) of four implant systems placed immediately after tooth extraction in a dog model., Material and Methods: The premolars of eight beagle dogs were bilaterally extracted with a full-thickness flap, and root-form dental implants were placed on the root extraction socket. Implants (n = 16 each) with different surface treatments were placed from sites 1 to 4 and alternated between animals to allow evaluation of the same number of implants at sites and evaluation time points. Implant surface treatments were as follows: anodized, discrete crystalline deposition, SLActive, and microblasted. The left and right side provided implants that stayed for 2 and 4 weeks, respectively. Submerged healing was allowed and bone-to-implant contact (BIC) and buccal bone loss were morphometrically measured. Linear mixed models (P < 0.05) were used to assess differences between groups, across time, and their interaction., Results: Buccal bone loss was observed to approximately double between 2 and 4 weeks (P = 0.01). BIC also increased between 2 and 4 weeks, by 20-25% (P = 0.01). These changes were statistically similar for each surface., Conclusion: When placed immediately after tooth extraction, the evaluated histomorphometric parameters vary only with time., (© 2012 John Wiley & Sons A/S.)

Introduction: As a consequence of extraction, the height of the buccal wall tends to decrease and results in the disappearance of bundle bone. To modify bone remodelling after extraction, various ridge preservation techniques have been proposed. The present research was drawn up with the following considerations in mind: to evaluate and to compare changes of hard and soft tissues in post-extraction sockets which received a ridge preservation procedure, with post-extraction sockets which had healed naturally., Materials and Methods: Each patient was randomly allocated to a test or control group using a specific software package. After extraction, the sockets were carefully inspected and any granulation tissue was removed. The control sites received silk sutures to stabilize the clot without any grafting material. The test sites were grafted with corticocancellous porcine bone and a collagen membrane. All experimental sites had the membranes left exposed to the oral cavity with a secondary wound healing. The thickness of the buccal alveolar bone, if present, was carefully measured at the time of tooth extraction using a calliper at 1 mm from the edge of the wall. The following clinical parameters were evaluated at baseline and after 4 months at implant placement: vertical bone changes, horizontal bone changes and width of keratinized gingiva. The length, diameter and need for additional bone augmentation were assessed for both groups at the time of implant insertion., Results: The control group showed vertical bone resorption of 1 ± 0.7 mm, 2.1 ± 0.6 mm, 1 ± 0.8 mm and 2 ± 0.73 mm at the mesial, vestibular, distal and lingual sites respectively. Moreover, changes in horizontal dimension showed an average resorption of 3.6 ± 0.72 mm. The test sites showed a horizontal bone remodelling of 0.3 ± 0.76 mm, 1.1 ± 0.96 mm, 0.3 ± 0.85 mm, 0.9 ± 0.98 mm at the mesial, vestibular, distal and lingual sites respectively. The horizontal bone resorption at the test sites was 1.6 ± 0.55 mm. The keratinized gingiva showed a coronal shift of 0.7 mm in the control group when compared to 1.1 mm in the test group. In addition, 42% of sites in the control group required an additional bone augmentation at implant placement, when compared to 7% in the test sites., Conclusions: This study clearly points out that an alveolar ridge preservation technique performed with collagenated porcine bone and a resorbable membrane--according to the procedure reported in this study--was able to limit the contour changes after tooth extraction. Finally, the test sites showed a better preservation of facial keratinized tissue when compared to control sites; grafted sites allowed the placement of longer and wider implants when compared to implants inserted in non-grafted sites., (© 2012 John Wiley & Sons A/S.)

Objective: This prospective randomized match-paired controlled trial aimed to evaluate the impact of implant platform diameter on marginal bone level around implants restored according to the platform switching (PS) concept., Material and Methods: A total of 24 implants were examined in 12 patients. All patients received two adjacent implants inserted at the crestal level: 4.3 mm (control group) and 4.8 mm (test group) in diameter. Mesio-distal implant position was randomly performed. According to the PS concept, for restoration, a 3.8 and 4.3 mm diameter abutment was used, respectively in the control and test groups, resulting, in both groups, with 0.25 mm of implant/abutment mismatching. Implant restorations were splinted. Eighteen months after final restoration, periapical standardized digital radiographs were taken to evaluate marginal bone level alterations after loading. The Wilcoxon Signed-Rank Test was selected to identify differences between groups., Results: At the last follow-up, control implants exhibited a mean bone loss value of 1.10 mm (SD: 0.47 mm); the test group showed a mean value of 1.09 mm (SD: 0.08 mm). No statistically significant differences were found between test and control groups., Conclusions: Within the limits of this study, the present results suggest that bone resorption is mostly related to biologic (biologic width re-establishment) rather than to biomechanical factors (implant platform diameter). Furthermore long-term studies with a wider sample size are needed to confirm the platform diameter influence on hard tissue response around implants restored according to the PS concept., (© 2011 John Wiley & Sons A/S.)

Background: Previous studies assessed bone remodeling after a single tooth extraction; however, the effect of multiple contiguous teeth extractions around immediate implant remains unknown. The aim of this microcomputed tomographic investigation is to analyze the alveolar bone remodeling around immediate implants placed in accordance with the extraction socket classification (ESC)., Methods: Under general anesthesia, 10 beagle dogs underwent atraumatic tooth extractions. Animals were randomly divided into three groups, with 16 sites per group: 1) ESC-1, single tooth extraction; 2) ESC-2, two contiguous teeth extraction; and 3) ESC-3, more than two contiguous teeth extractions. Immediate implants were inserted in each socket, and postoperative plaque control measures were undertaken. After euthanasia, the jaw segments were evaluated for bone thickness, marginal bone loss (MBL), and bone-to-implant contact (BIC) using microcomputed tomography., Results: The mean buccal bone thickness (P <0.05) and MBL (P <0.05) was compromised in jaws in ESC-3 compared to those in ESC-1 and ESC-2. The BIC was significantly higher among jaws in ESC-1 compared to those in ESC-2 and ESC-3 (P <0.05). There was no significant difference in the buccal bone thickness, MBL, and BIC among the groups in the maxilla and mandible. Lingual bone remodeling did not reveal any significant differences among the groups in either jaw., Conclusion: Buccal bone remodeling is significantly more extensive around immediate implants placed in multiple contiguous tooth extraction sites compared to immediate implants placed in single tooth extraction sites.

