Factors in implant integration failure after bone grafting: an osteometric and endocrinologic matched analysis

Impact of Osteoporosis on Autogenous Bone Graft Resorption

BACKGROUND

Osteoporosis is a common disorder that is characterized by decreased bone density and increased bone resorption. This bone resorption may affect the grafted bone during the maxillofacial reconstruction.

PURPOSE

This study aimed to measure the association between osteoporosis and resorption of anterior iliac crest bone grafts used to reconstruct the atrophic anterior maxillae.

STUDY DESIGN, SETTING, SAMPLE

This prospective cohort study included female patients requiring bone augmentation of the anterior maxilla. Patients with a ridge width of <4 mm and ridge height of >7 mm were enrolled in the study. Exclusion criteria were chronic use of corticosteroids or intravenous bisphosphonates, history of maxillofacial radiation therapy, current smoking, and underlying conditions contributing to bone metabolism (eg, hyperparathyroidism, chronic renal failure, and hypophosphatemia).

PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE

Osteoporosis status was a predictor variable. Patients were allocated to the osteoporosis or control group based on T-scores obtained by dual-energy x-ray absorptiometry. Mean T-scores ≤ -2.5 were assigned to the osteoporosis group.

MAIN OUTCOME VARIABLE(S)

The outcome variable was graft resorption, defined as the difference in ridge width between measurements made immediately (T1) and 6 months postoperatively (T2) using cone-beam computed tomography.

COVARIATES

Patient age, preoperative (T0) bone width, and the amount of bone augmentation, defined as the differences in ridge width between measurements made preoperatively (T0) and immediately after grafting (T1), were covariates of this study.

ANALYSES

Descriptive, analytic, and general linear models were computed. Statistical significance was set a P < .05.

RESULTS

Thirty-two patients were included in the study (15 in the osteoporosis group and 17 in the control group). The amount of graft resorption at 6 months after grafting was 2.57 ± 0.59 mm in the osteoporosis group and 0.97 ± 0.59 mm in the control group (P < .001). A significant correlation was found between the mean T-score and graft resorption 6 months after grafting (P < .001).

CONCLUSION AND RELEVANCE

A significant correlation was observed between osteoporosis and graft resorption in the anterior maxilla after 6 months.

Does the Outcome of Graft Materials at Dental Implant Sites Differ Between Patients With Normal and Compromised Bone Health?

The objective of this paper was to assess the outcome of bone graft material at alveolar bone augmentation sites combined with dental implants in postmenopausal women with compromised bone health by evaluating cone beam computerized tomography (CBCT) scans at multiple time points.CBCT scans were analyzed on 55 postmenopausal women with compromised bone health status to determine the fate of alveolar bone augmentation. CBCT scans were taken immediately after surgery and 9 and 24 months postoperatively. The patient's medication regimens and durations were recorded, and the pixel intensity value (PIV) was measured and standardized using scoring criteria and visual assessment. Statistical analyses included 2-sample t tests for continuous variables and Fisher's exact tests for categorical variables.Among the normal patients, 73% received a grade 2 visual score, and 27% received a grade 1 visual score. After 24 months, 45% of patients received a grade 2 score, and 27% received a grade 3 score. In the osteoporotic group receiving medication, 77% of participants received a grade 1 visual score at the 9-month postoperative evaluation, while 23% received a grade 2 score. At the 24-month assessment, 55% of patients received a grade 1 score, 41% received a grade 2 score, and only 5% received a grade 3 score. Notably, although the graft material did not remodel into native bone, it was a scaffold for implants in controlled osteoporotic patients. The study's results show that the pixel intensity values of particulate graft materials are similar across the three different time points, suggesting that the graft material's pixel intensity value remains constant in postmenopausal women with osteoporosis. The study's limitations include a small sample size and a restricted 24-month follow-up period. This limited time frame may need to capture long-term changes or variations in graft materials adequately. Future research should include a larger sample size and have a longer follow-up duration to provide a more comprehensive understanding of the change in graft materials between patients with normal and compromised bone health.

Bone reconstruction of extensive maxillomandibular defects in adults

Reconstruction of significant maxillomandibular defects is a challenge that has been much discussed over the last few decades. Fundamental principles were developed decades ago (bone bed viability, graft immobilization). Clinical decision-making criteria are highly relevant, including local/systemic factors and incision designs, the choice of material, grafting technique, and donor site morbidity. Stabilizing particulated grafts for defined defects-that is, via meshes or shells-might allow significant horizontal and vertical augmentation; the alternatives are onlay and inlay techniques. More significant defects might require extra orally harvested autologous bone blocks. The anterior iliac crest is often used for nonvascularized augmentation, whereas more extensive defects often require microvascular reconstruction. In those cases, the free fibula flap has become the standard of care. The development of alternatives is still ongoing (i.e., alloplastic reconstruction, zygomatic implants, obturators, distraction osteogenesis). Especially for these complex procedures, three-dimensional planning tools enable facilitated planning and a surgical workflow.

Bone regeneration in implant dentistry: Which are the factors affecting the clinical outcome?

The key factors that are needed for bone regeneration to take place include cells (osteoprogenitor and immune-inflammatory cells), a scaffold (blood clot) that facilitates the deposition of the bone matrix, signaling molecules, blood supply, and mechanical stability. However, even when these principles are met, the overall amount of regenerated bone, its stability over time and the incidence of complications may significantly vary. This manuscript provides a critical review on the main local and systemic factors that may have an impact on bone regeneration, trying to focus, whenever possible, on bone regeneration simultaneous to implant placement to treat bone dehiscence/fenestration defects or for bone contouring. In the future, it is likely that bone tissue engineering will change our approach to bone regeneration in implant dentistry by replacing the current biomaterials with osteoinductive scaffolds combined with cells and mechanical/soluble factors and by employing immunomodulatory materials that can both modulate the immune response and control other bone regeneration processes such as osteogenesis, osteoclastogenesis, or inflammation. However, there are currently important knowledge gaps on the biology of osseous formation and on the factors that can influence it that require further investigation. It is recommended that future studies should combine traditional clinical and radiographic assessments with non-invasive imaging and with patient-reported outcome measures. We also envisage that the integration of multi-omics approaches will help uncover the mechanisms responsible for the variability in regenerative outcomes observed in clinical practice.

