Delayed immediate implants: alveolar bone chamzes durinrr the healing period

Delaying the placement of immediate fixtures by 6–8 weeks after extraction of the natural dentition allows for the elimination of associated infective processes, the achievement of maximum osteoblastic activity that theoretically could help the osseointegration process and complete wound covering that simplifies the placement of grafts or membranes. This study examines the healing associated with 21 fixtures in 14 patients. The fixtures were placed into sockets 6–8 weeks after tooth extraction without the use of barrier membranes or bone substitutes. Measurements were taken immediately prior to fixture placement and 3–6 months later at the abutment placement. Alveolar bone height, the remaining socket depth and diameter and the depth to which a 3.75 mm fixture could be inserted into the socket were measured. After fixture placement the vertical and horizontal measurements from the cover screw to the surrounding alveolar bone and the distance from the cover screw to the CEJ of the adjacent tooth were recorded. All fixtures were integrated at exposure with 1 failure during the follow-up period. The distance from the cover screw to the buccal plate decreased by a mean of 2.17 mm. There was an increase in the mean vertical bone height at all 4 surfaces. When horizontal defects were present, the mean vertical distance decreased from 2.5±0.37 mm to 0.36±0.64 mm. When horizontal defects were absent, the mean vertical distance decreased from 3.86±0.58 mm to 0.48±0.25 mm. There was also a marked decrease in the horizontal distance between the bone margin and the surface of the fixture from 1.6±l.73 mm 1 to 0.02±0.02 mm. These results indicate a strong tendency for the defects to fill-in in the horizontal plane and for bone growth to occur in the vertical plane to the height of the cover screw. In conclusion the delayed immediate placement of fixtures has a good short-term prognosis with bone regeneration occurring around the defect without the use of barrier membranes or bone substitutes.     

Tapered implants in jaws with soft bone quality: a clinical and radiographic 1-year study of the Brånemark System Mark IV fixture

Background: The survival rate of oral implants in soft‐quality bone has been demonstrated to be inferior to that of implants inserted in good‐quality bone. A possible way to increase the survival rate in soft‐quality bone may be to use a tapered implant. Such an implant has been developed and manufactured by Nobel Biocare AB, Gothenburg, Sweden. So far, there have been only a few publications regarding this implant. Purpose: The aim of the study was to compare the outcome of using the tapered Branemark System Mark IV fixture with the outcome of using earlier Brånemark fixtures in a controlled prospective study. Materials and Methods: The study was performed as a multicenter study including seven specialist centers. The material consisted of 40 patients in need of implant‐supported bridges in the maxilla. Twenty‐five patients belonged to the test group, in which the tapered Mark IV implants were inserted, and 15 patients belonged to the control group, in which Branemark Standard or Mark II implants were used. The patients were allocated to the test group or the control group according to randomization schedules. The implants were inserted according to the guidelines for Branemark implants. A two‐stage surgical protocol was used, and abutment connection was made 6 months after fixture insertion. The test group comprised 97 Mark IV implants, and the control group made up 92 implants. The prosthetic procedure followed the guidelines for Brånemark implants, and all patients were provided with full fixed maxillary bridges. The patients were followed up with clinical and radiographie records for 1 year after loading. Results: The survival rate was 96.9% for the Mark IV implants and 98.9% for the control implants. There was no significant difference between the two groups. There was a mean marginal bone loss of 0.2 mm during the observation period, and there was no difference between test implants and control implants. Conclusions: With regard to survival rate and marginal bone level changes, no differences could be demonstrated between the Mark IV tapered implant and the Brånemark implants used earlier. However, compared with earlier results of Brånemark implants in soft‐quality bone, the Mark IV implant demonstrated an improved survival rate.     

