Influence of residual alveolar bone height on osseointegration of implants in the maxilla: a pilot study

Aims/Background: For sinus floor augmentation and simultaneous implant placement, a minimum of 5 mm of residual bone height has been recommended empirically. This study was designed to test this assumption in an experimental animal trial. Material and methods: In eight mini pigs, three premolars and two molars were removed on one side of the maxilla. Three months later, the animals were assigned to four groups of two animals each. A cavity was created at the base of the alveolar process so that the residual bone height was reduced to 2, 4, 6 and 8 mm, respectively. Six implants were installed and an inlay augmentation procedure was carried out using a particulated iliac bone graft. Implants were loaded with fixed provisional restorations after a healing period of 6 months. The animals were sacrificed after 6 months of functional loading. Histologic specimens were prepared and histomorphometric analysis was performed [bone‐to‐implant contact (BIC) ratio, interthread bone area, peri‐implant bone area, crestal bone resorption (CBR)]. Results: Two implants were lost during follow‐up and fibrous encapsulation was detected in one additional implant. All failures occurred in one animal with a residual alveolar height of 2 mm. On the buccal aspect, BIC turned out to be significantly higher for 6 mm when compared with 2/4 mm (75.8 ± 26.1 vs. 58 ± 23.2/53.9 ± 22.8; P<0.05), while on the palatal aspect, BIC was significantly higher for 6/8 mm when compared with 2/4 mm (80 ± 17.8/78.9 ± 10.3 vs. 55.8 ± 26.5/55.6 ± 21.3; P<0.05). For an alveolar height of 8 mm, CBR tended to be significantly lower than for bone heights of 2/4 mm (3.8 ± 2.3 vs. 5.3 ± 2.6/5.8 ± 3.9; P<0.05). Correlation analysis revealed a significant association of BIC and interthread bone area as well as a negative association to CBR on the palatal aspect. Conclusion: The results of the present study show that the combination of maxillary inlay grafting and simultaneous implant placement does not hinder osseous integration even though the alveolar crest has been reduced to a residual height of 4 mm and below. However, according to histomorphometry, the highest predictability is gained in sites with residual bone heights of 6 and 8 mm.     

Osteotome Maxillary Sinus Lift Using Bovine Bone and Calcium Sulfate: A Case Series

Purpose: The purpose of this longitudinal study was to evaluate the success of bovine bone and calcium sulfate (CaSO₄) as sinus augmentation material with osteotome maxillary sinus lift. Materials and Methods: Thirty‐one osteotome sinus lift procedures were performed for 18 healthy patients (7 males and 11 females). A mixture of bovine bone and CaSO₄ (ratio, 4:1) was used as sinus augmentation material with simultaneous implant placement. Implants were loaded 4 to 5 months postimplant surgery. Cases were followed for an average of 23.4 months postloading (range, 12–60 months). Results: The mean age of the study group was 49.7 ± 10.66 years. The residual height of the alveolar ridge ranged from 5.5 to 11 mm (mean, 8.16 ± 1.52 mm). Four to 5 months after implant placement, the x‐ray showed a 1.5 to 5 mm apical shift of the sinus floor (mean, 3.47 ± 0.97 mm), which was maintained to the end of the evaluation period. At 12 months postloading, crestal bone loss ranged from 0.5 to 1.5 mm (mean, 0.87 ± 0.26 mm), and pocket depth ranged from 2 to 4 mm (mean, 2.9 ± 0.67 mm). No significant change in crestal bone loss or pocket depth was noticed afterward. Conclusion: Bovine bone plus CaSO₄ can be used successfully as a sinus augmentation material with osteotome sinus elevation. The use of CaSO₄ significantly improved the handling properties of bovine bone and helped to stabilize the bone graft particles during healing.     

