早期不同时间种植体骨界面改建的骨组织定量测定

目的建立种植体植入Beagle犬下颌骨的动物模型,应用Micro-CT对早期的种植体周围骨组织情况进行分析研究。方法选用4只健康纯系雄性Beagle犬,随机分A、B两组,拔除下颌双侧第4前磨牙、第1磨牙,3个月后在相应缺牙区植入8枚植体,分别在植入后2周、4周处死两只Beagle犬,并对其作相应临床检查及Micro-CT检测。结果各组实验犬拔牙创愈合良好,种植体成功植入相应拔牙位点,各项临床指标无明显差异,Micro-CT检测显示种植体植入后2周的骨体积分数大于植体植入后4周的骨体积分数,且两组具有显著统计学差异(P≤0.01),其余骨微结构计量无统计学差异。结论成功建立口腔种植Beagle犬动物实验模型,早期植体周围骨愈合是一个骨吸收骨生成的骨组织改建或骨组织修复过程,植体植入后4周其周围骨吸收大于骨生成,Micro-CT能很好地应用于口腔种植骨微结构分析研究。     

Local application of the osteogenic inducer sustained-release system promotes early bone remodeling around titanium implants

Enhanced osseointegration and a shortened healing time are required for dental implant treatment. The aim of this study was to evaluate whether topical application of the osteogenic inducer (OI) sustained-release system over the implant promotes early bone remodeling around the implant. The mandibular canines of 15 New Zealand White rabbits were extracted. After 3 months of healing, implants coated with poly(lactic-co-glycolic acid) (PLGA)+OI, PLGA alone, or no material (control) were inserted into the canine sites. After 4 weeks, specimens were harvested from the three groups and evaluated. Implant stability recorded by Periotest revealed significantly higher values for the PLGA + OI group (?2.61 ± 0.43) than for the PLGA (?1.47 ± 0.45) and control groups (?1.08 ± 0.19) (P < 0.001). Moreover, the PLGA+OI group had improved bone volume and structural parameters around the implants at 4 weeks, as shown by significantly increased BV/TV, BSA/BV, Tb.Th, and BIC (P < 0.05), as well as decreased Tb.Sp (P = 0.010) compared with the other groups. The histological results showed more trabecular bone and bone matrix around the implants in the PLGA+OI group. Therefore, local application of the OI sustained-release system might be able to promote early bone remodeling around titanium implants and facilitate faster and better osseointegration.     

The influence of antineoplastic agents on the peri-implant bone around osseointegrated titanium implants: an in vivo histomorphometric and immunohistochemical study

Clinical Oral Investigations - The interaction between antineoplastic drugs used for treating cancer and non-affected tissues remains poorly assessed and may be critical for maintaining the quality...     

Bone remodeling in immediately loaded and unloaded titanium dental implants: a histologic and histomorphometric study in humans

Remodeling is thought to prevent microdamage accumulation caused by repetitive loading and to increase the fatigue life of bone. The bone remodeling rate (BRR) is the period of time needed for new bone to replace the existing bone and to allow for the adaptation of bone to its environment. BRR is expressed as a percentage or volume of new bone within a specific time period. The aim of the present study was to evaluate bone remodeling events on submerged and immediately loaded dental implants. Twelve patients with edentulous mandibles participated in this study. All patients were rehabilitated with fixed mandibular prostheses, with 10 dental implants per patient. An additional implant was inserted in the most distal posterior mandibular jaw region. In 6 patients, these additional implants were loaded with a fixed provisional prosthesis the same day of the implant surgery and loaded. In the other 6 patients, the additional implants were left submerged and not loaded. After 6 months, all the additional implants were retrieved with a trephine. The percentage of woven and lamellar bone, number of osteoclasts and osteoblasts, and percentage of bone labeled by tetracycline at 0.5 mm and 2 mm from the implant surface were evaluated. The percentage of lamellar bone, number of osteoblasts, and percentage of bone tetracycline labeling was significantly higher in the loaded implants than in the unloaded implants (P =.0001). Also in the loaded implants, the percentage of woven and lamellar bone, number of osteoclasts and osteoblasts, and percentage of bone tetracycline labeling was significantly higher at 0.5 mm than at 2 mm from the implant surface (P =.0001). No such differences were found in unloaded implants (P =.377). In conclusion, we found that (1) loading appeared to stimulate bone remodeling at the interface, (2) a higher percentage of lamellar bone was found in loaded implants, (3) the percentage of bone labeling was higher at the interface of loaded implants, (4) no differences were found in the BRRs between immediately loaded and unloaded implants, and (5) immediate loading had not interfered on the lamellar bone formation at the interface and had not produced formation of woven bone at the interface.     

