Morbidity of chin bone harvesting

The chin is a very common donor site for autogenous bone grafts. The aim of this retrospective study was to evaluate long-term morbidity of the donor site following chin bone graft harvesting. One to three years after grafting of local bone defects of the anterior maxilla with chin bone, 21 patients were recalled for objective assessment of any residual morbidity at the harvesting area. Morbidity as well as satisfaction of the patients were evaluated by a survey of the medical record, a mail-in questionnaire, and a standardized physical examination. The outcome of this study showed that there was good acceptance of the chin bone harvesting procedure. The objective morbidity was low, but subjectively almost half of the patients reported a changed (decreased) sensibility in the harvesting area. This subjective change in sensibility did not result in noteworthy complaints or discomfort by the patients, however. Although bone harvesting from the chin is generally considered as a good option for reconstruction of local bony defects, the patients should be informed about the potential hazard of a changed sensibility in the chin region.     

Clinical application of a new compact CT system to assess 3-D images for the preoperative treatment planning of implants in the posterior mandible A case report

When treatment planning before placing dental implants in the posterior region of the mandible, the locations of the inferior alveolar nerve and mental foramen need to be ascertained, as they determine the bone height available and the implant length selected. The purpose of this study was to introduce the clinical application of a newly developed compact computed tomography system (Ortho-CT) to assess three-dimensional (3-D) images for the preoperative treatment planning of implants in the posterior region of the mandible. To evaluate the 3-D images, we scanned using the Ortho-CT system the mandible with a radiopaque template placed in the posterior region. The Ortho-CT images provided excellent information for evaluating the morphology of the mandible, and for showing the location of the inferior alveolar nerve, mental foramen and the relationship of the template to the bone. We consider that Ortho-CT is a useful aid to preoperative treatment planning of implant therapy in the mandible.     

Biologic and mechanical stability of single-tooth implants: 4- to 7-year follow-up

Background: Single‐tooth implants have been reported to achieve a high level of surgical and prosthetic success. However, close inspection of the literature reveals a paucity of data on the follow‐up of single‐tooth implants in function for 5 years or more. Since unsplinted implants may be considered to be subject to greater functional stresses, there is a need to report on the long‐term biologic and mechanical integrity of such implant‐supported restorations. Purpose: To report on the long‐term follow‐up of single‐tooth implants, restored and in function for 4 to 7 years. Materials and Methods: Twenty‐seven Astra Tech single‐tooth implants were subject to a clinical audit to evaluate implant and prosthetic success as well as response of both hard and soft tissues over a 1‐ to 4‐year follow‐up. This current report presents data on the biologic and mechanical integrity of 23 of these single‐tooth implants, which have been in function for up to 7 years (mean, 63 mo). Data are provided with respect to implant survival, maintenance of marginal bone levels, soft‐tissue health, and the recording of any adverse events, including prosthetic complications. Results: Only 14 implants in 13 patients were available for review, with no failures for this group of implants. One patient from the original group, who was lost to follow‐up, was known to have suffered an implant failure. Furthermore, in accordance with established criteria, the remaining 13 implants that are not included in this report must at this time also be considered as potential failures. As such, the best‐case scenario would be a 95.6% success rate for the 23 implants included in this review and the worst‐case scenario would be a 60.8% success rate. Mean marginal bone loss measured 0.49 mm mesially and 0.76 mm distally, with a frequency of bone loss of 50%. Soft tissues were clinically healthy. There were few adverse events, with only one case of abutment screw loosening, detected at the 6‐year review. In addition, crown decementation was recorded three times in two patients. Conclusions: It can be concluded that the Astra Tech single‐tooth implant can achieve long‐term biologic and mechanical stability when used to restore single missing teeth, over the long‐term.     

Early loading of ITI implants supporting maxillary fixed full-arch prostheses

Objective: To evaluate the predictability of the early‐loaded sand‐blasted, large‐grit and acid‐etched (SLA) implants supporting maxillary‐fixed full‐arch prostheses. Material and methods: Ninety‐one ITI SLA implants were placed in 12 edentulous maxillae. The impressions were taken at 4 weeks post‐surgery. The abutments were tightened and the final fixed prostheses were cemented at 6 weeks after implant placement. Resonance frequency analysis (RFA) was conducted on the day of the surgery, at 4 and 6 weeks post‐surgery. Panoramic radiographs were taken immediately after surgery, at 4 weeks post‐surgery, immediately after prostheses attachment (baseline) and at the yearly follow‐ups. Results: The survival rate of implants was 98.90%. The success rate of prostheses was 100% during the follow‐ups. The radiographic result showed no radiolucency around the implants and the marginal bone level revealed no significant resorption compared with the baseline. The marginal bone level remained coronally beyond the first thread. The RFA results revealed Implant Stability Quotient (ISQ) values of 63.44±4.32, 57.14±4.25 and 66.43±3.78 for the three time points. Conclusions: The findings of this study indicated that early loading of ITI implants supporting maxillary fixed full‐arch prostheses should be predictable.     

