Impact of systemic diseases and medication on osseointegration

Comprehensive Overview of Interface Strategies in Implant Osseointegration

With the improvement of implant design and the expansion of application scenarios, orthopedic implants have become a common surgical option for treating fractures and end‐stage osteoarthritis. Their common goal is rapidly forming and long‐term stable osseointegration. However, this fixation effect is limited by implant surface characteristics and peri‐implant bone tissue activity. Therefore, this review summarizes the strategies of interface engineering (osteogenic peptides, growth factors, and metal ions) and treatment methods (porous nanotubes, hydrogel embedding, and other load‐release systems) through research on its biological mechanism, paving the way to achieve the adaptation of both and coordination between different strategies. With the transition of the osseointegration stage, interface engineering strategies have demonstrated varying therapeutic effects. Especially, the activity of osteoblasts runs almost through the entire process of osseointegration, and their physiological activities play a dominant role in bone formation. Furthermore, diseases impacting bone metabolism exacerbate the difficulty of achieving osseointegration. This review aims to assist future research on osseointegration engineering strategies to improve implant‐bone fixation, promote fracture healing, and enhance post‐implantation recovery.

Dental implants in patients suffering from autoimmune diseases: A systematic critical review

PURPOSE

This systematic review aimed to evaluate complications and survival rates of dental implants placed in patients suffering from autoimmune diseases.

MATERIALS AND METHODS

A systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic review guidelines (PRISMA), using Google scholar and PubMed electronic databases with a stop date of September 2021. The eligibility criteria included all full text human studies in the English language literature reporting on patients with autoimmune diseases treated with dental implants.

RESULTS

Fifty-five studies reporting on nine distinct autoimmune diseases were analyzed: 17 on Sjögren's syndrome (SS), 11 on oral lichen planus (OLP), 8 on Type 1 diabetes, 6 on rheumatoid arthritis (RA), 4 on systemic scleroderma (SSc), 3 on Crohn's disease (CD), 3 on systemic lupus erythematosus (SLE), 2 on mucous membrane pemphigoid (MMB) and 1 on pemphigus vulgaris (PV). Despite the heterogeneity and methodological limitations of most of the studies, results showed that dental implant survival rates were comparable to those reported in the general population. However, patients with secondary SS or erosive OLP were more susceptible to developing peri-mucositis and increased marginal bone loss.

CONCLUSION

This review suggested that dental implants may be considered as a safe and viable therapeutic option in the management of edentulous patients suffering from autoimmune diseases. Nevertheless, scrupulous maintenance of oral hygiene and long-term follow-up emerge as being the common determinants for uneventful dental implant treatment.

The Effect of Controlled Diabetes and Hyperglycemia on Implant Placement with Simultaneous Horizontal Guided Bone Regeneration: A Clinical Retrospective Analysis

Diabetes represents a challenge in implant therapy because hyperglycemia may negatively affect bone regeneration, directly compromising clinical outcomes and increasing clinical failures. The aim of this retrospective study is to analyse the prognostic significance of HbA1c levels in patients undergoing implant placement associated with horizontal guided bone regeneration. Thirty-four patients were divided into 3 groups according to their HbA1c levels: nondiabetic normoglycemic patients (HbA1c < 5.7%), nondiabetic hyperglycemic patients (HbA1c < 6.5%), and controlled diabetic patients (HbA1c < 7%). Primary outcomes were dimensional changes in height (VDH) and width (DW) of the peri-implant defect. Secondary outcomes were evaluations of periodontal parameters of adjacent tooth sites, wound healing, marginal bone loss (MBL), and survival and success rates. At T₁ (6 months), mean VDH values in groups 1, 2, and 3 were, respectively, 0.07, 0.5, and 0.25 mm. Mean DW values in those same groups were, respectively, 0.07, 0.38, and 0.33 mm. HbA1c levels were not statistically related to VDH and DW values at T₁. No statistically significant differences were observed in MBL between groups (p = 0.230). Implant survival and success rates were, respectively, 98% and 96%. Simultaneous guided bone regeneration is a feasible procedure for the treatment of horizontal bone deficiencies in controlled diabetic patients.

Potential risk factors for early and late dental implant failure: a retrospective clinical study on 9080 implants

Background

The aim of this study was to analyze potential risk factors for early and late dental implant failure (DIF) in a clinical cohort trial.

