Vitality of autologous retromolar bone grafts for alveolar ridge augmentation after a 3-months healing period: A prospective histomorphometrical analysis.

OBJECTIVES: The incorporation of retromolar bone grafts used for alveolar ridge augmentation is not well understood. This prospective observational study aims to supply histomorphometrical data from bone graft biopsies taken at the time of retrieval and after a 3-month healing period using patient-matched biopsies. MATERIALS AND METHODS: In 17 patients, trephine biopsies of the graft were acquired at the time of graft retrieval and after a 3-month healing period. The biopsies were compared histomorphometrically regarding the number of osteocytes, appearance of osteocyte lacunae, quantity, surface area, and activity of the Haversian canals. RESULTS: All grafts appeared clinically stable after screw removal and 17 implants were placed. Histomorphometric analysis revealed no significant difference in the number of osteocytes (p = .413), osteocyte lacunae (p = .611), the ratio of filled/empty osteocyte lacunae (p = .467) and active Haversian canals (p = .495) between the biopsies retrieved after a 3-months healing period with those at the time of grafting. The only significant difference was noted in the mean surface area of the Haversian canals (p = .002). Specifically, the grafts post 3-month healing showed a significantly larger mean area (0.069 mm2) compared to the time of grafting (0.029 mm2). CONCLUSION: This study demonstrates, compared to other data, a high rate of vital structures in retromolar bone block grafts after 3 months of healing, exhibiting the same histological features in comparison to the biopsies from the native alveolar ridge. Standard histomorphometrical parameters, e.g., the amount of filled or empty osteocyte lacunae for the description of the vitality of the graft need to be reappraised.

Impurities in commercial titanium dental implants - A mass and optical emission spectrometry elemental analysis.

OBJECTIVE: Titanium (Ti) is considered bioinert and is still regarded as the "gold standard" material for dental implants. However, even 'commercial pure' Ti will contain minor fractions of elemental impurities. Evidence demonstrating the release of Ti ions and particles from 'passive' implant surfaces is increasing and has been attributed to biocorrosion processes which may provoke immunological reactions. However, Ti observed in peri-implant tissues has been shown to be co-located with elements considered impurities in biomedical alloys. Accordingly, this study aimed to quantify the composition of impurities in commercial Ti dental implants. METHODS: Fifteen commercial titanium dental implant systems were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES). RESULTS: The elemental composition of implants manufactured from commercially pure grades of Ti, Ti-6Al-4V, and the TiZr alloy (Roxolid) conformed to the respective ISO/ASTM standards or manufacturers´ data (TiZr/Roxolid). However, all implants investigated included exogenous metal contaminants including Ni, Cr, Sb, and Nb to a variable extent. Other contaminants detected in a fraction of implants included As and the radionuclides U-238 and Th-232. SIGNIFICANCE: Although all Ti implant studies conformed with their standard compositions, potentially allergenic, noxious metals and even radionuclides were detected. Since there are differences in the degree of contamination between the implant systems, a certain impurity fraction seems technically avoidable. The clinical relevance of these findings must be further investigated, and an adaptation of industry standards should be discussed.

Comparison of the 3D-Microstructure Between Alveolar and Iliac Bone for Enhanced Bioinspired Bone Graft Substitutes.

In oral- and maxillofacial bone augmentation surgery, non-vascularized grafts from the iliac crest demonstrate better clinical performance than alveolar bone grafts. The underlying mechanisms are not fully understood but are essential for the enhancement of bone regeneration scaffolds. Synchrotron Radiation µ-CT at a pixel size of 2.3 µm was used to characterize the gross morphology and the vascular and osteocyte lacuna porosity of patient-matched iliac crest/alveolar bone samples. The results suggest a difference in the spatial distribution of the vascular pore system. Fluid simulations reveal the permeability tensor to be more homogeneous in the iliac crest, indicating a more unidirectional fluid flow in alveolar bone. The average distance between bone mineral and the closest vessel pore boundary was found to be higher in alveolar bone. At the same time, osteocyte lacunae density is higher in alveolar bone, potentially compensating for the longer average distance between the bone mineral and vessel pores. The present study comprehensively quantified and compared the 3D microarchitecture of intraindividual human alveolar and iliac bone. The identified difference in pore network architecture may allow a bone graft from the iliac crest to exhibit higher regeneration potential due to an increased capacity to connect with the surrounding pore network of the residual bone. The results may contribute to understanding the difference in clinical performance when used as bone grafts and are essential for optimization of future scaffold materials.

