Influence of surgical technique and surface roughness on the primary stability of an implant in artificial bone with different cortical thickness: a laboratory study

Objective: The aim of this biomechanical study was to assess the interrelated effect of both surface roughness and surgical technique on the primary stability of dental implants. Material and methods: For the experiment, 160 screw‐designed implants (Biocomp^®), with either a machined or an etched surface topography, were inserted into polyurethane foam blocks (Sawbones^®). As an equivalent of trabecular bone, a density of 0.48 g/cm³ was chosen. To mimic the cortical layer, on top of these blocks short‐fibre‐filled epoxy sheets were attached with a thickness varying from 0 to 2.5 mm. The implant sites were prepared using either a press‐fit or an undersized technique. To measure the primary stability of the implant, both the insertion and the removal torques were scored. Results: Independent of the surgical technique used, both implant types showed an increased insertion and removal torque values with increasing cortical thickness, although >2 mm cortical layer no further increase in insertion torque was observed. In the models with only trabecular bone (without cortical layer) and with a 1 mm cortical layer, both implant types showed a statistically higher insertion and removal torque values for undersized compared with the press‐fit technique. In addition, etched implants showed a statistically higher insertion and removal torque mean values compared with machined implants. In the models with 2 and 2.5 mm cortical layers, with respect to the insertion torque values, no effect of either implantation technique or implant surface topography could be observed. Conclusion: The placement of etched implants in synthetic bone models using an undersized preparation technique resulted in enhanced primary implant stability. A correlation was found between the primary stability and the cortical thickness. However, at or above a cortical thickness of 2 mm, the effect of both an undersized surgical approach, as also the presence of a roughened (etched) implant surface, had no extra effect. Besides the mechanical aspects, the biological effect of undersized drilling, i.e. the bone response on the extra insertion torque forces should also be elucidated. Therefore, additional in vivo studies are needed. To cite this article:
Tabassum A, Meijer GJ, Wolke JGC, Jansen JA. Influence of surgical technique and surface roughness on the primary stability of an implant in artificial bone with different cortical thickness: a laboratory study.
Clin. Oral Impl. Res. 21 , 2010; 213–220.
doi: 10.1111/j.1600‐0501.2009.01823.x     

Study of the osseointegration of dental implants placed with an adapted surgical technique

Objective: To study the osseointegration of dental implants placed with a modified surgical technique in Beagle dogs and to compare it with the conventional method. Materials and methods: Dental implants were placed bilaterally in the mandible of Beagle dogs using the press‐fit as well as undersized implant bed preparation technique. Micro computer tomography (micro‐CT) and histometric methods were used to analyze the bone implant contact and bone volume (BV) around the implants. Results: The bone‐to‐implant contact percentage (BIC: expressed as %), first BIC (1st BIC: expressed in mm), sulcus depth (SD: expressed in mm) and connective tissue thickness (CT: expressed in mm) were analyzed for both groups. The BIC percentage was significantly higher for the undersized installed implants (P=0.0118). Also, a significant difference existed between the undersized and press‐fit installed implants for the first screw thread showing bone contact (P=0.0145). There were no significant differences in mucosal response (SD and CT) for both installation procedures. Also, no significant difference was found in the BV, as measured using micro‐CT, between the implants placed with an undersized technique (59.3±4.6) compared with the press‐fit implants (56.6±4.3). Conclusion: From the observations of the study, it can be concluded that an undersized implant bed can enhance the implant–bone response. To cite this article:
Al‐Marshood MM, Junker R, Al‐Rasheed A, Al Farraj Aldosari A, Jansen JA, Anil S. Study of the osseointegration of dental implants placed with an adapted surgical technique
Clin. Oral Impl. Res. 22 , 2011; 753–759
doi: 10.1111/j.1600‐0501.2010.02055.x     

The effects of implant surface roughness and surgical technique on implant fixation in an in vitro model

