Screw-shaped Titanium Implants Research Articles

Molecular Response to Nanopatterned Implants in the Human Jaw Bone.

Implant surface modification by nanopatterning is an interesting route for enhancing osseointegration in humans. Herein, the molecular response to an intentional, controlled nanotopography pattern superimposed on screw-shaped titanium implants is investigated in human bone. When clinical implants are installed, additional two mini-implants, one with a machined surface (M) and one with a machined surface superimposed with a hemispherical nanopattern (MN), are installed in the posterior maxilla. In the second-stage surgery, after 6–8 weeks, the mini-implants are retrieved by unscrewing, and the implant-adherent cells are subjected to gene expression analysis using quantitative polymerase chain reaction (qPCR). Compared to those adherent to the machined (M) implants, the cells adherent to the nanopatterned (MN) implants demonstrate significant upregulation (1.8- to 2-fold) of bone-related genes (RUNX2, ALP, and OC). No significant differences are observed in the expression of the analyzed inflammatory and remodeling genes. Correlation analysis reveals that older patient age is associated with increased expression of proinflammatory cytokines (TNF-α and MCP-1) on the machined implants and decreased expression of pro-osteogenic factor (BMP-2) on the nanopatterned implants. Controlled nanotopography, in the form of hemispherical 60 nm protrusions, promotes gene expressions related to early osteogenic differentiation and osteoblastic activity in implant-adherent cells in the human jaw bone.

Habitual caffeine intake affects implant osseointegration: An in vivo study.

This study aimed to evaluate the effect of habitual caffeine (CAF) intake on stability, bone regeneration, and expression of bone markers at the bone-implant interface. Studies show that habitual CAF alters bone health and remodeling. Yet, there is no information regarding CAF effects on osseointegration of bone-anchored implants. Wistar rats were divided into two groups: one received tap drinking water alone (control) and the other received tap water with CAF (300mg/L). After 12weeks, their tibiae received screw-shaped titanium implants. After another 12weeks, CAF (n=5) and control (n=5) animals were sacrificed and the implant stability was evaluated using a removal torque (RTQ) device. Thereafter, the implants were processed for gene expression analysis, and the implantation sites were harvested for histology. Implants with the surrounding bone were dissected en bloc and subjected to micro-computed tomography (micro-CT). The results showed that implants in the CAF group had an 87% significant increase in RTQ compared to the control. Further, micro-CT revealed a higher proportion of mineralized bone filling the implant threads in the CAF group. The molecular analysis indicated higher expression of bone formation (ALP), remodeling (CatK), and vascularization (VEGF) genes in implant-adherent cells in the CAF group. Histology suggested increased vascularity in the tissue surrounding the implant in the CAF group. Within the limit of this study, it is concluded that habitual CAF intake conveys a positive, promoting effect on long-term osseointegration. Clinical studies are worth pursuing to verify this experimental observation.

Comparative study of bone height changes around immediately loaded porous tantalum parallel sided Trabecular & Screw shaped implants retaining mandibular implant- overdentures using CBCT (RCT)

Objective: This study was conducted to evaluate the crestal bone height changes of immediately loaded Porous trabecular tantalum dental implants (PTTM ) and screw shaped titanium implants in mandibular two implant overdenture with CBCT scan. Subjects & Methods: Fourteen completely edentulous patients were rehabilitated with maxillary complete dentures & immediately loaded mandibular two implant overdentures. Patients were selected according to certain inclusion & exclusion criteria. Conventional maxillary & mandibular complete dentures were constructed for all patients. Patients were then randomly divided into two equal groups according to the implant type. Group (I-Intervention Group): TM implants & Group (II- control Group): Conventional titanium Screw implants were utilized. Implants were installed in the mandibular interforaminal region. Implants were immediately loaded with ball retained overdentures. Radiographic Evaluation of crestal bone height changes around the implants was made with CBCT scan; at the denture insertion visit, 6, 12 , & 24 months after denture insertion. Data were collected, tabulated & statistically analyzed. Results: All patients were satisfied with their implant overdentures, No implant loss were recorded during the follow-up Period. The results of this study had revealed that the crestal bone height gradually decreased throughout the study period in the two studied groups. The mean values of crestal bone loss were (0.497mm± 0.161, 0.362mm ±0.045, 0.120mm.±0.13, 0.9 mm±0.67) and (0.65mm± 0.076 , 0.338mm±0. 047, 0.75 ±0.407, 1.20 ±0.108) in group I & Group II respectively at 0-6 month, 6- 12 month, 12- 18 month and from 0-24 month intervals. On comparing the studied Groups: The crestal bone loss was greater in Group (II) than Group (I) along the whole follow-up intervals. In the 1st & 2nd follow -up intervals; (0-6month & 6-12 Months) bone loss was greater in Group (II) than Group- I with statistically insignificant difference (P-values 0.069 ns &0.400 ns respectively). However, in the 3rd interval (6-12months) & (12-18 months) and( 0-24months), bone loss was significantly higher in Group-II than Group-I; with (P=0.000*). Conclusions: Within the limitation of the current study: Trabecular Tantalum Dental Implants (PTTM) may induce less crestal bone loss than conventional screw-shaped titanium implants in immediately loaded mandibular implant overdentures.