Understanding the thrust force evolution and primary stability for dental implantation – An in-vitro experimental investigation

The dental implant is challenging due to the unstable quality of the surrounding bone. This study aimed to explore the feasibility of using thrust force characteristics to identify different bone types and the influencing mechanisms of spindle speed and feed rate on primary stability of dental implants through in-vitro experiments. 13 groups of osteotomy experiments were performed on mandibles and maxillae of pigs with different bone types (I, II, and III) under different spindle speeds (600 and 800 rpm) and feed rates (20 and 60 mm/min). The thrust force evolution under different conditions was extracted and analysed to elaborate the distribution and thickness of the cortical and trabecular bone layers on different bone types. Dental implant placements were performed, and corresponding primary stabilities were obtained. Furthermore, histologic observation was conducted to reveal the bone/implant contact morphology. From the results, the amplitude and trend of thrust force show a regular variation during drilling different bone types. The highly dynamic information of thrust force can be analysed to characterise the distribution and thickness of the cortical and trabecular bone layers, hence effectively detecting different bone types. Since a lower feed rate and resulting bone temperature elevation lead to more thermal damages, primary stability decreases with the decrease of feed rate. Spindle speed has no significant effect. This study establishes a more in-depth understanding into the thrust force evolution and also provide a clinical option for reducing the complexity of bone type and drilling parameters determination in osteotomy.

Etiology and Management of Complications Associated with Sinus Augmentation Procedures

Sinus floor elevation is a predictable procedure for vertical bone augmentation in the atrophic posterior maxilla. As with most surgical procedures, complications can be encountered during sinus floor elevation/augmentation. A clinician should have a thorough knowledge of factors that can lead to complications and possible ways to manage. Presurgical evaluation of the sinus is a prerequisite in identifying the concomitant presence of systemic disease and maxillary sinus disease that may lead to postoperative complications. Despite the best efforts, one may encounter adverse events. Complications can broadly be divided into intraoperative, acute, and chronic complications based on the timing of its occurrence. The most commonly encountered complications include membrane perforation and excessive bleeding. Evaluation of anatomic deviations and sound surgical skill is required to reduce intraoperative complications. Prevention is better than cure. It is always better to know how and when a complication might occur so that the clinician might take the necessary steps to avoid it. This article reviews the management of most commonly encountered complications and the best possible ways to manage them.

Histological and Histomorphometric Analyses of Bone Regeneration in Osteoporotic Rats Using a Xenograft Material

We evaluated the effect of osteoporotic induction after eight weeks of initial healing of bone defects grafted with a xenograft material in a rat model. Bone defects were created in the femoral condyles of 16 female Wistar rats (one defect per rat). The defects were filled with bovine bone (Inter-Oss) granules. After eight weeks of bone healing, rats were randomly ovariectomized (OVX) or sham-operated (SHAM). At 14 weeks of bone healing, all animals were euthanized. Bone specimens were harvested and processed for histological and histomorphometric analyses to assess new bone formation (N-BF%), remaining bone graft (RBG%) and trabecular bone space (Tb.Sp%) within the defect area. After 14 weeks of bone healing, histological evaluation revealed a significant alteration in trabecular bone in OVX rats compared to SHAM rats. There was lower N-BF% in OVX rats (22.5% ± 3.0%) compared to SHAM rats (37.7% ± 7.9%; p < 0.05). Additionally, the RBG% was significantly lower in OVX (23.7% ± 5.8%) compared to SHAM (34.8% ± 9.6%; p < 0.05) rats. Finally, the Tb.Sp% was higher in OVX (53.8% ± 7.7%) compared to SHAM (27.5% ± 14.3%; p < 0.05) rats. In conclusion, within the limitations of this study, inducing an osteoporotic condition in a rat model negatively influenced bone regeneration in the created bone defect and grafted with a xenograft material.

Ovariectomy and timing of impaired maxillary alveolar bone regeneration: An experimental study in rats

BACKGROUND

The aim of this study was to seek the critical time for impairment of alveolar bone regeneration after ovariectomy (OVX) in rats.

METHODS

A total of 32 female rats were used. Test group rats were divided into a 2M group (n = 8), a 3M group (n = 8) and a 4M group (n = 8) according to the duration from OVX to defect creation. Bilateral OVX was performed in all test groups, and a sham operation was performed in the control group (n = 8). Drill-hole defects (1.5 mm diameter, 2 mm length) were created on both sides of the maxilla. All rats were euthanized 2 and 4 weeks after the surgery. Microcomputed tomographic (micro-CT), histological, and histomorphometric analyses and in vitro experiments were performed.

RESULTS

The 4M group showed significantly less new bone formation and a lower bone mineral density than the other groups in the micro-CT analysis. The histomorphometric analysis also revealed that the 4M group showed significantly less new bone formation than the control and 2M groups. The rats in the 4M group showed significantly higher alkaline phosphatase expression levels and a larger number of calcified nodules than rats in the other groups, whereas osteoclastic activity was significantly lower in the 4M group than in the other groups.

CONCLUSIONS

The critical time for impairment of alveolar bone regeneration was 4 months after OVX in rats.

Tibial Implants: Biomechanical and Histomorphometric Studies of Hydroxyapatite-Coated and Uncoated Stainless Steel and Titanium Screws in Long-Term Ovariectomized Sheep

This study was designed to evaluate osteointegration of HA-coated and uncoated titanium and stainless steel screws in the cortical bone of long-term (24 months) ovariectomized sheep (OVX group), in comparison with Sham-aged sheep (control group). The screws were tested biomechanically (extraction torque) and histomorphometrically (affinity index: Al) 12 weeks after their implantation in tibial diaphyses. Tibial cortical bone parameters showed significant differences between the groups, showing a reduction of the selected parameters in the OVX group. ANOVA showed significant effects for both material and ovariectomy factors on obtained extraction torque (material: F=159.26, p < 0.0005; ovariectomy: F=20.04, p < 0.0005) and Al data (material: F=8.04, p < 0.001; ovariectomy: F=7.17, p < 0.05). In both groups the extraction torque for coated screws of both materials was significantly higher than for uncoated screws, and uncoated titanium had a better extraction torque than uncoated stainless steel. In the OVX group, the HA-coated stainless steel and titanium Al data were significantly higher than uncoated Al data. In conclusion, the biomechanical and histomorphological results obtained suggest employing HA-coated screws in the presence of osteopenic cortical bone.

