Stability of dental implants in microvascular osseous transplants

Microvascular iliac crest and scapula transplants have been used in reconstruction of the lower jaw following tumor surgery. It has only been with the insertion of dental implants that a satisfactory prosthetic rehabilitation of the patient has been achieved. For this study, a follow-up of 38 patients with lower jaw tumors was carried out. The patients had been treated with partial resection of the lower jaw and neck dissection with microvascular iliac crest transplants (n = 20) or microvascular scapula transplants (n = 18); this was followed with dental implants (n = 143) in the region of the transplants or the local lower jaw. One hundred thirty-nine of the 143 dental implants were loaded by prosthetic superstructures. In all patients, the implant situation was evaluated on average 2 years 5 months after implantation. Periotest values, periimplant probing depths, and contact bleeding were registered, and the extent of periimplant bone loss was defined radiographically. The clinical situation in the region of the implant was compared for both types of implants and also with the nonresected lower jaw. The average Periotest values were within the normal range for all groups. In one scapula implant, however, a better average of Periotesting, -3.3, was found compared with implants of the iliac crest with Periotest values of -0.7. A measurement of -2.1 was found for the local lower jaw, similar to that of scapula implants. Pathologic probing depths were found for all three compared groups. The radiographically determined vertical loss of bone was the same for all three groups, on average 1 mm at 27 months postoperatively. The highest incidence of sulcus bleeding was found in the scapula implant group. Thus, it can be stated that the scapula transplants provide a similar transplant site to local lower jaw bone, whereas implants in iliac crest transplants show lesser bony stability. Periimplant soft-tissue conditions are worse for both types of transplants compared with local tissue of the lower jaw.     

标尺模板在Branemark种植修复中的制作和应用

目的:制作并观察标尺模板在指导Branemark种植手术,提高手术安全性方面的作用。方法:选择15例患者52颗种植体,铸造制作标尺模板后戴入口腔拍摄曲面体层片。根据影象所显示的适宜种植区域与颏孔、上颌窦等颌骨重要解剖结构的位置,结合上部修复设计选择Branemark种植体数量与植入点,并借助标尺模板的定位网格予以记录。手术时将标尺模板戴入口腔,根据记录结果在颌骨表面显示种植体入点与颌骨重要解剖结构的位置,指导手术进行。术后戴入标尺模板拍摄对照片,判断种植体与预定位置的吻合性。结果:52颗种植体中,除1颗种植体因术中临时改变种植位置,其余51颗种植入位置均与术前计划一致。结论:在Branemark种植修复中制作并应用标尺模板,能方便直观地帮助术者将种植体植入预定位置,避免损伤颏孔等颌骨重要解剖结构,提高了手术的正确性与安全性。     

Age-related satisfaction with complete dentures,desire for improvement and attitudes to implant treatment

In the edentulous lower jaw implant stabilised dentures have proved clinically so successful that the indication for this treatment is now being discussed more often with geriatric patients. The aim of this study of edentate subjects was to determine the age-relation of the demand for denture improvement, the risks and feasibility of implant treatment. Sixty four complete denture wearers aged from 42 to 84 years took part in the study. A questionnaire was used to determine the subjective demand for denture improvement. For 33 subjects implants seemed possible. For these patients fear and scepticism concerning implant treatment were specified and quantified. Impaired general health was the most frequent absolute contra-indication for implants; the local oral prerequisites tended to be slightly less favourable in elderly. Older patients were more satisfied with poorly fitting dentures and were less prepared to take trouble to achieve denture improvement. Although scepticism concerning implant treatment was not age-related, patients who were keen for an improvement of their dentures were significantly younger and less sceptical about implants.     