Clinical results of alveolar ridge augmentation with mandibular block bone grafts in partially edentulous patients prior to implant placement

A group of 15 partially edentulous patients who needed alveolar ridge augmentation for implant placement, were consecutively treated using a two-stage technique in an outpatient environment. A total of 18 alveolar segments were grafted. During the first operation bone blocks harvested from the mandibular ramus or symphysis were placed as lateral or vertical onlay grafts and fixed with titanium osteosynthesis screws after exposure of the deficient alveolar ridge. After 6 months of healing the flap was re-opened, the screws were removed and the implants placed. Twelve months after the first operation implant-supported fixed bridges could be provided to the patients. Mean lateral augmentation obtained at the time of bone grafting was 6.5 +/- 0.33 mm, that reduced during healing because of graft resorption to a mean of 5.0 +/- 0.23 mm. Mean vertical augmentation obtained in the 9 sites where it was needed was 3.4 +/- 0.66 mm at bone grafting and 2.2 +/- 0.66 mm at implant placement. Mean lateral and vertical augmentation decreased by 23.5% and 42%, respectively, during bone graft healing (before implant insertion). Mandibular sites showed a larger amount of bone graft resorption than maxillary sites. All the 40 implants placed were integrated at the abutment connection and after prosthetic loading (mean follow-up was 12 months). No major complications were recorded at donor or recipient sites. Soft tissue healing was uneventful, and pain and swelling were comparable to usual dentoalveolar procedures. A visible ecchymosis was present for 4 to 7 days when the bone was harvested from the mandibular symphysis. From a clinical point of view this procedure appears to be simple, safe and effective for treating localised alveolar ridge defects in partially edentulous patients.     

软组织瓣早期裂开或穿孔对种植体颈缘部骨组织的影响

放射线性片评估种植手术后软件组织瓣早开裂或穿孔对种植体周边缘骨吸收的影响。方法：１７例种植患者,植入的３２颗两段式骨内种植体,其中１７颗出现软组织瓣早期裂开或穿孔,导致种植体早期暴露。根据种植体入当天及种植Ⅱ期手术（安装愈合基台）前的Ｘ线片（根尖片）,测量出种植体颈部边缘骨高度的变化。结果：早期暴露的种植体均产生明显吸收,近中平均１．９５ｍｍ,远中平均２．１５ｍｍ;而正常愈合种植体（非裂开）骨变化     

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys

The aim of this study was to evaluate clinically, histologically and histometrically the use of anorganic bovine bone matrix (i.e. Bio-oss®) as a grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (i.e. Mucaca mulattu) the 1st 2nd and 3rd maxillary molars on one side of the jaws were extracted. The remaining bone between the alveolar crest and the bottom of the sinus was then reduced to 3–4 mm. After 3 months, maxillary sinus augmentation procedures were performed on one side of the jaws in each monkey and the sinuses were grafted with the bovine bone matrix. At that time, 2 IMZ pure titanium plasma coated implants were immediately placed into the augmented sinuses (i.e. simultaneous implants-loaded group). After 4 months, 2 additional similar implants were placed into these previously augmented sinuses (i.e. delayed implants-loaded group). Four months later, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received the same treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous implants-unloaded group and delayed implants-unloaded group) were obtained. Clinically, all loaded implants were stable at the day of sacrifice. Histologically, the grafted sinuses exhibited significant bone formation with integration of the bovine bone matrix particles to the new bone. Direct mineralized bone-to-implant contact was greater for the delayed implant placement groups than for the implants installed simultaneously with the sinus augmentation. Furthermore, the percentage of direct mineralized bone-to-implant contact was greater in the residual bone than in the augmented area. It was concluded that the anorganic bovine bone matrix facilitated bone formation and implant osseointegration in the augmented sinuses and that the delayed implant placement in combination with the sinus augmentation procedure seemed to be preferable.     