The Ovariectomised Sheep as a Model for Testing Biomaterials and Prosthetic Devices in Osteopenic Bone: A Preliminary Study on Iliac Crest Biopsies

A histomorphometric and ultrastructural evaluation on sheep iliac bone was performed. Six sheep were ovariectomised (OVX Group) and 6 were left intact (Sham-aged, Control Group). An iliac crest biopsy was performed randomly in 6 animals at the beginning of the study, then, in all the animals, after 12 and 24 months. A significant decrease in trabecular bone volume, trabecular thickness (p<0.0005) and cell volume (p<0.005) was observed in OVX animals. A modest decrease in trabecular number and osteoid thickness together with an increase in trabecular separation were observed in OVX animals at 12 and 24 months. The osteoid volume showed a significant difference (p<0.05) between the groups. In OVX animals, at 12 months, Scanning Electron Microscopy revealed an enlargement of the trabecular space and a progressive replacement of bone matrix with adipose tissue. These signs were accentuated at 24 months.

In conclusion, OVX sheep showed a loss of trabecular bone starting at 12 months after ovariectomy. The developed osteopenic state may be considered as a useful tool when doing research on biomaterial osteointegration. (Int J Artif Organs 2000; 23: 275–81)

Osseointegration of Sandblasted or Anodised Hydrothermally-Treated Titanium Implants: Mechanical, Histomorphometric and Bone Hardness Measurements

The improvement of the implant-bone interface is still an open problem in the long-term mechanical stability of cementless fixed implants. Mechanical, histomorphometric and bone hardness measurements were performed in sheep femoral cortical bone implants at 8 and 12 weeks from surgery to compare in vivo the osseointegration of titanium screws (Ø 3.5 mm × 7 mm length) with two different surface treatments: sandblasting with 70–100 μm HA followed by acid etching with HNO3 (Group A) and Ca-P anodization followed by a hydrothermal treatment (Group B). No significant differences were found for maximum push-out force and interfacial strength between groups at both experimental times. No significant difference was observed for Bone Ingrowth between groups at both experimental times, while the Affinity Index of Group B was significantly higher (7.5%, p<0.05) and lower (10.2%, p<0.05) than that of Group A at 8 and 12 weeks, respectively. Finally, a significant increase in bone microhardness measured within 200 μm from the interface and inside the thread depth of Group A was observed between the two experimental times (p<0.05). In conclusion, present findings show that osseointegration may be accelerated by adequate surface roughness and bioactive ceramic coating such as current tested treatments which enhance bone interlocking and mineralization.

Sandblasted Titanium Osteointegration in Young, Aged and Ovariectomized Sheep

To evaluate how aging and estrogen deficiency influence the success rate of Sandblasted Titanium (Ti/SA) implants, the osteointegration of Ti/SA rods was studied in the cortical and trabecular bone of 5 young, 5 aged and 5 ovariectomized (OVX) sheep.

The characterization of the host bone by transiliac biopsies of the iliac crest showed a progressive rarefaction of trabecular bone in aged and OVX animals when compared to young ones. A significant reduction, both in cortical and trabecular bone, of the osteointegration rate of Ti/SA rods in the presence of estrogen deficiency compared to young animals was observed, while only a minor reduction was observed in aged animals. These results were confirmed by the pushout test in cortical bone.

Bone quality affected the biological response of bone to Ti/SA implants in both trabecular and cortical bone; consequently, strategies to maximize the bone osteogenic properties of osteoporotic patients should be adopted.

Enhanced osseointegration of titanium implants in a rat model of osteoporosis using multilayer bone mesenchymal stem cell sheets

The present study aimed to investigate whether bone marrow-derived mesenchymal stem cell (BMSC) sheets combined with titanium implants enhanced implant osseointegration in an ovariectomized (OVX) rat model of osteoporosis. Sprague-Dawley rats were randomly assigned into a test group and control group. Allogenic BMSCs were collected from the rats, cultured and stored via cryopreservation. At 6 months post-ovariectomy, establishment of the OVX model was confirmed by micro-computed tomography (CT) measurements. BMSC sheets were subsequently layered and wrapped over titanium implants for implantation. Unmodified implants served as the control. At 8 weeks post-implantation, samples were observed by micro-CT reconstruction and histomorphometric evaluation. Micro-CT reconstruction identified a marked improvement in the surrounding bone volume following treatment, with data analyses indicating a significant increase in bone volume in the BMSC-implant group compared with the control implant group (P<0.05). In addition, histological staining identified new bone formation and an increased rate of bone-implant contact surrounding the BMSC-implant constructs. These results indicate that the use of BMSC sheets as a novel tissue engineering approach improves the osseointegration of titanium implants in an osteoporosis model. This method may expand the operative indications in patients with osteoporosis and improve the success rate of clinical dental implant treatments.

Dental implants in patients affected by systemic diseases

Several systemic diseases (and relative medications) have been reported to impair or in some cases complicate dental implant surgery. In broader terms, when dealing with patients suffering from systemic diseases, the monitoring of the medical condition and of the related post-operative complications is of great importance in order to avoid risks which could jeopardise the health of the patient. In this review, the available evidence on implant survival/success, as well as relevant surgical recommendations in patients affected by systemic diseases, are evaluated and when possible, practical suggestions for the clinician are provided.