OBJECTIVES: The aim of the present study was to determine the relationship between implant surface parameters, surgical approach and initial implant fixation. MATERIAL AND METHODS: Sixty tapered, conical, screw-shaped implants with machined or etched surface topography were implanted into the explanted femoral condyle of goats. The implant sites were prepared either by a conventional technique, by undersized preparation, or by the osteotome technique. Peak insertion & removal torque, bone-to-implant contacts (BIC) and morphological bone appearance were assessed by scanning electron microscope (SEM) and micro-computer tomography. (micro-CT). RESULTS: Insertion and removal torque values were significantly higher for etched implants inserted with the undersized technique (115.2 +/- 31.1, 102.9 +/- 36.4 N cm) respectively. Also, the average BIC value was higher for the etched implants placed with the undersized technique (87.5 +/- 5.6), which was statistically significant compared with machined and etched implants inserted by conventional technique. CONCLUSION: In conclusion, this study shows that the surgical technique has a decisive effect on implant fixation (represented in this study by installation torque value/removal torque value and histomorphometric evaluation) in trabecular bone. Nevertheless, additional in vivo studies have to be done to prove the importance of surgical protocol for the final implant-bone response.     

Biological limits of the undersized surgical technique: a study in goats

Objective: The purpose of the present study was to investigate the influence of different implant placement techniques on the early bone healing response in an animal model. Material and methods: In the present study, 24 cylindrical‐screw‐type implants with a diameter of 4.2 mm (Dyna^®) were installed, using three different surgical techniques; (1) 5% undersized, using a final drill diameter of 4 mm; (2) 15% undersized, using a final drill diameter of 3.6 mm; and (3) 25% undersized, using a final drill diameter of 3.2 mm. After 3 weeks of implantation period, the peri‐implant bone response was histologically evaluated and the percentage of bone–implant contact (%BIC) calculated. Results: New bone formation was more pronounced for implants placed with the 5% undersized or 15% undersized technique, as compared with implants installed with the 25% undersized technique. Histomorphometrical data corroborates these findings as the %BIC was significantly higher for implants inserted with the 5% undersized (47.7 ± 11.1) or 15% undersized protocol (47.5 ± 9.5) as compared with implants inserted with the 25% undersized technique (32.1 ± 9.7). No significant difference in %BIC could be observed between the 5% undersized and 15% undersized installed implants. Conclusion: Within the limitation of the present study, it was concluded that excessive compression of the host bone, when a discrepancy between implant and final drill diameter more than 15%, can result in an inferior tissue response in the early stage of healing. To compare research results in the future, it is advised to specify the term “undersized” by mentioning the real reduction in diameter. To cite this article:
Tabassum A, Meijer GJ, Walboomers XF, Jansen JA, Biological limits of the undersized surgical technique: a study in goats.
Clin. Oral Impl. Res. 22 , 2011; 129–134.
doi: 10.1111/j.1600‐0501.2010.02016.x     

Influence of surgical technique,implant shape and diameter on the primary stability in cancellous bone

Summary Achievement of primary stability during surgical placement of dental implants is one of the most important factors for successful osseointegration depending on various anatomical, surgical and implant‐related factors. Resonance frequency analysis (RFA) has been shown as a non‐invasive and objective technique for measuring the stability of implants. The aim of this study was to evaluate the effect of some surgical and implant‐related factors in enhancing primary stability and to estimate a correlation between RFA and insertion torque (IT) in proximal regions of cow ribs representing cancellous bone. Fifteen implant beds were prepared in the most proximal region of six fresh cow ribs. Ninety implants with three different shapes and two different diameters were placed with two different surgical techniques, and the primary stability was compared using RFA and IT. Significantly higher RFA and IT values were achieved when under‐dimensioned drilling was used as the surgical method (P < 0·01); significantly higher IT values were obtained with the use of wider implants (P < 0·01) and partially conical Astra Tech implants showed the highest IT values (P < 0·01). When all the implants were considered, significant correlations between the IT and RFA values were noted (%40·6, P < 0·05). Partially conical implants with a wide diameter to be placed with the modified surgical technique proposed appear to be useful in enhancing the primary stability in cancellous bone.     