Objective: The aim of this study was to evaluate the influence of mucosal properties and relining material on the stress distribution in peri-implant bone tissue during masticatory function with a conventional complete denture during the healing period through finite element analysis., Materials and Methods: Three-dimensional models of a severely resorbed mandible with two recently placed implants in the anterior region were created and divided into the following situations: (i) conventional complete denture and (ii) relined denture with soft lining material. The mucosal tissue properties were divided into soft, resilient and hard. The models were exported to mechanical simulation software; two simulations were carried out with a load at the lower right canine (35 N) and the lower right first molar (50 N). Data were qualitatively evaluated using Maximum Principal Stress, in MPa, given by the software., Results: All models showed stress concentrations in the cortical bone corresponding to the cervical part of the implant. The mucosal properties influenced the stress in peri-implant bone tissue showing a different performance according to the denture base material. The simulations with relined dentures showed lower values of stress concentration than conventional ones., Conclusions: It seems that the mucosal properties and denture reline have a high influence on the stress distribution in the peri-implant bone during the healing period., (© 2011 The Gerodontology Society and John Wiley & Sons A/S.)

Purpose: This study is a retrospective assessment of the long-term efficacy of dental implant therapy in periodontally susceptible patients., Materials and Methods: A private-practice chart review was conducted to identify partially dentate subjects treated with implant-supported restorations that had been monitored annually for at least 9.5 years. Subjects were assigned to either a periodontal group or a control group according to their health histories. Data were entered into spreadsheets on a personal computer and analyzed statistically with dedicated software., Results: Thirty periodontal subjects were treated with 138 implants and 45 prostheses, and 16 control subjects were treated with 35 implants and 21 prostheses. The mean follow-up was 130 months. One implant failed before loading in the periodontal group. Cumulative 10-year survival rates were 99.3% (n = 137/138) for periodontal implants and 100% (n = 35/35) for control implants. Most surviving implants had no bone loss (n = 109/172, 63.4%). Most of the surviving implants with bone loss (n = 63/172, 36.6%) were concentrated in the periodontal cohort (90%, n = 57/63) and among women (60%, n = 15/25) regardless of cohort. Prosthesis failure was 25.2% (n = 16/66), with 12 porcelain fractures, 2 cement failures, and 2 framework fractures. In all cases, failed prostheses were immediately replaced and patients continued to function., Conclusions: Periodontal susceptibility resulted in increased bone loss but did not affect implant survival. The cause of greater bone loss in women could not be determined from the data but may have been related to the postmenopausal status of the subject population (mean age = 54 years).

Objectives: The fresh extraction socket in the alveolar ridge represents a special challenge in everyday clinical practice. Maintenance of the hard and soft tissue envelope and a stable ridge volume were considered important aims to allow simplifying subsequent treatments and optimizing their outcomes in particular, when implants are planned to be placed., Material and Methods: Prior to the consensus meeting four comprehensive systematic reviews were written on two topics regarding ridge alteration and ridge preservation following tooth extraction and implant placement following tooth extraction. During the conference these manuscripts were discussed and accepted thereafter. Finally, consensus statements and recommendations were formulated., Results: The systematic reviews demonstrated that the alveolar ridge undergoes a mean horizontal reduction in width of 3.8 mm and a mean vertical reduction in height of 1.24 mm within 6 months after tooth extraction. The techniques aimed at ridge preservation encompassed two different approaches: i) maintaining the ridge profile, ii) enlarging the ridge profile. Regarding timing of implant placement the literature showed that immediate implant placement leads to high implant survival rates. This procedure is primarily recommended in premolar sites with low esthetic importance and favorable anatomy. In the esthetic zone, however, a high risk for mucosal recession was reported. Hence, it should only be used in stringently selected situations with lower risks and only by experienced clinicians. In molar sites a high need for soft and hard tissue augmentation was identified., Conclusions: Future research should clearly identify the clinical and patient benefits resulting from ridge preservation compared with traditional procedures. In addition, future research should also aim at better identifying parameters critical for positive treatment outcomes with immediate implants. The result of this procedure should be compared to early and late implant placement., (© 2011 John Wiley & Sons A/S.)

The host-implant interface is remarkably enduring given the functional and biologic challenges it faces, and our success in assisting patients to lead better lives because of implant biotechnology is the envy of many other health care practitioners. It is therefore vital that dentists accept that clinically significant marginal bone loss is uncommon and that implant failure is rare. In this paper, important elements regarding why implants experience marginal bone loss, why implants may fail as a result of such bone loss, and how to describe the continuum of bone loss with respect to patient-mediated outcomes are outlined.

Purpose: The effect of stress levels and distributions around the internal nonsubmerged type implants after vertical bone resorption was investigated in this study., Materials and Methods: An HSII implant was placed in 4 cylindrical alveolar bone models with differing degrees of thread exposures. The load applied to each implant was von Mises stress and principal stress, 250 N in axial direction and 30 degrees lateral pressure. The difference in the load between the bone and the connective portion of the implant was obtained using ANSYS analysis., Results: Bone loss in the cervical area of the implant was more obvious under lateral pressure. When more threads were exposed, bone level decreased and the maximum load applied on the fixture increased., Conclusions: It was concluded that higher bone level has a biomechanical advantage with respect to stress concentration.