Effect of a dietary supplement on peri-implant bone strength in a rat model of osteoporosis

PURPOSE

Osteoporosis contributes to impaired bone regeneration and remodeling through an imbalance of osteoblastic and osteoclastic activity, and can delay peri-implant bone formation after dental implant surgery, resulting in a prolonged treatment period. It poses several difficulties for individuals with large edentulous areas, and decreases their quality of life. Consequently, prompt postoperative placement of the final prosthesis is very important clinically. Peri-implant bone formation may be enhanced by systemic approaches, such as the use of osteoporosis supplements, to promote bone metabolism. We aimed to confirm whether intake of synthetic bone mineral (SBM), a supplement developed for osteoporosis, could effectively accelerate peri-implant bone formation in a rat model of osteoporosis.

METHODS

Thirty-six 7-week-old ovariectomized female Wistar rats were randomly assigned to receive a standardized diet with or without SBM (Diet with SBM group and Diet without SBM group, respectively; n=18 for both). The rats underwent implant surgery at 9 weeks of age under general anesthesia. The main outcome measures, bone mineral density (BMD) and pull-out strength of the implant from the femur, were compared at 2 and 4 weeks after implantation using the Mann-Whitney U test.

RESULTS

Pull-out strength and BMD in the Diet with SBM group were significantly greater than those in the Diet without SBM group at 2 and 4 weeks after implantation.

CONCLUSIONS

This study demonstrated that SBM could be effective in accelerating peri-implant bone formation in osteoporosis.

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.

Tissue response: biomaterials, dental implants, and compromised osseous tissue

Tissue response represents an important feature in biocompatibility in implant procedures. This review article highlights the fundamental characteristics of tissue response after the implant procedure. This article also highlights the tissue response in compromised osseous conditions. Understanding the histologic events after dental implants in normal and abnormal bone reinforces the concept of case selection in dental implants.

Nasal Floor Elevation for Implant Treatment in the Atrophic Premaxilla: A Within-Patient Comparative Study

BACKGROUND

There is a lack of evidence regarding success of implants placed in atrophic premaxilla using the nasal floor elevation technique.

PURPOSE

This study aimed to compare implants placed in augmented bone in the anterior maxilla using the nasal floor elevation technique with implants placed in the maxillary sinus region using the sinus lift technique.

MATERIALS AND METHODS

A within-patient controlled clinical trial was performed on 14 patients receiving 78 implants. The implants were assigned to one of two study groups on the basis of implant location. A total of 37 implants were placed in the nasal fossa region (NF group), and 41 implants were placed in the maxillary sinus region (MS group). Patients were followed up for 4.5 ± 2.2 years, with comparable follow-up times for implants in NF and MS groups (4.7 ± 2.1 and 4.9 ± 2.1 years, respectively; p > .05). Treatment outcomes were assessed and statistically analyzed.

RESULTS

Implant success rate was 89.2% in the NF group and 95.0% in the MS group, with no statistically significant difference between them (p > .05). No nasal or sinus membrane perforation or other complications were reported within the follow-up period. Significant differences were found between the two groups in terms of residual bone height, augmented bone height, and implant diameter.

CONCLUSIONS

Nasal floor elevation is an effective and safe procedure that can be used for implant placement in atrophic premaxilla with success rates that are comparable to those of implants placed in the maxillary sinus.

The osseointegration behavior of titanium-zirconium implants in ovariectomized rabbits

OBJECTIVE

The aim of this study is to compare the osseointegration behavior of titanium (Ti) and titanium-zirconium (TiZr) implants in ovariectomized (OVX) rabbits.

MATERIALS AND METHODS

Twelve ovariectomized New Zealand rabbits submitted to a hypocalcic diet and 12 sham-aged rabbits were used. After the bone mass loss induction period, TiZr or Ti implants both benefiting from a SLActive surface treatment were randomly inserted in the tibia and femur of each animal. The total of 24 rabbits were divided in four groups (n = 6): SHAM + Ti, OVX + Ti, SHAM + TiZr,OVX + TiZr. The animals were respectively sacrificed 3 and 6 weeks after dental implant placement. Six implants in each group at each time point were subjected to removal torque testing, and the remaining implants were prepared for histomorphometric analysis.

RESULTS

At the end of the healing period, all implants were osseointegrated. The removal torque value of the SHAM-TiZr group was significantly higher than those of the SHAM-Ti group (P < 0.001). The removal torque of the OVX-Ti group was significantly lower than those of the OVX-TiZr group. All groups demonstrated an increase in the peak torque value after 6 weeks: 46.0 and 50.8 Ncm for the OVX and the SHAM animals, respectively, in the case where Ti implants were used. When TiZr implants were inserted, the values reached 60.7 and 76.2 Ncm with a similar group configuration. The BIC and the BA/TA analysis showed an increase between week 3 and 6 in the case of nonovariectomized animals. From week 3 to 6, the BIC went from 37.1 ± 14.3 to 47.7 ± 8.7 for the SHAM + Ti group and from 37.6 ± 10.9 to 50.4 ± 11 for the SHAM + TiZr group. The BIC values were not significantly different between groups.

CONCLUSION

The parameters intended to be representative of the bone morphology (BIC & BATA) did not help to discriminate between Ti and TiZr which appeared to behave similarly in this experimental model. However, the removal torque values for the TiZr group were statistically higher than those of the Ti group in both the SHAM and the ovariectomized animals. That likely reflected an increased quality of bone around the TiZr implants.

Dental implants in the medically compromised patient

OBJECTIVE

It has been suggested that some local and systemic factors could be contraindications to dental implant treatment. The objective of this paper was to evaluate whether success and survival rates of dental implants are reduced in the medically compromised patient.

DATA/SOURCES

An extensive literature search was conducted using PubMed/Medline, Scopus, Scirus and Cochrane databases up to November 8, 2012.

CONCLUSIONS

There are very few absolute medical contraindications to dental implant treatment, although a number of conditions may increase the risk of treatment failure or complications. The degree of systemic disease-control may be far more important that the nature of the disorder itself, and individualized medical control should be established prior to implant therapy, since in many of these patients the quality of life and functional benefits from dental implants may outweigh any risks.

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.

