Enhancing primary implant stability by undersizing implant site preparation: A human cadaver study.

INTRODUCTION: The aims of this human cadaver study were to analyze the primary stability of dental implants inserted by using different methods of preparation and to explore correlations among the bone density, peak insertion torque and resonance frequency analysis values. MATERIALS AND METHODS: Forty-eight implants were placed into six human cadaver mandibles. The bone density of each implant recipient site was preoperatively measured by using computerized tomography (CT) in Hounsfield Units (HU). Three test groups were created according to the final drill size. The diameters of the final twist drills were 3 mm, 3.4 mm, and 3.8 mm in group T1, group T2, and group T3, respectively. The peak insertion torque and resonance frequency analysis values were recorded. RESULTS: The mean bone density, insertion torque, and RFA values were 285 ± 90 HU, 42.8 ± 5 Ncm, and 74 ± 6 ISQ for all 48 implants, respectively. Statistically significant correlations were noted between bone density and insertion torque values (P < 0.05), bone density and RFA values (P < 0.01), and insertion torque and RFA values (P < 0.001). When considering the three test groups, the mean insertion torque, and RFA values were 47.1 ± 3 Ncm, and 83.1 ± 6 ISQ in Group T1, and 43.4 ± 5 Ncm and 73.4 ± 6 ISQ in Group T2, and 37.9 ± 6 Ncm, and 65.3 ± 5 ISQ in Group T3. CONCLUSION: The results of this study suggest that undersized implant site preparations may be helpful in enhancing primary implant stability and that there are significant correlations among bone density, maximum insertion torque, and RFA values.

Evaluation of maxillary sinus septa: a retrospective clinical study with cone beam computerized tomography (CBCT).

OBJECTIVE: To determine the prevalence, height, location, orientation, and type of maxillary sinus septa in atrophic, non-atrophic, and partially atrophic maxillary segments using cone beam computerized tomography (CBCT). PATIENTS AND METHODS: This cross-sectional study was conducted on a retrospective evaluation of CBCT images of 1000 maxillary sinus with 500 subjects from December 2009 to December 2012. The differences among gender, left and right side of maxillary sinus, type of crest and feature of septa were statistically analyzed. RESULTS: A total of 297 septa was recorded in 1000 maxillary sinuses (29.7%) with a mean height was 4.62±2.50 mm. Forty-four (8.7%) septa were located in the anterior area, 123 (24.5%) in the middle area, and 131 (26.4%) in the posterior area. Seventy maxillary sinus septa (26.1%) were observed with a mediolateral type orientation. There were no significant differences between all features of maxillary sinus septa and gender or type of crest. The only significant association identified was between type of crest and type of septa. CONCLUSIONS: The maxillary sinus septa exhibited variable characteristics according to orientation and type of crest. CBCT analysis is very important and should be performed before maxillary sinus surgery to prevent possible complications.

Which device is more accurate to determine the stability/mobility of dental implants? A human cadaver study.

Non-invasive devices including resonance frequency (RF) analysis and mobility measuring (MM) damping capacity assessment are used to measure implant stability/mobility. The aims of the study were to compare the primary stability of implant inserted into extraction sockets by using RF with cable, RF wireless and new wireless MM device, to clarify the relation between these devices and to understand the correlations between peri-implant bone levels and implant stability. A total of 30 screw-type implants (3.75 x 11 and 4.2 x 11 mm) were inserted into extraction sockets of eight mandibular pre-molar regions of human cadavers. The primary stability of implants was measured by three devices after insertion. Peri-implant vertical defects were created in millimetre increments ranging between 0 and 5 mm, and stability/mobility of implants were analysed. At placement, the mean implant stability quotient of RF with cable, RF wireless and MM device values was 46 +/- 1, 57.8 +/- 9 and -5.4 +/- 1, respectively. Statistical correlations were demonstrated between these devices (P = 0.001). Statistically significant differences were presented for all peri-implant detects ranging between 0 and 5 mm for RF with cable and RF wireless at all increments. However, only a significant decrease was found between 0 and 1 mm defects, and 4 and 5 mm defects in MM device. Although RF with cable and RF wireless seem to be suitable to detect peri-implant bone loss around implants in 1 mm increments, the new MM device may not be suitable to detect the 1 mm peri-implant bone changes in human dried cadaver mandibles.