OSFE植骨与不植骨种植修复的临床效果对比研究

目的:比较上颌窦挤压内提升(OSFE)植骨与不植骨种植修复的临床效果。方法:选择上颌后牙区种植修复的35例患者,其剩余牙槽嵴高度(RBH)为4~8 mm,共植入43颗种植体。A组16例患者为植骨组,20个种植位点,牙槽骨可用骨高度平均(5.87±1.19)mm,植入人工骨粉后植入种植体;B组19例患者为不植骨组,23个种植位点,缺牙区牙槽骨可用骨高度平均(5.67±1.10)mm,上颌窦提升后直接植入种植体。6个月后行二期手术完成修复。采用临床检查、X线检查及视觉模拟评分法(visual analogue scale,VAS)进行效果评价。结果:两组病例的牙槽嵴高度差异比较无统计学意义。在平均约36.7个月的随访期内,A组种植体的存留率为100%(20/20),B组中有1枚种植体因咬合力过大及口腔卫生较差脱落,种植体的存留率为95.6%(22/23),两组病例的存留率比较无统计学差异。两组患者的VAS值比较亦相当。所有种植体骨结合良好,种植体周围软组织无炎症,种植义齿咀嚼功能良好。结论:在严格控制适应症、准确掌握种植技巧的前提下,RBH在4~8 mm之间的病例无需额外植入骨代替材料即可取得理想的修复效果,简化了手术的操作,减少了手术的风险和创伤,节省了手术的时间和费用,易被患者接受。     

Densitometric analysis of dental implant placement between flapless technique and the two-stage technique--a pilot study

Flapless technique is a surgical approach of implant placement without raising a mucoperiosteal flap. Such approach has many advantages: shorter surgical treatment, minimal bleeding, postoperative discomfort for the patient is reduced; possibility of immediate loading of the inserted implant, faster procedure of implant placement and by that less time is needed for the complete implant-prosthetic restoration. Purpose of this pilot study was radiographic assessment of flapless technique and determination of its clinical values in comparison with two-stage dental implant technique through computerized densitometric analysis. The sample consisted of 10 patients with missing teeth in the premolar region in the upper jaw. An implant was placed in that position. In the first group of 5 patients the implants were inserted with the flapless technique, and in the other group of 5 patients implant insertion was done with a two-stage technique. All inserted implants were loaded with metal-ceramic crowns 3 months after placement. The patients were followed for 18 months through clinical follow-ups and radiovisiographical (RVG) images made after 3, 12 and 18 months. After comparing the average densities, the results showed similar decrease of density in both groups, conventional two-stage technique showed 3.24 and flapless technique 1.23. It can be concluded that flapless technique in everyday clinical usage has the same result as the two-stage dental implant technique.     

KOM—段式种植体即刻种植的动物实验研究

目的:观察KOM一段式种植体即刻种植骨愈合过程,探索即刻种植的可行性。材料与方法:将6只狗分3组分别作实验。每组2只动物行KOM一段式种植体即刻种植愈合过程观察;动物分别于术后1、2、3个月各处死2只行大体标本观察、X线片、光镜、扫描电镜观察;结果:KOM一段式种植体即刻种植可以达到骨性愈合。结论:1、KOM一段式种植体的即刻种植是一种临床可行的种植方式。2、即刻中植时种植体与骨组织之间的骨间隙是否充填生物替代材料,除了考虑种植体周围骨间隙的大小,还要考虑种植体的初期稳定性。     

Influence of custom-made implant designs on the biomechanical performance for the case of immediate post-extraction placement in the maxillary esthetic zone: a finite element analysis

Due to the increasing adoption of immediate implantation strategies and the rapid development of the computer aided design/computer aided manufacturing technology, a therapeutic concept based on patient-specific implant dentistry has recently been reintroduced by many researchers. However, little information is available on the designs of custom-made dental implant systems, especially their biomechanical behavior. The influence of the custom-made implant designs on the biomechanical performance for both an immediate and a delayed loading protocol in the maxillary esthetic zone was evaluated by means of the finite element (FE) method. FE models of three dental implants were considered: a state of the art cylindrical implant and two custom-made implants designed by reverse engineering technology, namely a root-analogue implant and a root-analogue threaded implant. The von Mises stress distributions and micro-motions around the bone-implant interfaces were calculated using ANSYS software. In a comparison of the three implant designs for both loading protocols, a favorable biomechanical performance was observed for the use of root-analogue threaded implant which approximated the geometry of natural anterior tooth and maintained the original long-axis. The results indicated that bone-implant interfacial micro-motion was reduced and a favorable stress distribution after osseointegration was achieved.     