下颌后牙区骨组织与种植体初期稳定性的相关性研究

目的:研究下颌骨后牙区骨组织结构对种植体初期稳定性的影响。方法:20名患者术前拍摄CT,通过软件SimPlant测量得到种植体周围平均骨密度及种植体颈部骨皮质厚度。共植入24枚种植体,术中植入后即刻用Osstell仪器测量得到种植体稳定系数(ISQ)。所有数据通过SPSS 17软件包进行统计学分析(P<0.05)。结果:种植体颈部骨皮质厚度与ISQ相关(P<0.05),颌骨后牙区骨密度与ISQ无相关关系(P>0.05),性别、年龄与ISQ无相关关系(P>0.05)。结论:术前对下颌骨后牙区骨密度的测量不能预测种植体初期稳定性,种植体初期稳定性与种植体颈部骨皮质厚度相关;与种植体初期稳定性相关的因素还需进一步研究。     

Effects of implant surface roughness and stiffness of grafted bone on an immediately loaded maxillary implant: a 3D numerical analysis

summary   This study investigated the effects of the stiffness of a maxillary sinus graft and the surface roughness of an immediately loaded implant using a non-linear three-dimensional finite element (FE) analysis (3D). Six FE models were created, including two stiffness values of grafted bone (345 and 3450 MPa of elastic modulus) and three conditions of implant–bone interfaces (Frictional coefficient of 0·3 for machined surface, 0·45 for rough implant surface and a bonded implant–bone interface for an osseointegrated implant). Computer tomographic images of a human skull were used to construct a posterior maxillary model. All implants were designed via the computer aided design software with a spiral threaded configuration. Three loading scenarios were investigated for each of the six models; axial loading and lateral loadings at 30° and 60°. The results showed that a 60° lateral loading has scored the highest level of bone stresses among the three loading conditions. Immediately loaded implants with 0·3 frictional coefficient have suffered the highest bone stresses which were higher than those with bonded interface by about 57%. Increasing the frictional coeffecient to 0·45, however, did not show any benefits in reducing the peak bone stress. Raising the stiffness of grafted bone diminished the bone stress by about 10% in both the immediately loaded and the osseointegrated implants. It was also noted that increasing graft stiffness and implant surface roughness reduced the sliding at the implant-bone interface which may improve the implant stability and long-term survival.     

Multivariate study of factors influencing primary dental implant stability

Objectives: The purpose was to determine by multivariate analysis in a large series of dental implants the variables associated with primary endosseous dental implant stability (DIS). Material and methods: A 10‐year retrospective study was conducted of 1084 Brånemark^® implants placed in 316 patients. Clinical variables (age, gender, smoking habit, and periodontal status), implant diameter, implant length, and Periotest^® values (PTVs) were analyzed in bivariate and multivariate studies in order to determine their influence on DIS, using a cut‐off PTV value of ?2. Results: The site of implant insertion showed the strongest association with primary DIS failure among the study variables. Implants in the anterior mandible had a 6.43‐fold lower risk of primary DIS risk vs. those at other sites [95% confidence interval (CI) 3.28–12.61], and implants in the maxillary had a 2.70‐fold higher risk of primary DIS failure vs. those in the mandible (95% CI 1.82–4). Among other variables, females had a 1.54‐fold higher risk of primary DIS failure vs. males (95% CI 1.88–2.22) and implants <15 mm in length had a 1.49‐fold higher risk of failure vs. longer implants (95% CI 1.09–2.04). Conclusion: According to these findings, primary DIS failure is more likely in females, at sites other than the anterior mandible, and with dental implants shorter than 15 mm, at least when non‐threaded titanium implants are used. These data may be of value in the identification of patients at a high risk of primary DIS failure with immediate implant loading.     