Is there a lower threshold value of bone density for early loading protocols of dental implants?

This clinical study aimed to determine the bone density in dental implant recipient sites using computerized tomography (CT) and to establish a lower threshold value of bone density for early loading protocols. The study group was composed of 100 early loaded implants in 42 patients. A total of four groups were established according to the loading time and implant sites. The bone density of each recipient site for implant placement was determined using CT. The maximum insertion torque values were recorded with torque controlling machine. Implant stability measurements were performed with resonance frequency analyser. The bone density values varied from 528 to 1231 HU. It was found that mean bone density, insertion torque and resonance frequency analysis values were 887 +/- 180 HU, 41.2 +/- 6 Ncm, and 73.7 +/- 4 ISQ, respectively. Strong correlations were found between these three parameters. CT may be a useful tool for assessing the bone density of recipient areas before implant placement, and the early loading of dental implants may be possible in the implant sites where bone density is over 528 HU.     

Safety of dental implant surgery in patients undergoing anticoagulation therapy: a prospective case-control study

Objectives: Several studies have described oral surgical procedures in patients receiving anticoagulant therapy, but no prospective studies on dental implant surgery during anticoagulant treatment are currently available, and only a limited number of case reports refer to endosseous dental implant treatment in these patients. In the setting of oral surgery, it has been suggested that anticoagulant treatment is not required when the International Normalized Ratio (INR) is <4 and local haemostatic measures are applied. The purpose of this preliminary study was to evaluate the incidence of bleeding complications following surgical implant therapy in a group of 50 consecutive patients receiving oral anticoagulant therapy (warfarin) without interruption or modifications to their therapy (group A). Materials and methods: One hundred and nine otherwise healthy patients comparable for age, sex, extent and site of the implant surgical procedure formed the control group (group B). In both groups, a standard protocol of local haemostasis, including non‐reabsorbable sutures and compressive gauzes soaked with tranexamic acid, was applied. Surgeons, blind to the group allocation, performed all the procedures in an outpatient setting. Results: Two and three late‐bleeding complications were reported in group A and group B, respectively, without significant difference in the bleeding risk (relative risk = 1.45; P= 0.65; 95% confidence interval 0.2506–8.4271). These complications were managed using a compressive gauze soaked with tranexamic acid at the site of the surgical wound. Conclusion: According to our preliminary results, local haemostasis in dental implant surgery is able to prevent bleeding complications in patients on oral anticoagulants, allowing these surgical procedures to be performed on an outpatient basis. To cite this article:
Bacci C, Berengo M, Favero L, Zanon E. Safety of dental implant surgery in patients undergoing anticoagulation therapy: a prospective case–control study.
Clin. Oral Impl. Res. 22 , 2011; 151–156.
doi: 10.1111/j.1600‐0501.2010.01963.x     

Histologic evaluation of the buccal and lingual bone plates in anterior dog teeth: possible influence on implant dentistry

Background: Recent studies in animals have shown pronounced resorption of buccal bone plate after immediate implantation. The sectioning of experimental material for histologic evaluation of the bone plates could provide valuable information about the possible effect of bone exposure in periodontal and implant surgeries. Methods: Twenty‐four incisors were collected from dogs. After decalcification, the blocks were immersed in paraffin and bucco‐lingual histologic sections were examined under light microscope. Some sections were reserved for immunohistochemical analysis. Results: The bone density, the width of the bone plates, and the percentage of vessels presented in the periodontal ligament and periosteum were analyzed in the buccal and lingual bone plates, which were divided corono‐apically into thirds. The buccal bone plates showed statistically higher bone density compared to the lingual bone plates in the coronal thirds. The width of both bone plates increased from the coronal to the apical third, but all the buccal thirds were significantly thinner compared to the lingual thirds. No statistically significant differences were found between the bone plates for the percentage of area occupied by the blood vessels in the periodontal ligament or periosteum. Conclusion: It is reasonable to conclude that the higher bone density, represented by the lower number of marrow spaces, in association with the thinner aspect of the buccal bone plates made them more fragile to absorb compared to the lingual bone plates, especially during mucoperiosteal procedures.     