Segmental mandibulectomy and immediate free fibula osteoseptocutaneous flap reconstruction with endosteal implants: an ideal treatment method for mandibular ameloblastoma

Thirteen patients with large ameloblastomas of the mandible underwent segmental mandibulectomy and immediate reconstruction, with simultaneous placement of osseointegrated implants. All patients received palatal mucosal grafts around the dental implants 6 to 10 months after surgical treatment and received implant-supported prostheses another 1 to 2 months later. There were five female and eight male patients, with a mean age of 32 years (range, 17 to 50 years). The mean length of the mandibular defect was 8.8 cm (range, 5 to 13 cm). All free fibula flap procedures were successful, with no reexplorations or partial flap losses. There was no clinical or radiographic evidence of failure during the osseointegration process for any implant. With functional occlusal loading, the marginal bone loss around the implants was less than 1.5 mm in a mean follow-up period of 40 months (range, 18 to 70 months). There were no recurrences during that time. The technique described allows improved access to the bone at the time of reconstruction, immediate assessment of alveolar ridge relationships, and accurate fixation of the implant-fibula construct. The advantages of this procedure include a reduced risk of recurrence with segmental resection, reliable mandibular reconstruction, and reduction of the number of surgical procedures, allowing full oral rehabilitation in a shorter time. It is concluded that segmental mandibulectomy and immediate vascularized fibula osteoseptocutaneous flap reconstruction, with simultaneous placement of osseointegrated implants, represent an ideal treatment method for large ameloblastomas of the mandible.     

Procedure for intrapleural implantation in mice by thoracotomy

An intrapleural implantation procedure by thoracotomy was developed for application in mice. Animal survival was found to depend on the following: (A) slow induction and quick reversal of a pneumothorax by controlled pleural air injection and withdrawal, (B) keeping the pleura open for the shortest possible time by quick insertion of the implant and immediate tight closure with prepositioned sutures, and (C) use of the right, not the left, pleural cavity especially for maximum size implants which for a 30-gram mouse was 12 X 5 X 4 mm. Surgical and postsurgical mortality was below 5% (n = over 300).     

Decalcified tooth matrix powder induces new bone formation and hematopoietic microenvironment in the mouse

Implants of bone and tooth matrix powder were placed subcutaneously (s.c.) on intraperitoneal (i.p.) Mitex or Polyvic membranes. Implants were removed for histology after 1-24 weeks. Macrophages, fibroblasts, and vascular sinusoids infiltrated around bone and tooth matrix particles after one week. In the s.c. tooth matrix implants, a few sites of cartilage formation and ossification developed at two weeks, and by three weeks granulocytopoiesis and megakaryocytopoiesis developed adjacent to new bone; erythropoiesis was not observed. In s.c. bone matrix implants and in the i.p. artificial membranes coated with bone or tooth matrix powder, ossification or hematopoiesis was not observed. Small numbers of CFU-s, CFU-nm, BFU-e, and CFU-e appeared 10-20 days after s.c. implantation of tooth matrix; none were detected in s.c. bone matrix implants.     

Multi-factorial analysis of variables influencing the bone loss of an implant placed in the maxilla: Prediction using FEA and SED bone remodeling algorithm

The aim of this study was to investigate the interactions of implant position, implant–abutment connection and loading condition influencing bone loss of an implant placed in the maxilla using finite element (FE) analysis and mathematical bone remodeling theory. The maxilla section contours were acquired using CT images to construct FE models containing RS (internal retaining-screw) and the TIS (taper integrated screwed-in) implants placed in SC (along the axis of occlusal force) and RA (along the axis of residual ridge) positions. The adaptive strain energy density (SED) algorithm was combined with FE approach to study the preliminary bone remodeling around implant systems under different load conditions. The simulated results showed that the implant position obviously influenced the bone loss. An implant placed in the RA position resulted in substantially increased bone loss. Implant receiving a lateral load slightly increased bone loss compared with an axial load. The implant type did not significantly influence bone loss. It was found that buccal site suffered the most bone loss around the implant, followed by distal, lingual and mesial sites. The implant position primarily influenced bone loss and it was found most obviously at the buccal site. Implant placed along the axial load direction of a proposed prosthesis could obtain less bone loss around the implant. Attaining proper occlusal adjustments to reduce the lateral occlusal force is recommended in implant–bone–prosthesis system. Abutments of internal engagement with or without taper-fit did not affect the bone loss in the surrounding bone.     