In a private practice, 9080 implants were inserted during a period of 10 years. In case of DIF, data were classified into early and late DIF and compared to each other in regard of gender, age, site of implantation, implant geometry, and patients’ systemic diseases.

Results

Three hundred fifty-one implants failed within the observation period (survival rate: 96.13%). Early DIF occurred in 293 implants (83.48%) compared to late DIF in 58 implants (16.52%). Significant earlier DIF was seen in the mandible (OR = 3.729, p < 0.001)—especially in the posterior area—and in younger patients (p = 0.017), whereas an increased likelihood of late DIF was associated with maxillary implants (OR = 3.729, p < 0.001) and older patients.

Conclusions

Early DIF is about twice as common as late DIF. Main risk factors for early DIF are implant location in the (posterior) mandible as well as younger age. On contrary, late DIF is rather associated with older patients, cancellous bone quality, and longer implants.

Increasing the Stability of Dental Implants: the Concept of Osseodensification

One of the most important factors that affect osseointegration is the primary stability of the implant. Dental implants inserted at the posterior region of the maxilla exhibit the lowest success rates as the low density bone in this area often jeopardize rigid fixation of the implant. Many surgical techniques have been developed to increase the primary stability of an implant placed in low density bone, such as bicortical fixation of the implant, undersized preparation of the implant bed and bone condensation by the use of osteotomes. A new promising technique, named osseodensification, has been recently developed that creates an autograft layer of condensed bone at the periphery of the implant bed by the aid of specially designed burs rotating in a clockwise and anti-clockwise direction. The purpose of this review is to emphasize that implant primary stability is strongly influenced by the surgical technique, to quote and briefly analyse the various surgical procedures laying weight to osseodensification procedure.

The relationship between dental implant stability and trabecular bone structure using cone-beam computed tomography

Purpose

The objective of this study was to investigate the relationships between primary implant stability as measured by impact response frequency and the structural parameters of trabecular bone using cone-beam computed tomography(CBCT), excluding the effect of cortical bone thickness.

Methods

We measured the impact response of a dental implant placed into swine bone specimens composed of only trabecular bone without the cortical bone layer using an inductive sensor. The peak frequency of the impact response spectrum was determined as an implant stability criterion (SPF). The 3D microstructural parameters were calculated from CT images of the bone specimens obtained using both micro-CT and CBCT.

Results

SPF had significant positive correlations with trabecular bone structural parameters (BV/TV, BV, BS, BSD, Tb.Th, Tb.N, FD, and BS/BV) (P<0.01) while SPF demonstrated significant negative correlations with other microstructural parameters (Tb.Sp, Tb.Pf, and SMI) using micro-CT and CBCT (P<0.01).

Conclusions

There was an increase in implant stability prediction by combining BV/TV and SMI in the stepwise forward regression analysis. Bone with high volume density and low surface density shows high implant stability. Well-connected thick bone with small marrow spaces also shows high implant stability. The combination of bone density and architectural parameters measured using CBCT can predict the implant stability more accurately than the density alone in clinical diagnoses.

The dynamic interface: A review

The implant-to-tissue interface is an extremely dynamic region of interaction. Generally, a surgical procedure is performed on a patient to insert a foreign material into the bone, and the body is called on to “heal” the wound. The time schedule crucial for a healing process that is expected to result in restitution ad integrum must be determined with respect to the condition of the individual patient and tissue to be treated. There are various factors responsible for the formation of an adequate bone–implant interface. A comprehensive review of the response of bone to implant is described.

Mandibular bone mineral density in patients with Behçet's disease

OBJECTIVES

Behçet's disease (BD) is a chronic, recurring vasculitis of unknown etiology. Patients with BD may use a lot of medications associated with the clinical symptoms. Drugs that are used in the treatment of BD may cause bone loss. The aims of the current study were to compare the bone mineral density (BMD) values between BD and healthy volunteers and describe the effect of disease duration on mandibular BMD.

MATERIALS AND METHODS

The study comprised 30 healthy volunteers (15 males and 15 females, mean age 35.50±6.80 years) and 45 patients with BD (24 males and 21 females, mean age 38.93±8.93 years). The BD group was subdivided according to disease duration (0-5, 6-10, and >10 years). The BMD value of the mandibular body was determined by the dual energy X-ray absorptiometry technique.