Resorption of retromolar bone grafts after alveolar ridge augmentation-volumetric changes after 12 months assessed by CBCT analysis.

In this pilot study, a volumetric analysis of retromolar onlay bone grafts over a period of 12 months was conducted, using repeated CBCT imaging combined with automated image registration.Eleven patients being treated with 16 bone grafts taken from the retromolar area were examined by CBCT scanning prior to bone augmentation (T0), immediately after bone augmentation (T1) and after a healing time of 12 months after augmentation (T2). Graft volumes were measured at each time point after automated image registration of consecutive CBCT scans.The mean volume of the augmented site was 372.2 ± 179.4 mm3. Resorption relative to the original augmented volume was 43.7% ± 19.0% after 12 months.Three-dimensional graft resorption could be precisely depicted by the use of automated image registration for CBCT data over a period of 12 months and demonstrated extensive volumetric changes of bone grafts taken from the ascending ramus of the mandible.Graft resorption and continuous bony remodeling of the grafted site before and after implant insertion have to be carefully considered by the clinician.

Horizontal bone grafting using equine-derived cancellous bone blocks is associated with severe complications: A prospective clinical and histological pilot study.

AIMS: The aim of this prospective, clinical study was to evaluate the clinical performance and histological outcome of a new equine hydroxyapatite collagenated bone block (eHAC) for horizontal bone grafting prior to implant placement. MATERIALS AND METHODS: Five patients (two male/three female) with a mean age of 51.6 years (range 22-66 years) and a reduced horizontal bone width of the alveolar ridge (mean 3.5 mm) underwent horizontal bone grafting using eHAC at 10 grafting sites. Reentry was performed 6.9 months after the horizontal grafting procedure. Clinical follow-up (mean 28.9 month) considered width gain of the alveolar ridge, soft tissue healing, and complications. To evaluate graft incorporation, four additional patients underwent histological assessment of equine blocks adjacent to autologous blocks 3 and 6 months after grafting. RESULTS: The study was terminated after graft failure was observed in four of five patients. Mean horizontal bone width had increased by 3.6 ± 1.22 mm. Three out of nine implants placed had to be removed due to graft failure. Histological evaluation revealed large amounts of soft connective tissue within the grafts (mean 67.3 ± 9.5%). The proportion of new bone formation 3 months after the lateral grafting procedure revealed an average of 8.6%, compared to 11.4% after 6 to 7 months. CONCLUSION: Lateral ridge grafting using eHAC achieved measurable horizontal width gain but revealed high rates of severe complications. CLINICAL IMPLICATIONS: Within the limitations of this study, eHAC bone blocks cannot be recommended for horizontal bone grafting.

Sinus Floor Elevation with Biphasic Calcium Phosphate or Deproteinized Bovine Bone Mineral: Clinical and Histomorphometric Outcomes of a Randomized Controlled Clinical Trial.

PURPOSE: To clinically and histomorphometrically compare a biphasic calcium phosphate (BCP) and deproteinized bovine bone mineral (DBBM) for sinus floor elevation. MATERIALS AND METHODS: Sinus floor elevation procedures (lateral window) were performed randomly applying either BCP (test) or DBBM (control). At 6 months, bone biopsy specimens were harvested and dental implants were placed. The proportions of new bone, residual grafting material, and nonmineralized soft tissue were calculated. Four months after implant placement, the prosthetic reconstructions were inserted and the implant survival was assessed. RESULTS: Fifty-one patients were treated; 25 were randomly allocated to the BCP group and 26 to the DBBM group. After 6 months in 50 patients, bone biopsy specimens could be harvested, and a total of 121 implants could be placed subsequently. The histomorphometric analysis revealed a comparable percentage of new bone in both groups (BCP 35.9%, DBBM 35.4%; P > .05). The remaining grafting material was significantly lower with BCP (25.3%) compared with DBBM (45.9%; P < .001). Nonmineralized tissue was significantly higher for the BCP group (38.1%) compared with the DBBM group (18.2%; P < .001). The implant survival rate at loading was assessed at the level of the patients (96.0% for BCP and 88.8% for DBBM; P > .05) and at the level of the implants (96.9% for BCP and 94.7% for DBBM; P > .05). CONCLUSION: Grafting with DBBM or BCP showed similar percentages of new bone 6 months after sinus floor elevation. Implant survival presented no significant difference until loading.