Peri-implant alveolar bone resorption in an innovative peri-implantitis murine model: Effect of implant surface and onset of infection.

To compare the difference in alveolar bone resorption around implants after immediate placement in a bacterial induced experimental periimplantitis murine model. The various conditions that were examined were: Effect of implant surface characteristics and the onset of the induced infection. Screw-shaped titanium implants, smooth-surface or sand-blasted large-grit acid-etched (SLA) coated, were inserted immediately after extraction of the first upper left molar, in 90 5-6-week-old BALB/c mice. The mice were infected with Porphyromonas gingivalis and Fusobacterium nucleatum 21 (early infection) or 42 days (delayed infection) after implantation. Six weeks post infection, bone volume around inserted implants was measured using micro-CT, and was compared to alveolar bone level around teeth. Histological analysis was also performed. The level of bone loss was significantly higher around the implants compared to the teeth, for smooth surface implants the bone loss was higher than of the SLA surface in both control and infected groups with no statistical significance. The survival rate of the implants in immediate infection was 75% compared of the 100% survival of the delayed infection and control mice. There is no significant difference between the early and the delayed infection in alveolar bone loss level around the implants. This model can assist in studying the differences in alveolar bone resorption in different implants and their effect on the development of the disease.

Is there a need for standardization of tightening force used to connect the transducer for resonance frequency analysis in determining implant stability?

The purpose of this in vitro study was to determine the minimum installation torque required to attach the transducer (measuring peg) to the implant to provide an accurate assessment of implant stability using resonance frequency analysis. One hundred 4 ×11-mm screw-shaped titanium implants were inserted into a uniform polyurethane block with similar density to bone in a standardized surgical protocol. The implants were distributed into 10 groups, with 10 implants each (G1 to G10). In G1, the transducer was manually attached by a female operator and in G2 by a male operator using the manual connector provided by the manufacturer. For the remaining groups (G3 to G10), the transducers were installed using a connector adapted to a digital torque wrench with different torque settings: 3 Ncm (G3), 4 Ncm (G4), 5 Ncm (G5), 6 Ncm (G6), 10 Ncm (G7), 13 Ncm (G8), 17 Ncm (G9), and 20 Ncm (G10). Stability was measured for all groups using the Osstell equipment (Diagnosis of Integration) and the implant stability quotient (ISQ) annotated for statistical comparison between the groups. The mean ± standard deviation ISQ values for groups G1 to G10 were 9.50 ± 5.54, 19.05 ± 2.67, 29.25 ± 4.22, 26.55 ± 5.37, 40.90 ± 0.99, 69.60 ± 2.41, 71.30 ± 0.82, 71.20 ± 1.32, 72.40 ± 0.97, and 70.90 ± 0.88, respectively. Statistical comparisons determined that the amplitudes of the confidence intervals, relative to the standard deviations, were lowest for groups G5, G7, G8, G9, and G10. For the means, the lowest amplitudes of the confidence intervals were observed in G6, G7, G8, G9, and G10. When checking the conjugated confidence intervals (mean and standard deviation), the results were homogenous for G7, G8, G9, and G10. When the torque of 20 Ncm was reached, the connection between the transducer and the implant failed. In this in vitro model experiment, transducer torques between 10 and 17 Ncm appear to be adequate for accurate measurement of implant stability, allowing more precise comparisons without damaging the prosthetic connection in the implant.