Biological and biomechanical evaluation of bone remodelling and implant stability after using an osteotome technique

The influence of the osteotome technique on the osseointegration and biomechanical behaviour of cylinder implants (SLA, ITI was compared with conventional preparation of the implant site in an animal model. A total of 56 implants were placed in the cranial and caudal tibia condyle of six Gottinger minipigs. The implant site was prepared either by the conventional technique with drills (control group A) or by the osteotome technique (experimental group B). Resonance frequency measurements (RFMs) were made on each implant at the time of fixture placement and at the time of scarification. Half of the minipigs were sacrificed 7 days and 28 days after implant placement and the implants were removed with the surrounding bone. Bone tissue responses were evaluated by histological analysis and removal torque testing. For histological evaluation 30-50 microm-thick ground sections were examined. Biomechanical testing revealed a significantly higher stability of implants in the control group (A) than in the experimental group (B) (P = 0.004) at day 7. After 28 days implant stability in the control group remained significant higher (47%) than those of group B (P > 0.001). RFM demonstrated no significant difference between both groups and during the experimental course. Histological analysis demonstrated fractured trabeculae in peri-implant bone in the experimental group at day 7, while they were not posed at day 28. We conclude that the decreased implant stability by using the osteotome technique is based on microfractures in peri-implant bone.     

Combined effect of undersized surgical technique and axial compression on the primary implant stability and host bone architecture

AimThe aim of this study was to investigate the combined effect of the lateral-compression of host-bone (undersized-osteotomy-preparation) and axial-compression of host-bone (not drilling the full length of the implant) on the primary-implant-stability and the host-bone-architecture.Materials and MethodsIn this experimental-study, 44 dental implants (diameter-4.2 mm; length-10 mm; Dyna®) were installed in the femoral-condyles of four cadaver-goats using four different surgical approaches (11 implant/surgical approach; n = 11). Approach-1: Standard preparation according to the manufacturer's guidelines. The bone-cavity was prepared up to 10 mm in depth and 4 mm in diameter. Approach-2: Preparation up to 8 mm in depth and 4 mm in diameter. Approach-3: Preparation up to 10 mm in depth. Approach-4: The bone-cavity was prepared up to 8 mm in depth and 3.6 mm in diameter. Insertion torque (n = 11), removal torque (n = 7) and % bone-implant contact (n = 4) measurements were recorded. Bone architecture was assessed by micro-computer tomography and histological analysis (n = 4).ResultsFor approaches 2, 3, and 4 (P < .05), insertion-torque values were significantly higher as compared to approach 1. Regarding the bone-implant-contact percentage (%BIC), approach 3 and 4 were significantly higher compared to approach 1 and 2 (P<.05). For approach 2, the %bone volume (%BV) was significantly higher as compared to approach 1 (P<.05) for the most the inner zone of host bone in proximity of the implant.ConclusionLateral and axial compression improved the primary-implant-stability and therefore this new surgical-technique should be considered as an alternative approach especially for placing implants in low-density bone. Nevertheless, additional in vivo studies should be performed.     

Relationship between the bone density estimated by cone-beam computed tomography and the primary stability of dental implants