Peri-implantitis is an infectious disease, which leads to loss of supporting bone around dental implants. To evaluate the extent and location of bone loss, 43 patients with peri-implantitis were examined. The bone loss was clinically measured at the time of dental surgery. Data revealed that 25% of subjects had bone loss associated with all their implants although the majority of the subjects had fewer than 50% of their implants affected by bone loss. A total number of 264 implants were examined and 131 of those had peri-implantitis associated bone loss. The pattern of bone loss at implants varied between and within subjects and location in the jaws. The highest proportion of implants with peri-implantitis was found in the upper jaw and within this group, at implants located in the incisor area of the upper jaw; the lowest was the canine area of the lower jaw. The highest proportion of implants that lost ≥ 2/3 of their bone support was found in the incisor area of the maxilla. We concluded that in the presence of peri-implant inflammation, bone quantity and characteristics may influence the progression of peri-implantitis bone loss at dental implants. We hypothesize that the ability of the bone to withstand occlusal forces will be altered as consequence of the loss of bone at the neck of the implants. To achieve an understanding of the local degradation of bone due to peri-implantitis, we need to analyze the microstructure of the bone as well the cellular biology of the peri-implant inflammation., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Aim: Implant primary stability is a prerequisite for implant success. A dehiscence or a circumferential defect (CD) at the time of implant placement presents a challenge for achieving primary stability. The aim of this study was to examine the correlations between implant primary stability determined by resonance frequency analysis (RFA) and periimplant bone levels., Materials: Ten implants were placed in 2 cadaver heads. A series of different sizes of narrow (NDD) and wide (WDD) dehiscence defects and CDs were surgically created around 6 and 4 implants, respectively. Implant primary stability in each size of the 3 different defect types was measured with RFA. For each defect type, the association between the RFA readings and the defect size was plotted and statistically analyzed., Results: In NDD study, the RFA readings were not correlated with the defect size. In WDD study, the association was significant for most implants, with the coefficient correlation (r) ranging from -0.88 to -0.97. In CD study, there was also a significant association between the implant stability quotient readings and the bone levels, and the r ranged from -0.94 to -0.99., Conclusion: The association between implant primary stability measured by RFA and the size of surrounding bone defects was defect type dependent. The correlation was highly significant for WDD and CD but not for NDD.

The authors identified no report describing implant primary stability obtained by external fixation as a means to achieve osseointegration in craniofacial settings. This article describes a situation in which an implant was placed without direct contact with the resident bone; primary stability was provided by an external device. An edentulous patient was restored with 5 endosseous titanium implants to support a mandibular fixed prosthesis. An implant placed in the right central incisor position was removed after 48 hours and replaced with a shorter and narrower implant without contact with resident bone. Thus, primary stability for the implant was provided by rigid fixation to the prosthesis rather than by bone anchorage. At recall examinations after 6 and 27 months, all implants, including the implant in the right central incisor position, showed clinical and radiographic signs of osseointegration. Resonance frequency analysis indicated acceptable stability and osseointegration for all implants. Observations of this patient suggest that implant osseointegration can be achieved by providing primary stability using a fixed complete denture. Primary bone anchorage/contact does not appear to be critical to the osseointegration process., (Copyright © 2010 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)

Purpose: The success of zygomatic implants following the two-stage, as well as the immediate loading, concept has been well documented. This graftless approach for the treatment of the completely edentulous resorbed maxilla allows for rehabilitation with an implant-supported fixed prosthesis. The purpose of this prospective study is to report on the 7-year follow-up of patients treated with zygomatic implants in conjunction with two to four anterior maxillary implants placed into immediate function and restored with a definitive fixed prosthesis., Materials and Methods: This prospective study involved 36 patients treated with 74 zygomatic implants and 98 anterior maxillary implants supporting fixed prostheses between 2003 and 2005., Results: Two zygomatic implants in two patients were identified as mobile at stage-two surgery; replacement implants resulted in successful osseointegration. All anterior maxillary implants were determined as osseointegrated at stage two. Three patients experienced unilateral maxillary sinus infections that were refractory to oral antibiotics and were treated with functional endoscopic sinus surgery, which resolved the infections. All patients treated with the immediate loading concept were restored with definitive fixed profile prostheses as planned., Conclusion: The high survival rate, reduced morbidity, and high rate of patient acceptance for the zygomatic implant concept allowed the rehabilitation of the resorbed edentulous maxilla with fixed implant-supported prosthesis, rendering this procedure a viable and a predictable treatment option.

Non-invasive devices including resonance frequency (RF) analysis and mobility measuring (MM) damping capacity assessment are used to measure implant stability/mobility. The aims of the study were to compare the primary stability of implant inserted into extraction sockets by using RF with cable, RF wireless and new wireless MM device, to clarify the relation between these devices and to understand the correlations between peri-implant bone levels and implant stability. A total of 30 screw-type implants (3.75 x 11 and 4.2 x 11 mm) were inserted into extraction sockets of eight mandibular pre-molar regions of human cadavers. The primary stability of implants was measured by three devices after insertion. Peri-implant vertical defects were created in millimetre increments ranging between 0 and 5 mm, and stability/mobility of implants were analysed. At placement, the mean implant stability quotient of RF with cable, RF wireless and MM device values was 46 +/- 1, 57.8 +/- 9 and -5.4 +/- 1, respectively. Statistical correlations were demonstrated between these devices (P = 0.001). Statistically significant differences were presented for all peri-implant detects ranging between 0 and 5 mm for RF with cable and RF wireless at all increments. However, only a significant decrease was found between 0 and 1 mm defects, and 4 and 5 mm defects in MM device. Although RF with cable and RF wireless seem to be suitable to detect peri-implant bone loss around implants in 1 mm increments, the new MM device may not be suitable to detect the 1 mm peri-implant bone changes in human dried cadaver mandibles.

Most biomechanical studies of implant-supported restorations have not taken into account the biologic changes that occur following exposure of the implants to the oral environment. Therefore, the present finite element analysis study was designed to compare the biomechanical response of three types of implant-abutment configurations both before and after establishment of a new biologic width. The three functional units studied were: a 5-mm implant platform connected with an external hexagon to a 5-mm-diameter abutment (type 1), a 5-mm implant platform connected with an external hexagon to a 4.1-mm-diameter abutment (type 2), and a 4.8-mm implant platform connected with an internal hexagon to a 4.1-mm-diameter abutment (type 3). The type 3 design, which combined platform switching with an internal connection, exhibited the smallest distortions in stress distribution after bone modeling, and the stress was distributed over the entire contact surface most smoothly and uniformly. Bone resorption following creation of the biologic width changes the biomechanical behavior of a restoration. In this study, the two implant-abutment designs featuring a smaller-diameter abutment on a larger-diameter implant platform achieved better results than the implant featuring the same-diameter implant platform and abutment, even though their initial bio?mechanical load potential was lower. (Int J Periodontics Restorative Dent 2009;29:479-487.).