Maxillary reconstruction with a fibula osteoseptocutaneous free flap and simultaneous insertion of osseointegrated dental implants

The fibula osteoseptocutaneous flap is a good option for reconstruction of three-dimensional composite maxillary defects. This flap provides both bone and soft-tissue reconstruction and allows osseointegrated dental implantation, either simultaneously or in a second-stage procedure. Simultaneous placement of osseointegrated dental implants reduces operative sessions and allows faster oral rehabilitation for properly selected patients. The defects may result from trauma or resection of benign tumors or low-grade malignancies. Between August of 1999 and July of 2001, three patients underwent maxillary reconstruction with the fibula osteoseptocutaneous flap and simultaneous osseointegrated dental implants. The cause of the defect was trauma in two cases and resection of an adenoid cystic carcinoma in the other. The mean length of the fibula used for bony reconstruction was 4.7 cm. One osteotomy was performed in one case and no osteotomy was necessary in the other two. Skin islands of 8 x 2.5 cm and 16 x 3.5 cm were used for two patients. For the other patient, a double skin island was used for both nasal (6 x 4 cm) and oral (6 x 5 cm) reconstructions. Two osseointegrated implants were inserted into the fibular bone for each patient. Six months after the first-stage procedure, palatal rotation flaps or mucosa grafts were used to cover the exposed implant necks and prepare the implants for prostheses. One month after the second-stage procedure, prostheses were placed. An implant-supported prosthesis was used for one patient and implant/tissue-supported prostheses were used for the others. At a mean follow-up time of 30 months (range, 16 to 38 months), all patients were able to use the dental prosthesis for chewing (beginning 6 weeks after the final procedure) and all patients were satisfied with the cosmetic results.     

Breast cancer after augmentation mammaplasty: treatment by skin-sparing mastectomy and immediate reconstruction

Breast conservation has been associated with poor cosmetic outcome when used to treat breast cancer in patients who have undergone prior augmentation mammaplasty. Radiation therapy of the augmented breast can increase breast fibrosis and capsular contraction. Skin-sparing mastectomy and immediate reconstruction are examined as an alternative treatment.Six patients with prior breast augmentation were treated for breast cancer by skin-sparing mastectomy and immediate reconstruction. One patient underwent a contralateral prophylactic skin-sparing mastectomy. Silicone gel implants had been placed in the submuscular location in five patients and in the subglandular position in one patient a mean of 10.2 years (range, 6 to 20 years) before breast cancer diagnosis. The mean patient age was 41.3 years (range, 33 to 56 years). Four independent judges reviewed postoperative photographs to grade the aesthetic results in comparison with the opposite native or reconstructed breast.The American Joint Committee on Cancer staging was stage 0 in one patient, stage I for four patients, and stage II for one patient. Five of the six patients presented with a palpable breast mass. Latissimus dorsi flap reconstruction was performed in four patients (bilaterally in one) and a transverse rectus abdominis muscle (TRAM) flap was used in two patients. Three patients were treated by skin-sparing mastectomy with preservation of the breast implant (two patients with latissimus flaps, and one patient with a TRAM flap). The tumor location necessitated the removal of implants in two patients (one patient with a latissimus flap and one with a TRAM. A saline implant was placed under the latissimus flap after gel implant removal. The patient who underwent bilateral skin-sparing mastectomies desired explantation and placement of saline implants. No remedial surgery was performed on the opposite breast to achieve symmetry. Complications occurred in two patients at the latissimus dorsi donor site (seroma in one patient, and seroma and infection in one). Five patients underwent complete nipple reconstructions. The mean duration of follow-up was 33.6 months (range, 15.5 to 70.3 months), and there were no recurrences of breast cancer. The aesthetic results were judged to be good to excellent in all cases.Skin-sparing mastectomy and immediate reconstruction can be used in patients with prior breast augmentation, with good to excellent cosmetic results. Depending on the tumor and implant location, the implant may be preserved without compromising local control.     