RESULTS

The mean mandibular body BMD values were 1.294±0.21 g/cm(2) in the control group and 1.216±0.22 g/cm(2) in the BD patients, although there was no statistically significant difference. The BMD was observed to decrease with increased disease duration but not to a statistically significant degree.

CONCLUSION

The results of this study showed that although the BMD value decreased as the duration of the disease increased, no statistically significant difference was found between the BD patients and the healthy control group.

Diabetes and oral implant failure: a systematic review

The aim of this systematic review and meta-analysis was to investigate whether there are any effects of diabetes mellitus on implant failure rates, postoperative infections, and marginal bone loss. An electronic search without time or language restrictions was undertaken in March 2014. The present review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Eligibility criteria included clinical human studies. The search strategy resulted in 14 publications. The I (2) statistic was used to express the percentage of total variation across studies due to heterogeneity. The inverse variance method was used for the random effects model when heterogeneity was detected or for the fixed effects model when heterogeneity was not detected. The estimates of an intervention for dichotomous outcomes were expressed in risk ratio and in mean difference in millimeters for continuous outcomes, both with a 95% confidence interval. There was a statistically significant difference (p = .001; mean difference = 0.20, 95% confidence interval = 0.08, 0.31) between diabetic and non-diabetic patients concerning marginal bone loss, favoring non-diabetic patients. A meta-analysis was not possible for postoperative infections. The difference between the patients (diabetic vs. non-diabetic) did not significantly affect implant failure rates (p = .65), with a risk ratio of 1.07 (95% confidence interval = 0.80, 1.44). Studies are lacking that include both patient types, with larger sample sizes, and that report the outcome data separately for each group. The results of the present meta-analysis should be interpreted with caution because of the presence of uncontrolled confounding factors in the included studies.

Peptide linkers for the immobilization of bioactive molecules on biphasic calcium phosphate via a modular immobilization system

Herein we describe the use of peptide linkers to establish a nucleic acid-based immobilization system based on biphasic calcium phosphates (BCP), with which different molecules can be immobilized at the same time in defined ratios. It consists of single-stranded oligonucleotides, anchor strands (AS) which are immobilized to the surface and conjugates of complementary strands (CS) and bioactive molecules that bind to the AS via Watson-Crick base pairing. AS immobilization can be achieved on calcium phosphate ceramics using conjugates of AS and peptides that bind specifically to the ceramic. We successfully immobilized three different peptide sequences on BCP. Among them, we identified Stath (DpSpS EEK FLR RIG RFG, phosphoserine) as the most suitable one and further immobilized Stath-AS conjugates on BCP. This immobilized AS was able to hybridize with CS. Unspecific adsorption of oligonucleotides on the BCP surface was negligible. The stability of the system was proven by short term desorption experiments. The amounts of immobilized peptides, oligonucleotides and peptide-AS conjugates were determined by an enzymatic assay using biotin-streptavidin interactions, and were found to reach surface densities that are of therapeutic relevance (0.03 pmol cm(-2)).

Comparison of mandibular bone mineral densities in dentate and edentulous patients

PURPOSE

In contemporary implant dentistry, bone mineral density (BMD) of the jaws is a patient-associated prognostic factor. The aim of this study was to compare the mandibular body BMD of dentate and edentulous patients using the dual-energy X-ray absorptiometry (DXA) technique.

MATERIALS AND METHODS

A total of 39 patients, 20 dentate and 19 edentulous, were included in this cross-sectional study. Mandibular body BMD was measured using the DXA technique. The variables were normally distributed; thus, the independent samples t-test was used for the determination of statistical significance between the dentate and edentulous groups (age, body mass index [BMI], DXA). Chi-square test was performed for identification of the gender differences between the groups. The Pearson correlation analysis was used to analyze the relationship between age, BMI, and mandibular body BMD. Note that p < 0.01 was accepted as the significance level.

RESULTS

There was no statistically significant difference between the dentate and edentulous groups in matching variables (age, BMI, and gender) (p > 0.01). There was a statistically significant difference regarding the mandibular body BMD in the dentate and edentulous group (p < 0.01) controlling for age, gender, and BMI. The edentulous group patients had higher mandibular body BMD values (1.27 ± 0.31 g/cm(2)) than those in the dentate group (0.94 ± 0.22 g/cm(2)).