Clinical study on the insertion torque and wireless resonance frequency analysis in the assessment of torque capacity and stability of self-tapping dental implants.

Resonance frequency (RF) analysis is a non-invasive, objective and sensitive technique developed for implantology where it measures the stability of the implant in osteotomy site. Although many studies were performed by the previous electronic version of RF analyzer, a very limited number of studies were carried out with the new magnetic wireless version. The aim of the study was to evaluate the relation between insertion torques, primary and secondary stability of self-tapping tapered implant systems. Thirteen subjects were treated with 42 endosseous implants using two-stage surgical procedure. The maximal insertion torque values were recorded prior to RF analysis during surgery. Six months after surgery, the secondary stability values were measured by the RF analysis. The average maximal insertion torque and primary and secondary magnetic RF values were 33 +/- 11 N cm and 66 +/- 12 ISQ and 71.9 +/- 6 ISQ for 42 implants respectively. The correlation between insertion torque and RF values were indicated to be statistically significant (P < 0.01). Significantly higher maximal insertion torque, and primary and secondary magnetic RF values were achieved in mandibular sites compared with maxillary areas (P < 0.01). No significant differences were measured for all parameters when both systems were compared with each other (P > 0.05). There was a strong correlation between the insertion torque, primary and secondary magnetic RF values of self-tapping tapered endosseous implant used. Further studies are needed to understand the impact of the wireless magnetic RF analysis technique in clinics.

Possible impact of inflammatory status on C-telopeptide pyridinoline cross-links of type I collagen and osteocalcin levels around oral implants with peri-implantitis: a controlled clinical trial.

Detection of progression level of peri-implantitis may help in the prevention of oral implant failure. C-telopeptide pyridinoline crosslinks of Type I collagen (ICTP) and osteocalcin (OC) are specific markers of bone turnover and bone degradation. Determination of the ICTP and OC levels in the peri-implant sulcus fluid (PISF) may predict the metabolic and/or inflammatory changes in the peri-implant bone. The aim of this clinical study was to evaluate ICTP and OC levels in the PISF for oral implants with and without peri-implant bone destruction and correlate these levels with the traditional clinical peri-implant parameters (probing depth, plaque index, gingival index and gingival bleeding time index) and radiographic bone level measurements. Fifteen patients with 30 peri-implant sites with bone destruction (radiographic bone loss) and health were included. Clinical parameters were measured and PISF was collected from the sites. Peri-implant sulcus fluid ICTP and OC levels were detected by radioimmunoassay technique from PISF samples. All clinical parameters demonstrated a significant increase in peri-implantitis sites compared with healthy sites. The PISF volume of the peri-implantitis sites was also significantly higher than of the healthy peri-implant sites. Although not statistically significant, a trend of increase was demonstrated in ICTP PISF samples sampled from peri-implantitis sites compared with healthy sites. A significant increase was noticed for OC PISF level in peri-implantitis sites compared with healthy ones. As well as peri-implant clinical measurements, volumetric changes at PISF may be counted as an important clinical parameter to distinguish the bone destruction sites from healthy sites around oral implants.

Relationships between implant stability, image-based measures and nitric oxide levels.