Elemental analysis of commercial zirconia dental implants - Is "metal-free" devoid of metals?

OBJECTIVES: The interest in ceramic dental implants made of yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) or alumina toughened zirconia (ATZ) has increased in recent years. However, in the light of aging, corrosion, and potential impurities of zirconia ceramics, the material composition of these implants and the associated term "metal-free" is persistently questioned. Thus, the present study aimed to conduct an elemental analysis of commercial zirconia dental implants to specify their elemental composition and to identify contaminants. METHODS: Nine commercial zirconia dental implant systems and corresponding material samples were analyzed using inductively coupled plasma-mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES). RESULTS: While the elemental composition was dominated by the main components Zr, Y and Al (in ATZ samples), all investigated samples contained impurities with Hf and contamination with alkali and alkali earth elements (Na, K, Mg, Ca), essential trace elements (e.g. Fe, Cu, Zn) but also potentially noxious metal elements (e.g. Ni, Cr). Furthermore, ultra-trace level contamination with the radionuclides U-238 and Th-232 was found in the majority of samples. SIGNIFICANCE: The results indicate that, although all the investigated Y-TZP and ATZ dental implants meet the currently relevant ISO standards and manufacturer's specifications, from an elemental point of view, they are not devoid of metals. Due to the lack of a universal definition and thresholds for the term "metal-free", the question of whether the examined zirconia dental implants can be holistically classified as "metal-free" or not remains a controversial, philosophical one.

The Alveolar Ridge Splitting Technique on Maxillae: A Biomechanical Human Cadaveric Investigation.

The alveolar ridge splitting technique (ARST) offers an alternative to classic ridge augmentation techniques for successful insertion of dental implants. However, the buccal lamella is at risk of fracturing during ARST distraction. To better understand the fracture mechanisms and displacement limits of the split lamella, this study conducted biomechanical tests on human cadaveric maxilla specimens having extremely atrophied alveolar ridges treated with ARST. A total of 12 standardized alveolar splits were prepared on the maxillae of 3 elderly female donors using an oscillating piezoelectric saw. Mimicking the surgical distraction process of the lamella, each split was tested to failure using a dental osteotome attached to the crosshead of an electromechanical testing system. All specimens were scanned by means of high-resolution peripheral quantitative computed tomography prior to and post testing to evaluate split geometries and failure modes. Split stiffness, failure force, and displacement were 27.4 ± 18.7 N/mm, 12.0 ± 8.4 N, and 0.97 ± 0.31 mm, with no significant differences between anatomical sides and split locations (p ≥ 0.17). Stiffness correlated significantly with failure force (R 2 = 0.71, p < 0.01). None of the alveolar split widths correlated significantly with the outcomes from biomechanical testing (p ≥ 0.10). The results suggest that simple geometrical measures do not predict the allowed extent of lamella distraction prior to failure. More sophisticated methods are required for surgical planning to optimize the ARST outcomes. Still, the present study may advocate a clinical protocol for the maxilla where the implant site is prepared directly after osteotomy setting and immediately before full lamella dislocation, when the lamella is still stable, resistant to mechanical stress, and bone loss caused by the abrasion of the burr is minimized.

Finite Element Analysis and Biomechanical Testing to Analyze Fracture Displacement of Alveolar Ridge Splitting.