Nicotine and bone density around titanium implants: a histometric study in rabbits

This study investigated the influence of nicotine on bone density around titanium implants inserted in rabbits. Thirty-two New Zealand rabbits were included. After anesthesia, the tibiae surfaces were exposed and two screw-shaped, commercially available, pure titanium implants of 7.0 mm in length and 3.75 mm in diameter were placed bilaterally. A total of 128 implants were inserted: 64 blasted with Al2O3 particles (group 1) and 64 with a machined surface finish (group 2). The animals were randomly assigned to one of four treatment subgroups, and daily subcutaneous injections of nicotine were administered. After 42 days, the animals were killed and undecalcified sections were prepared. The bone density was measured in the cortical passage of the implant. Statistical analysis (two-way analysis of variance) revealed no significant difference neither regarding the effect of nicotine nor the effect of surface design on bone density around the implants (P > 0.05). Within the limits of the present study, it can be assumed that daily nicotine administration may not statistically influence bone density around titanium implants.     

Osseointegration of commercial microstructured titanium implants incorporating magnesium: a histomorphometric study in rabbit cancellous bone

Objective: Recent studies have suggested that magnesium (Mg) ions exert a beneficial effect on implant osseointegration. This study assessed the osseointegration of nanoporous titanium (Ti) surface incorporating the Mg produced by hydrothermal treatment in rabbit cancellous bone to determine whether this surface would further enhance bone healing of moderately rough‐surfaced implants in cancellous bone, and compared the result with commercially available micro‐arc oxidized Mg‐incorporated implants. Material and methods: The Mg‐incorporated Ti surfaces (RBM/Mg) were obtained by hydrothermal treatment using an alkaline Mg‐containing solution on grit‐blasted moderately rough (RBM) implants. Untreated RBM and recently introduced Mg‐incorporated microporous Ti implants produced by micro‐arc oxidation (M) were used controls in this study. The surface characteristics were evaluated by scanning electron microscopy, X‐ray photoelectron spectroscopy and optical profilometry. Twenty‐four threaded implants with a length of 10 mm (eight RBM implants, eight RBM/Mg implants and eight M implants) were placed in the femoral condyles of 12 New Zealand White rabbits. Histomorphometric analysis was performed 4 weeks after implantation. Results: Hydrothermally treated and untreated grit‐blasted implants displayed almost identical surface morphologies and R_a values at the micron‐scale. The RBM/Mg implants exhibited morphological differences compared with the RBM implants at the nano‐scale, which displayed nanoporous surface structures. The Mg‐incorporated implants (RBM/Mg and M) exhibited more continuous bone apposition and a higher degree of bone‐to‐implant contact (BIC) than the untreated RBM implants in rabbit cancellous bone. The RBM/Mg implants displayed significantly greater BIC% than untreated RBM implants, both in terms of the all threads region and the total lateral length of implants (P<0.05), but no statistical differences were found between the RBM/Mg and M implants except BIC% values in total lateral length. Conclusion: These results indicate that a nanoporous Mg‐incorporated surface may be effective in enhancing the osseointegration of moderately rough grit‐blasted implants by increasing the degree of bone?implant contact in areas of cancellous bone. To cite this article :
Park J‐W, An C‐H, Jeong S‐H, Suh J‐Y. Osseointegration of commercial microstructured titanium implants incorporating magnesium: a histomorphometric study in rabbit cancellous bone.
Clin. Oral Impl. Res. 23 , 2012; 294–300.
doi: 10.1111/j.1600‐0501.2010.02144.x     

Early trabecular bone healing around titanium implants: a histologic study in rabbits