Clinical Outcomes of an Osteotome Technique and Simultaneous Placement of Neoss Implants in the Posterior Maxilla

Background: Insufficient bone volume often hamper placement of dental implants in the posterior maxilla. Purpose: The aim of the present clinical study was to evaluate retrospectively the clinical outcome of implant placement in the resorbed posterior maxilla using an osteotome technique without adding any grafting material. Materials and Methods: Twenty patients with 5 to 9 mm of residual alveolar bone height in the posterior maxilla received twenty‐nine implants (Neoss Ltd., Harrogate, UK) using an osteotomy technique without bone grafts. Intraoral radiographs were taken before and after implant placement, at the time of loading and after 11 to 32 months of loading (mean 16.4 months), to evaluate bone formation below the sinus membrane and marginal bone loss. Implant stability measurements (Osstell^TM, Gothenburg, Sweden) were performed after implant installation and at abutment connection 5 months later. All implants were installed with the prosthetic platform level with the bone crest. Results: No implant was lost giving a survival rate of 100% after a mean follow‐up time of 16.4 months. The average vertical bone height was 7.2 ± 1.5 mm at placement and 10.0 ± 1.0 mm after 11 to 32 months. The average increase of 2.8 ± 1.1 mm was statistically significant. There was a statistically significant improvement in implant stability from 70.7 ± 9.2 implant stability quotient (ISQ) at placement to 76.7 ± 5.7 ISQ at abutment connection, 5 months later. The mean marginal bone loss amounted to 0.7 ± 0.3 mm after 11 to 32 months of loading. Conclusion: It is concluded that the osteotome technique evaluated resulted in predictable intrasinus bone formation, firm implant stability, and good clinical outcomes as no implants were lost and minimal marginal bone loss was observed.     

自体块状骨结合引导骨再生技术重建前牙区骨量不足的临床研究

目的：比较自体块状骨结合引导骨再生(GBR)技术重建前牙区骨量不足术后种植位点和非种植位点骨量变化的差异。方法：2010年12月—2011年8月间,术前全景片及CT评估14例患者(73个缺牙位点)前牙区骨量不足,于颏部或下颌支处取自体块状骨结合GBR技术重建前牙牙槽骨,并延期行种植体植入术(共植入42颗种植体)。术后即刻、3、6、9个月和最长随访时间点(平均13.8个月)行CT检查。利用Simplant 11.04软件三维重建并测量牙槽嵴顶骨宽度(alveolar crestal bone width, ACBW)、牙槽骨中部骨宽度(alveolar midway bone width, AMBW)和牙槽骨高度(alveolar bone height, ABH)。测量的所有数据按照种植位点(即种植体植入的位点)和非种植位点(即未植入种植体,后期利用桥体修复的位点)分为2组。采用SAS 9.0软件包对该2组数据进行配对t检验。结果：14例患者均顺利完成植骨和种植体植入手术,术后无头晕、头痛等不适,切口均愈合良好,42颗种植体在愈合和随访期内骨结合良好。术后2组骨改建评价显示：对种植位点的ACBW和AMBW,术后即刻骨增量和术后3个月骨吸收量有显著差异(P<0.05),而对ABH术后即刻骨增量,术后3、6个月骨吸收量有显著差异(P<0.05),其他时间段则无显著差异(P>0.05);对非种植位点的ACBW和ABH,术后即刻骨增量,术后3、6和9个月骨吸收量有显著差异(P<0.05),而对AMBW术后即刻骨增量,术后3、6个月骨吸收量有显著差异(P<0.05),其他时间段则无显著差异(P>0.05)。术后2组中ACBW、AMBW和ABH的骨量变化显示：术后即刻骨增量,术后3、6个月骨吸收量无显著差异(P>0.05);术后9个月和最长随访时间点骨吸收量存在显著差异(P<0.05)。结论：非种植位点较种植位点在种植体植入后发生更多的骨吸收,其原因是二期种植体植入手术产生的创伤和种植体能保存骨量两者相互作用所致。因此,即刻或同期植入种植体,避免二次手术,对骨量保存具有重要意义。     

Vertical ridge augmentation of the atrophic posterior mandible with interpositional bloc grafts: bone from the iliac crest vs. bovine anorganic bone. Clinical and histological results up to one year after loading from a randomized-controlled clinical trial