Objective: New approaches to enhance vertical bone regeneration in clinically relevant implant models are needed. Therefore, we analyzed the impact of recombinant human bone morphogenic protein 2 (rhBMP-2) on the healing of large buccal alveolar defects during osseointegration of transgingivally inserted implants., Study Design: Twenty-four dental implants were inserted transgingivally in the mandibles of 6 labrador/golden retriever cross-bred dogs. Before implantation, a standardized buccal bone defect was created and refilled with either calcium phosphate as a carrier containing rhBMP-2 or calcium phosphate alone. Either ceramic abutments that enabled immediate implant loading or healing distance collars to prevent loading were mounted. Sixteen weeks after intervention, bone implant units were analyzed by radiofrequency analysis and histomorphometry., Results: In total, 14 implants (58.3%) were available for further analysis. The mean depth of the bone defects, the gain of regenerated bone, the vertical osseointegration of the implants, and the bone-to-implant contact in the newly formed bone were slightly greater in the rhBMP-2-containing samples. In contrast, the osseointegration in the preexisting bone was even superior within the non-rhBMP-2-treated specimen. However no differences were statistically significant., Conclusions: When rhBMP-2-conducted bone regeneration was compared with control samples, no significant differences of newly formed bone were found at the bone-implant interface. The amounts of rhBMP-2 applied do not seem suitable to enhance implant osseointegration in large buccal defects.

Statement of Problem: Load transfer mechanisms and possible failure of osseointegrated implants are affected by implant shape, geometrical and mechanical properties of the site of placement, as well as crestal bone resorption. Suitable estimation of such effects allows for correct design of implant features., Purpose: The purpose of this study was to analyze the influence of implant diameter and length on stress distribution and to analyze overload risk of clinically evidenced crestal bone loss at the implant neck in mandibular and maxillary molar periimplant regions., Material and Methods: Stress-based performances of 5 commercially available implants (2 ITI, 2 Nobel Biocare, and 1 Ankylos implant; diameters of 3.3 mm to 4.5 mm, bone-implant interface lengths of 7.5 mm to 12 mm) were analyzed by linearly elastic 3-dimensional finite element simulations, under a static load (lateral component: 100 N; vertical intrusive component: 250 N). Numerical models of maxillary and mandibular molar bone segments were generated from computed tomography images, and local stress measures were introduced to allow for the assessment of bone overload risk. Different crestal bone geometries were also modelled. Type II bone quality was approximated, and complete osseous integration was assumed., Results: Maximum stress areas were numerically located at the implant neck, and possible overloading could occur in compression in compact bone (due to lateral components of the occlusal load) and in tension at the interface between cortical and trabecular bone (due to vertical intrusive loading components). Stress values and concentration areas decreased for cortical bone when implant diameter increased, whereas more effective stress distributions for cancellous bone were experienced with increasing implant length. For implants with comparable diameter and length, compressive stress values at cortical bone were reduced when low crestal bone loss was considered. Finally, dissimilar stress-based performances were exhibited for mandibular and maxillary placements, resulting in higher compressive stress in maxillary situations., Conclusions: Implant designs, crestal bone geometry, and site of placement affect load transmission mechanisms. Due to the low crestal bone resorption documented by clinical evidence, the Ankylos implant based on the platform switching concept and subcrestal positioning demonstrated better stress-based performance and lower risk of bone overload than the other implant systems evaluated.

Resonance frequency (RF) analysis is a non-invasive and objective technique developed for implantology, where it measures the stability of the implant in the bone socket. A limited number of studies were performed to compare different stability measurement devices. The aim of the study was to evaluate the association between the implant stability and peri-implant vertical defect by using the new wireless RF analyser. Micro-textured rough-surfaced implants with diameters of 3.7 and 4.8 mm and with a length of 12 mm were used. The peak insertion torque was recorded with the help of the torque control system only during the implant placement. The peri-implant defects were created in millimetre increments ranging between 0 and 5 mm to the same extent on all implants. The RF analysis values were measured by using the RF analyser. Significant correlation was found between insertion torque (44.3 +/- 3 N cm) and implant stability quotient (ISQ) (all implants: r = 0.76, 3.7 mm diameter: r = 0.65, 4.8 mm diameter: r = 0.80). For 3.7 x 12-mm(2) implants, the mean ISQ values were 72.6 +/- 2.4, 69.8 +/- 2, 67.2 +/- 1.8, 64.3 +/- 1.9, 61.2 +/- 2 and 57.2 +/- 2.5 when peri-implant vertical defects were 0, 1, 2, 3, 4 and 5 mm; and the corresponding values were 76.5 +/- 2.2, 74.5 +/- 2.2, 72.3 +/- 2, 70 +/- 1.9, 67 +/- 1.9 and 63.4 +/- 2.3, respectively, for 4.8 x 12-mm(2) implants. All values were significantly different when compared with each other. The wireless RF analyser seems to be a suitable and reliable device to determine the implant stability. Peri-implant bone loss simulated by using acrylic models may result with a decrease in ISQ values for osseo-integrated implants measured by the RF analyser.

Background: Peri-implantitis is associated with the presence of submarginal plaque, soft-tissue inflammation and advanced breakdown of the supporting bone. The progression of peri-implantitis following varying periods of continuing plaque accumulation has been studied in animal models., Objective: The aim of the current experiment was to study the progression of peri-implantitis around implants with different surface roughness., Material and Methods: In five beagle dogs, three implants with either a sandblasted acid-etched surface (SLA) or a polished surface (P) were installed bilaterally in the edentulous premolar regions. After 3 months on a plaque control regimen, experimental peri-implantitis was induced by ligature placement and plaque accumulation was allowed to progress until about 40% of the height of the supporting bone had been lost. After this 4-month period, ligatures were removed and plaque accumulation was continued for an additional 5 months. Radiographs of all implant sites were obtained before and after 'active' experimental peri-implantitis as well as at the end of the experiment. Biopsies were harvested and the tissue samples were prepared for light microscopy. The sections were used for histometric and morphometric examinations., Results: The radiographic examinations indicated that similar amounts of bone loss occurred at SLA and P sites during the active breakdown period, while the progression of bone loss was larger at SLA than at polished sites following ligature removal. The histological examination revealed that both bone loss and the size of the inflammatory lesion in the connective tissue were larger in SLA than in polished implant sites. The area of plaque was also larger at implants with an SLA surface than at implants with a polished surface., Conclusion: It is suggested that the progression of peri-implantitis, if left untreated, is more pronounced at implants with a moderately rough surface than at implants with a polished surface.

