Development of implant stability during early healing of immediately loaded implants.

PURPOSE: To monitor the development of stability of immediately loaded implants during early healing. MATERIALS AND METHODS: A total of 90 interforaminally placed implants with an alkali-treated surface were considered. The stability of each implant was examined at placement and 1, 2, 3, 4, 5, 6, 8, and 10 weeks after the surgery using resonance frequency analysis (RFA) and damping capacity measurement. The development of implant stability, focusing on the decrease in stability (as measured by implant stability quotient [ISQ]) and the interplay of primary (ISQ0) and secondary implant stability, was evaluated. The implants were divided into three groups based on primary stability: group L (ISQ0 < 68), group M (ISQ0 68 to72), and group H (ISQ0 > 72). Stability curves for each group were created and analyzed statistically. Implant stability measurement results gained with RFA and damping capacity were compared employing the Wilcoxon paired test, correlation coefficients, and regression analysis. The threshold for statistical significance was set at P < .05. RESULTS: The most pronounced decrease in ISQ values occurred 1 week after implant placement (mean decrease of 2.2 ISQ). During the 10-week experiment, mean ISQ rose by 5.5 in group L and by 1.3 in group M and dropped by 1.8 in group H (P < .001). The coefficient of determination R2 = 0.06 showed a weak dependence of RFA on the damping capacity (P < .001). CONCLUSIONS: Implants with low primary stability showed a significant increase in stability during healing. In contrast, implants with high primary stability lost some stability over time.

Relationship between subsinus bone height and bone volume requirements for dental implants: a human radiographic study.

PURPOSE: To analyze the vertical dimension of subsinus alveolar bone that is available for placement of endosseous implants. MATERIALS AND METHODS: Subsinus alveolar bone height (SBH) was determined via radiographs and categorized into three groups: Group A corresponded to SBH < 5 mm; group B SBH of 5 to 9 mm; and group C, SBH > 9 mm. Statistical analysis was carried out using the Wilcoxon paired test with the threshold for statistical significance set at P < .05. RESULTS: Five hundred eighty-three panoramic radiographs of edentulous maxillae were analyzed. In 96.9% of radiographs, the anterior border of the maxillary sinus was above the first premolar. Mean SBH values for canine, first premolar, second premolar, first molar, and second molar sites were 11.4 ± 6.2 mm, 10.6 ± 3.8 mm, 5.9 ± 2.5 mm, 3.3 ± 2.2 mm, and 4.5 ± 2.4 mm, respectively. Representations of groups A, B, and C in the canine region were 14.3%, 21.4%, and 64.3%, respectively; in the first premolar region they were 8.3%, 22.3%, and 69.4%, respectively; in the second premolar region, these were 31.6%, 60.9%, and 7.5%, respectively; in first molar region, the values were 73.1%, 25.4%, and 1.5%, respectively; and in the second molar region they were 54.2%, 41.7%, and 4.1%, respectively. CONCLUSIONS: The mean SBH is the highest in the area of the anterior border of the sinus; it declines significantly toward the posterior maxilla, reaches its minimum in the area of the first molar, and increases again significantly in the second molar region. From a clinical point of view, the lateral window technique of sinus elevation remains the dominant augmentative procedure in the molar area, whereas in the premolar area, less invasive alternative methods may be more appropriate.

The analysis of forces needed for the suturing of elliptical skin wounds.

There is a lack of information regarding the forces required for suturing human wounds. The knowledge of suturing forces serves as complementary information for setting up the limiting geometry when using tissue adhesives and it might also be used in robot-assisted surgery. The main purpose of this paper was to evaluate the forces required for suturing selected skin wounds. An elliptical wound was chosen for our study. In this study a numerical analysis and in vivo experiments were performed. Regarding the numerical models, the maximum forces occurred in the middle of the elliptical wound in all cases. In the case of highest pre-stress used in these analyses the maximal force varied from 0.5 N for the smallest wound (30 × 5 mm) to 1.5 N for the largest wound (30 × 15 mm). The maximum peak force for the wound with a size of 46 × 13 mm was 3.2 N. The minimum peak force for the wound with a size of 36 × 5 mm was 1.1 N.

Changes in stability after healing of immediately loaded dental implants.

PURPOSE: To investigate the parameters that affect primary stability of dental implants, to determine how primary stability influences posthealing stability, and to ascertain the effect of primary stability and insertion parameters on marginal bone loss. MATERIALS AND METHODS: A total of 940 immediately loaded implants were considered. Using resonance frequency analysis, primary stability (primary implant stability quotient [pISQ]) and stability after 4 months (tISQ) were recorded. When the differences between pISQ and tISQ exceeded 5 units, marginal bone loss was measured. The implants were placed into three groups based on their primary stability: high (pISQ > 72), moderate, and low (pISQ < 68). Changes in stability after 4 months of loading were evaluated. The relationships between pISQ, insertion parameters, DISQ (ie, tISQ - pISQ), and marginal bone loss were analyzed. The Student t test, one-way analysis of variance, and Spearman nonparametric correlation coefficient were employed for statistical evaluation. RESULTS: Of the 940 implants, tISQ was recorded in 526 implants and marginal bone loss was measured in 76 implants. There was no statistical relationship between pISQ and insertion torque. Primary stability was influenced by implant diameter but not by implant length. There was a significant relationship between implant insertion torque and bone type. The low primary stability group showed a significant increase in stability during healing. However, high primary stability implants demonstrated a significant reduction in their stability. The linear regression analysis demonstrated that at a pISQ of 69.2, tISQ value would equal pISQ value. Correlations between marginal bone loss and final insertion torque and between marginal bone loss and DISQ values were observed. CONCLUSIONS: Stability of immediately loaded implants with high pISQ decreased significantly during the initial 4 months of healing. However, stability of implants with low primary stability increased significantly. DISQ and insertion torque showed correlation with marginal bone loss.