Short implants versus bone augmentation in combination with standard-length implants in posterior atrophic partially edentulous mandibles: systematic review and meta-analysis with the Bayesian approach

The use of short implants as an alternative to bone reconstruction techniques for the placement of standard-length dental implants is a debated topic. The aim of this study was to perform a systematic review and meta-analysis in order to assist in the clinical decision making about the most appropriate approach for the fixed rehabilitation of the posterior atrophic partially edentulous lower jaws. Only randomized trials with at least 1-year follow-up were included. Of the 1024 studies initially retrieved, 14 articles were selected and independently evaluated by two reviewers. Finally, four studies were included, and underwent data extraction and meta-analysis with the Bayesian approach. Both treatment approaches provide high implant survival rate after 1year of function. However, the probability of survival rate of short implants being greater than standard length implants is 84%, and the probability of complications using short implants being greater than standard-length implants is 15.7%. In spite of similar survival rates when the residual bone is sufficient for placement of short implants, the latter should be preferred to augmentation techniques and standard-length implants due to fewer complications, lower morbidity and greater comfort for patients.     

牙种植体植入同期植骨增加种植床骨量的临床观察

对３８例牙缺失伴局部骨量不足的患者,在牙种植体植入同期,分别采用羟基磷灰石ＨＡ、ＨＡ加自体骨、脱钙骨和自体骨移植,增加种植床的三维骨量,３７例获得成功,１例失败。结果表明：牙种植体植入同期植骨修复局部骨缺损是可行的,有利于拓我齿修复的适应症和提高长期成功率。ＨＡ,ＨＡ加自体骨、脱钙骨和自体骨均可作为植骨材料,但应根据骨量不足的类型进行选择。     

Use of a Surgical Template for Autologous Bone Grafting of Alveolar Defects

This article describes the fabrication of a surgical template for planning and performing the harvest and placement of autologous bone grafts for the reconstruction of alveolar defects before implant placement. A diagnostic cast is altered to replicate the anticipated bone anatomy. The ideal bony contours for implant placement are then created on the cast to form the template. This template may then be used for treatment-planning donor sites for the harvest of corticocancellous bone grafts. The template is sterilized and used by the surgeon in procuring and placing the bone graft. This template allows communication of the prosthetic requirements of the ridge augmentation, as well as ensuring adequate volume and proper positioning of the block graft for eventual implant placement.     

Evaluation of Effects of Topic Melatonin on Implant Surface at 5 and 8 Weeks in Beagle Dogs

Purpose: The aim of this study was to evaluate the effect of the topical application of melatonin on osteointegration of dental implants in Beagle dogs 5 and 8 weeks after their insertion. Materials and Methods: For subsequent insertion of dental implants, upper and lower premolars and molars were extracted from 12 Beagle dogs. Each mandible received cylindrical screw implants of 3.25 mm in diameter and 10 mm in length. The implants were randomly assigned to the mesial and distal sites on each side of the mandible. Prior to implanting, 1.2 mg lyophylized powder melatonin was applied to one bone hole at each side of the mandible. None was applied at the control sites. Eight histological sections per implant were obtained for histomorphometric studies. Results: After 5‐ and 8‐week treatment periods, melatonin significantly increased the inter‐thread bone (p < 0.05) and new bone formation (p < 0.05) in comparison to control implants in both weeks. There were no significant increases in the bone‐to‐implant contact and peri‐implant bone (p > 0.05). Conclusion: Topical application of melatonin may act as a biomimetic agent in the placement of endo‐osseous dental implants at 5 and 8 weeks after the implantation.     

Stability Evaluation of Implants Integrated in Grafted and Nongrafted Maxillary Bone: A Clinical Study from Implant Placement to Abutment Connection