Objective: To assess the impact of overloading on peri-implant bone level and the bone-to-implant contact (BIC) in the presence of healthy or inflamed peri-implant tissues., Materials and Methods: Four screw-shaped machined implants were placed bilaterally in the mandible of four beagle dogs and left submerged for 3 months. Prosthetic abutments were connected either in supra-occlusal contact with the opposite teeth (overloaded) or in infra-occlusal position (unloaded). In each dog, cotton floss ligatures were placed unilaterally around abutments to promote plaque accumulation; the contralateral side was brushed three times a week. There were four experimental sites, two implants in each: loaded uninflamed (LU), loaded inflamed (LI), unloaded uninflamed (UU), and unloaded inflamed (UI). Clinical and radiographic parameters were recorded at baseline and every 3 months throughout the observation period. At 12 months, the dogs were sacrificed and histomorphometric analysis was performed., Results: Implants with ligature-induced peri-implantitis presented high inflammatory indices throughout the observation period. Clinical parameters did not change from baseline for both LU and UU. Loading significantly increased the percentage of BIC (BIC%) (P<0.05) and slightly increased crestal bone resorption, but not apical to the implant neck. Both LI and UI groups showed significant peri-implant bone loss (P<0.01), mostly horizontal on the buccal aspect and angular on the lingual aspect, which exposed implant threads. Loading significantly (P<0.05) increased implant thread exposure due to buccal and lingual vertical bone resorption., Conclusions: In the presence of uninflamed peri-implant mucosa, overloading of implants in the dog model increased BIC% and slightly reduced marginal bone level. However, resorption did not progress beyond the implant neck. Overloading aggravated the plaque-induced bone resorption when peri-implant inflammation was present.

Objectives: The aim of the present study was to evaluate and compare naturally occuring and ligature-induced peri-implantitis bone defects in humans and dogs., Material and Methods: Twenty-four partially and fully edentulous patients undergoing peri-implant bone augmentation procedures due to advanced peri-implant infections were included in this study (n=40 implants). Furthermore, peri-implantitis was induced by ligature placement and plaque accumulation in five beagle dogs for three months following implant insertion (n=15 implants). The ligatures were removed when about 30% of the initial bone was lost. During open flap surgery, configuration and defect characteristics of the peri-implant bone loss were recorded in both humans and dogs., Results: Open flap surgery generally revealed two different classes of peri-implant bone defects. While Class I defects featured well-defined intrabony components, Class II defects were characterized by consistent horizontal bone loss. The allocation of intrabony components of Class I defects regarding the implant body allowed a subdivision of five different configurations (Classes Ia-e). In particular, human defects were most frequently Class Ie (55.3%), followed by Ib (15.8%), Ic (13.3%), Id (10.2%), and Ia (5.4%). Similarly, bone defects in dogs were also most frequently Class Ie (86.6%), while merely two out of 15 defects were Classes Ia and Ic (6.7%, respectively)., Conclusions: Within the limits of the present study, it might be concluded that configurations and sizes of ligature-induced peri-implantitis bone defects in dogs seemed to resemble naturally occurring lesions in humans.

Purpose: The aim of this study was to describe the stress and strain fields around orthodontically loaded dental implants using the finite element method and to evaluate the relationship between the generated strain and the biologic reaction expressed through histomorphometric parameters. Finally, this study aimed to evaluate the interaction between the orthodontic loading and the deformation generated by normal occlusal function., Materials and Methods: Sixteen titanium dental implants were inserted in extraction sockets after the removal of the second premolars and first molars of 4 adult Macaca fascicularis monkeys. After 17 weeks of healing, the implants were loaded by a pair of Sentalloy springs (50 cN) for 16 weeks. After sacrifice, tissue blocks including the implants and surrounding bone were excised. Five tissue blocks were scanned with a synchrotron radiation-based microtomography (microCT) scanner and sample-specific finite element models were generated. Subsequently all samples were prepared for histomorphometric analysis., Results: All implants were osseointegrated, although the surrounding alveolar bone differed from sample to sample. As a consequence the finite element analyses showed that the stresses and strains in the peri-implant alveolar bone greatly varied among the samples. A high level of remodeling activity was found close to the implants., Discussion: Individual differences between the receptors (in this case, the monkeys) have a large effect on both the biologic and morphologic parameters. These variations were indeed found to have a substantial impact on the (re)modeling dynamics and the load transfer mechanisms around the implants., Conclusions: By integrating different analysis techniques to evaluate bone (re)modeling around orthodontically loaded implants, this study has demonstrated the complexity and case-specific character of alveolar adaptation to orthodontic loading. Furthermore, stresses generated by combined functional and orthodontic forces should not be neglected.

Objectives: The aim of the present study was to evaluate bone regeneration in dehiscence-type defects at titanium implants with chemically modified (mod) and conventional sand-blasted/acid-etched (SLA) surfaces., Material and Methods: Standardized buccal dehiscence defects (height: 3 mm, width: 3 mm) were surgically created following implant site preparation in both the upper and lower jaws of four beagle dogs. modSLA and SLA implants were inserted bilaterally according to a split-mouth design. The animals were sacrificed after 2 and 12 weeks (n=2 animals each). Dissected blocks were processed for histomorphometrical analysis: defect length, new bone height (NBH), percent linear fill (PLF), percent of bone-to-implant contact (BIC-D) and area of new bone fill (BF)., Results: Wound healing at SLA implants was predominantly characterized by the formation of a dense connective tissue at 2 and 12 weeks, without significant increases in mean NBH, PLF, BIC-D or BF values. In contrast, modSLA implants exhibited a complete defect fill at 12 weeks following implant placement. In particular, histomorphometrical analysis revealed the following mean values at 12 weeks: NBH (3.2+/-0.3 mm), PLF (98%), BIC-D (82%) and BF (2.3+/-0.4 mm(2))., Conclusion: Within the limits of the present study, it was concluded that modSLA titanium surfaces may promote bone regeneration in acute-type buccal dehiscence defects at submerged implants.

