The effect of internal versus external abutment connection modes on crestal bone changes around dental implants: a radiographic analysis

Background: To the best of our knowledge, the influence of external versus internal implant–abutment connections on crestal bone remodeling has not been reported. The aim of the present study is to investigate the influence of the abutment connection on peri‐implant crestal bone levels (CBLs) using radiographic recordings. Methods: Radiographic recordings from 40 single‐tooth implants (20 external and 20 internal octagonal connections; one implant/patient) in 40 patients (15 males and 25 females; mean age: 54.3 years) were selected for analyses. The radiographic evaluation included the following: 1) linear bone change (LBC); 2) dimensional change (DC); and 3) angle between the implant and adjacent bone (AIB). Differences in LBC, DC, and AIB between implant placement and 1 year after loading for each system were evaluated using a paired t test. Comparison of LBC, DC, and AIB between systems at 1 year after loading was done using analysis of covariance. The significance level was set at P ≤0.05. Results: Radiographic CBLs (LBCs) were reduced at 1 year after loading compared to those at implant placement to reach statistical significance for the external connection (P = 0.000) but not the internal connection (P = 0.939). CBL changes were significantly greater for the external compared to the internal connection (P = 0.000). Similarly, the DC for the external connection was significantly greater compared to that for the internal connection (P = 0.004). Conclusion: Within the limitations of this study, the implant–abutment connection technology appears to have a significant impact on peri‐implant CBLs, with the external connection paralleled by a significant reduction of CBLs.     

Evaluation of osteoblastic activity around dental implants using bone scintigraphy

Objectives: The aim of this study was to evaluate the osteoblastic activity around delay‐loaded intraosseous dental implants using nuclear medicine imaging techniques. Material and methods: Seven totally edentulous patients (two females and five males, between 48 and 57 years of age) were included in the study. Two implants were inserted into mandibular canine regions and removable prostheses were produced after 3 months. Whole‐body bone scintigraphies with 20 mCi technetium 99m labelled methylene diphosphonate were taken from the patients before implant insertion, 3 months after implant placement just before the prostheses were made and 1 year after implant placement. Standardized count/pixel (SC/P) rates were calculated for each patient. Preimplantation SC/P values were compared with the 3‐ and 12‐month values. Three‐month values were compared with the 12‐month values as well. Results: SC/P rates in the third month were significantly higher (P<0.05) than preoperative values and the SC/P rates of the 12th month were significantly lower (P<0.05) than 3‐month values. The SC/P rates of the 12th month were relatively higher than first scintigraphies but the difference was insignificant (P>0.05). Conclusions: Within the limitations of this study, in which delayed loading was applied, we showed that osteoblastic activity persisted more in delay loaded implants than immediate and early loading. After 1 year, there was no cellular activity around two implants and this implied that two implants were sufficient for a total prosthesis. To cite this article:
Kalayci A, Durmus E, Tastekin G, Isik K, Inan Ö. Evaluation of osteoblastic activity around dental implants by using bone scintigraphy.
Clin. Oral Impl. Res. 21 , 2010; 209–212.
doi: 10.1111/j.1600‐0501.2009.01822.x     

Breast metastasis around dental implants: a case report

Background Metastases to the oral cavity and to the jaws are rare; hence, the clinical manifestations of the oral metastasis lesion could frequently be simulating general pathologic entities, making the diagnosis a challenging process to the dental team. Local factors, such as trauma, have been observed to facilitate the growth of blood‐borne tumors. To this end, surgical procedures such as fixture placement might cause cancer cells to spread. Purpose Careful clinical examination is a valuable help in diagnosing oral lesions, which can improve the quality of life of patients and reduce the risks of oral complications. Materials and Methods A female patient was referred to the clinic with symptoms of irritation, swelling, and pain associated with implants in the mandible and the maxilla. Results Clinical examination, x‐ray, and histopathology revealed that the patients suffered from a metastatic lesion, primary tumor being an adenocarcinoma of the breast diagnosed at the same time. Conclusion Optimal clinical examination in conjunction with radiography and histopathology is a necessity in order to discover malignant lesions in time. Routine dental check‐ups must comprise more thorough soft‐tissue examination.     