Effect of zoledronate acid treatment on osseointegration and fixation of implants in autologous iliac bone grafts in ovariectomized rabbits

One main problem associated with alveolar bone augmentation in implant dentistry is resorption of grafted bone, which may be further compromised by systemic skeletal disorders such as osteoporosis. Zoledronate acid (ZOL) is the most potent bisphosphonate to treat osteoporosis and therefore it is hypothesized to be able to invert the negative effect of osteoporosis on osseointegration and fixation of dental implants in autologous bone grafts. In this study, 56 rabbits received bilateral ovariectomy (OVX) (40 rabbits) or sham operation (16 rabbits). Three months later, 8 animals from each group were sacrificed for bone mineral density (BMD) examination. Then the remaining animals underwent bilateral autologous iliac bone grafting with simultaneous implantation of titanium implants in tibiae and were divided into 5 groups (n=8): Sham, OVX, Loc-ZOL (local treatment), Sys-ZOL (systemic treatment) and Loc+Sys-ZOL (local plus systemic) group. At 3 months after implantation, all animals were sacrificed and specimens were harvested for examinations. Both BMD and histological examinations of femurs showed osteoporotic changes after ovariectomy, while systemic treatment with ZOL restored mineralized bone. Micro-CT examination demonstrated that OVX group showed significant decrease of mineralized bone and implant-bone contact when compared with sham control, whereas both systemic and local treatments of ZOL significantly increased mineralized bone and implant-bone contact in ovariectomized animals. However, the best effects were observed in Loc+Sys-ZOL group (combined use of ZOL) and most of bone indices were similar to (IBCR, p>0.05) or higher than (BV/TV, Conn.D and Tb.N) (p<0.01) those of the sham group, except Tb.Th, which was still significantly lower (p<0.01), and Tb.Sp, which was further decreased (p<0.01). The aforementioned effects were also confirmed by histomorphometric analysis of bone indices on implant-bone contact and mineralized bone. In addition, biomechanical testing further supported the beneficial effect of ZOL treatment and maximal removal torque of titanium implants was observed in Loc+Sys-ZOL group. In conclusion, our study suggests that both systemic and local treatments with ZOL can invert negative effect of osteoporosis and promote osseointegration and fixation of dental implants in autologous bone grafts under osteoporotic condition. Combined systemic and local use of ZOL exerts best effects when compared to their single use.

Bone graft healing in reconstruction of maxillary atrophy

PURPOSE

Evaluate correlations between volume change for iliac crest bone grafts in maxillary reconstruction (graft volume change [GVC]) and bone mineral density (BMD), bone volume fraction (BVF), hematologic bone metabolic factors (I), and identify indicators of implant failure (II).

MATERIAL AND METHODS

Forty-six consecutive patients had their edentulous atrophic maxilla reconstructed with free autogenous bone grafts from anterior iliac crest. Endosteal implants were placed 6 months after graft healing. Computer tomography was performed after 3 weeks and 6 months after grafting. Bone biopsies were taken from the internal table of donor site for calculation (BVF), and blood samples were collected. Implant stability was measured at placement with resonance frequency analysis and expressed as implant stability quotient (ISQ). Implant failure was registered.

RESULTS

GVC in onlay bone graft was 37%. The BVF in iliac crest biopsies was 32%. Serum-IGFBP3 differed with 79% of the samples over normal range. Fifteen patients had one or more implant failures prior to loading (early failures). Forty-two patients were followed for a minimum of 3 years after implant loading and, in addition, 6/42 patients had one or more implants removed during the follow-up (late failures). GVC correlated to decreased BMD of lumbar vertebrae L2-L4 (Kruskal-Wallis test, p=.017). No correlation was found between GVC and hematologic factors (Pearson correlation test) or between GVC and BVF (Kruskal-Wallis test). No correlation was found between ISQ and GVC (Pearson correlation test, p=.865). The association between implant failures and the described factors were evaluated, and no significant correlations were found (unconditional logistic regression).

CONCLUSION

Onlay bone grafts decrease 37% during initial healing period, which correlate to BMD of lumbar vertebrae L2-L4. No other evaluated parameters could explain GVC. The evaluated factors could not explain implant failure.

The impact of ovariectomy and hyperglycemia on graft consolidation in rat calvaria

OBJECTIVE

Implant placement frequently depends on bone augmentation. However, the impact of systemic metabolic diseases on the consolidation of bone substitutes remains poorly understood. Our goal is to study the impact of ovariectomy and hyperglycemia on graft consolidation in rat calvaria.

MATERIAL AND METHODS

We determined a rat model in which methacrylate hemispheres filled with deproteinized bovine bone mineral were fixed on the calvaria. The first group received streptozotocin (STZ) to induce diabetes. The second group of animals underwent ovariectomy (OVX), causing osteoporosis. Control animals remained untreated, only receiving vehicle injections (STZ-control) but not sham operation, respectively. Specimens were assessed by histomorphometry and μCT.

RESULTS

Graft consolidation was similar between the two groups. The rate of new bone formation after 4 weeks was 0.61±0.53% in the STZ group (n=10) and 0.69±0.91% in the control group (n=8). After 8 weeks, the rates of new bone formation were 4.98±3.16% in the OVX group (n=7) and 2.35±1.30% in the control group (n=10). The volume occupied by the bone substitute was not affected by STZ or OVX treatment. The low amount of newly formed bone could not be quantified by μCT.

CONCLUSION

We conclude that neither STZ nor OVX altered the early phase of graft consolidation. Our findings are limited by the weak osteogenic potential of the rat calvaria in this augmentation model.

A meta-analysis of histomorphometric results and graft healing time of various biomaterials compared to autologous bone used as sinus floor augmentation material in humans

BACKGROUND

To date, no studies have been published in which histomorphometric data from a large group of patients comparing various biomaterials for sinus floor augmentation procedures were evaluated.

MATERIALS AND METHODS

A meta-analysis of the English literature from January 1993 till April 2009 was carried out. Out of 147 titles, according to our criteria, 64 articles were selected for analysis describing the use of autologous bone and their alternatives, such as allogenic, xenogenic, and alloplastic materials.