BACKGROUND: A detailed insight into the early healing response of trabecular bone to unloaded titanium implants is lacking. METHODS: Cylindrical implants were inserted in the tibial epiphysis of rabbits and left to heal for 1 to 42 days. Samples were processed into paraffin or methylmethacrylate sections and histomorphometrically analyzed. RESULTS: A hematoma was observed after 1 and 3 days of implant placement. In addition, small fragments of bone trabeculae were detected around the implant as a result of the implant installment procedure. Soon, osteoclasts were observed resorbing these fragments, whereas osteoblasts incorporated them in strands of new bone, thereby making them difficult to distinguish from day 7 onward. At that time, osteoblasts were detected at the edges of the preexisting bone, actively depositing new bone, resulting in maximal osteoid deposition around the implant after 28 days (58%). After 7 days of healing, the presence of basic remodeling units in the surrounding bone was already maximal (P <0.05 versus t = 1 and 3 days). This remodeling activity, together with the new bone formation, provided a firm anchoring of the implant in the trabecular bone. CONCLUSIONS: This study evaluated the early cellular events in trabecular bone surrounding titanium implants. The insertion of an implant into bone initiates a series of biologic processes, including the formation of a hematoma, shattered bone fragments adjacent to the implantation site, intensive bone remodeling, and the formation of new bone, eventually leading to the osseointegration of the implant.     

Estrogen deficiency affects bone healing around titanium implants: a histometric study in rats

The purpose of this study was to evaluate the influence of an estrogen-deficient state on bone around titanium implants placed in rats. Thirty female Wistar rats were divided into 2 groups: test (n = 15), ovariectomized rats (OVX); and control (n = 15), sham-operated rats. Screw-type titanium implants were placed bilaterally in rats 21 days after ovariectomy or sham surgery. After 60 days, the animals were killed and undecalcified sections obtained. Blood samples were collected to obtain serum levels of alkaline phosphatase at the time of killing. Bone-to-implant contact (BIC), bone area (BA) around the implants, and bone density (BD) in a 500 microns-wide zone lateral to the implant were obtained and arranged separately for the cortical (zone A) and cancellous (zone B) regions. In zone A, there was no significant difference between test and control groups regarding BIC and BD (P > 0.05). A lower BA was observed in the estrogen-deficient animals (P < 0.05). In zone B, data analysis showed that estrogen deficiency could result in a lower percentage of BIC, BA, and BD (P < 0.05). In addition, a higher concentration of alkaline phosphatase was observed for the test group. An estrogen-deficient state could affect bone healing and bone density around titanium implants placed in rats, especially in the cancellous bone area.     

Radiographic assessment of bone density around integrated titanium implants after ovariectomy in rats

OBJECTIVES: This study evaluated the influence of ovariectomy 8 weeks after implant placement on bone integrated to titanium implants. MATERIAL AND METHODS: Thirty-eight female rats were submitted to a titanium implant at the tibiae proximal methaphysis. After a healing period of 8 weeks the animals were randomly divided into three groups: control (CTL-10 animals), sham-operated (SHAM-14 animals) and ovariectomy (OVX-14 animals). The CTL group was then sacrificed in order to confirm integration of the implant. The SHAM group was submitted to fictitious surgery and the OVX group was submitted to bilateral ovariectomy. After 12 weeks post-implant placement, the SHAM and OVX groups were sacrificed. In order to confirm the systemic osteopenia in rats, a dual-energy X-ray absorptiometry (DXA) was performed. For the evaluation of bone density, digital radiographs were taken. The grey level of the bone adjacent to implant was measured using image software and the bone density was calculated at six points on both sides of the implant. RESULTS: Densitometry measurements of the femur confirmed systemic bone mass loss in the OVX group. Individualized bone analyses of different regions surrounding the implant showed a significantly lower radiographic bone density (P < 0.05) in the cancellous region of the OVX group (77.48 +/- 23.39 grey levels) when compared with the CTL and SHAM groups (91.61 +/- 32.10 and 102.57 +/- 32.50 grey levels, respectively). CONCLUSIONS: The present study showed a decrease of the radiographic bone density in the cancellous region of bone around titanium implants placed 8 weeks before ovariectomy in rats.     