The Effect of Non-Contact Conditions in a Splinted Fixed Partial Denture on the Load Sharing Mechanism: A Finite Element Study

A computer-aided design model for a fixed partial denture was constructed and used in a finite element analysis to study the overall load sharing mechanism between the fixed partial denture and oral structures while the denture base rested on the alveolar ridge.To investigate the consequences of non-contact conditions,three additional models were generated incorporating a uniform clearance of 0.125 mm,0.25 mm,and 0.5 mm,respectively.A 100 N static load located at the free end of the prosthesis was applied while the distal portion of the jaw was set fixed.The results show that whilst releasing the ridge almost entirely,the presence of the clearance drastically increased the load on the splinting teeth.A pull-out force on the canine tooth of about 44 N was computed,accompanied by a mesio-distal moment of about 500 N.cm.The combination of which was similar to the tooth extraction maneuver performed by the dentist.In contrast,the second premolar was found to bear a push-in force of almost 115N.The first molar,though barely solicited in the contact condition,became substantially loaded in non-contact conditions,which validates the choice of sacrificing three teeth to support the denture.     

Support Immersion Endoscopy in Post-Extraction Alveolar Bone Chambers: A New Window for Microscopic Bone Imaging In Vivo

Using an endoscopic approach, small intraoral bone chambers, which are routinely obtained during tooth extraction and implantation, provide visual in vivo access to internal bone structures. The aim of the present paper is to present a new method to quantify bone microstructure and vascularisation in vivo. Ten extraction sockets and 6 implant sites in 14 patients (6 men / 8 women) were examined by support immersion endoscopy (SIE). After tooth extraction or implant site preparation, microscopic bone analysis (MBA) was performed using short distance SIE video sequences of representative bone areas for off-line analysis with ImageJ. Quantitative assessment of the microstructure and vascularisation of the bone in dental extraction and implant sites in vivo was performed using ImageJ. MBA revealed bone morphology details such as unmineralised and mineralised areas, vascular canals and the presence of bleeding through vascular canals. Morphometric examination revealed that there was more unmineralised bone and less vascular canal area in the implant sites than in the extraction sockets.     

Implant failure: regional versus cumulative evaluation

In this paper the success rate of implant therapy in various bone regions is discussed. The objective is to determine whether differences existed in success rates of cylinder implants placed in different areas in the both maxilla and mandible. Forty four patients have been treated and reviewed five years after the placement of the fixed prosthetic restoration. The patients were provided with a total of 92 implants. Results from this study show very low survival rate for implants placed in anterior region of maxilla (55.6%) after five years. It is concluded that simple cumulative follow up studies do not entirely correspond to actual situations, positioning the implants has an important role in the planning of the implant therapy and that important factor for force compensation is not only the surrounding bone density, but also the region of the jaw where the implants are placed.     

Accelerated rehabilitation of an edentulous patient with an implant retained dental prosthesis: a case report

This case report details the successful rehabilitation of an edentulous patient using a complete upper prosthesis and a lower implant retained overdenture. The provision of care was split between a specialist centre and a primary care setting. This approach reduced inconvenience to the patient. Modern surgical and prosthodontic techniques also reduced the total delivery time. After initial consultation a new set of complete dentures was prescribed with changes in design to the originals. The patient was also planned for placement of two mandibular implants to stabilise and retain the mandibular denture. The first line of treatment involved provision of a new set of dentures constructed by the patient's general dental practitioner. Dental implants were then placed in a specialist centre and the patient returned to the dental practice for attachment of the lower denture to the dental implants. The benefits and success of mandibular implant retained dentures are well documented. With delivery of the overdenture, the patient reported increased satisfaction with his prostheses which allowed him to eat a greater range of foods and enabled him to feel confident when speaking and socialising.     