The alveolar ridge splitting technique enables reconstruction of atrophied alveolar ridges prior implantation. However, in cases of severe atrophy, there is an unpredictable risk of fracturing the buccal lamella during the expansion. Currently, there is no preoperative assessment to predict the maximum distraction of the lamella. The aim of this study was to develop a biomechanical model to mimic the alveolar ridge splitting and a finite element (FE) model to predict the experimental results. The biomechanical testing was conducted on porcine mandibles. To build the FE model high resolution peripheral quantitative computer tomography scans of one specimen was performed after the osteotomy outline, but before the lamella displacement. A servo-electric testing machine was used for the axial tension test to split the lamellae. Results showed, in line with clinical observations, that the lamellae broke primarily at the base of the splits with a median displacement of 1.27 mm. The FE model could predict fracture force and fracture displacement. Fracture force showed a nonlinear correlation with the height of the bone lamella. In conclusion, good correspondence between mechanical testing and virtual FE analysis showed a clinically relevant approach that may help to predict maximum lamella displacement to prevent fractures in the future.

Implant success and survival rates in daily dental practice: 5-year results of a non-interventional study using CAMLOG SCREW-LINE implants with or without platform-switching abutments.

BACKGROUND: The performance of dental implants in controlled clinical studies is often investigated in homogenous populations. Observational studies are necessary to evaluate the outcome of implant restorations placed in real-life situations, according to standard practice, and to assess the needs of the patients. The aim of this non-interventional study was to reveal the survival, success, and general performance of CAMLOG SCREW-LINE implants and their restorations in daily dental practice. METHODS: Seventeen private practices across five countries participated in this prospective multicenter study. Patients received implants in the maxilla and mandible which were restored either with platform-matching or platform-switching abutments. Patients were followed-up for up to 5 years post-loading. Radiographs and clinical parameters were evaluated and patient satisfaction was evaluated. RESULTS: From a total of 196 patients planned, 185 patients with 271 implants were restored with abutments and fulfilled the follow-up inclusion criteria. Three implant failures were recorded, resulting in a cumulative survival rate of 98.6% after 5 years post-loading. One persistent complication of peri-implantitis occurred. The soft tissue health remained stable, and the papilla height improved after loading. At 5-year follow-up, the mean crestal bone loss was - 0.28 ± 0.60 mm; over 99% of patients reported satisfaction with the restoration as excellent or good. CONCLUSIONS: Implants placed and restored with both platform-matching and platform-switching abutments in daily dental private practice achieved excellent clinical outcomes with highly satisfied patients after 5 years of function, confirming the results obtained in well-controlled clinical trials.

Sinusitis and oroantral fistula in patients with bisphosphonate-associated necrosis of the maxilla.

BACKGROUND: The management of bisphosphonate related necrosis of the jaw has become clinical routine. While approximately two thirds of the lesions are in the mandible, one third is located in the maxilla. In 40-50 % of maxillary necrosis the maxillary sinus is involved, leading to maxillary sinusitis and oro-antral communications. METHODS: This retrospective single center study includes all patients with diagnosis of BP-ONJ of the maxilla and concomitant maxillary sinusitis. The information collected includes age, gender, primary disease, bisphosphonate intake, involving type of bisphosphonate, route of administration and duration of BP treatment previous to surgical treatment and treatment outcome. RESULTS: A total of 12 patients fulfill the criteria of the diagnosis of maxillary sinusitis associated to maxillary necrosis, of which 6 Patients showed purulent sinusitis. All patients underwent surgical treatment with complete resection of the affected bone and a multilayer wound closure. A recurrence appeared in one patient with open bone and no sign of sinusitis and was treated conservatively. CONCLUSIONS: Purulent maxillary Sinusitis is a common complication of bisphosphonate-related necrosis of the maxilla. The surgical technique described can be suggested for the treatment of these patients.

Ridge preservation after ridge expansion with simultaneous guided bone regeneration: a preclinical study.