CONCLUSION

Comparison of the mandibular body BMD revealed that dentate patients had less dense bone than the edentulous patients. Further investigations are needed to determine the BMD of the jaws in different regions and for different systemic conditions.

Evaluation of mandibular bone mineral density using the dual-energy X-ray absorptiometry technique in edentulous subjects living in an endemic fluorosis region

OBJECTIVES

Fluoride is one of the biological trace elements with a strong affinity for osseous, cartilaginous and dental tissue. The dental and skeletal effects of high fluoride intake have already been studied in the literature, but little is known about the effects of high fluoride intake on edentulous mandibles. The purpose of this study was to evaluate the effects of high fluoride intake on mandibular bone mineral density (BMD) measured by the dual-energy X-ray absorptiometry (DXA) technique in edentulous individuals with systemic fluorosis.

METHODS

32 people who were living in an endemic fluorosis area since birth and 31 people who were living in a non-endemic fluorosis area since birth (control group) participated in this study. Systemic fluorosis was diagnosed in the patients using the sialic acid (NANA)/glycosaminoglycan (GAG) ratio. The BMDs of the mandibles were determined by the DXA technique.

RESULTS

The serum NANA/GAG ratios in the fluorosis group were significantly lower than those in the control group (p < 0.001). There was also a statistically significant difference in mandibular BMD measurements (p < 0.05) between the systemic fluorosis and control groups, as measured by the DXA technique. Mandibular body BMD measurements were higher in the fluorosis group (1.25 ± 0.24 g cm(-2)) than in the control group (1.01 ± 0.31 g cm(-2)).

CONCLUSIONS

The results of the study showed that fluoride intake higher than the optimum level causes increased mandibular BMD in edentulous individuals. Further dose-related studies are needed to determine the effects of high fluoride intake on bony structures of the stomatognathic system.

The effect of oestrogen and alendronate therapies on postmenopausal bone loss around osseointegrated titanium implants

OBJECTIVES

This study evaluated the influence of oestrogen deficiency and its therapies on bone tissue around osseointegrated implants.

METHODS

Implants were placed in 66 female rats tibiae. The animals were assigned into five groups: control (CTL), sham, ovariectomy (OVX), oestrogen (EST), and alendronate (ALE). While CTL was sacrificed 60 days after implant placement, other groups were subjected to ovariectomy or sham surgery according to group and euthanized after 90 days. Blood and urine samples were collected at sacrifice day for osteocalcin (OCN) and deoxypyridinoline (DPD) quantification. Densitometry of femur and lumbar vertebrae was performed in order to evaluate rats' skeletal impairment. Non-decalcified sections were referred to fluorescent and light microscopy for analyses of mineral apposition rate (MAR), eroded and osteoclastic surfaces, bone-to-implant contact (BIC), and bone area fraction occupancy (BAFO).

RESULTS

Results from the OVX group showed significantly lower bone mineral density (BMD), BIC, BAFO, and MAR, while OCN, deoxipiridinoline, eroded surface and ostecoclastic surface were increased compared with the other groups of the study. ALE reduced OCN and DPD concentrations, MAR, osteoclastic and eroded surfaces, and no difference was in BIC and BAFO relative to SHAM. EST and CTL showed similar results to SHAM for measurements.

CONCLUSIONS

Oestrogen deficiency exerted a negative influence on bone tissue around implants, while oestrogen replacement therapy and alendronate were effective against its effects. Although alendronate therapy maintained the quantity of bone around implants, studies evaluating bone turnover kinetics are warranted.

Biological nano-functionalization of titanium-based biomaterial surfaces: a flexible toolbox

Surface functionalization with bioactive molecules (BAMs) on a nanometre scale is a main field in current biomaterial research. The immobilization of a vast number of substances and molecules, ranging from inorganic calcium phosphate phases up to peptides and proteins, has been investigated throughout recent decades. However, in vitro and in vivo results are heterogeneous. This may be at least partially attributed to the limits of the applied immobilization methods. Therefore, this paper highlights, in the first part, advantages and limits of the currently applied methods for the biological nano-functionalization of titanium-based biomaterial surfaces. The second part describes a new immobilization system recently developed in our groups. It uses the nanomechanical fixation of at least partially single-stranded nucleic acids (NAs) into an anodic titanium oxide layer as an immobilization principle and their hybridization ability for the functionalization of the surface with BAMs conjugated to the respective complementary NA strands.