Background: Clinical studies have shown a higher degree of implant failures in grafted bone compared with normal nongrafted maxillary bone. Additionally, a prolonged time for integration of titanium implants in grafted block bone has been shown by means of resonance frequency analysis (RFA). Purpose: The aim of this prospective study was to compare the stability of implants placed in particulate bone, onlay block bone, interpositional bone, and nongrafted maxillary bone during the early phase of osseointegration using RFA and implant failure. Material and Methods: Thirty‐five patients with edentulism in the maxilla were included in the study. In all, 260 Astra Tech TiOblast? implants (Astra Tech AB, Mölndal, Sweden) were installed. Twenty‐five of these patients had severe maxillary atrophy and were treated with iliac bone grafts 5 to 6 months prior to implant placement, 19 with lateral onlay block grafts on one side (group A, 38 implants) and particulate bone for lateral augmentation on the other (group B, 38 implants). These 19 patients also got bilateral sinus floor augmentation with particulate bone (group C, 76 implants). Six patients had an unfavorable sagittal relation between the jaws and underwent a LeFort I operation with interpositional bone blocks grafted to the nasal and sinus floors (group D, 48 implants). The remaining 10 patients could be treated with implants without bone augmentation and served as control (group E, 60 implants). RFA was performed at implant placement and abutment connection 6 months later and an implant stability quotient (ISQ) value was given for each implant. Results: Four implants (1.5%) were found mobile at abutment connection and removed (two in group A and two in group D). RFA showed a slight increase in stability from installation to abutment connection but the differences were not statistically significant in any of the groups (Wilcoxon signed rank test for comparison of paired data). Implants installed in group D had a significantly lower ISQ value at both measurements compared with the other groups (Wilcoxon Rank Sum test for comparisons of independent samples, p = .05). Conclusion: It is concluded that TiO₂‐blasted implants placed in nongrafted and grafted maxillary bone using a two‐staged protocol show similar stability during the early phase of osseointegration. Patients reconstructed with interpositional bone graft after a LeFort I osteotomy showed lower implant stability values than nongrafted patients and other grafting techniques.     

Guided bone regeneration around non-submerged implants in narrow alveolar ridges: a prospective long-term clinical study

OBJECTIVES: This prospective clinical study investigates long-term survival and clinical parameters of non-submerged implants with large buccal dehiscences treated with a deproteinized bovine bone mineral xenograft and a non-resorbable membrane in a one-stage approach. MATERIAL AND METHODS: Sixteen consecutive non-submerged implants (ITI Straumann) were installed in narrow alveolar ridges in 13 patients (age range: 25-61 years). All patients were non-smokers. On the buccal site the bone dehiscence ranged between 3 and 9 mm. Primary stability was achieved in all but one implant. The exposed threads were covered with a xenograft (Bio-Oss) and a non-resorbable expanded polytetrafluoroethylene membrane. The flap was sutured leaving the implant head non-submerged. The membrane was removed when (1) the membrane became exposed or (2) after a maximum of 24 weeks. All implants received singular cemented crowns. The implants were followed for a period ranging from 12 to 114 months. Whole-mouth plaque index (Pl), the % of bleeding on probing (BOP), probing depth and signs of peri-implantitis were recorded. Every year periapical radiographs were taken using a long cone technique. RESULTS: All but one implant integrated successfully. At the time of membrane removal, all previously exposed threads were completely covered with richly vascularized tissue except for two implants where the coverage reached 63% and 87%, respectively. The whole-mouth plaque score and BOP remained low in all patients during the observation period. None of the implants had plaque and, except for one implant BOP never occurred. All implants were stable and in function. Swelling, redness or purulence was never observed. On the periapical radiographs no bone resorption was observed on the mesial and distal site except for one implant in one patient with a mesial and distal bone resorption of 2 and 3 mm. Probing depth was never higher than 3 mm except for one patient where the implant was placed deeply subgingival for esthetical reasons. CONCLUSION: This prospective long-term study shows that with the use of non-submerged transmucosal implants, large bony dehiscences can be treated in a one-stage approach using a stiff non-resorbable membrane combined with a xenograft.     

Short Implants: A Descriptive Study of 273 Implants

Purpose: The study aims to assess the performance of short implants in a series of patients with severe alveolar resorption. Materials and Methods: A review is made of 273 implants measuring 10 mm or less, placed by conventional surgery or using osteotomes, and with a postloading follow‐up of between 18 months and 12 years (mean 81 months). Results: A total of 20 failures were recorded (7.33%), with a global implant survival of 92.67%. The survival rate for 10 mm implants was 92.82%, versus 92.5% in the case of those measuring less than 10 mm. Overall, the failure rate was lowest for the treated surface implants (2.56% vs 4.76%). On considering the implants measuring under 10 mm, the failure rates were similar in both groups (3.77%). Conclusions: Short implants are a good treatment alternative for patients with severe alveolar resorption of both jaws.     