Objectives: To compare two different techniques for vertical bone augmentation of the posterior mandible: bone blocs from the iliac crest vs. anorganic bovine bone blocs used as inlays.
Materials and methods: Ten partially edentulous patients having 5–7 mm of residual crestal height above the mandibular canal had their posterior mandibles randomly allocated to both interventions. After 4 months implants were inserted, and after 4 months, provisional prostheses were placed. Definitive prostheses were delivered after 4 months. Histomorphometry of samples trephined at implant placement, prosthesis and implant failures, any complication after loading and peri-implant marginal bone-level changes were assessed by masked assessors. All patients were followed up to 1 year after loading.
Results: Four months after bone augmentation, there was statistically significant more residual graft (between 10% and 13%) in the Bio-Oss group. There were no statistically significant differences in failures and complications. Two implants could not be placed in one patient augmented with autogenous bone because the graft failed whereas one implant and its prosthesis of the Bio-Oss group failed after loading. After implant loading only one complication (peri-implantitis) occurred at one implant of the autogenous bone group. In 16 months (from implant placement to 1 year after loading), both groups lost statistically significant amounts of peri-implant marginal bone: 0.82 mm in the autogenous bone group and 0.59 mm in the Bio-Oss group; however, there were no statistically significant differences between the groups.
Conclusions: Both procedures achieved good results, but the use of bovine blocs was less invasive and may be preferable than harvesting bone from the iliac crest.     

Augmentation grafting of the maxillary sinus and simultaneous implant placement in patients with 3 to 5 mm of residual alveolar bone height.

This study assessed the efficacy of augmentation grafting of the maxillary sinus with simultaneous placement of dental implants in patients with less than 5 mm of alveolar crestal bone height in the posterior maxilla prior to grafting, although the procedure has traditionally been contraindicated based on empirical data. A total of 160 hydroxyapatite-coated implants was placed into 63 grafted maxillary sinuses in 63 patients whose crestal bone height in this region ranged from 3 to 5 mm. Patients were followed for 2 to 4 years after the placement of definitive prostheses. There were no postoperative sinus complications. Following uncovering of the implants at 9 months after surgery, there was no clinical or radiographic evidence of crestal bone loss around the implants. Histologic examination of bone cores from the grafted sites revealed successful integration and a high degree of cellularity. All patients maintained stable implant prostheses during follow-up. These findings indicate that the single-step procedure is a feasible option for patients with as little as 3 mm of alveolar bone height prior to augmentation grafting, utilizing hydroxyapatite-coated implants and autogenous bone.     

Nasal floor elevation combined with dental implant placement

Objectives: The aim of the present study was to report on the survival of dental implants placed in conjunction with nasal floor elevation. Methods: A retrospective cohort of 32 consecutive patients from two private practices was evaluated. All patients presented with alveolar bone height deficiency in the anterior region, which was not sufficient to place a dental implant according to a computed tomography (CT) scan preformed prior to implantation. Elevation and augmentation of the nasal mucosa was performed simultaneously with dental implant placement. Data collection included demographic information, as well as records of the pre‐operative available bone height, implant dimensions, bone addition following nasal floor augmentation, and survival of the implants at last follow‐up. Results: Overall, 32 patients received 100 implants that were performed in conjunction with nasal floor elevation. The average pre‐operative available bone height according to a CT scan that was preformed prior to implantation was 9.1 ± 0.9 mm and ranged from 7.3 to 11.2 mm. Bone addition following nasal floor augmentation was 3.4 ± 0.9 mm and ranged between1.1 and 5.7 mm. The mean follow‐up time was 27.8 ± 12.4 months, and during that follow‐up period, no implant failure was recorded, resulting in 100% implant survival. Conclusion: Nasal floor elevation might serve as a predictable procedure, which allows implant placement in areas with significant atrophy together with increased implant stability due to the bicortical support.     