Oligonucleotide-RGD peptide conjugates for surface modification of titanium implants and improvement of osteoblast adhesion

A new concept for modular biosurface engineering of titanium implants based on the self-assembly of complementary oligonucleotides was biochemically investigated and optimized. This study describes the synthesis and characterization (RP-HPLC and Sakaguchi assay) of oligodeoxyribonucleotide (ODN) conjugates of the hexapeptide GRGDSP containing the RGD sequence as the recognition motif for cellular adhesion receptors (integrins). The peptide was chosen exemplarily as a model molecule, because it is a simple but potent bioactive molecule and relatively well investigated. The conjugation products must fulfill two main requirements: (I) the ability to hybridize and (II) the preservation of biological activity of the RGD peptide for the enhancement of osteoblast adhesion. In the following text, the term "hybridization" is generally used for Watson-Crick base pairing. The ability of the conjugates to hybridize to surface-immobilized complementary ODN was verified by competitive hybridization with radiolabeled ((32)P) complementary strands and by hybridization experiments using a quartz crystal microbalance (QCM). Surface hybridization was further characterized using different adsorption isotherms (e.g., Freundlich and Frumkin types), since the type of isotherm and the derived thermodynamic parameters may reveal characteristic differences between ODN and conjugates thereof. Biological activity of the conjugates was examined in vitro with osteoblasts. The cells were either cultured directly on the ODN-GRGDSP modified titanium implants or used for competition adhesion studies with dissolved ODN-GRGDSP conjugates. All results support the successful establishment of the new surface modification system. Hybridization of RGD peptide-modified nucleic acids to ODN-modified titanium implant materials is thus a promising method for osteoblast attachment in a modular and self-organizing system on implant surfaces.

Titanium allergy in dental implant patients: a clinical study on 1500 consecutive patients

BACKGROUND

In dentistry, allergic reactions to Ti implants have not been studied, nor considered by professionals. Placing permanent metal dental implants in allergic patients can provoke type IV or I reactions. Several symptoms have been described, from skin rashes and implant failure, to non-specific immune suppression.

OBJECTIVE

Our objective was to evaluate the presence of titanium allergy by the anamnesis and examination of patients, together with the selective use of cutaneous and epicutaneous testing, in patients treated with or intending to receive dental implants of such material.

MATERIAL AND METHODS

Thirty-five subjects out of 1500 implant patients treated and/or examined (2002-2004) were selected for Ti allergy analysis. Sixteen presented allergic symptoms after implant placement or unexplained implant failures [allergy compatible response group (ACRG)], while 19 had a history of other allergies, or were heavily Ti exposed during implant surgeries or had explained implant failures [predisposing factors group (PFG)]. Thirty-five controls were randomly selected (CG) in the Allergy Centre. Cutaneous and epicutaneous tests were carried out.

RESULTS

Nine out of the 1500 patients displayed positive (+) reactions to Ti allergy tests (0.6%): eight in the ACRG (50%), one in the PFG (5.3%)(P=0.009) and zero in the control group. Five positives were unexplained implant failures (five out of eight).

CONCLUSIONS

Ti allergy can be detected in dental implant patients, even though its estimated prevalence is low (0.6%). A significantly higher risk of positive allergic reaction was found in patients showing post-op allergy compatible response (ACRG), in which cases allergy tests could be recommended.

Impact of local and systemic factors on the incidence of late oral implant loss

BACKGROUND

This retrospective study was set to assess the influence of systemic and local bone and intra-oral factors on the occurrence of implant loss from abutment connection up to 2 years.