The influence of controlled surface nanotopography on the early biological events of osseointegration

This study provides a first line of evidence that pre-determined nanopatterns on clinically relevant, screw-shaped, titanium implants can be recognized by cells in the complex in vivo environment. Until now, most of the knowledge relating to cell interactions with nanopatterned surfaces has been acquired from in vitro studies involving mostly two-dimensional nanopatterned surfaces of varying chemical composition. We have managed to superimpose pre-determined nanoscale topography on polished and micro-rough, screw-shaped, implants, without changes in the microscale topography or chemistry. This was achieved by colloidal lithography in combination with a thin titanium film coating on top of both nanopatterned and control implants. The early events of osseointegration were evaluated at the bone interface to these implants. The results revealed that nanotopography, as such, elicits downregulatory effects on the early recruitment and activity of inflammatory cells while enhancing osteogenic activity and woven bone formation.

A Murine Model of Lipopolysaccharide-Induced Peri-Implant Mucositis and Peri-Implantitis.

Dental implants are a widely used treatment option for tooth replacement. However, they are susceptible to inflammatory diseases such as peri-implant mucositis and peri-implantitis, which are highly prevalent and may lead to implant loss. Unfortunately, the understanding of the pathogenesis of peri-implant mucositis and peri-implantitis is fragmented and incomplete. Therefore, the availability of a reproducible animal model to study these inflammatory diseases would facilitate the dissection of their pathogenic mechanisms. The objective of this study is to propose a murine model of experimental peri-implant mucositis and peri-implantitis. Screw-shaped titanium implants were placed in the upper healed edentulous alveolar ridges of C57BL/6J mice 8 weeks after tooth extraction. Following 4 weeks of osseointegration, Porphyromonas gingivalis -lipolysaccharide (LPS) injections were delivered to the peri-implant soft tissues for 6 weeks. No-injections and vehicle injections were utilized as controls. Peri-implant mucositis and peri-implantitis were assessed clinically, radiographically (microcomputerized tomograph [CT]), and histologically following LPS-treatment. LPS-injections resulted in a significant increase in soft tissue edema around the head of the implants as compared to the control groups. Micro-CT analysis revealed significantly greater bone loss in the LPS-treated implants. Histological analysis of the specimens demonstrated that the LPS-group had increased soft tissue vascularity, which harbored a dense mixed inflammatory cell infiltrate, and the bone exhibited noticeable osteoclast activity. The induction of peri-implant mucositis and peri-implantitis in mice via localized delivery of bacterial LPS has been demonstrated. We anticipate that this model will contribute to the development of more effective preventive and therapeutic approaches for these 2 conditions.

Evaluation of bone healing on sandblasted and Acid etched implants coated with nanocrystalline hydroxyapatite: an in vivo study in rabbit femur.

This study aimed at investigating if a coating of hydroxyapatite nanocrystals would enhance bone healing over time in trabecular bone. Sandblasted and acid etched titanium implants with and without a submicron thick coat of hydroxyapatite nanocrystals (nano-HA) were implanted in rabbit femur with healing times of 2, 4, and 9 weeks. Removal torque analyses and histological evaluations were performed. The torque analysis did not show any significant differences between the implants at any healing time. The control implant showed a tendency of more newly formed bone after 4 weeks of healing and significantly higher bone area values after 9 weeks of healing. According to the results from this present study, both control and nano-HA surfaces were biocompatible and osteoconductive. A submicron thick coating of hydroxyapatite nanocrystals deposited onto blasted and acid etched screw shaped titanium implants did not enhance bone healing, as compared to blasted and etched control implants when placed in trabecular bone.

Serum bone formation marker correlation with improved osseointegration in osteoporotic rats treated with simvastatin