A collagenated porcine bone substitute for augmentation at Neoss implant sites: a prospective 1-year multicenter case series study with histology

Background: The presence of localized defects and/or small amounts of bone below the maxillary sinus is a common finding, which may compromise implant placement. There is therefore a need for predictable techniques for bone augmentation in such situations. Purpose: The study aims to clinically and histologically evaluate a porcine bone (PB) substitute used for augmentation of the alveolar crest or the maxillary sinus floor prior to or in conjunction with implant placement. Materials and Methods: Nineteen patients were treated with a porcine bone substitute and barrier membranes (OsteoBiol, Tecnoss Dental, Turin, Italy) for lateral bone augmentation (Group 1a) and healing of bone defects (Group 1b) or for augmentation of the maxillary sinus floor using either a replaceable (Group 2a) or an infractured bone window (Group 2b). A total of 34 implants (Neoss Ltd., Harrogate, UK) were placed in conjunction or 5 to 7 months after the procedure. Implants were followed with implant stability measurements at placement and abutment connection, and with intraoral radiographs at abutment connection and after at least 1 year of loading. A biopsy for histology and morphometry was taken at the first reentry operation. Results: All but one of the procedures was successful (94.7%) as one maxillary sinus procedure (Group 2a) resulted in insufficient bone for implant placement. One of the 34 implants failed, giving an implant survival rate of 97.1% after 1 year. Implant stability measurements showed a mean stability of 71.9 ± 7.7 implant stability quotient (ISQ) at placement, which significantly increased to 75.3 ± 6.8 ISQ at abutment connection (p = .03). The average bone loss was 0.5 ± 0.7 mm during 1 year. Histology revealed new bone formation at the PB surface, which formed bridges between particles and between particles and preexisting bone. The presence of scalloped resorption lacunae and new osteons inside the particles indicated ongoing resorption/remodeling of the particles. The histomorphometric analyses showed that the total specimen area consisted of, in average, 56.5 ± 15.7% mineralized tissue of which 24.8 ± 13.9% of the total area was PB particles. Conclusion: This study showed good clinical results when using a PB substitute and barrier membranes for augmentation of the alveolar crest and maxillary sinus. Histology revealed bone condensation properties and indicated that the material can be resorbed with time.     

Influence of a machined collar on crestal bone changes around titanium implants: a histometric study in the canine mandible

Background: It has been shown that peri‐implant crestal bone reactions are influenced by both a rough–smooth implant border in one‐piece, non‐submerged, as well as an interface (microgap [MG] between implant/abutment) in two‐piece butt‐joint, submerged and non‐submerged implants being placed at different levels in relation to the crest of the bone. According to standard surgical procedures, the rough–smooth implant border for implants with a smooth collar should be aligned with the crest of the bone exhibiting a smooth collar adjacent to peri‐implant soft tissues. No data, however, are available for implants exhibiting a sandblasted, large‐grit and acid‐etched (SLA) surface all the way to the top of a non‐submerged implant. Thus, the purpose of this study is to histometrically examine crestal bone changes around machined versus SLA‐surfaced implant collars in a side‐by‐side comparison. Methods: A total of 60 titanium implants (30 machined collars and 30 SLA collars) were randomly placed in edentulous mandibular areas of five foxhounds forming six different subgroups (implant subgroups A to F). The implants in subgroups A to C had a machined collar (control), whereas the implants in subgroups D to F were SLA‐treated all the way to the top (MG level; test). Furthermore, the MGs of the implants were placed at different levels in relation to the crest of the bone: the implants in subgroups A and E were 2 mm above the crest, in subgroups C and D 1 mm above, in subgroup B 3 mm above, and in subgroup F at the bone crest level. For all implants, abutment healing screws were connected the day of surgery. These caps were loosened and immediately retightened monthly. At 6 months, animals were sacrificed and non‐decalcified histology was analyzed by evaluating peri‐implant crestal bone levels. Results: For implants in subgroup A, the estimated mean crestal bone loss (± SD) was ?0.52 ± 0.40 mm; in subgroup B, +0.16 ± 0.40 mm (bone gain); in subgroup C, ?1.28 ± 0.21 mm; in subgroup D, ?0.43 ± 0.43 mm; in subgroup E, ?0.03 ± 0.48 mm; and in subgroup F, ?1.11 ± 0.27 mm. Mean bone loss for subgroup A was significantly greater than for subgroup E (P = 0.034) and bone loss for subgroup C was significantly greater than for subgroup D (P <0.001). Conclusions: Choosing a completely SLA‐surfaced non‐submerged implant can reduce the amount of peri‐implant crestal bone loss and reduce the distance from the MG to the first bone–implant contact around unloaded implants compared to implants with a machined collar. Furthermore, a slightly exposed SLA surface during implant placement does not seem to compromise the overall hard and soft tissue integration and, in some cases, results in coronal bone formation in this canine model.     