MATERIALS AND METHODS

The files of 700 patients, have been collected randomly from the total patient group treated by means of endosseous Brånemark system implants (Nobel Biocare, Gothenburg, Sweden) at the Department of Periodontology of the University Hospital of the Catholic University of Leuven. The end point observation was evaluating the loss of the implants 2 years after abutment installation. The study involved all implants that did not encounter early loss and implants for which it was possible to evaluate its status 2 years after abutment surgery. Thus, data of 412 patients (240 females) provided with 1514 implants were analyzed. For each patient, the medical history was carefully checked. Data collection and analysis were mainly focused on endogenous factors such as hypertension, coagulation problems, osteoporosis, hypo- hyperthyroidism, chemotherapy, diabetes type I or II, Crohn's disease, some local factors [e.g. bone quality and quantity, implant (length, diameter, location), type of edentulism, PTV, radiotherapy], smoking habits, and breach of sterility during surgery.

RESULTS

Radiotherapy, implant (diameter and location), and higher PTV at implant insertion and abutment connection, all affected significantly the implant loss.

CONCLUSION

Implant location in the oral cavity and radiotherapy seem predominant to explain the occurrence of implant loss. On the other hand, smoking and systemic health factors do not seem to be prominent players in the etiology of late implant loss.

Influence of estrogen deficiency and its treatment with alendronate and estrogen on bone density around osseointegrated implants: radiographic study in female rats

OBJECTIVE

This study evaluated the influence of estrogen deficiency and its treatment on bone density around integrated implants.

STUDY DESIGN

Implants were placed in female rat tibiae. The animals were assigned to 5 groups: control, sham, ovariectomy, estrogen, and alendronate. The control group was humanely killed to confirm integration of the implant. The others were submitted to ovariectomy or sham surgery. Bone density was measured by digital radiographs at 6 points on sides of the implant.

RESULTS

The analysis of radiographic bone density revealed estrogen privation had a negative impact only in the cancellous bone. The estrogen group differed significantly (P < .05) from the ovariectomy and alendronate groups. The alendronate group presented the highest density for all evaluated regions.

CONCLUSION

Ovariectomy caused a decrease in the radiographic bone density in the cancellous region. Estrogen replacement therapy and alendronate were effective treatments in preventing bone mass loss around integrated implants.

Dental endosseous implants in the medically compromised patient

The literature contains numerous observations on the significance of systemic disorders as contraindications to dental endosseous implant treatment, but the justification for these statements is often apparently allegorical. Although implants are increasingly used in healthy patients, their appropriateness in medically compromised patients is less equivocal. Perhaps surprisingly, the evidence of their efficacy in these groups of patients is quite sparse. Indeed, there are few if any randomized controlled trials (RCTs) in this field. Furthermore, any health risks from the placement of implants are unclear. We review the current evidence for the risks associated with endosseous implants in a range of systemic disorders. There is clearly a need for prospective systematic trials. The degree of disease-control may be far more important that the nature of the disorder itself, and individualized assessment, including the medical condition, quality of life and life expectancy is indicated. The benefits of implants to many of these patients may outweigh any risks. However, proper informed consent is mandatory.

Impact of local and systemic factors on the incidence of failures up to abutment connection with modified surface oral implants

AIM

This study aimed to assess the influence of systemic and local bone and intra-oral factors on the occurrence of early TiUnite implant failures.

MATERIAL AND METHODS

A total of 283 consecutive patients (187 females; mean age 56.2), who received a total of 720 TiUnite implants, at the Department of Periodontology of the University Hospital of the Catholic University of Leuven, were prospectively followed. The following aspects were particularly assessed: hypertension, cardiac problems, gastric problems, osteoporosis, hypo- or hyperthyroid, hypercholesterolaemia, asthma, diabetes types I or II, Crohn's disease, rheumatoid arthritis, chemotherapy, hysterectomy and intake of medication (antidepressants, steroids, hormone replacement), radiotherapy of the concerned area, breach of sterility during surgery, implant parameters, bone (quality, quantity, dehiscence or perforation), type of edentulism, antibiotics prescription, fenestration of the implant in the sinus/nasal cavity, immediate implant placement, apical lesion detection and insertion torque.

RESULTS AND CONCLUSION

A global failure rate of 1.9% was recorded. Owing to the very few failures, no definitive conclusion concerning statistical significance can be achieved. However, a tendency for more failures was noticed for apical lesions, vicinity with natural dentition, smoking, hormone replacement, gastric problems, Crohn's disease, diabetes I and radical hysterectomy.