雌激素对骨质疏松时种植体骨愈合的影响:Ⅰ组织学观察

目的：研究雌激素替代治疗对骨质疏松时种植体骨愈合的影响。方法：选用36只雌性SD大鼠并随机分为假手术组，卵巢切除组及雌激素组，术后12周于每个大鼠胫骨近中干骺端植入纯钛螺纹状种植体，雌激素组大鼠从植入术后第一日起肌注苯甲酸雌垢醇20μg/kg/3日，其他两组注射等量生理盐水，种植术后4周和12周分两批处死大鼠，制作带种植体的不脱钙切片，行组织学与荧光观察，结果：在4周及12周两个时间点上，假手术组和雌激素组松质骨区种植体周围包绕骨板较厚，种植体周围骨小梁密度及与骨组织接触面积均优于卵巢切除组，种植4周时雌激素组荧光染色强度及双标记线宽度均优于卵巢切除组，而与假手术组相似，种植12周时雌激素组荧光染色表现与卵巢切除组相近。结论：雌激素替代治疗可促进骨质疏松大鼠松质骨区种植体骨愈合；从而有利于提高种植体成功率。     

The combined effects of undersized drilling and implant macrogeometry on bone healing around dental implants: an experimental study

This study investigated the effect of undersized preparations with two different implant macrogeometries. There were four experimental groups: group 1, conical implant with an undersized osteotomy of 3.2 mm; group 2, conical implant with an undersized osteotomy of 3.5 mm; group 3, cylindrical implant with an undersized osteotomy of 3.2 mm; group 4, cylindrical implant with an undersized osteotomy of 3.5 mm. Implants were placed in one side of the sheep mandible (n = 6). After 3 weeks, the same procedure was conducted on the other side; 3 weeks later, euthanasia was performed. All implants were 4 mm × 10 mm. Insertion torque was recorded for all implants during implantation. Retrieved samples were subjected to histological sectioning and histomorphometry. Implants of groups 1 and 2 presented significantly higher insertion torque than those of groups 3 and 4 (P < 0.001). No differences in bone-to-implant contact or bone area fraction occupied were observed between the groups at 3 weeks (P > 0.24, and P > 0.25, respectively), whereas significant differences were observed at 6 weeks between groups 1 and 2, and between groups 3 and 4 (P < 0.01). Undersized drilling affected the biological establishment of bone formation around both dental implant macrogeometries.     

实验性骨质疏松对种植体周骨缺损植骨愈合的影响

目的：探讨骨质疏松对种植体周植骨材料愈合的影响。方法：选用36只32周龄雌性SD大鼠，随机分成两组。实验组行双侧卵巢摘除术，对照组行假手术。术后12周于大鼠胫骨处植入种植体，并造成骨缺损，应用羟基磷灰石（HA）植骨。种植术后4周、12周后两批处死大鼠，进行组织学观察及骨计量学测量。结果：实验组种植体结合骨板宽度、HA颗粒包被骨壁厚度及包被率均显著低于对照组（P＜0．05或P＜0．01）；HA颗粒与骨髓腔直接接触处可见类骨质。结论：骨质疏松阻碍种植体周围植骨材料愈合。     

The ability of topical and systemic statins to increase osteogenesis around dental implants: a systematic review of histomorphometric outcomes in animal studies

The purpose of this systematic review was to evaluate the quantitative histomorphometric outcomes of animal studies investigating statins as a pro-osteogenic agent to enhance the osseointegration of dental implants. Some animal studies have suggested a beneficial action of statins on bone tissue. Electronic and manual literature searches, without date or language restriction, ??were performed by two independent review authors up to February 2017. Eligibility criteria included animal trials quantitatively analysing the pro-osteogenic effect of statins on dental implants. The quality of the included studies was assessed using the ARRIVE guidelines. The search and selection process yielded 12 studies, published between 2004 and 2015. The experimental animals models used were rats and dogs. The statins used in the studies were simvastatin and fluvastatin, which were administered locally or systemically, or applied to the implant surface. All of the selected studies showed a statistically significant positive effect of statins on bone formation around implants. The mean quality assessment score (ARRIVE) of the studies was 11.5 ± 2.27 out of a possible total of 25 points. The histomorphometric data from available preclinical studies suggest a positive effect of statins on increasing osteogenesis around dental implants.     