OBJECTIVE: To evaluate ridge preservation after ridge splitting with simultaneous implant placement and guided bone regeneration (GBR) in a miniature pig model. MATERIAL AND METHODS: In miniature pigs, the mandibular premolars and first molars were extracted together with removal of the interdental and buccal bone. Three months later, ridge splitting and expansion of the buccal plate were performed with simultaneous placement of two titanium implants per quadrant. On the test side, access by a mucoperiosteal flap followed by GBR with a biphasic calcium phosphate and a collagen membrane was performed. On the contralateral control side, a mucosal flap (MF), leaving the periosteum attached to the buccal bone, was elevated. After healing periods of 6 and 12 weeks, eight and four animals, respectively, were sacrificed for histological and histometric evaluation. RESULTS: In the MF group, all 16 implants were osseointegrated, while in the GBR group, one bone fracture occurred, and six of 16 implants were lost. After 6 weeks, significantly higher bone crest levels were found for the GBR group than for the MF group both buccally and lingually (P < 0.001), and buccal bone thickness was greater in the GBR group than in the MF group (P < 0.001 at the implant shoulder [IS]). After 12 weeks, bone was significantly higher in the GBR group compared to the MF group. Furthermore, buccal bone thickness in the GBR group was 0.93, 4.5, and 5.94 mm at, and 2 and 4 mm apical to the IS, respectively. The corresponding values in the MF group were greatly reduced (0, 0.21, and 2.56 mm). Bone loss on the buccal side compared to the lingual side was significantly greater only in the MF group. CONCLUSIONS: In this ridge expansion model in miniature pigs, the buccal bone volume was significantly better preserved with GBR when compared to a mucosal access flap, provided that soft tissue healing occurred complication free.

Piezosurgery in implant dentistry.

Piezosurgery, or the use of piezoelectric devices, is being applied increasingly in oral and maxillofacial surgery. The main advantages of this technique are precise and selective cuttings, the avoidance of thermal damage, and the preservation of soft-tissue structures. Through the application of piezoelectric surgery, implant-site preparation, bone grafting, sinus-floor elevation, edentulous ridge splitting or the lateralization of the inferior alveolar nerve are very technically feasible. This clinical overview gives a short summary of the current literature and outlines the advantages and disadvantages of piezoelectric bone surgery in implant dentistry. Overall, piezoelectric surgery is superior to other methods that utilize mechanical instruments. Handling of delicate or compromised hard- and soft-tissue conditions can be performed with less risk for the patient. With respect to current and future innovative surgical concepts, piezoelectric surgery offers a wide range of new possibilities to perform customized and minimally invasive osteotomies.

Long-term peri-implant bone level changes of non-vascularized fibula bone grafted edentulous patients.

Long-term results of reconstructions and prosthetic rehabilitation of patients presenting severely atrophied edentulous ridges remains a challenge for clinicians. Among the various available augmentation materials there is evidence that avascular fibula bone grafts possess a reliable resistance against resorption and may thus provide a valuable source to reduce the loss of vertical bone height after reconstruction of the severely atrophied mandible and maxilla. The purpose of the present study was to assess long-term crestal bone level stability in avascular fibula bone grafts. 8 edentulous female patients (average age 70.6 years) with Class-VI-atrophy and less than 5 mm residual bone volume received onlay-grafting with avascular fibula bone grafts and were monitored with a mean observation time of 133.7 months (121-186). A total of 39 implants were placed in the maxilla and mandible. Three patients received immediate and five patients delayed implant placement 3 months after grafting. All patients were provided with bar-retained dentures. Postoperative evaluation included clinical implant success (Buser) and radiographic examinations (orthopantomogram) to quantify crestal bone resorption. Grafting was successfully performed in all patients with no regrafting necessary. All implants but one, lost 2 years after abutment connection, remained successfully integrated and fulfilled the Buser criteria, rendering to a success rate of 97%. Mean bone resorption after 10 years was mesial 1.4 mm and distal 1.4 mm at each implant-site. Maximum bone resorption occurred between postoperative and first year, thereafter no significant resorption was measured in re-examinations up to 15 years. Avascular fibula grafts are a reliable bone graft for augmentation procedures in atrophied edentulous ridges. Dental implants that integrated in the autogenous fibular bone grafts showed a stable crestal peri-implant bone level up to 15 years after implant placement.

2-Dimensional changes of the soft tissue profile of augmented and non-augmented human extraction sockets: a randomized pilot study.