Localized Management of Sinus Floor Technique for Implant Placement in Fresh Molar Sockets

Background: The use of osteotome for vertical bone augmentation and localized sinus elevation with minimal surgical trauma represents a suitable procedure to increase the vertical dimension of available bone for implant placement. Purpose: The aim of this study was to report clinical and radiographic results of localized management of sinus floor (LMSF) in fresh molar sockets at 13‐year follow‐up. Materials and Methods: Fifty‐three patients, needing one or two maxillary molar extraction, were enrolled in this study. LMFS procedure was performed and 68 implants were positioned. A presurgical distance from the alveolar crest to the floor of the maxillary sinus and the amount of new radiopacity between the sinus floor and alveolar crest were measured from the mesial and distal surfaces of each dental implant surface. Results: After a mean follow‐up period of 9.76 ± 5.27 years (ranged from 4 to 17 years) a survival rate of 100% was reported. Mean bone height at temporary prosthesis placement was 7.99 ± 1.16 mm. They were stable over time, reporting a mean value of 8.01 ± 1.46 mm at 13‐year follow‐up. Conclusions: The results of this study demonstrated that LMSF procedure in fresh molar sockets allowed to expand the dimensions of resorbed posterior maxillary alveolar bone both vertically and horizontally with a success rate of 100% of implant osseointegration over time.     

A comparative study of bilateral sinus lifts performed with platelet-rich plasma alone versus alloplastic graft material reconstituted with blood

The objective of this study was to compare the alveolar bone growth in the 2 sides of the maxillary sinus after bilateral sinus lift procedures were performed with the simultaneous placement of dental implants in 20 consecutive patients. After elevation of the Schneiderian membrane, one side had only platelet-rich plasma (PRP) gel applied, while the other had placed only alloplastic graft material reconstituted with blood. Both open window and closed window techniques were used in ridges with > or =9 mm residual crest of bone. Results indicate that using PRP alone in cases with >7 mm residual crest can produce bone growth. Preliminary results indicate that in cases with a minimum of 7-mm crestal bone, it is possible to use a crestal approach for sinus grafting, with PRP alone and implant placement for bone growth.     

Two-stage reconstruction of the severely deficient alveolar ridge: bone graft followed by alveolar distraction osteogenesis

Distraction osteogenesis for the augmentation of severe alveolar bone deficiency has gained popularity during the past two decades. In cases where the vertical bone height is not sufficient to create a stable transport segment, performing alveolar distraction osteogenesis (ADO) is not possible. In these severe cases, a two-stage treatment protocol is suggested: onlay bone grafting followed by ADO. An iliac crest onlay bone graft followed by ADO was performed in 13 patients: seven in the mandible and six in the maxilla. Following ADO, endosseous implants and prosthetic restorations were placed. In all cases, the onlay bone graft resulted in inadequate height for implant placement, but allowed ADO to be performed. ADO was performed to a mean total vertical augmentation of 13.7 mm. Fifty-two endosseous implants were placed. During a mean follow-up of 4.85 years, two implants failed, both during the first 6 months; the survival rate was 96.15%. In severe cases lacking the required bone for ADO, using an onlay bone graft as a first stage treatment increases the bone height thus allowing ADO to be performed. This article describes a safe and stable two-stage treatment modality for severely atrophic cases, resulting in sufficient bone for implant placement and correction of the inter-maxillary vertical relationship.     