Maxillary sinus augmentation using different grafting materials and osseointegrated dental implants in monkeys. Part IV Evaluation of hydroxyapatite‐coated implants.

The aim of this study was to evaluate clinically, histologically and histometrically the use of hydroxyapatite-coated dental implants in conjunction with maxillary sinus augmentation procedures. In 4 adult male Rhesus monkeys (Mucaca muluttu) the 3 maxillary molars on 1 side of the jaws were extracted and the remaining bone between the alveolar crest and the floor of the sinus was reduced to 3–4 mm. After 3 months, maxillary sinus augmentation procedures were performed in each monkey and the sinuses were grafted with a porous hydroxyapatite bone graft (Interpore-200®). At the same time, 2 hydroxyapatite-coated cylinder implants (IMZ®) were immediately placed into the augmented sinuses (i.e. simultaneous-implants-loaded group). Four months later, 2 additional similar implants were placed into the previously augmented sinuses (i.e. delayed-implants-loaded group). After 4 months, the abutment connection was performed, and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received the same treatment with the exception that removal of the maxillary molars was performed 7 months after those in the opposite side, and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous-implants-unloaded group and delayed-implants-unloaded group) were obtained. Clinically, all loaded and unloaded implants were stable the day of sacrifice. Histologically, the grafted sinuses exhibited a significant amount of new bone formation, with integration of the porous hydroxyapatite graft particles and hydroxyapatite-coat of the dental implants to the new bone. Histometric analysis indicated that on the loaded side the implants placed simultaneously with the sinus lift procedure exhibited greater direct mineralized bone-to-implant contact than the delayed placed implants. In addition, the percentage of direct mineralized bone-to-implant contact was significantly greater in the residual bone in comparison to the augmented area in all groups. Loading of the implants exhibited a positive effect on the percentage of direct mineralized bone-to-implant contact in the augmented area. It could be concluded that hydroxyapatite-coated implants may be of benefit when used in conjunction with sinus augmentation procedures.     

Healing of transplanted composite bone grafts-implants: a pilot animal study

This experimental pilot study was undertaken to evaluate healing of titanium implants transplanted with the surrounding bone into recipient osseous sites in the rabbit mandible. One short implant was inserted in the horizontal portion of the mandible in each of 10 New Zealand rabbits. Subsequently, and during the same session, the implant with 1.5-2.0 mm of bone circumferentially was removed using a trephine bur and immediately transplanted in a through-and-through hole prepared in the contralateral aspect of the mandible. Three months following the transplantation, the animals were sacrificed and the mandibles processed for histological evaluation. The healing pattern was assessed in relation to (1) bone bridging at the interface between the bone core and the surrounding recipient osseous tissue, (2) differences in bone density between the transplanted bone cylinder and the bone at the margins of the recipient site, and (3) bone-to-implant contact (BIC) at the interface. The transplanted graft-implant cores were integrated within the recipient sites in five out of the 10 specimens while the remaining five bone-implant cores showed fibrous encapsulation. Various patterns of resorption were observed within the peri-implant transplanted hard tissues. Percentage BIC ranged between 1% and 72% in the fibrous-encapsulated specimens and between 20% and 62% in the integrated transplants. Within the limits of this pilot study, the results suggest that immediate transplantation of endosseous implants with their surrounding bone into congruous recipient osseous sites cannot predictably yield graft-implant incorporation and osseointegration of the implants. This alternative surgical modality of immediately transplanting a composite bone graft-implant from highly cortical intraoral or extraoral sites to enhance bone quality and/or volume in implant recipient sites such as the maxillary sinus and tuberosity areas needs to be further investigated.