AIM: This study identified the soft tissue changes of the alveolar ridge at different time points within 12 weeks after tooth extraction with and without socket augmentation. MATERIALS AND METHODS: In 38 patients with single tooth extractions, 40 sockets were augmented and 39 extraction sockets were not augmented. At 2, 4, 6, 8 and 12 weeks impressions were taken and casts digitized with a laser scanner. The horizontal and vertical changes were compared between augmented and non-augmented sites. A p-value <0.05 was considered statistically significant. RESULTS: The mean changes of augmented sockets were between 0.4 mm (2 weeks) and 0.8 mm (12 weeks). In non-augmented sockets changes of 0.7 mm (2 weeks) and of 1.0 mm (12 weeks) were demonstrated. The mean values differed significantly between the buccal and oral region (p < 0.01). Overall, there were significant differences of the mean dimensional changes regarding time (p < 0.01) and augmentation (p < 0.01). CONCLUSIONS: Augmented sockets showed less resorption within 4 weeks after extraction compared to non-augmented sockets. Non-augmented sockets showed a continuous dimensional loss with a great variation over 12 weeks whereas augmented sockets had the highest degree of resorption between 4 and 6 weeks. At 12 weeks a comparable resorption in augmented and non-augmented sockets was observed.

Survival analysis of dental implants and implant-retained prostheses in oral cancer patients up to 20 years.

OBJECTIVES: The purpose of this study was to evaluate the long-term survival rate and potential influencing factors of dental implants and implant-retained prostheses in oral cancer patients who had undergone surgical tumor resection. MATERIAL AND METHODS: In the present study, 157 patients (95 females and 62 males with a mean age of 53.7 years) with 830 implants were included. All patients were diagnosed with a malignant tumor in the oral cavity and had undergone ablative surgery. In 55 patients (292 implants), the surgical procedure was followed by an additional radiochemotherapy (RCT) before implant placement. Nicotine users who received RCT were excluded from this study. Patients were clinically examined every 6 or 12 months according to a standard procedure. RESULTS: Of the 830 examined implants, 450 were placed in the maxilla and 380 in the mandible. A total of 65 implants were lost, 36 in the maxilla and 29 in the mandible; of these, 42 implants (65%) were documented as lost due to the patient's death. The mean observation period was 121 months. The cumulative survival rate was 94.9% at 3 years and 92.5% at 7 years. With an observation period up to 20 years, the cumulative survival rate remained constant after 11 years with 90.8%. Age, gender, and localization (maxilla/mandible) of implants did not show any influence on the survival of the implants. However, radiochemotherapy was determined as a significant factor influencing the survival rate. CONCLUSIONS: The results of this study demonstrate that the survival rate of implants was significantly lower in oral cancer patients who had been treated by ablative surgery and additional radiochemotherapy than in patients without RCT. Since there is no significant difference in the mortality rate of patients with additional RCT compared to patients who underwent sole ablative surgery, the higher loss ratio is due to a late failure of osseointegration. CLINICAL RELEVANCE: Dental implants in oral cancer patients who had been treated by ablative surgery show a high and steady cumulative survival rate after 11 years. Implant survival of patients with additional RCT is significantly lower. Non-smoking-irradiated patients seem to have a better implant survival.

Bone loss after ridge expansion with or without reflection of the periosteum.