Early cortical bone healing around loaded titanium implants: a histological study in the rabbit

Objectives: To identify the role of immediate implant loading on the early phases of the bone healing responses.
Material and methods: Implants were placed in rabbit tibial diaphyses and left to heal for 3, 7, 14, 28 or 42 days. Half of the animals received an immediate loading protocol of 2.2 N at 3 Hz for 1800 cycles and 5 days/week, whereas the others served as unloaded controls. Histological assessment was combined with histomorphometrical measurements.
Results: At early time-points, an endosteal and periosteal new bone formation was found, while the cortex itself contained damaged osteocytes. At later time-points, new bone formation was also found at the cortical level itself. Differences between groups were found mainly in this new bone formation process, with larger reactions for the endosteal and periosteal bone in the loaded group after 28 and 42 days, respectively. At the end-point of the experiment, bone formation at the cortical level was reduced in the loaded group compared with the control group.
Conclusions: These results show that the immediate loading protocol caused no differences in the sequential events leading to osseointegration in cortical bone. However, the processes of new bone formation originating from the endosteum and the periosteum lasted longer compared with the unloaded controls.     

The effects of loading time on osseointegration and new bone formation around dental implants: a histologic and histomorphometric study in dogs

BACKGROUND: Immediate loading of dental implants has been introduced as a method of reducing implant treatment time without compromising its prognosis. In this research, the effects of loading time on the amount of bone-to-implant contact and bone formation around dental implants were evaluated histologically. METHODS: Three months prior to implantation, the lower premolar teeth of 15 dogs were extracted. Three or four dental implants were placed in the healed extraction sites for each dog (N = 48). Dividing the dogs into three groups, the implants were either loaded 48 hours or 1 week later with metallic or prefabricated acrylic crowns or were left unloaded until the time of sacrifice. Three months after implant insertion, the animals were sacrificed and samples were investigated to define the amount of bone-to-implant contact, lamellar and woven bone percentage, and local inflammation of the newly formed bone. RESULTS: No significant difference in the observed criteria was reported among the three groups (P >0.05); however, the unloaded group had the highest degree of bone-to-implant contact and the group loaded 48 hours after the primary implant insertion had the least. The prosthesis type had no significant effect on the implant success rate (P >0.05). The lamellar and woven bone percentage of newly formed bone also did not differ in the three groups (P >0.05). One implant from each group failed in this study. CONCLUSION: Loading time does not seem to significantly affect the degree of osseointegration and bone-to-implant contact and the composition of newly formed bone around dental implants.     

A removal torque and histomorphometric study of commercially pure niobium and titanium implants in rabbit bone

Screw-shaped commercially pure (c.p.) niobium and c.p. titanium implants were inserted in rabbit bone. After a healing period of 3 months, a significantly higher removal torque was demonstrated to unscrew the niobium implants (average 32.9 Ncm) compared to the c.p. titanium implants (average 25.3 Ncm). In the histomorphometric part of the study, there were no significant differences in bone-to-metal contact between the 2 implant materials. An average of 41.1% bony contact was demonstrated for the niobium screws compared to an average of 37.2% for the c.p. titanium ones. Our removal torque findings could be related to the differences that we observed between the 2 implant surfaces as indicated by SEM. Since niobium implants showed a more irregular surface topography and niobium is a softer metal than c.p. titanium, this seems the most probable reason for the differences observed in removal torque between the 2 metals. Hypothetically, a more "positive biocompatibility" of the c.p. niobium in comparison to the c.p. titanium remains as another possible reason for the observed differences. However, against such a difference in biocompatibility between c.p. niobium and c.p. titanium, there is the very similar amount of bony contact registered in the histomorphometric analysis.     