Bone microvascular pattern around loaded dental implants in a canine model

The vascularity of the implant bed is a very important parameter in both bone formation and maintenance after dental implants insertion. The relationship between bone and vessels network organization is still unknown. The aim of this study was to investigate the three-dimensional bone vascular canals of the peri-implant bone after loading. A total of ten implants with sandblasted and acid-etched surface were placed in the mandible of a beagle dog. Three months later, the implants were connected and loaded. The dog was killed after 12 months. The specimens were embedded and processed for scanning electron microscopy (SEM) analysis. After a 1-year loading period, a very intricate vessel network could be seen around the implants. The vessels, with neighbouring soft tissues, were round in shape and showed a lot of anastomoses with a mesh-like appearance. They ran circularly around the dental implant. In the bone, the majority of the vessels appeared to ran parallel to the mandibular canal. After a 1-year loading period, the peri-implant bone vasculature looked like a mesh that surrounded the implants. Nevertheless, the presence of many thick vessels inside the peri-implant crestal bone indicates a high metabolic need and also a different bone organization, as no osteons were noted. The crater-like bone loss around the marginal part of the implant could be related to the microvasculature “strain”. A high strain level could continuously activate the osteocyte–vessel syncytium, producing a net bone loss.     

Effect of membranes and porous hydroxyapatite on healing in bone defects around titanium dental implants. An experimental study in monkeys.

The purpose of the present study was to examine the effect of treating bony craters around titanium dental implants with polytetrafluoroethylene membranes PTFE, with and without grafting of hydroxyapatite (HA), and with HA alone. 4 standardized bone defects were prepared in the alveolar ridge of edentulous areas in each of 7 monkeys. A titanium implant was then placed centrally in each defect, and in each monkey, the defects were treated with 1 of the following 4 treament modalities: 1 coverage with PTFE membrane;(2) grafting of HA and covering with a PTFE membrane;(3) HA grafting;(4) no treatment. Following a healing period of 12 weeks, all animals were sacrificed and mesiodistal ground sections of the treated areas were prepared. The histological analysis showed that all bone defects around the implants treated with PTFE membranes and 5 of the defects treated with HA and PTFE membranes were completely filled with new bone. The defects treated with HA alone and the control defects with no treatment only demonstrated new bone formation in the bottom of the defects. The results suggest that bone defects around titanium implants can be 1 treated successfully with PTFE membranes.     

Influences of internal tapered abutment designs on bone stresses around a dental implant: three-dimensional finite element method with statistical evaluation

Background: The aim of this study is to determine the effects of various designs of internal tapered abutment joints on the stress induced in peri‐implant crestal bone by using the three‐dimensional finite element method and statistical analyses. Methods: Thirty‐six models with various internal tapered abutment–implant interface designs including different abutment diameters (3.0, 3.5, and 4.0 mm), connection depths (4, 6, and 8 mm), and tapers (2°, 4°, 6°, and 8°) were constructed. A force of 170 N was applied to the top surface of the abutment either vertically or 45° obliquely. The maximum von Mises bone‐stress values in the crestal bone surrounding the implant were statistically analyzed using analysis of variance. In addition, patterns of bone stress around the implant were examined. Results: The results demonstrate that a smaller abutment diameter and a longer abutment connection significantly reduced the bone stresses (P <0.0001) in vertical and oblique loading conditions. Moreover, when the tapered abutment–implant interfaced connection was more parallel, bone stresses under vertical loading were less (P = 0.0002), whereas the abutment taper did not show significant effects on bone stresses under oblique loading (P = 0.83). Bone stresses were mainly influenced by the abutment diameter, followed by the abutment connection depth and the abutment taper. Conclusion: For an internal tapered abutment design, it was suggested that a narrower and deeper abutment–implant interface produced the biomechanical advantage of reducing the stress concentration in the crestal region around an implant.     

全瓷基台的研究进展

近年来,随着物质生活水平的提高和种植义齿学的飞速发展,口腔临床医生和患者对修复美学有着越来越高的要求.传统的钛基台在牙龈较薄或种植体肩部位置过高的患者会有不同程度金属颜色的暴露而影响美观,而全瓷基台因其具有良好的美学性能更受口腔修复医生和患者的欢迎.本文综述了全瓷基台的种类及制作方式、优点、机械性能和在临床种植修复中的应用.尽管全瓷基台受价格和机械强度的影响尚未成为种植修复常规的选择,但随着材料和技术的进步,相信其应用将越来越广.     