Objectives: The aims of this study were to objectively assess bone quality with density values obtained by cone‐beam computed tomography (CBCT) and to determine the correlations between bone density and primary stability of dental implants. Material and methods: Eighteen Straumann implants were inserted into 18 fresh femoral heads of swine. The bone densities of implant recipient sites were preoperatively determined by the density value using CBCT. The maximum insertion torque value of each implant was recorded using a digital torque meter. Resonance frequency, which represented a quantitative unit called the implant stability quotient (ISQ), was measured using an Osstell^® Mentor immediately after the implant placement. Spearman's correlation coefficient was calculated to evaluate the correlations among density values, insertion torques, and ISQs at implant placement. Results: The density values ranged from 98 to 902. The mean density value, insertion torque, and ISQ were 591±226, 13.4±5.2 Ncm, and 67.1±8.1, respectively. Statistically significant correlations were found between the density values and insertion torque (r_s=0.796, P<0.001), density values and ISQ (r_s=0.529, P=0.024), and insertion torque and ISQ (r_s=0.758, P<0.001). Conclusions: The bone quality evaluated by specific CBCT showed a high correlation with the primary stability of the implants. Hence, preoperative density value estimations by CBCT may allow clinicians to predict implant stability. Whether the density values obtained by the CBCT device used in the present study could be applied to other devices requires further elucidation. To cite this article:
Isoda K, Ayukawa Y, Tsukiyama Y, Sogo M, Matsushita Y, Koyano K. Relationship between the bone density estimated by cone‐beam computed tomography and the primary stability of dental implants.
Clin. Oral Impl. Res. 23 , 2012; 832–836
doi: 10.1111/j.1600‐0501.2011.02203.x     

Microbial analysis of bone collected during implant surgery: a clinical and laboratory study

Dental implant surgery produces bone debris which can be used to correct bone defects in the "simultaneous-augmentation" technique. However, this debris is potentially contaminated with oral bacteria. Therefore, this study examined bone debris collected during dental implant surgery in order 1) to identify the microbial contaminants and 2) to compare the effects of two different aspiration protocols on the levels of microbial contamination. Twenty-four partially dentate patients were randomly allocated into two equal groups and underwent bone collection using the Frios Bone Collector during surgery to insert two endosseous dental implants. In group S (using a stringent aspiration protocol), bone collection occurred within the surgical site only. In group NS (utilizing a non-stringent aspiration protocol), bone collection and tissue fluid control was achieved using the same suction tip. Bone samples were immediately transported for microbial analysis. Colonial and microscopic morphology, gaseous requirements and identification kits were utilized for identification of the isolated microbes. Twenty-eight species were identified including a number associated with disease, in particular, Enterococcus faecalis and Staphylococcus epidermidis as well as the anaerobes Actinomyces odontolyticus, Eubacterium sp., Prevotella intermedia, Propionibacterium propionicum and Peptostreptococcus asaccharolyticus. In group S (stringent aspiration protocol), significantly fewer organisms were found than in group NS, the non-stringent aspiration protocol (P=0.001). Gram-positive cocci dominated the isolates from both groups. It is concluded that if bone debris is collected for implantation around dental implants, it should be collected with a stringent aspiration protocol (within the surgical site only) to minimize bacterial contaminants.     

Relations between the bone density values from computerized tomography, and implant stability parameters: a clinical study of 230 regular platform implants

Aims: The objective of this study was to determine the relationship between bone density, insertion torque, and implant stability at implant placement. Materials and Methods: One‐hundred and eight patients were treated with 230 Brånemark System implants. A computerized tomography (CT) machine was used for pre‐operative evaluation of the jaw bone for each patient. The maximum insertion torque values were recorded with the OsseoCare equipment. Implant stability measurements were performed with the Osstell machine for only 142 implants. Results: The mean bone density and insertion torque values were 721±254 Hounsfield unit (HU) and 39.1±7 N cm for 230 implants, and the correlation was significant (r=0.664, p<0.001). The mean bone density, insertion torque, and resonance frequency analysis values were 751±257 HU, 39.4±7 Nc m, and 70.5±7 implant stability quotient (ISQ), respectively, for 142 implants. Statistically significant correlations were found between bone density and insertion torque values (p<0.001); bone density and ISQ values (p<0.001); and insertion torque and ISQ values (p<0.001). Conclusion: The bone density values from pre‐operative CT examination may provide an objective assessment of bone quality, and significant correlations between bone density and implant stability parameters may help clinicians to predict primary stability before implant insertion.     