Alveolar split osteotomy for the treatment of the severe narrow ridge maxillary atrophy: a modified technique

Alveolar bone splitting and immediate implant placement have been proposed for patients with severe atrophy of the maxilla in the horizontal dimension. A new modification of the classical alveolar bone splitting for the treatment of the narrow ridge in the maxilla is provided. Thirty-three dental implants in eight consecutive patients were evaluated retrospectively following the described modified split-crest osteotomy. Inclusion criteria were: inadequate maxillary buccolingual dimension, 3-4 mm of crestal width, and sufficient height from alveolar ridge tip to maxillary sinus floor. Primary stability was calculated using resonance frequency analysis (RFA). Alveolar bone height was measured in the panorex pre- and postoperatively. Histological bone examination was assessed following trephine bone harvesting during the second operation. Mean follow-up was 28.33 months. Bone regeneration of the inter-cortical gap occurred in 98% of implant sites (implant survival rate 100%). Mean implant stability quotient (ISQ) for the whole series of implants was 69.48. At the second operation, mean loss of the alveolar bone height was 0.542 mm. Predictable results are obtained using the modified split-crest osteotomy. This technique provides an acceptable inter-cortical gap, decreases the risk of necrosis of the outer cortex, and provides a firm-wall box for the placement of particulate bone grafting.     

Simultaneous dental implant placement and endoscope-guided internal sinus floor elevation: 2-year post-loading outcomes

Aims: To determine whether endoscope‐guided sinus elevation procedures can be consistently used to create sufficient bone support for stable implant placement and long‐term implant success. Material and methods: Sixty‐two implants were surgically placed into 30 patients (14 men and 16 women) following internal sinus elevation without the use of graft material. Panoramic radiographs were made pre‐, post‐operative and after 24 months in order to evaluate the peri‐implant bone and maxillary sinuses. Resonance frequency analysis (RFA) was used to evaluate implant stability immediately upon placement and just before prosthesis delivery. Results: The average pre‐operative height of the maxillary alveolar bone was 8.4±2.2 mm at the premolar and 7.3±3.1 mm at the molar regions. The average bone gain was 3.5±1.8 and 4.5±1.9 mm in the premolar and molar sites, respectively. Clinical parameters and the RFA (4 and 12 weeks post‐operative) outcomes show sufficient stability (ISQ=60) of the inserted implants. Three implants failed during the healing period of 12 weeks. The overall implant success rate was 94%. After loading, no further implant failure was observed. The overall success rate after beginning of implant loading was 100%. Conclusions: Sinus floor elevation is a well‐established procedure for augmentation of the atrophic maxillary posterior region. The minimally invasive internal sinus floor elevation procedure visually guided by an endoscope helped to prevent, diagnose and manage complications such as sinus membrane perforation. The clinical outcomes of this study show that endoscope‐controlled internal sinus floor elevation combined with implant placement results in low intra operative trauma, good implant stability upon placement, low incidence of post‐operative symptoms and high success rates after 24 months of loading.     

Use of titanium mesh for staged localized alveolar ridge augmentation: clinical and histologic-histomorphometric evaluation