Purpose: A 3-dimensional finite element model was developed to investigate the cause of different crestal bone loss patterns observed around sintered porous-surfaced and machined (turned) threaded dental implants used for orthodontic anchorage in a previously reported animal study., Materials and Methods: Twenty-noded structural solid elements with parabolic interpolation between nodes were used for modeling the bone-implant interface zone. A 3-N traction force acting between either 2 porous-surfaced or 2 machined threaded implants placed in canine premolar mandibular sites and bone profiles observed at initiation and 22 weeks of orthodontic loading were modeled., Results: Higher maximum stresses in peri-implant bone next to the coronal region of the implants were predicted with the machined threaded implants at both the initial and final time points, with the values 20% greater than those predicted after the 22-week loading period. These values were approximately 200% greater than those predicted for the porous-surfaced implants, for which a more uniform stress distribution was predicted., Discussion: The finite element model results indicated that the observed greater retention of crestal bone next to the porous-surfaced implants was attributable to lower peak stresses developing in crestal peri-implant bone with this design, which decreased the probability of bone loss related to local overstressing and bone microfracture., Conclusion: The predicted lower stresses were a result of the more uniform transfer of force from implant to bone with the porous-surfaced implants, which was a consequence of the interlocking of bone and implant possible with this design.

Purpose: To evaluate maximal occlusal bite forces (MOF) and marginal bone level (MBL) changes in patients with implant-tooth-supported fixed partial prostheses (FPP)., Material and Methods: Twenty nine partially edentulous patients consecutively who received 34 three-occlusal unit FPP with terminal implant and tooth support were subjected to quantification of MOFs using a sub-miniature load cell connected to a data acquisition system and measurement of the MBL changes around implants in digitalized periapical radiographs obtained at prostheses delivery and 24-month follow-up., Results: MOFs for implant support (mean: 353.61 N) significantly differed from tooth support (mean: 275.48 N) (P < 0.05), while gender did not influence MOFs (P > 0.05). MBL changes at mesial and distal sites of the implants at 24 months of functional loading were 0.28 and 0.097 mm respectively., Conclusion: Although MOFs under functional loading might indicate an increase in load participation for supporting implant, the rigid connection between implant and natural tooth via three-occlusal unit FPP does not jeopardize the time-dependent MBL stability of the implant under functional loads.

Purpose: The authors' aim was to perform a histomorphometric study of the healing of bone defects created adjacent to titanium and hydroxyapatite (HA) -coated implants and covered with either a resorbable or a nonresorbable membrane in combination with different filler materials and to evaluate to what degree coating, membrane, and/or filler influenced the healing of the defects., Materials and Methods: Posterior teeth were extracted from the mandibles of 10 baboons, and 12 implants were placed in each animal in the edentulous areas. The implants were either titanium or HA-coated, the membranes were either Vicryl, Gore-Tex, or Resolut, and the filler was either demineralized freeze-dried bone (DFDB), autogenous bone, or Biocoral. The implants were observed for either 3, 6, 9, 12, or 18 months. The volume of newly generated tissue and the relative contribution of bone, marrow, and filler were evaluated, as was relative extension of resorption, formation, and quiescent surface., Results: The results indicated that autogenous bone is still the gold standard, but both the DFDB and Biocoral compared favorably to it. Both filler materials were being gradually replaced by bone; this process was not yet finished at 18 months postsurgery., Discussion: Since even the sterilization of DFDB cannot exclude the possibility of a disease transmission, it is important to find an appropriate substitute. Both filler and membranes contributed to the re-establishment of the original volume; better results were achieved with the Vicryl and Gore-Tex membranes than with the Resolut. Biocoral can be considered an effective material., Conclusion: A bony defect is not necessarily a contraindication for the placement of an implant. (More than 50 references.)

Background: Histologic studies have demonstrated the possibility to reestablish direct bone-implant contacts after ligature-induced periimplantitis. The influence of the reosseointegration on the stability of implants is not known., Purpose: The aim of the present investigation was to study bone tissue and associated implant stability alterations that occurred during induction and resolution of periimplantitis using resonance frequency analysis (RFA), radiography, and histology., Materials and Methods: Three implants with smooth (turned) or roughened (SLA) surfaces were placed in each side of the edentulous mandible of four dogs. Experimental periimplantitis was induced for 3 months. Five weeks later, the animals were treated with antibiotics and surgical therapy and were followed for another 6 months. Periapical radiographs and RFA were used to evaluate marginal bone levels and implant stability throughout the study period. After termination, the tissue-implant interface was evaluated by light microscopy in ground sections., Results: There was a linear relationship between radiographic and RFA findings because continuous loss of marginal bone and a decrease in implant stability were observed for both implant surfaces during the periimplantitis period. Antibiotic treatment and surgical therapy resulted in some reosseointegration, which was more marked for the SLA surface. The resonance frequency values corresponded well to the histometric measurements because reosseointegration resulted in an increase in implant stability., Conclusions: The findings from the present study indicate a linear relationship between marginal bone level and resonance frequency value. It is suggested that the RFA technique is sensitive and may be used to detect even a minor change in the level of bone-implant contact.

Human biopsy of immediately loaded implants is the most important way to determine the occurrence of osseointegration. Implants inserted in sites with poor bone quality have been associated with lower success rates. The aim of this study is to document the early healing processes in a man around an immediately loaded implant retrieved after a 2-month loading period. An implant was inserted in the mandible of a 32-year-old patient and was loaded into a nonfunctional loading mode with a fixed provisional prosthesis the same day of the implant surgery. After 2 months, because the patient had difficulty accepting the implant, the implant was retrieved with a 5-mm trephine drill. Before retrieval, the implant appeared to be clinically osseointegrated, and no mobility was present. The preexisting bone quality was type D4. The implant was surrounded by newly formed bone lamellae with a width of 200 to 400 microm. In many areas it was possible to observe osteoblasts producing osteoid matrix directly on the implant surface. Bone-to-implant contact percentage was 71% +/- 3.2%. Even in a poor bone site and after a healing period of only 2 months, we observed a high bone-to-implant contact percentage. We can confirm that immediately loaded implants placed in soft spongy bone after a 2-month healing period can present mineralized tissue at the interface.