Mandibular bone remodeling under a choline-deficient diet: a histomorphometric study in rats

BACKGROUND: A deficiency of lipotropic factors in the rat induces renal, hepatic, and/or hematic damage. The aim of the present study was to evaluate the effect of a choline-deficient diet and refeeding on mandibular bone remodeling. METHODS: Fifty Wistar rats were divided into 5 groups: group 1 (G1): control diet for 15 days; group 2 (G2): choline-deficient diet for 15 days; group 3 (G3): control diet for 30 days; group 4 (G4): choline-deficient diet for 30 days; and group 5 (G5): choline-deficient diet for 15 days and control diet for 15 days. All animals were sacrificed by ether overdose. The mandibles were resected, radiographed, decalcified, processed, and embedded in paraffin. Bucco-lingually oriented sections were obtained at the level of the interradicular bone of the medial roots of the left first molar, and stained with hematoxylin and eosin (H & E). Bone tissue density and bone remodeling were determined histomorphometrically. Body weight, food intake, hematocrit, and hemoglobinemia were also recorded. RESULTS: Microscopic observation revealed that osteogenesis was lower in rats fed a choline-deficient diet, at both 15 and 30 days, and that this decrease did not revert with a control diet. Histomorphometric evaluation showed 37% and 27% reduction in bone tissue density at 15 and 30 days, respectively, and a 30% decrease in bone formation at 30 days, compared to controls. CONCLUSION: In this experimental model, a choline-deficient diet led to altered bone remodeling as observed by a marked reduction in osteogenesis.     

Thyroid hormones may influence cortical bone healing around titanium implants: a histometric study in rats

BACKGROUND: The aim of the present study was to evaluate, by histometric analysis, the influence of the thyroid hormones, triiodothyronine (T(3)) and thyroxine (T(4)), on bone healing around titanium implants inserted in rat tibiae. METHODS: Forty-two male Wistar rats were randomly assigned to the experimental groups: G1 = healthy animals (control; N = 15); G2 = hypothyroidism (N = 13); and G3 = hyperthyroidism (N = 14). Once alterations were confirmed by total serum levels of T(3) and T(4), one screw-shaped titanium implant was placed in the rat tibiae. Sixty days later, the animals were sacrificed, and undecalcified sections were obtained. Bone-to-implant contact (BIC), bone area within the limits of the implant threads, and bone density in a 500-microm-wide zone lateral to the implant were obtained separately for the cortical (zone A) and cancellous (zone B) bone regions. RESULTS: Intergroup analysis demonstrated that thyroid hormones may significantly affect cortical bone healing around titanium implants. Hyperthyroidism significantly increased the area of newly formed bone in zone A (P <0.05), whereas hypothyroidism significantly decreased the area of newly formed bone and bone density around the implant in zone A (P <0.05) compared to the healthy group. In addition, hyperthyroidism significantly increased BIC extension in zone A compared to hypothyroidism (P <0.05). CONCLUSION: Thyroid hormones may influence the healing process in the cortical bone around titanium implants placed in rats, whereas cancellous bone seems to be less sensitive to changes in T(3) and T(4) serum levels.     

Immediate functional and non-functional loading of dental implants: a 2- to 60-month follow-up study of 646 titanium implants

BACKGROUND: The aim of this study was the evaluation, from a clinical point of view, of implants subjected to immediate functional loading (IFL) and to immediate non-functional loading (INFL) in various anatomical configurations. METHODS: The study included 152 patients who had given their informed consent. A total of 646 implants were inserted. The implants were placed in 39 totally edentulous mandibles, 14 edentulous maxillae, 23 edentulous posterior mandibles, 16 edentulous anterior mandibles, 16 edentulous anterior maxillae, and 15 edentulous posterior maxillae. Fifty-eight implants were used to replace single missing teeth. In 65 cases, IFL was carried out for 422 implants. INFL was carried out in 116 cases, (224 implants). RESULTS: In the IFL group 6 of 422 implants failed (1.4%); in the INFL group 2 of 224 implants failed (0.9%). All the other implants appeared, from clinical and radiographic observations, to have successfully osseointegrated and have been functioning satisfactorily since insertion. All failures were observed in the first few months after implant loading. CONCLUSION: Immediate functional and non-functional loading seems to be a technique that gives satisfactory results in selected cases.     