The use of titanium mesh for localized alveolar ridge augmentation was evaluated by clinical, radiographic, laboratory, and histologic-histomorphometric evaluation. Seventeen patients participated in this study. All patients required localized alveolar ridge augmentation before placement of dental implants. An equal mixture of autogenous bone graft and inorganic bovine mineral (Bio-Oss) was used as a bone graft material. Autogenous bone graft was harvested intraorally. Titanium mesh was submerged for 8.47 months (SD 2.83). Impressions were taken intraorally before bone grafting, 6 months after bone grafting, and 6 months after implant placement. Impressions were used to measure the volume of alveolar ridge augmentation and provide linear laboratory measurements regarding the results of bone augmentation. Bone quality (type II-IV) was recorded during implant surgery. Standardized linear tomographs were taken before bone grafting and before implant placement. A biopsy was harvested with a trephine bur from the grafted area during implant surgery for histologic-histomorphometric evaluation. In all cases the grafted area had adequate bone volume and consistency for placement of dental implants. Early mesh exposure (2 weeks) was observed in 2 patients, and late exposure (>3 months) was observed in 4 patients. Volumetric laboratory measurements indicated 0.86 cc (SD 0.69) alveolar augmentation 1 month after bone grafting, 0.73 cc (SD 0.60) 6 months after bone grafting, and 0.71 cc (SD 0.57) 6 months after implant placement. This indicated 15.11% resorption 6 months after bone grafting, and no further resorption occurred after implant placement. Linear laboratory measurements indicated vertical augmentation of 2.94 mm (SD 0.86) 1 month after bone grafting, 2.59 mm (SD 0.91) 6 months after bone grafting, and 2.65 mm (SD 1.14) 6 months after implant placement. The corresponding measurements for labial-buccal augmentation were 4.47 mm (SD 1.55), 3.88 mm (SD 1.43), and 3.82 mm (SD 1.47). Radiographic evaluation indicated 2.56 mm (SD 1.32) vertical augmentation and 3.75 mm (SD 1.33) labial-buccal augmentation. Histomorphometric evaluation indicated 36.47% (SD 10.05) new bone formation, 49.18% (SD 6.92) connective tissue, and 14.35% (SD 5.85) residual Bio-Oss particles; 44.65% (SD 22.58) of the Bio-Oss surface was in tight contact with newly formed bone. The use of titanium mesh for localized alveolar ridge augmentation with a mixture of autogenous intraorally harvested bone graft and Bio-Oss offered adequate bone volume for placement of dental implants. Intraorally harvested autogenous bone graft mixed with Bio-Oss under a titanium mesh offered 36.47% new bone formation, and 15.11% resorption occurred 6 months after bone grafting.     

Clinical efficacy of autogenous dentin grafts with guided bone regeneration for horizontal ridge augmentation: a prospective observational study

The aim of this study was to evaluate the efficacy of autogenous dentin grafts with guided bone regeneration (GBR) for horizontal ridge augmentation. Nineteen patients with dentition and bone defects in whom tooth/teeth extraction was indicated were recruited. Autogenous teeth were prepared, fixed on the buccal sides of the defects, and covered with bone powder and resorbable membranes before implantation. The horizontal bone mass at 0 mm (W1), 3 mm (W2), and 6 mm (W3) from the alveolar crest was recorded using cone beam computed tomography, before, immediately after, and 6 months after dentin grafting. All adverse effects were recorded. The implant stability quotient (ISQ) was measured 6 months after implantation. Twenty-eight implants were placed 6 months after dentin grafting. At this time point, the bone mass was 4.72 ± 0.72 mm (W1), 7.35 ± 1.57 mm (W2), and 8.96 ± 2.38 mm (W3), which was significantly different from that before the surgery (P < 0.05). The bone gain was 2.50 ± 0.72 mm (W1), 4.10 ± 1.42 mm (W2), and 4.56 ± 2.09 mm (W3). No soft tissue dehiscence or infection was observed. Overall, 26.3% of the patients experienced severe pain after dentin grafting. The ISQ was 78.31 ± 6.64 at 6 months after implantation. Autogenous tooth roots with GBR might be effective for horizontal ridge augmentation. This technique could be an alternative to augmentation using autogenous bone grafts.     

Clinical case reports of injectable tissue-engineered bone for alveolar augmentation with simultaneous implant placement

This clinical study was undertaken to evaluate the use of tissue-engineered bone, mesenchymal stem cells, platelet-rich plasma, and beta-tricalcium phosphate as grafting materials for maxillary sinus floor augmentation or onlay plasty with simultaneous implant placement in six patients with 3- to 5-mm alveolar crestal bone height. All 20 implants were clinically stable at second-stage surgery and 12 months postloading. A mean increase in mineralized tissue height of 7.3+/-4.6 mm was evident when comparing the pre- and postsurgical radiographs. Injectable tissue-engineered bone provided stable and predictable results in terms of implant success.     