RESULTS

On the basis of autologous bone grafting, a reference value for total bone volume (TBV) of 63% was found. Particulation of the bone graft resulted in a general reduction of −18% in TBV. Delayed implant placement reduced the TBV with −7%. Overall TBV was 8% or 6% higher if a biopsy was, respectively, taken before 4.5 months or after 9.0 months after initial sinus augmentation surgery. Allogenic, xenogenic, alloplastic, or combinations of graft materials all resulted in a significant lower amount of TBV compared to autologous bone grafting ranging from −7% to −26%. Inventorying the effect of "biopsy time" for autologous bone, the TBV was significantly higher before 4.5 and after 9.0 months of healing time compared to period in between. Surprisingly, no significant differences in TBV with respect to "biopsy time" for bone substitutes were found.

CONCLUSIONS

On the basis of the aspect of TBV autologous bone still has to be considered to be the gold standard in sinus augmentation surgery. However, the consequence of the TBV for implant survival is still unraveled yet.

Influence of prognostic risk indicators on osseointegrated dental implant failure: a matched case-control analysis

Dental implant treatment is an important therapeutic modality with documented long-term success for replacement of missing teeth. However, dental implants can be susceptible to disease conditions or healing complications that may lead to implant loss. This case-control study identified several risk indicators associated with failure such as smoking and alcohol consumption. The use of postoperative antibiotics or wide-diameter implants may significantly reduce implant failure. Knowledge of patient-related risk factors may assist the clinician in proper case selection and treatment planning.

Extraordinary Implant Failure

Every attempt must be made to keep implant failures to a minimum. Dental implant failure can roughly be divided into 3 broad categories: bacterial factors, occlusal (mechanical factors), and systemic and psychologic factors. All failures should be carefully analyzed and evaluated to identify their causes in order to prevent future reoccurrence. Failures should be documented and used to advantage when treatment planning future implant cases. A panoramic radiograph, mounted diagnostic casts, medical and dental histories, and surgical guides are accepted standards of care prior to beginning oral implant procedures. The identification and management of nutritional deficiencies is a useful adjunct to successful implant treatment.

Surface modification of biomedical and dental implants and the processes of inflammation, wound healing and bone formation

Bone adaptation or integration of an implant is characterized by a series of biological reactions that start with bone turnover at the interface (a process of localized necrosis), followed by rapid repair. The wound healing response is guided by a complex activation of macrophages leading to tissue turnover and new osteoblast differentiation on the implant surface. The complex role of implant surface topography and impact on healing response plays a role in biological criteria that can guide the design and development of future tissue-implant surface interfaces.

PERICELLULAR PARTIAL OXYGEN PRESSURE (pO2) MEASUREMENT IN OSTEOPENIC BONE-DERIVED OSTEOBLAST CULTURES

In order to achieve further information on the in vitro behaviour of osteoblasts derived from osteopenic bone, in the present study comparative measurements of some parameters of cell proliferation, metabolism and differentiation and also of the pericellular partial oxygen pressure (pO2) were performed on normal and osteopenic bone derived osteoblasts from heathy and osteopenic rats. The respiration rate was increased in osteoblasts derived from osteopenic bone as compared to normal cells at 48 hours and 7 days, involving a significant decrease in pericellular pO2 in the culture medium. At 48 hours, in osteopenic bone-derived cells, a significant increase in MTT and a significant decrease of osteocalcin were observed. At 7 days, cell count highlighted a significant slowing down of the proliferation of osteopenic bone-derived osteoblasts. No significant differences were observed for alkaline phosphatase activity, nitric oxide and type I collagen production. The present preliminary results may be taken into consideration also in in vitro comparative biocompatibility or osteointegration studies of biomaterials in normal and osteopenic bone-derived cells because a decrease in pericellular pO2 in these tissue cultures could influence results on material behaviour.

Comparison of implant survival with implants placed in acceptable and compromised bone: a literature review

BACKGROUND

Survival rates for conventional dental implant systems are relatively high in normal healthy bone. However, there are subgroups of patients that are at an increased risk of implant failure. In particular, patients with compromised quantity or quality of bone present a significant challenge to the dental implantologist.

OBJECTIVE

To perform a review of the literature in an attempt to quantify the relative risk of implant failure in compromised bone compared to good or acceptable bone and to identify whether certain anatomical regions are at greater risk.

SEARCH STRATEGY

We conducted a systematic electronic database search of Medline, Cinhahl and the Cochrane Library through March 2006 identifying articles meeting the eligibility criteria.

RESULTS

We calculated an increased risk of implant failure in compromised bone compared to healthy bone in both the maxilla and the mandible using conventional dental implant systems. Relative risks ranged from 2 to 12 with the highest risk of failure in the maxilla. Conventional systems are often used in combination or after bone augmentation procedures or more innovative methods for stimulating bone growth in patients with compromised bone. These approaches do have their limitations including high costs, the accumulation of the surgical risks, and delayed time to loading.

DISCUSSION

Quantifying the risk of implant failure in patients with compromised bone should assist the implantologist in treatment decision making and patient counseling. Alternative methods for treating patients with compromised bone include zygomatic and lateral implants, neither of which typically require bone augmentation procedures. More studies are needed to evaluate their safety and efficacy.

Surface modifications of dental implants

Dental implant surface technologies have been evolving rapidly to enhance a more rapid bone formation on their surface and hold a potential to increase the predictability of expedited implant therapy. While implant outcomes have become highly predictable, there are sites and conditions that result in elevated implant loss. This paper reviews the impact of macro-retentive features which includes approaches to surface oxide modification, thread design, press-fit and sintered-bead technologies to increase predictability of outcomes. Implant designs that lead to controlled lateral compression of the bone can improve primary stability as long as the stress does not exceed the localized yield strength of the cortical bone. Some implant designs have reduced crestal bone loss by use of multiple cutting threads that are closely spaced, smoothed on the tip but designed to create a hoop-stress stability of the implant as it is completely seated in the osteotomy. Following the placement of the implant, there is a predictable sequence of bone turnover and replacement at the interface that allows the newly formed bone to adapt to microscopic roughness on the implant surface, and on some surfaces, a nanotopography (<10(-9) m scale) that has been shown to preferably influence the formation of bone. Newly emerging studies show that bone cells are exquisitely sensitive to these topographical features and will upregulate the expression of bone related genes for new bone formation when grown on these surfaces. We live in an exciting time of rapid changes in the modalities we can offer patients for tooth replacement therapy. Given this, it is our responsibility to be critical when claims are made, incorporate into our practice what is proven and worthwhile, and to continue to support and provide the best patient care possible.