This study quantifies the changes in bone height noted in the body of the edentulous mandibles when the load of the complete denture is born by an RA Ramus Frame Implant (Pacific Implant, Rio Dell, Calif). Eighty-three patients with implants were followed for 3 to 24 years. Pre- and postoperative panoramic films were taken and again at each succeeding 5-year follow-up. The results of the bone changes were gathered retrospectively and calculated. The data revealed a significant increase in bone height from 4.413 to 13 mm and statistically significant P values of <.0003 were determined. The growth of bone appears to be influenced by the design of the posterior feet, dominant chewing side, and a range of extreme atrophy from 5.9 mm to 15 mm. Also, the previously lost anatomical structures appear to repair, such as the luman of the mental foramen and the superior wall over the inferior alveolar canal. All mandibles were loaded postoperatively with an appliance having cutting bars and porcelain teeth or just porcelain teeth in both appliances.

An important parameter that influences the long-term success of oral implants is the bone quality of the implant bed. Posterior areas of the jaws have been avoided in implant dentistry because of their poor bone quality, higher chewing forces, and presumed higher implant failure rates. Several researchers have deemed soft bone implant sites to be a great potential risk situation, and most failures have been found in sites where the bone density was already low. The inferior success rates in the posterior maxilla have been attributed to a lower bone density and a lesser bone-implant interface. The aim of the present study was a histological and histomorphometrical analysis of the bone response to submerged implants inserted in posterior areas of the human jaws and retrieved, for different causes, after healing periods varying from 6 weeks to 12 months. Eight submerged implants that had been retrieved for different causes after different healing periods were evaluated in the present study. All implants were submerged and unloaded. Three implants had been removed for inadequate patient adaptation, 2 for inability of the implant to meet changed prosthetic needs, 1 for not optimal position from esthetic and hygiene aspects, and the last 2 for pain and dysesthesia. All the implants were retrieved with a 5-mm trephine bur. Newly formed peri-implant bone was found in all implants even after shorter healing periods. The bone-implant contact percentage varied from 30% to 96%. In conclusion, some surfaces have an improved characteristic of contact osteogenesis in soft bone, with coverage of the implant surface with a bone layer as a base for intensive bone formation and remodeling. We documented osseointegration of implants with a rough surface even after an insertion period of less than 2 months, both in the mandible and in the maxilla. From these results, we tentatively extrapolate that these implants might be carefully loaded after 2 months of healing, even when inserted in soft bone. A higher removal torque value might lead to a more predictable use of shorter implants, to a support of a prosthesis with fewer implants, or to shorter healing periods.

Objectives: Although bone loss around implants is reported as a complication when it progresses uncontrolled, resorption does not always lead to implant loss, but may be the result of biomechanical adaptation to stress. To verify this hypothesis, a three-dimensional finite element analysis was performed and the influence of marginal bone resorption amount and shape on stress in the bone and implant was investigated., Material and Methods: A total of nine bone models with an implant were created: a non-resorption (Base) model and eight variations, in which three different resorption depths were combined with pure vertical or conical (vertical-horizontal) resorption. Axial and buccolingual forces were applied independently to the occlusal node at the center of the superstructure., Results: Regardless of load direction, bone stresses were higher in the pure vertical resorption (A) models than in the Base model, and increased with resorption depth. However, cortical bone stress was much lower in the conical resorption models than in both the Base and A models of the same resorption depth. An opposite tendency was observed in the cancellous bone under buccolingual load. Under buccolingual load, highest stress in the implant increased linearly with the resorption depth for all the models and its location approached the void existing below the abutment screw., Conclusions: The results of this analysis suggest that a certain amount of conical resorption may be the result of biomechanical adaptation of bone to stress. However, as bone resorption progresses, the increasing stresses in the cancellous bone and implant under lateral load may result in implant failure.

Purpose: Resonance frequency (RF) analysis has been used by several investigators to assess the boundary conditions of dental implants. However, a scientific investigation of the association between the structural condition of the alveolar bone and the dynamic behavior of dental implants has not yet been reported. The aim of this study was to assess the factors influencing the RF of dental implants using an in vitro modal analysis., Materials and Methods: Resonant vibration within implants was induced by an impulse-force hammer. The induced vibration signal was subsequently detected using an acoustic microphone and analyzed by fast Fourier transform. The resultant data were further analyzed to test the statistical effects of the embedding-material boundary height, thickness, and density on the RF values of the sample implants., Results: Significant changes (P <.05) in RF values were revealed for implants embedded within a high-density block when decreasing boundary height reached 6, 5, and 4 mm, at respective thickness increments of 10, 15, and 20 mm. For analogous low-density samples, significant changes (P <.05) in RF values were found when respective decreasing boundary height reached 6, 4, and 3 mm., Conclusions: Our findings indicate that boundary height, width, and density factors can influence the RF of dental implants and that a lower boundary density and greater boundary thickness can lead to more obvious RF changes.