Simvastatin has been shown to enhance osseointegration of pure titanium implants in osteoporotic rats. This study aimed to evaluate the relationship between the serum level of bone formation markers and the osseointegration of pure titanium implants in osteoporotic rats treated with simvastatin. Fifty-four female Sprague-Dawley rats, aged 3months, were randomly divided into three groups: Sham-operated group (SHAM; n=18), ovariectomized group (OVX; n=18), and ovariectomized with simvastatin treatment group (OVX+SIM; n=18). Fifty-six days after ovariectomy, screw-shaped titanium implants were inserted into the tibiae. Simvastatin was administered orally at 5mg/kg each day after the placement of the implant in the OVX+SIM group. The animals were killed at either 28 or 84days after implantation and the undecalcified tissue sections were processed for histological analysis. Total alkaline phosphatase (ALP), bone-specific alkaline phosphatase (BALP) and bone Gla protein (BGP) were measured in all animal sera collected at the time of euthanasia and correlated with the histological assessment of osseointegration. The level of ALP in the OVX group was higher than the SHAM group at day 28, with no differences between the three groups at day 84. The level of BALP in the OVX+SIM group was significantly higher than both OVX and SHAM groups at days 28. Compared with day 28, the BALP level of all three groups showed a significant decrease at day 84. There were no significant differences in BGP levels between the three groups at day 28, but at day 84, the OVX+ SIM group showed significantly higher levels than both the OVX and SHAM groups. There was a significant increase in BGP levels between days 28 and 84 in the OVX+SIM group. The serum bone marker levels correlated with the histological assessment showing reduced osseointegration in the OVX compared to the SHAM group which is subsequently reversed in the OVX+SIM group. The results from this study indicate that the serum level of bone formation markers, especially BALP and BGP, could be correlated with the degree of osseointegration around titanium implants in osteoporotic rats treated with simvastatin.

Electrochemical growth behavior, surface properties, and enhanced in vivo bone response of TiO2 nanotubes on microstructured surfaces of blasted, screw-shaped titanium implants

TiO(2) nanotubes are fabricated on TiO(2) grit-blasted, screw-shaped rough titanium (ASTM grade 4) implants (3.75 x 7 mm) using potentiostatic anodization at 20 V in 1 M H(3)PO(4) + 0.4 wt.% HF. The growth behavior and surface properties of the nanotubes are investigated as a function of the reaction time. The results show that vertically aligned nanotubes of approximately 700 nm in length, with highly ordered structures of approximately 40 nm spacing and approximately 15 nm wall thickness may be grown independent of reaction time. The geometrical properties of nanotubes increase with reaction time (mean pore size, pore size distribution [PSD], and porosity approximately 90 nm, approximately 40-127 nm and 45%, respectively for 30 minutes; approximately 107 nm, approximately 63-140 nm and 56% for one hour; approximately 108 nm, approximately 58-150 nm and 60% for three hours). It is found that the fluorinated chemistry of the nanotubes of F-TiO(2), TiOF(2), and F-Ti-O with F ion incorporation of approximately 5 at.%, and their amorphous structure is the same regardless of the reaction time, while the average roughness (Sa) gradually decreases and the developed surface area (Sdr) slightly increases with reaction time. The results of studies on animals show that, despite their low roughness values, after six weeks the fluorinated TiO(2) nanotube implants in rabbit femurs demonstrate significantly increased osseointegration strengths (41 vs 29 Ncm; P = 0.008) and new bone formation (57.5% vs 65.5%; P = 0.008) (n = 8), and reveal more frequently direct bone/cell contact at the bone-implant interface by high-resolution scanning electron microscope observations as compared with the blasted, moderately rough implants that have hitherto been widely used for clinically favorable performance. The results of the animal studies constitute significant evidence that the presence of the nanotubes and the resulting fluorinated surface chemistry determine the nature of the bone responses to the implants. The present in vivo results point to potential applications of the TiO(2) nanotubes in the field of bone implants and bone tissue engineering.

Generation of microdamage around endosseous implants

The aim of this study was to investigate the occurrence of microdamage as a result of osteotomy preparation and/or insertion of endosseous screw-shaped titanium implants into the dog mandible. The mandibular premolar regions of four young adult male Beagle dogs were used for the study. Four implant sites were prepared in the edentulous area of each mandible on each side and the sites were divided into four experimental groups. Group I included sites that contained an osteotomy preparation only. Group II included sites that contained an osteotomy preparation and were tapped but did not receive any implant. Group III included sites that contained an osteotomy preparation and were not tapped but received an implant. Group IV included sites that contained an osteotomy preparation and were tapped before implant placement. Control sites (Group V) were randomly selected from different mandibular sites. Ground sections were prepared from biopsies taken at 2 days and were examined using epifluorescence microscopy. Total number and length of microcracks for each side were compared (left vs. right) using descriptive statistical methods. The control group (V) had fewer microcracks compared with the modalities I-IV. There were no differences in microcrack lengths between the jaw sides, treatment modalities, jaw regions and between the treatment modalities and controls. The results of this study suggest that most of the microcracks were generated by the osteotomy preparation and the other modalities did not appear to have any major additional effects.