Impact of postmenopausal osteoporosis on the oral and maxillofacial surgery patient

With aging, there is a loss of skeletal mass in women and men, but the rate of loss accelerates in perimenopausal women. With the loss of bone mass there is increased risk for fracture in the axial and appendicular skeleton. The mandible and maxilla also experience age-related declines in some parameters of architecture and trabecular pattern, but those do not seem to be directly associated with fracture risk. Although the literature is controversial regarding the generalizability of the impact of systemic osteoporosis on the oral/maxillofacial patient, it is prudent to give consideration to an individual patient's osteoporosis status, risk, and anti-osteoporosis therapies when planning oral and maxillofacial surgical procedures.

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.

A review of the association between osteoporosis and alveolar ridge augmentation

OBJECTIVE

Because of increasing life expectancy and popularity of dental implants, surgeons face a larger number of osteoporotic patients who require bone augmentation. Relationship between low bone density/osteoporosis and bone graft success is still not clear. The purpose of this article is to review and summarize the literature regarding the success of alveolar bone augmentation in osteoporosis.

STUDY DESIGN

The study design includes a literature review of relevant preclinical and clinical articles that address the association between osteoporosis and alveolar bone augmentation.

RESULTS

Increased rate of complications such as resorption of bone graft, non-integration of bone graft, delayed healing time, and implant failure in augmented bone especially in the maxilla may be associated with compromised bone health.

CONCLUSIONS

Despite the decreased success rate, osteoporosis is not an absolute contraindication for bone augmentation and dental implant placement. The modifiable risk factors for osteoporosis should be eliminated before surgery.

Osteointegration of titanium and hydroxyapatite rough surfaces in healthy and compromised cortical and trabecular bone: in vivo comparative study on young, aged, and estrogen-deficient sheep

The osteointegration rate of titanium (Ti; TI01) and duplex Ti plus HA (HT01) coating systems with high surface roughness was investigated in healthy, aged, and oestrogen-deficient sheep. After having evaluated the bone quality, TI01 and HT01 rods were implanted in the tibial diaphyses (two implants for each tibia) and epiphyses (1 implant for each tibia) of five young (YOUNG), five aged (AGED), and five aged and ovariectomized (OVX) sheep. The iliac crest trabecular bone volume (BV/TV) and number (Tb.N) in OVX sheep were respectively 33.5% and 28.5% lower than in YOUNG sheep (p < 0.005) and lower than in the AGED group (BV/TV, -17%; Tb.N, -13.5%; not significant); in the OVX group the trabecular separation was 77.9% higher than in YOUNG (p < 0.05) and 30.9% higher than in AGED animals. Lumbar vertebrae L5 bone mineral density was significantly lower in AGED (8.9%, p < 0.05) and OVX sheep (19.3%, p < 0.0005) when compared with YOUNG animals. Five samples of five sheep from each group were analyzed for each observation. At 3 months, in cortical bone both affinity index and pushout test results showed no significant differences between the two materials in each group of animals. In trabecular bone, the affinity index of HT01 was significantly higher than that of TI01 in each group of animals (YOUNG, 90.7%; AGED, 76.9%; OVX, 49.9%) with no significant differences between groups. In conclusion, the performance of TI01 and HT01 surfaces was high not only in YOUNG, but also in OVX animals and, therefore, they might be useful for aged and osteoporotic patients.

Reconstruction of the Atrophic Edentulous Maxilla with Free Iliac Crest Grafts and Implants: A 3-Year Report of a Prospective Clinical Study

PURPOSE

The purpose of this study was to perform a longitudinal follow-up study of implant stability in grafted maxillae with the aid of clinical, radiological, and resonance frequency analysis (RFA) parameters.

MATERIALS AND METHODS

The atrophic edentulous maxillae in 29 patients were reconstructed with free iliac crest grafts using onlay/inlay or interpositional grafting techniques. The endpoint of the resorption pattern in the maxilla determined the grafting technique used. Endosteal implants were placed after 6 months of bone-graft healing. Implant stability was measured four times using RFA: when the implants were placed, after 6 to 8 months of healing, after 6 months and 3 years of bridge loading. Individual checkups were performed at the two later RFA registrations after removal of the supraconstructions (Procera Implant Bridge, Nobel Biocare AB, Göteborg, Sweden). Radiological follow up of marginal bone level was performed annually.

RESULTS

Twenty-five patients remained for the follow-up period. A total of 192 implants were placed and with a survival rate of 90% at the 3-year follow up. Women and an implant position with a class 6 resorption prior to reconstruction were factors with significant increased risk for implant failure (multivariate logistic regression). Twelve of the 20 failed implants were lost before loading (early failures). The change in the marginal bone level was 0.3 +/- 0.3 mm between baseline (bridge delivery) and the 3-year follow up. The implant stability quotient (ISQ) value for all implants differed significantly between abutment connection (60.2 +/- 7.3) and after 6 months of bridge loading (62.5 +/- 5.5) (Wilcoxon signed ranks test for paired data, p=.05) but were nonsignificant between 6 months of bridge loading and 3 years of bridge loading (61.8 +/- 5.5). There was a significant difference between successful and failed implants when the ISQ values were compared for individual implants at placement (Mann-Whitney U test, p=.004). All 25 patients were provided with fixed implant bridges at the time of the 3-year follow up.

CONCLUSION

This clinical follow up using radiological examinations and RFA measurements indicates a predictable and stable long-term result for patients with atrophic edentulous maxillae reconstructed with autogenous bone and with delayed placement of endosteal implants. The ISQ value at the time of placement can probably serve as an indicator of level of risk for implant failure.