OBJECTIVE: To evaluate the role of the periosteum in preserving the buccal bone after ridge splitting and expansion with simultaneous implant placement. MATERIAL AND METHODS: In 12 miniature pigs, the mandibular premolars and first molars were removed together with the interdental bone septa and the buccal bone. Three months later, ridge splitting and expansion of the buccal plate was performed with simultaneous placement of two titanium implants per quadrant. Access by a mucosal flap (MF) was prepared on test sides, while a mucoperiosteal flap (MPF) with complete denudation of the buccal bone was increased on control sides. After healing periods of six and 12 weeks, the animals were sacrificed for histologic and histometric evaluation. RESULTS: In the MF group, all 16 implants were osseointegrated, while in the MPF group, four of 16 implants were lost. Noticeable differences of bone levels on the implant surface and of the bone crest (BC) were found between the MF and the MPF group. Buccally after 6 weeks, the median distance between the implant shoulder (IS) and the coronal-most bone on the implant (cBIC) was for the MF group -1.42 ± 0.42 mm and for the MPF group -4.80 ± 2.72 mm (P = 0.15). The median distance between the IS and the buccal BC was -1.24 ± 0.51 mm and -2.78 ± 1.98 mm (P = 0.12) for the MF and MPF group, respectively. After 12 weeks, median IS-cBIC was -2.12 ± 0.84 mm for MF and -7.19 mm for MPF, while IS-BC was -2.08 ± 0.79 mm for MF and -5.96 mm for MPF. After 6 weeks, the median buccal bone thickness for MF and MPF was 0.01 and 0 mm (P < 0.001) at IS, 1.48 ± 0.97 mm and 0 ± 0.77 mm (P = 0.07) at 2 mm apical to IS, and 2.12 ± 1.19 mm and 1.72 ± 01.50 mm (P = 0.86) at 4 mm apical to IS, respectively. After 12 weeks, buccal bone thickness in the MF group was 0 mm at IS, 0.21 mm at 2 mm apical to IS, and 2.56 mm at 4 mm apical to IS, whereas complete loss of buccal bone was measured from IS to 4 mm apical to IS for the MPF group. CONCLUSIONS: In this ridge expansion model in miniature pigs, buccal bone volume was significantly better preserved when the periosteum remained attached to the bone.

The bone splitting stabilisation technique--a modified approach to prevent bone resorption of the buccal wall.

The aim of this case series was to clinically demonstrate successful prevention of bone resorption of the buccal wall after alveolar bone splitting by additional stabilization of the lateral bone plate using a biphasic ceramic bone substitute. In three patients alveolar bone splitting was performed with a piezoelectric device. Clinical as well as radiological results after two and five years revealed stable hard and soft tissue conditions with no soft tissue recessions and peri-implant bone loss in three patients. The advantage of this one-stage procedure was the ability to insert dental implants into a very compromised bony site in a simultaneous procedure. Yet the bone splitting stabilisation technique appeared to be a more user-sensitive method.

Comparison of four different allogeneic bone grafts for alveolar ridge reconstruction: a preliminary histologic and biochemical analysis.

OBJECTIVES: Allograft material for alveolar ridge reconstruction is quite promising and appears to be as equally successful as bone autograft material. The aim of the present study was to compare four different allogeneic bone grafts in terms of their histologic structure and DNA content before grafting. STUDY DESIGN: Four allograft specimens from different suppliers were analyzed histologically, and the DNA content was analyzed before clinical use of the allografts. RESULTS: Organic tissue remnants were detected in all of the evaluated samples. In the present samples adipocytes, fibroblasts, osteocytes, and chondrocytes were identified and DNA isolation and purification was possible. CONCLUSION: Demineralized freeze-dried allogeneic bone transplants can stimulate new bone formation and are a viable alternative to bone autograft material. However, the well-tolerated use of allograft material in regard to our findings should be further investigated.

Follow-up of implant survival comparing ficoll and bone marrow aspirate concentrate methods for hard tissue regeneration with mesenchymal stem cells in humans.

OBJECTIVE: Clinical follow-up of implant survival in 11 patients comparing two different methods for mesenchymal stem cell (MSC) isolation (Ficoll and bone marrow aspirate concentrate [BMAC]) applied in maxillary sinus augmentation. METHODS: Mononuclear cells, including MSCs, were concentrated with either Ficoll (control group, n=6 sinus) or BMAC (test group, n=12 sinus) and transplanted in combination with bovine bone mineral. A total of 50 implants were placed in a second surgical intervention (17 Ficoll/33 BMAC) and loaded after 4 months. Overall implant survival was assessed with a Kaplan-Meier model using package survival under R. RESULTS: Implant survival of the Ficoll group was 100% compared with the BMAC group, which had 93.4% survival (95% confidence interval, 0.849-1). The difference between the groups was not significant (p=0.381). CONCLUSION: The BMAC system is an effective and suitable "chair-side" method for clinical application in hard tissue regeneration.