For monitoring of dental implants, practitioners seem to use simultaneously a variety of image-based and laboratory measurements. This longitudinal study was conducted to analyse the possible relationships between nitric oxide (NO) content of peri-implant sulcus fluid (PISF), marginal bone levels and implant stability in terms of resonance frequency analysis (RFA) at immediately (IL) and conventionally (CL) loaded mandibular molar dental implants from the same individuals. Dental implants were placed in 10 patients who had first molar loss bilaterally in the mandibular area. One site of the patient was determined as IL and the other site was CL. PISF samples, marginal bone level and RFA were taken for all dental implants during a 12-month follow-up period. For both types of loading, there were no significant changes at implant stability (ISQ) and PISF volume during the whole study period. The lowest total nitrite levels were observed at the end of 12 months. Marginal bone gain of 0.22 and 0.09 mm was noticed between 6 and 12 months in IL and CL groups, respectively. During the study period, negative correlation was noted between radiographic bone level and ISQ at both IL and CL sites; however, this correlation reached a significant level only at 6 months in CL implant group (P = 0.015). Although not significant, marginal bone loss seems to have a negative relationship with the implant stability values regardless of the mode of loading. NO metabolism around IL and CL dental implants may not demonstrate a significantly different pattern.

Relationship between dental implant stability determined by resonance frequency analysis measurements and peri-implant vertical defects: an in vitro study.

Resonance frequency (RF) analysis is a non-invasive and objective technique developed for implantology, where it measures the stability of the implant in the bone socket. A limited number of studies were performed to compare different stability measurement devices. The aim of the study was to evaluate the association between the implant stability and peri-implant vertical defect by using the new wireless RF analyser. Micro-textured rough-surfaced implants with diameters of 3.7 and 4.8 mm and with a length of 12 mm were used. The peak insertion torque was recorded with the help of the torque control system only during the implant placement. The peri-implant defects were created in millimetre increments ranging between 0 and 5 mm to the same extent on all implants. The RF analysis values were measured by using the RF analyser. Significant correlation was found between insertion torque (44.3 +/- 3 N cm) and implant stability quotient (ISQ) (all implants: r = 0.76, 3.7 mm diameter: r = 0.65, 4.8 mm diameter: r = 0.80). For 3.7 x 12-mm(2) implants, the mean ISQ values were 72.6 +/- 2.4, 69.8 +/- 2, 67.2 +/- 1.8, 64.3 +/- 1.9, 61.2 +/- 2 and 57.2 +/- 2.5 when peri-implant vertical defects were 0, 1, 2, 3, 4 and 5 mm; and the corresponding values were 76.5 +/- 2.2, 74.5 +/- 2.2, 72.3 +/- 2, 70 +/- 1.9, 67 +/- 1.9 and 63.4 +/- 2.3, respectively, for 4.8 x 12-mm(2) implants. All values were significantly different when compared with each other. The wireless RF analyser seems to be a suitable and reliable device to determine the implant stability. Peri-implant bone loss simulated by using acrylic models may result with a decrease in ISQ values for osseo-integrated implants measured by the RF analyser.

Analysis of the possibility of the relationship between various implant-related measures: an 18-month follow-up study.

Better clarification of the long-term relationship among the various implant-related measures could improve the evaluation process for dental implants. Thus, the aim of the present study was to determine the potential correlations among the volumetric features and nitric oxide content of peri-implant sulcus fluid (PISF) and measures of implant stability, and the marginal bone loss. Completely edentulous patients (n=15) treated with dental implants and ball attachment mandibular over dentures were included. Resonance frequency analysis (RFA), marginal bone level measurements, PISF volume and spectrophotometrically determined nitrite levels were recorded for all dental implant sites. Measures for early (n=16) and delayed (n=14) loaded dental implants were comparatively analysed for a period of 18 months. Some random correlations between PISF volume and marginal bone level, PISF nitrite level and marginal bone level and PISF volume and PISF nitrite content, and RFA and PISF volume were observed. However, the only constant correlation was noticed between implant stability (RFA scores) and marginal bone level. This correlation was negative and significant for all dental implants and for delayed loaded implants (P<0.05). The pattern of loading seemed to affect the extent, but not the pattern of this relationship. While some of the implant-related measures may be strongly associated (e.g. dental implant stability and marginal bone level), not all measures from a single implant site are likely to be related. Such associations may be under the influence of a variety of factors including the loading protocol of dental implants.