The effect of commercially pure titanium and alternative dental alloys on the marginal fit of one-piece cast implant frameworks

OBJECTIVES: The purpose of this study was to measure and compare the passive fit and vertical fit of one-piece cast frameworks fabricated with three different materials: commercially pure titanium (CP Ti), cobalt-chromium alloy (Co-Cr) and nickel-chromium-titanium alloy (Ni-Cr-Ti). METHODS: Fifteen frameworks simulating bars for fixed prosthesis in a model with five implants were fabricated and arranged into three different groups according to the material used. The fit of the framework abutment interface was measured using an optical microscope, when only one screw was manually tightened at a terminal abutment (passive fit) or when all framework screws were tightened to 10 N cm torque (vertical fit). Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney tests (alpha=0.05). RESULTS: Mean and standard deviation values of passive fit and vertical fit are presented, respectively: CP Ti [88 (74) microm and 22 (9) microm], Co-Cr [229 (184) microm and 66 (35) microm], Ni-Cr-Ti [200 (175) microm and 32 (24) microm]. There were no significant differences between passive fit of Co-Cr and Ni-Cr-Ti frameworks (p=0.313), but both alloys were statistically different from CP Ti (p<0.001 and 0.035, respectively), which showed the best results. As for vertical fit, CP Ti and Ni-Cr-Ti alloy were statistically similar (p=0.162) and they presented a better vertical fit than Co-Cr alloy (p<0.001). CONCLUSIONS: Within the limitations of this study, it was possible to conclude that one-piece cast frameworks resulted in unacceptable passive fit and vertical fit, no matter which material had been used to fabricate them. However, the best results were obtained using CP Ti followed by Ni-Cr-Ti and Co-Cr alloys, respectively.     

Soft tissue healing at titanium implants coated with type I collagen. An experimental study in dogs

Objective: To analyse the soft tissue healing at titanium implants coated with type 1 collagen. Material and methods: Six dogs were used. The mandibular pre‐molars and the three anterior maxillary pre‐molars were extracted. Three months later mucoperiosteal flaps were raised and two test and two control implants were installed (3i^® TG Osseotite^®3.75 × 10 and 2.8 mm transmucosal collar). The test implants were coated with a purified porcine type I collagen. Cover screws were placed and flaps were sutured. The sutures were removed 2 weeks later and a plaque‐control programme was initiated. Another 2 weeks later, the procedure was repeated in the contra‐lateral mandibular region. Four weeks after the second implant surgery, biopsies were obtained and prepared for histological examination. Results/Conclusion: The vertical dimensions of the epithelial and connective tissue components as well as the composition of the connective tissue portion facing the implant were similar at collagen‐coated and uncoated implants after 4 and 8 weeks of healing. It is suggested that soft tissue healing to implants coated with type I collagen was similar to that at non‐coated titanium implants and that no adverse reactions to the collagen‐coated implants occurred.     

Early implant failure. Prognostic capacity of Periotest: retrospective study of a large sample

Objectives: The objectives of this study were to determine the accuracy of Periotest^® to monitor primary implant stability at first‐stage surgery, to identify by multivariate analysis the variables associated with early implant failure and to compare Periotest^® with radiographic study in the diagnosis of implant stability at second‐stage surgery (during osseointegration period). Material and methods: A 10‐year retrospective study was conducted on 1084 Brånemark^® implants placed in 316 patients. Clinical variables, implant diameter and length, Periotest^® values (PTVs) and radiological variables were analyzed in bivariate and multivariate studies in order to determine their influence on early implant failure. Results: After examination of the sensitivity and specificity values obtained for different PTV cutoff points, a cutoff PTV of ?2 was selected (84% sensitivity and 39% specificity). In the bivariate analysis, early failure was significantly related to smoking habits, implant location, bone type, implant features and PTVs (?2 and ≥?2). In the final multiple logistic model, only age (odds ratio (OR)=4.53; 95% confidence interval (CI), 1.34–15.27), smoking habits (OR=2.5; 95% CI, 1.3–4.79), bone type (OR=1.93; 95% CI, 1.01–3.7) and PTV at first surgery (OR=3.01; 95% CI, 1.5–6.02) were independently related to early failure. Conclusions: The Periotest^® (with ?2 cutoff) at first surgery offers high sensitivity in the prognosis of early implant loss and shows a greater capacity to evaluate stability during the osseointegration period compared with radiographic study.