雌激素对骨质疏松时种植体骨愈合的影响:Ⅱ骨计量学和电镜观察

目的 :研究雌激素替代治疗对骨质疏松时种植体骨愈合的影响。方法 :选用32周龄雌性SD大鼠36只 ,并随机分为假手术组、卵巢切除组及雌激素组。卵巢切除12周后于大鼠胫骨近中干骺端植入纯钛螺纹状种植体 ,雌激素组同时肌注苯甲酸雌二醇。种植术后4周及12周分两批处死大鼠 ,摘取胫骨 ;标本分别进行扫描电镜观察和骨计量学测量。结果 :在种植后4周及12周时 ,雌激素组除12周时皮质骨结合率与卵巢切除组无显著差异外 ,其它各项骨计量学参数均显著高于卵巢切除组 (P<0.05或P<0.01) ;而与假手术组比较 ,除骨矿化速度及4周时单位骨量外 ,其他各项指标均无显著差异 (P>0.05)。电镜观察种植体—骨界面愈合雌激素组和假手术组均优于卵巢切除组。结论 :雌激素替代治疗可促进实验性骨质疏松大鼠种植体骨愈合 ;该方法有助于增加临床绝经性骨质疏松患者牙种植体骨整合率     

Oestrogen replacement therapy promotes bone healing around dental implants in osteoporotic rats

The aim of this study was to investigate the effect of oestrogen replacement therapy on bone healing around titanium implants in osteoporotic rats. Sixty 32-week-old female SD rats were used in this study. Ovariectomies were performed in 40 rats, and other 20 rats had sham operation. Eighty-four days after surgery, osteoporotic changes in proximal tibiae were seen in four ovariectomized rats when compared with two sham-operated rats. Then pure titanium implants were placed in the bilateral proximal metaphyses of the tibiae of the remaining animals. Oestrogen replacement therapy was administrated in 18 ovariectomized rats after implantation. Nine rats from each group (ovariectomized, oestrogen-treated and sham-operated) were killed at 28 and 84 days after implantation surgery respectively, and the tibiae specimens were harvested and examined. Both at 28 and 84 days after implantation surgery, most bone histomorphometric indices in the oestrogen-treated group were significantly increased compared with those in the ovariectomized group (P < 0.05 or P < 0.01). Although the oestrogen-treated group showed lower trabecular bone volume at 28 days after implant surgery and lower mineralization rate at both the two time points than the sham-operated group, there were no significant differences in other bone histomorphometric indices between the oestrogen-treated group and the sham-operated group both at 24 and 84 days after implantation. The results of this study suggest that oestrogen replacement therapy may promote bone healing around titanium implants under osteoporotic state, and therefore it seemed to be beneficial to long-term success of dental implants in clinical postmenopausal patients.     

Factors affecting soft tissue level around anterior maxillary single‐tooth implants

Background: Peri‐implant soft tissue recession is a major esthetic concern for the anterior implants. The aim of this study was to determine the factors that affected the facial marginal mucosal level and papilla level around single‐tooth implants in the anterior maxilla. Methods: Forty single‐tooth implants in the anterior maxilla were studied. Variables possibly associated with the soft tissue level were obtained from clinical measurements, study models, peri‐apical radiographs, and computerized tomograms. Fisher's exact test, analysis of variance, and binary logistic regression analysis were used to determine the influence of each factor on the facial marginal mucosal level and papilla level. Results: The majority of the implants (75%) replaced the upper central incisors. The facial mucosal margin of the implant was 0.5±0.9 mm more apical than that of the contralateral tooth. Half or more of papilla fill was observed in 89% of the samples. More apical level of the facial mucosal margin at the implant sites was significantly influenced by many factors including a thin peri‐implant biotype, a proclined implant fixture angle, more apical level of the facial bone crest, increased distance from the contact point to the bone crest, contact point to the platform, and contact point to implant bone. A thin biotype was the most significant factor in determining the facial marginal mucosal level. Increased distance from the contact point to the bone crest was the only factor significantly associated with less papilla fill. Conclusions: The papilla level around single‐tooth implants in the anterior maxilla was mainly influenced by the interproximal bone crest level of the adjacent tooth. Facial marginal mucosal level, on the other hand, was affected by multiple factors including the peri‐implant biotype, the facial bone crest level, the implant fixture angle, the interproximal bone crest level, the depth of implant platform, and the level of first bone to implant contact. To cite this article:
Nisapakultorn K, Suphanantachat S, Silkosessak O, Rattanamongkolgul S. Factors affecting soft tissue level around anterior maxillary single‐tooth implants.
Clin. Oral Impl. Res. 21 , 2010; 662–670.
doi: 10.1111/j.1600‐0501.2009.01887.x