Resonance frequency measurements in vivo and related surface properties of magnesium‐incorporated, micropatterned and magnesium‐incorporated TiUnite®, Osseotite®, SLA® and TiOblast® implants

To investigate implant stability using resonance frequency measurements of topographically changed and/or surface chemistry-modified implants in rabbit bone. Six groups of microstructured, screw-shaped titanium implants: two oxidized, cation-incorporated experimental implants [Mg implants and MgMp implants with micropatterned thread flanges (80-150 microm wide and 60-70 microm deep)] and four commercially available clinical implants (TiUnite((R)), Osseotite((R)), SLA((R)), and TiOblast((R))) were installed in 10 rabbit tibia for 6 weeks. The surface properties of the implants were characterized in detail using several analytical techniques. Implant stability was measured using a resonance frequency analyzer (Osstell(TM)). Surface characterization of the implants revealed microstructured, moderately rough implant surfaces varying 0.7-1.4 mum in S(a) (mean height deviation), but with clear differences in surface chemistry. After 6 weeks, all implants showed statistically significantly higher increases in implant stability. When compared with one another, MgMp implants showed the most significant mean implant stability quotient (ISQ) value relative to the others (P<or=0.016). In terms of increment (DeltaISQ) in implant stability, MgMp implants showed a significantly greater value as compared with Osseotite((R)) (P<or=0.005), TiOblast((R)) (P<or=0.005), TiUnite((R)) (P<or=0.005), SLA((R)) (P<or=0.007), and Mg implants (P<or=0.012). In addition, transducer direction dependence of resonance frequency analysis (RFA) measurements was observed such that the differences in the mean ISQ values between longitudinal and perpendicular measurements were significant at implant placement (P<or=0.004) and after 6 weeks (P<or=0). The present study found that implant surface properties influence RFA measurements of implant stability. Surface chemistry-modified titanium implants showed higher mean ISQ values than did topographically changed implants. In particular, cation (magnesium)-incorporated micropatterns in MgMp implants may play a primary role in DeltaISQ.

Clinical outcomes of GBR procedures to correct peri‐implant dehiscences and fenestrations: a systematic review

To analyze the clinical outcomes of endosseous implants following guided bone regeneration (GBR) procedures to correct dehiscence/fenestration defects associated with implant placement. METHODS/SEARCH STRATEGY: A Medline search was performed for human studies published in English focusing on GBR procedures for the correction of dehiscence/fenestration defects associated with the placement of screw-shaped titanium implants. The selected studies had to include at least 10 consecutively treated patients with a minimum follow-up of 12 months after the start of prosthetic loading. The clinical outcomes in terms of the complication rate of the GBR procedure, implant survival, and stability of marginal soft tissues around implants were evaluated. Seven publications were included in this review. A total of 238 patients received 374 implants. Defects were treated with resorbable or non-resorbable membranes, in association with or without graft materials. Patients were followed for 1-10 years after the start of prosthetic loading. In the postoperative period, 20% of the non-resorbable membranes and 5% of the resorbable ones underwent exposure/infection. However, in the majority of cases, a complete or an almost complete coverage of the initial defect was obtained. The overall survival rate of implants, irrespective of the type of membrane and grafting materials, was 95.7% (range: 84.7-100%). No significant modifications of probing depth and/or variation of clinical attachment level around implants were observed during the follow-up period. Despite the favorable results obtained, it was difficult to draw a significant conclusion as far as the more reliable grafting material and membrane barrier for the correction of dehiscence/fenestration defects are concerned, due to the limited sample of patients and the wide variety of grafting materials and membranes, used alone or in combination. Moreover, due to the lack of randomized clinical trials, it was impossible to demonstrate that such augmentation procedures are actually needed to allow the long-term survival of implants.

Effects of Simvastatin on bone healing around titanium implants in osteoporotic rats