Immediately loaded CAD-CAM manufactured fixed complete dentures using flapless implant placement procedures: a cohort study of consecutive patients

STATEMENT OF PROBLEM

Data available regarding the treatment outcome for completely edentulous jaws by means of a prefabricated fixed complete denture placed immediately after flapless implant insertion using a surgical guide are only short term.

PURPOSE

The purpose of this study was to follow the survival of implants inserted in completely edentulous jaws using a flapless procedure and immediately loaded with prefabricated fixed complete dentures for several years. A second purpose was to investigate whether there is a difference in marginal bone remodeling in smoking (S) and nonsmoking (NS) patients.

MATERIAL AND METHODS

During a 5-year period (mean time of follow-up 2.2 years), 30 consecutive patients, 12 women, 38-74 years of age (average 56 years) were treated for complete edentulism in 1 arch in the Department of Periodontology at the University Hospitals in Leuven. The S group included 13 and the NS group 17 patients. Descriptive statistics were used to analyze the data. Two outcome parameters were analyzed: the cumulative survival rate (CSR) of individual implants and the marginal bone remodeling for up to 5 years in the 2 groups.

RESULTS

Nine (4.9%) implants failed. Eight of the failures occurred in 3 smoking patients. The absolute survival rate for all patients was 95%, while the cumulative survival rate (CSR) after 5 years was 91.5%. For the NS group, the CSR was 98.9%, while for the S it was 81.2%. The mean marginal bone resorption was - 2.6 and - 1.2 mm in the S and NS groups, respectively.

CONCLUSIONS

The present findings indicate that the treatment protocol described results in good implant survival rate even after several years. Smoking may eventually compromise the efficacy of this treatment concept.

Effect of 17β-Estradiol and Alendronate on the Removal Torque of Osseointegrated Titanium Implants in Ovariectomized Rats

BACKGROUND

This study investigated the influence of estrogen deficiency and its treatment with estrogen and alendronate on the removal torque of osseointegrated titanium implants.

METHODS

Fifty-eight female Wistar rats received a titanium implant in the tibia metaphysis. After 60 days, which was needed for implant osseointegration, the animals were randomly divided into five groups: control (CTLE; N = 10), sham surgery (SHAM; N = 12), ovariectomy (OVX; N = 12), ovariectomy followed by hormone replacement (EST; N = 12), and ovariectomy followed by treatment with alendronate (ALE; N = 12). The CTLE group was sacrificed to confirm osseointegration, whereas the remaining groups were submitted to sham surgery or ovariectomy according to their designations. After 90 days, these animals were also sacrificed. Densitometry of femur and lumbar vertebrae was performed by dual-energy x-ray absorptiometry (DXA) to confirm systemic impairment of the animals. All implants were subjected to removal torque.

RESULTS

Densitometric analysis of the femur and lumbar vertebrae confirmed a systemic impairment of the animals, disclosing lower values of bone mineral density for OVX. Analysis of the removal torque of the implants showed statistically lower values (P <0.05) for the OVX group in relation to the other groups. However, the group treated with alendronate (ALE group) presented significantly higher torque values compared to the others.

CONCLUSION

According to this study, estrogen deficiency was observed to have a negative influence on the removal torque of osseointegrated implants, whereas treatment with alendronate increased the torque needed to remove the implants.

Impact of local and systemic factors on the incidence of oral implant failures, up to abutment connection

AIM

The aim of this retrospective study was to assess the influence of systemic and local bone and intra-oral factors on the occurrence of early implant failures, i.e. up to the abutment connection.

MATERIAL AND METHODS

The surgical records of 2004 consecutive patients from the total patient population who had been treated in the period 1982-2003 (with a total of 6946 Brånemark system implants) at the Department of Periodontology of the Catholic University Leuven were evaluated. For each patient the medical history was carefully checked. Data collection and analysis mainly focused on endogenous factors such as hypertension, coagulation problems, osteoporosis, hypo-hyperthyroidy, chemotherapy, diabetes type I or II, Crohn's disease, some local factors [e.g. bone quality and quantity, implant (length, diameter, location), type of edentulism, Periotest value at implant insertion, radiotherapy], smoking habits and breach of sterility during surgery.

RESULTS

A global failure rate of 3.6% was recorded. Osteoporosis, Crohn's disease, smoking habits, implant (length, diameter and location) and vicinity with the natural dentition were all significantly associated with early implant failures (p<0.05).