Spontaneous progression of ligature induced peri-implantitis at implants with different surface roughness: an experimental study in dogs

BACKGROUND: Peri-implantitis is associated with the presence of submarginal plaque, soft-tissue inflammation and advanced breakdown of the supporting bone. The progression of peri-implantitis following varying periods of continuing plaque accumulation has been studied in animal models. OBJECTIVE: The aim of the current experiment was to study the progression of peri-implantitis around implants with different surface roughness. MATERIAL AND METHODS: In five beagle dogs, three implants with either a sandblasted acid-etched surface (SLA) or a polished surface (P) were installed bilaterally in the edentulous premolar regions. After 3 months on a plaque control regimen, experimental peri-implantitis was induced by ligature placement and plaque accumulation was allowed to progress until about 40% of the height of the supporting bone had been lost. After this 4-month period, ligatures were removed and plaque accumulation was continued for an additional 5 months. Radiographs of all implant sites were obtained before and after 'active' experimental peri-implantitis as well as at the end of the experiment. Biopsies were harvested and the tissue samples were prepared for light microscopy. The sections were used for histometric and morphometric examinations. RESULTS: The radiographic examinations indicated that similar amounts of bone loss occurred at SLA and P sites during the active breakdown period, while the progression of bone loss was larger at SLA than at polished sites following ligature removal. The histological examination revealed that both bone loss and the size of the inflammatory lesion in the connective tissue were larger in SLA than in polished implant sites. The area of plaque was also larger at implants with an SLA surface than at implants with a polished surface. CONCLUSION: It is suggested that the progression of peri-implantitis, if left untreated, is more pronounced at implants with a moderately rough surface than at implants with a polished surface.     

Influence of preimplant surgical intervention and implant placement on bone wound healing

The aims of the present investigation were to study (1). the influence of preimplant (4 weeks) surgical intervention and (2). the influence of the implant placement per se on bone density and mineralized bone-implant contact (BIC) at implant sites in the rabbit jawbone. The experiment was performed in the edentulous area of the maxillas of 16 adult rabbits. In eight rabbits, the alveolar bone on the left side (test) was surgically exposed and a groove was prepared in the bone crest. Trabecular bone and marrow tissue were removed, and a bioabsorbable barrier membrane was placed to cover the groove. The right side underwent no treatment and served as the control. Four weeks later, a screw-shaped titanium implant was placed transversally through the maxilla, penetrating both the test and the control areas. After another 4 weeks of healing, the animals were killed to obtain ground sections for histomorphometry. Untreated jaws from eight rabbits served as reference specimens. In the rabbits subjected to surgery, the areas (mm2) of both mineralized bone and marrow tissue were similar for test and control (4.9 +/- 1.7 vs. 5.1 +/- 2.2 and 6.3 +/- 5.7 vs. 6.8 +/- 5.7 for bone and marrow, respectively). The BIC (%) for all threads was significantly lower on the test side than on the control side (32.1 +/- 27.7 vs. 47.7 +/- 20.3). The bone density (%) of the total experimental area was similar for test and control (48.5 +/- 12.1 vs. 46.5 +/- 9.3), as was the bone density in the area within the implant thread valleys and their mirror areas (43.0 +/- 13.9 vs. 41.3 +/- 13.5, and 40.2 +/- 11.0 vs. 40.3 +/- 7.2 for thread area and mirror area, respectively). The bone density of the total experimental area in the untreated rabbits was 35.9 +/- 5.2%. This value was significantly lower than the values in the total experimental areas (test and control) of the surgically treated rabbits. Similarly, the density of the reference area in the untreated rabbits was 25.4 +/- 5.3%, which was also significantly lower than the bone density of the periimplant area of the surgically treated rabbits. We conclude that the surgical trauma caused by the placement of implants in the maxilla of rabbits significantly enhanced the bone density of the implant sites. Surgical intervention in the implant sites 4 weeks prior to the implant placements, however, did not further enhance bone density or BIC.