Osteoporosis is known to impair the process of implant osseointegration. The recent discovery that statins (HMG-CoA reductase inhibitors) act as bone anabolic agents suggests that statins can be used as potential agents in the treatment of osteoporosis. Therefore, we hypothesized that statins will promote osteogenesis around titanium implants in subjects with osteoporosis. Fifty-four female Sprague Dawley rats, aged 3 months old, were randomly divided into three groups: Sham-operated group (SHAM; n=18), ovariectomized group (OVX; n=18), and ovariectomized with Simvastatin treatment group (OVX+SIM; n=18). Fifty-six days after being ovariectomized (OVX), screw-shaped titanium implants were inserted into the tibiae. Simvastatin was administered orally at 5 mg/kg each day after the placement of the implant in the OVX+SIM group. The animals were sacrificed at either 28 or 84 days after implantation and the undecalcified tissue sections were obtained. Bone-to-implant contact (BIC) and bone area (BA) within the limits of implant threads were measured around the cortical (zone A) and cancellous (zone B) bone regions. Furthermore, bone density (BD) of zone B in a 500 microm wide zone lateral to the implants was also measured. There were no significant differences in BIC and BA measurements in zone A in any of the three groups at either 28 or 84 days after implantation (P>0.05). By contrast, in zone B, significant differences in the measurement of BIC, BA, and BD were observed at 28 and 84 days between all three groups. Bone healing decreased with lower BIC, BA, and BD around implant in OVX group compared with other two groups, and Simvastatin reversed the negative effect of OVX on bone healing around implants with the improvement of BIC, BA, and BD in zone B. Osteoporosis can significantly influence bone healing in the cancellous bone around titanium implants and Simvastatin was shown to significantly improve the osseointegration of pure titanium implants in osteoporotic rats.

In vivo evaluation of the trabecular bone behavior to porous electrostatic spray deposition‐derived calcium phosphate coatings

Electrostatic spray deposition (ESD) is a new technique to deposit calcium phosphate (CaP) coatings. The aim of the present study was to evaluate the bone behavior of ESD CaP-coated implants with various degrees of crystallinities in the trabecular bone of the femoral condyle of goats. Using the ESD technique, thin porous CaP coatings were deposited on tapered, conical, screw-shaped titanium implants. Three different heat-treatments were applied, resulting in amorphous CaP (400 degrees C, ESD1), crystalline carbonate apatite (500 degrees C, ESD2), and crystalline carbonated hydroxyapatite (700 degrees C, ESD3). Implants were inserted into the trabecular bone of the femoral condyles of goats for 12 weeks, and titanium (Ti) implants served as controls. The results showed that ESD-derived coatings are osteocompatible. Histomorphometrical analysis showed that the application of a CaP coating resulted in more bone contact along the press-fit area of the implant compared with the Ti implants. Moreover, the percentage bone contact of the ESD3-coated implants was increased, compared with the Ti control group. Regarding the other coatings, no differences were found compared with the control group. Crystalline carbonated hydroxyapatite ESD-coated implants positively influenced the biological performance compared with Ti control implants.

Literature Reviews

Literature Reviews

Oxidized, bioactive implants are rapidly and strongly integrated in bone. Part 1 – experimental implants

The study presented was designed to investigate the speed and the strength of osseointegration of oxidized implants at early healing times in comparison which machined, turned implants. Screw-shaped titanium implants were prepared and divided into two groups: magnesium ion incorporated, oxidized implants (Mg implants, n=10) and machined, turned implants (controls, n=10). Mg implants were prepared using micro-arc oxidation methods. Surface oxide properties of implants such as surface chemistry, oxide thickness, morphology/pore characteristics, crystal structures and roughness were characterized with various surface analytic techniques. Implants were inserted into the tibiae of ten New Zealand white rabbits. After a follow-up period of 3 and 6 weeks, removal torque (RTQ), osseointegration speed (DeltaRTQ/Deltahealing time) and integration strength of implants were measured. Bonding failure analysis of the bone-to-implant interface was performed. The speed the and strength of osseointegration of Mg implants were significantly more rapid and stronger than for turned implants at follow-up periods of 3 and 6 weeks. Bonding failure for Mg implants dominantly occurred within the bone tissue, whereas bonding failure for turned implants mainly occurred at the interface between implant and bone. Oxidized, bioactive implants are rapidly and strongly integrated in bone. The present results indicate that the rapid and strong integration of oxidized, bioactive Mg implants to bone may encompass immediate/early loading of clinical implants.