CONCLUSION

The indication for the use of oral implants should sometimes be reconsidered when alternative prosthetic treatments are available in the presence of possibly interfering systemic or local factors.

Surface modification of titanium-based alloys with bioactive molecules using electrochemically fixed nucleic acids

A new method of surface modification for titanium (alloys) with bioactive molecules was developed with the intention of providing a new basis of implant adaptation for particular requirements of certain medical indications. Nucleic acid single strands are fixed electrochemically via their termini (regiospecifically) by growing an oxide layer on Ti6Al7Nb anodically. It could be shown that they are accessible to subsequent hybridization with complementary strands at physiological pH. Amount of nucleic acids immobilized and hybridized were determined radioanalytically using 32P-labelled nucleic acids. Stable fixation was attained at and above potentials of 4 V(SCE). Up to 4 pmol/cm2 of nucleic acid single strands could be immobilized and hybridization efficiencies up to 1.0 were reached. Hybridization efficiency was found to depend on surface density of immobilized oligonucleotides, while hybridization rates increased when MgCl2 was added. A conjugate consisting of an oligonucleotide complementary to the immobilized strand and the hexapeptide GRGDSP with RGD as an integrin recognition site was synthesized. This conjugate was able to bind to integrins on osteoblasts. It was shown that this conjugate binds to the anchor strand fixed on Ti6Al7Nb to an extent comparable with the unconjugated complementary strand.

Systemic diseases affecting osseointegration therapy

OBJECTIVES

To evaluate the impact of systemic diseases and their treatment on the success of osseointegration therapy.

MATERIAL AND METHODS

A search was made to find human studies including subjects treated with osseointegrated oral implants, with a diagnosis of 11 systemic diseases, and reporting at least implant survival.

RESULTS

For most conditions, no studies comparing patients with and without the condition in a controlled setting were found. The evidence to recommend implant therapy was low and consisted in presentations of some successfully treated cases. With regard to diabetes, three types of reports were found: eight case series of diabetic patients treated with implants, six cross-sectional, longitudinal or retrospective evaluations of groups of subjects treated with implants, including some diabetic patients, and one matched control retrospective chart survey. The heterogeneity of the material and the method of data reporting precluded a formal meta-analysis. No unequivocal tendency for subjects with diabetes to have higher failure rates emerged, but the largest of these studies indicated a significant increase in the relative risk of implant failure with diabetes. The data obtained from 17 papers reporting data from osteoporotic patients were also heterogeneous. The evidence for an association of osteoporosis and implant failure was low.

CONCLUSIONS

The level of evidence indicative of absolute and relative contraindications for implant therapy due to systemic diseases is low. Many conditions have been listed as potentially critical, but studies comparing patients with and without the condition in a controlled setting are sparse.

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.

Influence of cortical bone thickness and implant length on implant stability at the time of surgery--clinical, prospective, biomechanical, and imaging study

This clinical study is the first to quantitatively evaluate both regional bone structure by computed tomography preoperatively and dental implant stability by resonance frequency analysis at the time of surgery to explore the relation between local bone structure and dental implant stability in humans. Implant stability at the time of installation is often difficult to achieve in lower density bone and implant stability might influence treatment efficacy. Few clinical studies have reported detailed bone characteristics obtained using computed tomography prior to surgery and comprehensive implant stability measurements at the time of surgery. We hypothesized that thicker cortical bone would improve the stability of the dental implant at the time of placement. Before radiographic examination, diagnostic radiographic templates were made by incorporating radiopaque indicators. Computed tomography scans were obtained for 50 edentulous subjects prior to surgery. Preoperatively, the thickness of the cortical bone at the sites of implant insertion was measured digitally, and then implant insertion surgery was performed. A total of 225-implant stability measurements were made using a resonance frequency analyzer. There was a strong linear correlation between cortical bone thickness and resonance frequency (r = 0.84, P < 0.0001). The implant length had a weak negative correlation with stability (r = -0.25, P < 0.0005). These results suggest that the initial stability at the time of implant installation is influenced more by cortical bone thickness than by implant length. The cortical and cancellous ratio of local bone is extremely important for implant stability at the time of surgery and determining the local bone condition is critical for treatment success.