Experimental evaluation of bone quality measuring speed of sound in cadaver mandibles

OBJECTIVES

To demonstrate in vitro the feasibility of speed of sound (SOS) measurements through the mandible and to investigate the relationships between mandibular SOS, local bone mineral density (BMD), and the ratio between trabecular and cortical thicknesses (Tb.Th/Cort.Th). The long-term goal is to find a safe, simple test for bone quality in sites for dental implant placement.

METHODS

Excised human mandibles (N = 23) were used for the measurement of sound transmission with two 1.6 MHz transducers. Three regions of interest (ROIs) were selected in each of the specimens, namely incisor, premolar, and molar regions. To determine short-term precision, 10 measurements (with repositioning between measures) were performed for each ROI. Local BMD and mandibular cross-sectional morphological characteristics were determined by dual x-ray absorptiometry (DXA) and computed tomography (CT).

RESULTS

The coefficient of variation for SOS was found to be 1%. SOS measurements at different sites were significantly different. A significant linear relationship was found between SOS and BMD (r2 = 0.62; P < .0001), whereas a nonlinear relationship was found between SOS and Tb.Th/Cort.Th (r2 = 0.53; P < .0001).

CONCLUSION

This in vitro study demonstrated the feasibility of SOS measurement through the mandible. Mandibular SOS reflects local BMD and Tb.Th/Cort.Th. In vivo studies are now required to confirm the predictive power of SOS measurement for bone quality assessment and its potential usefulness as a clinical diagnostic technique.

Comparison between jaw bone augmentation by means of a stiff occlusive titanium membrane or an autologous hip graft: a retrospective clinical assessment

OBJECTIVES

Patients in need of bone augmentation procedures can be treated with a traditional hip graft or by neogenesis under a stiff occlusive titanium membrane, custom-fit on the basis of CT-scan data.

MATERIAL AND METHODS

Eighteen patients treated by means of a hip graft (H) were compared with 11 patients using a full titanium membrane (M) for the rehabilitation of upper jaws. In the H group, 17 patients (62 implants) in the anterior region (Ha) and 14 patients (23 implants) in the posterior region (Hp) were included. In the M group, nine patients (30 implants) in the anterior region (Ma) and seven patients (16 implants) in the posterior region (Mp) were included.

RESULTS

In group Ha, the CFR was 13.3% after 14 years compared with group Ma where the CFR was 17.4% after 9 years. In group Hp, the CFR was 22.8% after 16 years compared with group Mp where the CFR was 23.4% after 6 years. The marginal bone loss for group Ha after 20 years was 2.7 mm, for group Ma it was not even 1 mm after 9 years; for group Hp, it was 2.5 mm after 15 years compared with less than 1 mm after 3 years in group Mp.

CONCLUSIONS

The success rate of alveolar ridge augmentation therapy is lower than in a classical approach. These augmentation procedures, however, show acceptable results. The titanium membrane augmentation leads to less marginal bone loss probably because neo-formed bone has a better chance to adapt its mineralization to occlusal forces encountered. This technique could offer improvement if membrane exposure can be avoided.

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.

Implant survival in mandibles of irradiated oral cancer patients

OBJECTIVE

The aim of this study was to analyze long-term implant survival in the mandible after radiotherapy and radical surgery in oral cancer patients.

STUDY DESIGN

Between 1990 and 2003, 71 patients (15 females, 56 males; average age 57.8 years, range 16-84.1 years) were treated with dental implants after radiochemotherapy and ablative surgery of oral cancer. Radiation therapy was delivered in daily fractions of 2 Gy given on 25 days (total dose of 50 Gy). Oral defects were reconstructed microsurgically with jejunal, iliac crest or radial forearm grafts. Thereafter 316 dental implants were placed in the non-irradiated residual bone (84; 27%), irradiated residual bone (154; 49%) or grafted bone (78; 25%) at various intervals (mean interval 1.41 (+/- 1.01) years, range 0.34-6.35 years).

RESULTS

The mean follow-up time after implant insertion was 5.42 (+/- 3.21) years (range 0.3-13.61 years). The overall 2-, 3-, 5-, and 8-year survival rates of all implants were 95%, 94%, 91% and 75%. Forty-four implants were lost in 21 patients during the observation period. Irradiation of the mandibular bone showed significantly (P = 0.0028) lower implant survival compared with non-irradiated mandibular bone. The 8-year survival rate in the non-irradiated residual bone (two loss), irradiated residual bone (29 loss) or grafted bone (13 loss) were 95%, 72% and 54%, respectively. Time of implantation after irradiation showed no statistically significant influence. Implant brand, length or diameter or the incidence of resective surgery on the mandible and gender of patients had no statistically significant influence on implant survival.

CONCLUSION

Radiation therapy with 50 Gy was significantly related to shorter implant survival in mandibular bone. Survival was lowest in grafted bone. Time of implant placement had no statistically significant influence on survival under the conditions of this study. Although implant survival is lower in irradiated mandibles, implants significantly facilitate prosthodontic treatment and enhance outcome of oral rehabilitation in cancer patients.

Significance of osteoporosis in craniomaxillofacial surgery: a review of the literature

Osteoporosis is a common problem in orthopedic surgery. The purpose of this review of the literature was to examine whether osteoporosis is also an important factor in patient treatment in the field of craniomaxillofacial surgery. Emphasis was given to the consequences of osteoporosis for the maxilla and mandible, the influence of osteoporosis on fracture treatment, the use of dental implants, the importance of soft tissues and the effect of osteoporosis therapies. It was found that osteoporosis does affect the bones of the skull. The effect of osteoporosis on treatment, however, is controversial and necessitates better ways of quantifying bone loss. Large inter-individual and site-specific differences in bone density, as well as other effects such as removal of teeth, periodontitis, implant insertion, augmentation procedures and altered loading with dystrophic consequences need to be considered in future studies. Special attention should be given to osteoporosis during fracture treatment.