Influence of a nanometer-scale surface enhancement on de novo bone formation on titanium implants: a histomorphometric study in human maxillae

In this prospective randomized controlled clinical study, small titanium implants were placed in posterior maxillae for the purpose of assessing the rate and extent of new bone development. Nine pairs of site evaluation implants were placed in posterior areas of maxillae and retrieved with trephine drills after 4 or 8 weeks of unloaded healing. The amount of bone in linear contact (%) with the implant surface was used to determine the osteoconductive potential of the implant surface. Implant surfaces were dual acid etched (n = 9) (controls) or dual acid etched and further conditioned with nanometer-scale crystals of calcium phosphate (n = 9) (test implants), and the surfaces were compared. The implants and surrounding tissues were processed for histologic analysis. The mean bone-to-implant contact value for the test surface was significantly increased over that of the control implants at both time intervals (P <.01). For the implants/patients included in this study, the addition of a nanometer-scale calcium phosphate treatment to a dual acid-etched implant surface appeared to increase the extent of bone development after 4 and 8 weeks of healing.     

Osseointegration of titanium alloy and HA-coated implants in healthy and ovariectomized animals: a histomorphometric study

Objectives: The objective of the present study is to evaluate the response to dental implants in healthy and osteoporotic bone.
Materials and methods: Ten ovariectomized (OVX) New Zealand rabbits submitted to a hypocalcic diet and 10 sham-aged rabbits were used. All animals were submitted to bone mineral density (BMD) measurements before ovariectomy, and also 4 months afterwards, using dual energy X-ray absorptiometry. The BMD measurements showed a significant loss of bone mass, between the first and second examinations, only in the experimental group ( P <0.05). After the bone mass loss induction period, three different implants were installed in the proximal tibia metaphisis of each animal: a titanium alloy implant (Ti), a plasma-spray hydroxyapatite-coated implant (HA-PS), and another implant coated with hydroxyapatite with the biomimetic process (HA-B).
Results: After 3 months, histomorphometry showed a bone-to-implant contact (BIC) for Ti implants of 73.09±13.74% in healthy and 66.09±30.01% in OVX animals. The BIC for the HA-PS was 64.83±15.65% and 90.17±8.14% for healthy and OVX animals, respectively, and 88.66±5.30% and 87.96±10.71% for the HA-B implants placed in the same conditions. The differences between the implants in healthy and OVX conditions were not statistically significant ( P >0.05). The only significant difference within groups was observed in the healthy animals between HA-B and Ti implants ( P <0.06).
Conclusion: Within the parameters used in this animal model it was not possible to observe BIC differences between osteoporotic and healthy animals.     

Generation of new bone around titanium implants using a membrane technique: an experimental study in rabbits

Insufficient bone volume may be a significant problem in connection with dental implants. In this study, a technique based on the principle of guided tissue regeneration was tested for its ability to generate bone tissue around titanium implants. Implants were inserted in tibiae of rabbits. To create a secluded space for osteogenesis and to prevent soft-tissue ingrowth, a porous Teflon membrane was placed around exposed parts of the implant. Where a membrane had been used, the threads of the implant were completely covered with significant amounts of new bone. This study indicates that the membrane technique is a reconstructive surgical method that may be applicable to create new bone around exposed parts of titanium implants in a clinical setting.     

非埋植型与埋植型牙种植体骨界面改建的骨组织形态计量学研究

目的观察非埋植型与埋植型两种不同种植方式之间种植体—骨界面结合动态变化的异同。方法选用成年杂种犬8只，在其下颌分别植入埋植型与非埋植型种植体，分不同程期处死动物，采用骨组织形态计量学方法对非埋植型与埋植型种植体—骨界面愈合过程进行动态观察，比较了两者骨界面改建的异同，从定量的角度分析其变化的异同。结果非埋植型种植体骨结合率均略低于埋植型种植体，但它们之间无统计学差异。尽管非埋植型种植体植入后基桩在整个后基桩在整个愈合过程中承受了一定的咬合力，但它能与埋植型种植体一样获得良好的骨结合。结论埋植型与非埋植型种植体其新骨形成的速度与骨性结合的程度两者之间无明显差异。采用骨组织形态计量学方法定量、动态地研究种植体—骨界面结合动态变化有一定的应用价值。