Effect of Cigarette Smoke Inhalation and Estrogen Deficiency on Bone Healing Around Titanium Implants: A Histometric Study in Rats

It has been shown that cigarette smoke inhalation (CSI) and estrogen deficiency (OVX) may affect bone quality around titanium implants; however, their association has not been evaluated. Therefore, this study aimed to verify the effects of CSI associated with OVX on bone healing around titanium implants. The tibia surface of 45 female Wistar rats was surgically exposed, and screw-shaped titanium implants were placed. The animals were randomly assigned to OVX (ovariectomized rats; n = 15), SHAM (sham-operated rats; n = 15), and CSI + OVX (4 months of intermittent cigarette smoke inhalation, starting 2 months before implant placement in ovariectomized rats; n = 15). The implants were placed at the time of OVX or SHAM surgery. After 60 days, the animals were sacrificed and undecalcified sections obtained. The percentages of mineralized tissue (bone density [BD]) in a 500-microm-wide zone lateral to the implant, bone filling (BF) within the limits of the threads, and bone-to-implant contact (BIC) were measured in cortical (zone A) and cancellous (zone B) bone. In zone A, the CSI + OVX group showed a significant difference regarding BIC and BD (P <0.05) compared to the other groups. In zone B, data analysis showed that the CSI + OVX group presented the lowest percentage of BD and BIC, followed by the OVX and SHAM groups, respectively (P <0.05). Within the limits of the present study, it can be concluded that cigarette smoke inhalation amplified the deleterious effects of estrogen deficiency, affecting both preexisting and newly formed bone in the cortical and cancellous bone around titanium implants.

Age‐Related and Surgically Induced Estrogen Deficiencies May Differently Affect Bone Around Titanium Implants in Rats

Valuable information has been obtained using the ovariectomy model; however, clinical studies have indicated that such a model may not be appropriate to parallel with the postmenopausal condition and titanium implants. Thus, this study aimed to comparatively evaluate, by histometric analysis, the influence of age-related (ARED) and surgically induced (OVX) estrogen deficiencies on bone around titanium implants inserted in rats. Single screw-shaped titanium implants were placed in rat tibiae and animals were then assigned to one of the following groups: SHAM (N = 15): bilateral sham ovariectomies in 90-day-old rats, 21 days before implant placement; OVX (N = 15): bilateral ovariectomies in 90-day-old rats, 21 days before implant placement; and ARED (N = 15): implant placement in reproductive aged rats (22 months old). After 60 days, the animals were sacrificed and undecalcified sections obtained. Bone-to-implant contact (BIC) and bone area (BA) within the limits of implant threads and bone density (BD) in a 500 microm-wide zone lateral to the implant were obtained and arranged for cortical (zone A) and cancellous (zone B) bone regions. For zone A, intergroup analysis showed no significant differences regarding BIC and BA (P >0.05). In contrast, ARED negatively influenced BD around the implants (P <0.05). In zone B, OVX negatively affected BIC and BA (P <0.05), and both ARED and OVX groups demonstrated lower BD than the SHAM group (P <0.05). Within the limits of this study, it can be concluded that ARED mainly affects preexisting bone while OVX more significantly affects both newly formed and preexisting bone.

Peri-implant soft tissue integration of immediately loaded implants in the posterior macaque mandible: a histomorphometric study.

Today, one critical goal in implant placement is the achievement of optimal soft tissue integration. Reports thus far have demonstrated successful soft tissue preservation in delayed loaded implants placed in anterior jaws. The aim of this study was to histomorphometrically examine the soft tissues around immediately loaded implants placed in the macaque posterior mandible. Splinted crowns on screw-shaped titanium implants (8 mm length, 3.5 mm diameter) were utilized. Three implants each were placed in the premolar-molar edentulous mandibular segments of 6 adult monkeys (Macaca fascicularis); one side served as the control (delayed loading) and the other as the test sites (immediate loading). The animals were sacrificed after 3 months of loading. Histomorphometry of 6 soft tissue indices including the sulcus depth (SD), junctional epithelium (JE), connective tissue contact (CTC), biologic width (BW = SD + JE + CTC), DIM (distance between the implant top and coronal gingiva), and DIB (distance between the implant top and first implant-to-bone contact) was performed on non-decalcified sections. No significant differences in the mean soft tissue scores (mm) between the test (SD = 0.68 +/- 0.63; JE = 1.71 +/- 1.04; CTC = 1.51 +/- 1.14; DIM = 2.27 +/- 1.18; DIB = 1.32 +/- 1.21; BW = 3.9) and control (SD = 0.88 + 0.57; JE = 1.66 + 0.77; CTC = 1.24 +/- 0.92; DIM = 2.38 +/- 0.81; DIB = 1.19 +/- 0.91; BW = 3.78) groups were observed (P > 0.01). These findings suggest that the dimensions of the peri-implant soft tissues were within the biologic range and were not influenced by immediate functional loading or posterior location of the implants in the macaque mandible.