利用共振频率分析牙种植体骨愈合期稳定性变化 与早期边缘骨吸收的关系

目的:利用共振频率测量仪(Osstell)连续监测骨愈合期种植体稳定性变化与早期边缘骨吸收的关系。方法:本研究于2010-2011年期间根据纳入及排除标准连续纳入32名成年男性患者作为实验对象共植入45枚Strauman种植体,每名患者选择一颗(4.8mm×10mm)种植体,共计32颗种植体,种植区位于下颌后牙(骨质均为Ⅱ或Ⅲ类骨)。利用共振频率分析仪(Osstell)测量种植体的稳定性,测量时间点为植入时以及术后第1,2,3,4,6,8,12周。另外,影像学分析测量32颗种植体12周时的边缘骨吸收;结果:本实验中所有种植体在12周均实现骨结合,并成功完成种植修复。通过重复性方差分析,见表1,在种植体植入时,初期稳定系数(ISQ)均值为(79.03±6.756)。术后一周,种植体稳定系数(ISQ)均值均呈下降趋势,至术后第2周时达到最低点,与植入时稳定性有统计学差异(P<0.05)。从术后第3周开始种植体稳定系数(ISQ)均值逐渐上升。其中,稳定系数(ISQ)均值在第6周时与第12周无统计学差异,已达到延期稳定期。32颗种植体在第12周的边缘骨吸收均值为(0.86±0.068mm),而在第12周的种植体的稳定系数均值与种植体植入时的稳定系数均值无统计学差异。结论:本实验通过共振频率测量仪(OsstellTM)连续监测,目前的结果认为种植体愈合期边缘骨吸收对种植体愈合期稳定性变化没有影响。     

Tensile Mechanical Properties of Swine Cortical Mandibular Bone

Temporary orthodontic mini implants serve as anchorage devices in orthodontic treatments. Often, they are inserted in the jaw bones, between the roots of the teeth. The stability of the mini implants within the bone is one of the major factors affecting their success and, consequently, that of the orthodontic treatment. Bone mechanical properties are important for implant stability. The aim of this study was to determine the tensile properties of the alveolar and basal mandible bones in a swine model. The diametral compression test was employed to study the properties in two orthogonal directions: mesio-distal and occluso-gingival. Small cylindrical cortical bone specimens (2.6 mm diameter, 1.5 mm thickness) were obtained from 7 mandibles using a trephine drill. The sites included different locations (anterior and posterior) and aspects (buccal and lingual) for a total of 16 specimens from each mandible. The load-displacement curves were continuously monitored while loading half of the specimens in the oclluso-gingival direction and half in the mesio-distal direction. The stiffness was calculated from the linear portion of the curve. The mesio-distal direction was 31% stiffer than the occluso-gingival direction. The basal bone was 40% stiffer than the alveolar bone. The posterior zone was 46% stiffer than the anterior zone. The lingual aspect was stiffer than the buccal aspect. Although bone specimens do not behave as brittle materials, the diametral compression test can be adequately used for determining tensile behavior when only small bone specimens can be obtained. In conclusion, to obtain maximal orthodontic mini implant stability, the force components on the implants should be oriented mostly in the mesio-distal direction.     

Why change a good thing? Revisiting the fleur-de-lis reconstruction of the breast

Although the latissimus flap is known for its simplicity and reliability, use of the fleur-de-lis pattern was plagued by undesirable T-shaped donor sites and small breast volumes in thin patients. We report a modified technique for optimal shaping of the standard latissimus with the successful application of a modified fleur-de-lis pattern. Because a "wet" tumescent infiltration was utilized and large amounts of subcutaneous fat were harvested, these changes permitted application to a wide variety of patients, with generous breast volumes reducing the size of the implant placed and resulting in excellent donor-site scars.This is a retrospective cohort study of 53 delayed or immediate reconstructions performed consecutively by the principal author (M.E.A.) on 48 patients at a university-based, urban hospital. Each case was analyzed between April of 1995 and February of 1999, with a follow-up from 2.5 to 44 months. All patients underwent injection of tumescent solution into the subcutaneous plane and harvest of large amounts of subcutaneous fat with the neurologically intact latissimus muscle. The last 25 reconstructions utilized the modified fleur-de-lis skin pattern, an inferiorly based vertical limb and replacement of skin deficiency in both axes.Of 11 perioperatively irradiated patients, none required skin grafting, whereas 6 percent of all native mastectomy flaps were grafted. There was one instance of minor distal tip flap necrosis in a nonirradiated patient. No implants became infected or were extruded. Donor sites were without wound complications and unveiled a 16 percent overall seroma rate.Through selective addition of harvested tissue, this modified technique, particularly the fleur-de-lis pattern, permits improved volume and projection in the inferior pole. The T-shaped donor-site closure is not only acceptable, but is also desirable, with reduced wound tension and minimization of dog-ear formation. With a relative paucity of complications, this conceptually ideal modification is technically simple and aesthetically comparable to our transverse rectus abdominis muscle flap results.