Bone density assessments of oral implant sites using computerized tomography.

The type and architecture of bone are considered to affect its load-bearing capacity and it has been indicated that poorer quality bone is associated with higher implant failure rates. To date, bone classifications have only provided subjective methods for pre-operative assessment, which can be considered unreliable. The aim of this study was to evaluate variations of the bone density in designated endosseous implant sites using computerized tomography. One hundred and thirty-one designated implant sites in 72 patients were utilized. Computerized tomography results indicated that bone densities may vary markedly when different areas of a designated implant site are compared. It has been observed that a difference in the bone density exists for the four regions within the oral area, with the anterior mandible yielding mean density values of 944.9+/-207 Hounsfield units (HU)>anterior maxilla, 715.8+/-190 HU>posterior mandible, 674.3+/-227 HU>posterior maxilla and 455.1+/-122 HU. Computerized tomography may be a useful tool for determining the bone density of interest areas before implant placement, and this valuable information about the bone quality provides dental practitioners to make better treatment planning regarding the implant positions.

Assessment of correlation between computerized tomography values of the bone, and maximum torque and resonance frequency values at dental implant placement.

The aim of this study was to determine the bone density in the designated implant sites using computerized tomography (CT), the fastening torque values of dental implants, and the implant stability values using resonance frequency analysis. Further aim was to evaluate a possible correlation between bone density, fastening torque and implant stability. Eighty-five patients were treated with 158 Brånemark System implants. CT machine was used for preoperative evaluation of the jawbone for each patient, and bone densities were recorded in Hounsfield units (HU). The fastening torque values of all implants were recorded with the OsseoCare equipment. Implant stability measurements were performed with the Osstell machine. The average bone density and fastening torque values were 751.4 +/- 256 HU and 39.7 +/- 7 Ncm for 158 implants. The average primary implant stability was 73.2 +/- 6 ISQ for seventy implants. Strong correlations were observed between the bone density, fastening torque and implant stability values of Brånemark System TiUnite MKIII implants at implant placement (P < 0.001). These results strengthen the hypothesis that it may be possible to predict and quantify initial implant stability and bone quality from pre-surgical CT diagnosis.

Effects of endogenous sex hormones on the periodontium--review of literature.

Hormones are specific regulatory molecules that have potent effects on the major determinants of the development and the integrity of the skeleton and oral cavity including periodontal tissues. It is clear that periodontal manifestations occur when an imbalance of these steroid hormones take place. The authors conducted a Medline search up to 2004 and in addition, a manual search was also performed including bibliographies of relevant papers, review articles and books. This review focuses on the effects of endogenous sex hormones on the periodontium and the goal was to inform and update practitioners' knowledge about the impact of these hormones on periodontal status. In addition, this review article will analyze how these hormones influence the periodontium at different life stages such as puberty, menstruation, pregnancy, menopause and post-menopause. Moreover, the effects of contraceptives and hormone replacement therapies on the periodontium will be discussed. It is clear that endogenous sex steroid hormones play significant roles in modulating the periodontal tissue responses. A better understanding of the periodontal changes to varying hormonal levels throughout life can help the dental practitioner in diagnosis and treatment.

Effects of sex steroid receptor specificity in the regulation of skeletal metabolism.