Purpose: The aim of this study was to compare bone healing and crestal bone changes following immediate (Im) versus delayed (De) placement of titanium dental implants with acid-etched surfaces (Osseotite) in extraction sockets., Materials and Methods: Forty-six patients were randomly allocated to the Im or De group (n = 23 per group) and received 1 implant at the incisor, canine, or premolar region of the maxilla or the mandible. The implants were placed an average of 10 days following tooth extraction in the Im group and approximately 3 months after extraction in the De group. The widths (parallel and perpendicular to the implant) and the depth of marginal bone defects around the implants were measured clinically just after placement and 3 months later at the abutment surgery. The crestal bone changes mesially and distally to the implants were evaluated radiographically by linear measurements., Results: The survival rates were 91% in the Im group and 96% in the De group. In the Im group, the mean reductions in parallel width, perpendicular width, and depth of the largest defect of each implant amounted to 48% (from 4.4 to 2.3 mm), 59% (from 2.2 to 0.9 mm), and 48% (from 6.9 to 3.6 mm), respectively. The corresponding mean reductions in the De group amounted to 39% (from 3.1 to 1.9 mm), 77% (from 1.3 to 0.3 mm), and 34% (from 4.4 to 2.9 mm). The reduction over time was statistically significant in both groups (P < .04). For both groups, a higher degree of bone healing was achieved in the infrabony defects (> 60% for depth) than in dehiscence-type defects (approximately 25%). Furthermore, 70% of the 3-wall infrabony defects with a parallel width of up to 5 mm, a depth of maximum 4 mm, and a perpendicular width of maximum 2 mm had a capacity of spontaneous healing within a period of 3 months., Discussion and Conclusion: New bone formation occurs in infrabony defects associated with immediately placed implants in extraction sockets.

Animal studies have shown that a periodontal ligament may be produced around a titanium implant when it is in contact with fractured and retained roots. Formation of cementum and attachment connective tissue around titanium implants confirms that cementum progenitor cells are located in the periodontal ligament, since cementum and periodontal ligament are present at the implant-root interface, whereas the remainder of the implant, which is not in contact with the root, shows osseointegration. The aim was to evaluate histologically the characteristics of the tissue present between a titanium implant and a retained root, which were subsequently extracted as a result of peri-implantitis. The histologic examination revealed a continuous layer of cementum and numerous cementocytes on the implant surface. No blood vessel or collagen fibers were detected in the periodontal space. In contrast to experimental studies carried out on animals, the lack of connective tissue fibers and the presence of hypercementosis in this specimen could have been caused by the inflammatory process. Furthermore, the extrusive movement of the root might explain the presence of cementum hypertrophy. Further studies are required to establish whether the neoformation of cementum and collagen fibers on an implant in the presence of root residues occurs only in animal models or whether it may also occur in humans.

As part of a long-term evaluation of endosteal dental implants in primates, this paper describes the histological response to plate-form and root-form implants. Thirty-six primates received 48 mandibular distal abutment implants. After healing, the implants were restored with fixed partial dentures, which remained in function for two years. A subset of the group was ligated at the gingival sulcus to biologically stress tissues supporting the implants. Crestal bone height around implants was quantified using digital subtraction radiographic techniques. The ligated implants lost more crestal bone than non-ligated implants, as shown by ANOVA (P < 0.05). After retrieval, implants were embedded and sectioned for histomorphometric analysis including measurement of per cent osseointegration. Both plate-form and root-form non-ligated implants demonstrated about 60% osseointegration. When ligated, plate-form implants dropped to an average integration of only 34%, while root-form implants maintained 62% integration, a significant difference. These data show that in this primate model, plate-form and root-form implants maintained integration while in function for two years. When stressed with ligation, root-form implants maintained relative amounts of osseointegration, while per cent osseointegration of plate-form implants decreased.

Background: Generalized aggressive periodontitis is described as a clinical entity affecting both deciduous and permanent dentition with extensive alveolar bone loss, mobility, and exfoliation of all or many teeth. Controversy exists on dental implant use to restore missing dentition in younger patients., Methods: This case report presents a patient diagnosed with aggressive periodontitis who has lost all but 4 of her teeth. Her personal and functional desires led us to include implant therapy in her treatment plan. The hematological data are presented with an analysis of the immunological profile., Results: Dental implants were placed, and following 3 months of osseointegration, an implant-supported prosthesis was completed. The patient was followed up for 36 months., Conclusions: This case report presents an alternative treatment for rehabilitating dentition in a young patient treated for aggressive periodontitis. Similar case studies may help eliminate some of the controversy that exists regarding the use of dental implants in aggressive periodontitis patients.

Background: Previous experimental studies have shown a higher degree of bone-implant contact for surface-enlarged implants compared with machined implants. Yet, there is insufficient evidence that such implants show higher stability and an increased survival rate., Purpose: The purpose of this investigation was to study the integration and stability of grit-blasted implants with retention elements on the implant neck, with and without marginal bone defects, compared with machined implants without retention elements., Materials and Methods: After tooth extraction of the mandibular premolars in six dogs, two grit-blasted, partly microthreaded Astra Tech implants and one standard Brånemark implant were bilaterally placed in each dog. On one side, 3 x 3 mm large buccal defects were created, to expose three to four implant threads. The contralateral side served as control, and no defects were made. The animals were sacrificed after 4 months of healing. Implant stability was measured using resonance frequency analysis at implant installation and after 4 months of healing. Histologic and histomorphometric evaluation was made after 4 months of healing., Results: Resonance frequency analysis indicated that all implants in the test and control groups were osseointegrated after 4 months, with a tendency toward higher implant stability for the Astra Tech implants. There was a statistically significant higher increase in resonance frequency for the Astra test implants compared with their corresponding controls. Histology and histomorphometry showed well-integrated implants with varying degrees of bone repair at the defect sites. The greater bone-implant contact for the Astra implants was statistically significant. No significant difference between the implants in amount of bone filling the threads was recorded., Conclusions: The Astra Tech implants tested showed a higher degree of bone-implant contact and higher level of bone regenerated at defect sites compared with the Brånemark implants. Resonance frequency analysis demonstrated a significantly higher increase in the Astra test implants compared with their control groups than did the Brånemark test implants versus their controls.

Purpose: A retrospective study was performed to assess the success of short endosseous implants in combination with an implant-retained overdenture in the extremely resorbed mandible., Patients and Methods: Patients included had a mandible not exceeding a median height of 12 mm measured on a standardized lateral cephalometric radiograph. Seventeen patients (14 women, 3 men; mean age, 65 years) with 68 endosseous implants were clinically and radiographically evaluated., Results: During the follow-up period (mean, 77 months; range, 60 to 97 months), 8 implants were lost, bringing the cumulative survival rate to 88%. The peri-implant tissues were in good condition, and the bone loss around the implants was minimal., Conclusion: Because of the relative simplicity and low morbidity of this treatment strategy, it is a justified treatment option.