上颌前牙区牙槽嵴骨劈开增量同期种植术的临床研究

目的 :评价骨劈开增宽上颌前牙槽嵴 ,同期植入种植体的临床效果。方法 :15例患者 ,缺失上前牙1～4颗 ,有充足的牙槽嵴高度 (>13mm) ,但牙槽嵴骨厚度仅2～3mm ,采用骨劈开术 ,形成唇侧骨瓣。在唇侧骨瓣与腭侧骨板间植入3.4～4.5mm直径的Frialit-2种植体共25枚,骨板间隙充填Bio -Oss骨粉 ,覆盖Bio -Gide胶原膜或纯钛膜 ,无张力下缝合黏骨膜瓣。术后第10天和6个月时拍X线根尖周片观察种植体骨结合状况 ,并于术后6个月时行Ⅱ期手术 ,翻开软组织瓣 ,检查骨增量效果和种植体稳固性 ,测量牙槽嵴骨的宽度和拆除钛膜。结果 :1枚种植体术后1个月脱落 ,其余种植体稳固 ,且完全被骨质包埋 ,X线根尖周片证实种植体骨结合良好 ,牙槽嵴宽度增加达3～5mm ,平均增宽4.4mm。Ⅱ期手术时种植体成活率96 %。24枚种植体完成金属烤瓷修复 ,经2年的追踪观察,无一种植体松动或脱落。结论 :当前牙区牙槽嵴骨厚度2～3mm时 ,采用骨劈开术增宽牙槽嵴 ,使植种植体获得同期植入是一种行之有效的方法。     

Effect of interimplant distance (2 and 3 mm) on the height of interimplant bone crest: a histomorphometric evaluation

Background: Implants restored according to a platform‐switching concept (implant abutment interface with a reduced diameter relative to the implant platform diameter) present less crestal bone loss than implants restored with a standard protocol. When implants are placed adjacent to one another, this bone loss may combine through overlapping, thereby causing loss of the interproximal height of bone and papilla. The present study compares the effects of two interimplant distances (2 and 3 mm) on bone maintenance when bone‐level implants with platform‐switching are used. Methods: This study evaluates marginal bone level preservation and soft tissue quality around a bone‐level implant after 2 months of healing in minipig mandibles. The primary objective is to evaluate histologically and histomorphometrically the affect that an implant design with a horizontally displaced implant–abutment junction has on the height of the crest of bone, between adjacent implants separated by two different distances. Results: Results show that the interproximal bone loss measured from the edge of the implant platform to the bone crest was not different for interimplant distances of 2 or 3 mm. The horizontal position of the bone relative to the microgap on platform level (horizontal component of crestal bone loss) was 0.31 ± 0.3 mm for the 2‐mm interimplant distance and 0.57 ± 0.51 mm above the platform 8 weeks after implantation for the 3‐mm interimplant distance. Conclusions: This study shows that interimplant bone levels can be maintained at similar levels for 2‐ and 3‐mm distances. The horizontally displaced implant–abutment junction provided for a more coronal position of the first point of bone–implant contact. The study reveals a smaller horizontal component at the crest of bone than has been reported for non‐horizontally displaced implant–abutment junctions.     

Reconstruction of severely resorbed alveolar ridge crests with dental implants using a bovine bone mineral for augmentation

This study reviews the outcome of implant placement in 61 patients after augmentation of severely atrophic alveolar bone with a bovine bone mineral, Bio-Oss. Bone augmentation was performed at 4 different sites: alveolar crest width, alveolar crest height, antral cavity, or nasal cavity. After a mean healing time of 11.9 months, 231 implants were placed in Bio-Oss bone. The time of loading of the implants varied between 12 and 113 months. Calculated from the time of implant placement and irrespective of loading time, a survival rate of 80.5% for the individual implants was estimated. In most patients (73%), Bio-Oss was mixed with autogenous bone from the chin. However, the results indicated that autogenous bone may be excluded from the Bio-Oss graft.