The interaction between estrogens and androgens, with their protective effects in bone, and parathyroid hormone (PTH), a calcitropic peptide hormone, is complex but may be better understood with murine models. The purpose of this study was to characterize skeletal phenotypes of mice deficient in estrogen receptor alpha (ERalpha), androgen receptor (AR, mutant tfm), or both, and determine if ERalpha and AR alter osteoblast differentiation and/or PTH response in vitro. Loss of ERalpha resulted in increased long bone length in females, but reduced length in males, suggesting loss of ERalpha reversed sex steroid-dependent skeletal dimorphism. The AR deficient tfm mice (genetically male but phenotypically female) had the longest bones and, similar to males, lengths were reduced with loss of ERalpha. Loss of AR and/or ERalpha resulted in a reduction in femoral bone mineral density (BMD) compared to male wildtype (WT) mice, suggesting tfm mice follow the female sex for BMD. In males or tfm mice, but not females, loss of AR and/or ERalpha caused a reduction in cortical width of the tibia compared to male WT mice. Reduced trabecular bone was found in tibiae of female and tfm mice versus male littermates, suggesting that tfm mice follow the female sex for trabecular bone but loss of ERalpha did not alter trabecular bone levels. Primary calvarial osteoblasts of male WT mice were less responsive to PTH stimulation of cAMP than all other genotypes, suggesting the female chromosomal sex and/ or loss of ERalpha or AR results in increased sensitivity to PTH. In conclusion, tfm mice follow the male pattern of long bone development, but imitate females in bone density and trabecular bone. Loss of ERalpha and/or AR results in increased osteoblast sensitivity to PTH and may explain actions of PTH noted in hypogonadal humans.

Transgenic models of metabolic bone disease: impact of estrogen receptor deficiency on skeletal metabolism.

Estrogen has protective effects on the skeleton via its inhibition of bone resorption. Mechanisms for these effects and the selectivity to the estrogen receptor alpha (ER alpha) or ER beta are unclear. The purpose of our study was to determine the impact of the ER alpha on skeletal metabolism using murine models with targeted disruption of the ER alpha and beta. Mice generated by homologous recombination and Cre/loxP technology yielding a deletion of the ER alpha exon 3 were evaluated and also crossed with mice with a disruption of the exon 3 of the ER beta to result in double ER alpha and ER beta knockout mice. Skeletal analysis of long bone length and width, radiographs, dual X-ray absorptiometry, bone histomorphometry, micro computerized tomography, biomechanical analysis, serum biochemistry, and osteoblast differentiation were evaluated. Male ER alpha knockout mice had the most dramatic phenotype consisting of reduced bone mineral density (BMD), and bone mineral content (BMC) of femurs at 10 and 16 weeks and 8-9 months of age. Female ER alpha knockout mice also had reduced density of long bones but to a lesser degree than male mice. The reduction of trabecular and cortical bone in male ER alpha knockout mice was statistically significant. Male double ER alpha and ER beta knockouts had similar reductions in bone density versus the single ER alpha knockout mice suggesting that the ER alpha is more protective than the ER beta in bone. In vitro analysis revealed no differences in osteoblast differentiation or mineralized nodule formation among cells from ER alpha genotypes. These data suggest that estrogens are important in skeletal metabolism in males; the ER alpha plays an important role in estrogen protective effects; osteoblast differentiation is not altered with loss of the ER alpha; and compensatory mechanisms are present in the absence of the ER alpha and/or another receptor for estrogen exists that mediates further effects of estrogen on the skeleton.

Relationship between the quantity of gingival crevicular fluid and clinical periodontal status.

In order to analyze the possible relationship between the quantity of gingival crevicular fluid (GCF) and clinical periodontal status, the severity of gingival inflammation (gingival index (GI) scores) and probing depth (PD) were recorded and GCF samples were obtained from 1,111 sites. These sites were further analyzed on the basis of distinct tooth groups to evaluate the significance of particular anatomical sampling locations. Statistical analysis of cumulative data showed significant increases in GCF volume with greater GI scores and PD. Correlations between GCF volume and both of the clinical measures were also strongly positive and significant for all sites. However, significant differences in GCF volume were observed between the anterior and posterior sampling sites. Increases in volume with increasing GI and PD were more marked for incisor and canine teeth. Similarly, the relationship between the quantity of GCF and clinical periodontal status was more clear and absolute in the anterior region than in the premolar and molar areas. These findings suggest that the quantity of GCF is not constant throughout the entire dentition, and that the relationship between GCF measurements and clinical periodontal status is site-based. This unique feature of GCF seems to be an essential factor in the design of GCF-related studies.