Influence of the orientation of the Osstell transducer during measurement of dental implant stability using resonance frequency analysis: a numerical approach.

Stability of dental implants is measured by means of the Osstell device using a method of resonance frequency analysis. The aim of the study was to evaluate the role of direction-dependence of the Osstell transducer. For this purpose, a set of parametrical finite element analyses has been used. When rotating the transducer around the vertical axis the crucial phenomenon is the change in behavior of the system, which occurs in positions between 30 degrees and 80 degrees to the long axis of the alveolar crest. It seems from the presented results that, when measuring approximately perpendicularly to this long axis, the deviation from the ideal perpendicular position must not exceed 30 degrees. In this case, the first resonance frequency is recorded. When measuring in the approximately parallel position to the long axis of the alveolar crest, the second resonance frequency is recorded. The deviation from the ideal parallel position must not exceed 10 degrees. These values are not comparable with the previous ones.

Deproteinized bovine bone versus beta-tricalcium phosphate in sinus augmentation surgery: a comparative histologic and histomorphometric study.

PURPOSE: To compare the efficacy of 2 common materials in sinus augmentation surgery and to assess their contribution when enriched with autogenous bone. MATERIALS AND METHODS: The prospective human study was performed in 48 sinus grafting operations using beta-tricalcium phosphate or deproteinized bovine bone (pure or mixed with 10% to 20% autogenous bone) or autogenous bone. Biopsy specimens were taken after 9 months. Statistical evaluation was done with a 2-sample t test (P < .05). RESULTS: When autogenous bone was used, 49.2% +/- 3.1% of new bone was found, which is significantly higher than in all the other groups. A higher proportion (34.2% +/- 13.1%) of the new vital bone was found in the deproteinized bovine bone group, in comparison with the beta-tricalcium phosphate group (21.4% +/- 8.1%) and the beta-tricalcium phosphate composite graft group (24.0% +/- 6.6%; P < .05). No significant differences between single-component grafts and corresponding composite grafts were established. CONCLUSIONS: Sinus augmentation with the aforementioned augmentation materials is a well-accepted procedure. However, autogenous bone alone was the best material. More new bone was found using deproteinized bovine bone than beta-tricalcium phosphate. The addition of 10% to 20% autogenous bone to the bone substitute did not significantly influence the new bone formation.

Soft tissue esthetics in implant dentistry.

Dental implants have been considered to be a successful treatment modality. Recently, achieving a good osseointegration is not the ultimate goal for the restorative dentist. Successful implant treatment demands the best gingival esthetic success along with stability and function of the implant. This study was performed to obtain answers to some controversial points pertaining to esthetics and function of implants in maxilla. Immediate flapless implantation into the extraction sockets in maxillary anterior zone is an emerging treatment option in dentistry--the esthetic success of which was in debate for long. The proposed study compared the esthetic success of immediate flapless implants (ILA), to immediate implants with the need for flap (ILB) and, delayed implants (DSL) in single tooth restorations, in the anterior region of the maxilla. The other aim of the study was to find out if any relation exists between the interproximal crestal bone height and papilla height. Analysis was done irrespective of treatment procedure in the same study group using periodontal sounding and radiographs to find out the relation. From the study involving 106 participants, including 21 ILA, 22 ILB and 63 DSL cases, we received highest papillary index score of 2.6 average from group ILA, followed by ILB and DSL, after 3 months of prosthetic loading. From the periodontal sounding and radiographic study it was evident that, when the distance between the base of the contact point of crowns and height of interproximal bone was less than 5, the papilla was present 100% of the time, but when the distance increased to 6 and more than 7 mm, the papilla was present only 46.5 and 24 percentage of the time respectively.

Evaluation of the success of beta-tricalciumphosphate and deproteinized bovine bone in maxillary sinus augmentation using histomorphometry: a review.

Sinus lift operations have become a prerequisite for implantologists in the rehabilitation of atrophic posterior maxilla. Alloplasts and xenografts are the recent innovation in the world of grafting materials and have evolved in such a way as to compensate the need for autografts to be used in conjunction. In order to perfect the grafting materials, histomorphometry is the most often tool used to study the success of the augmentation. This article has tried to commemorate the importance of histomorphometry in maxillary antroplasty and also the success rate of beta-tricalciumphosphate and deproteinized bovine bone as an augmentation material in maxillary augmentation.

Aesthetics in implantology.

Aesthetics in implantology is a topic currently attracting lot of attention from dental implantologists all over the world. It includes both white and red aesthetics with much greater importance been given to the red aesthetics. In this article, both hard tissue and soft tissue procedures and techniques, used in the development of implant recipient sites will be presented and discussed, briefly outlining the treatment planning and also various dental materials used in enhancing aesthetics in implant restorative procedures.

Hardness of covalent and ionic crystals: first-principle calculations.

A new concept, the strength of bond, and a new form expressing the hardness of covalent and ionic crystals are presented. Hardness is expressed by means of quantities inherently coupled to the atomistic structure of matter, and, therefore, hardness can be determined by first-principles calculations. Good agreement between theory and experiment is observed in the range of 2 orders of magnitude. It is shown that a lower coordination number of atoms results in higher hardness, contrary to common opinion presented in general literature.

The sinus lift with phycogenic bone substitute. A histomorphometric study.

OBJECTIVES: The aim of this histomorphometric prospective study was to ascertain the efficacy of phycogenic bone substitute in an augmented sinus. The process of graft healing, bone remodeling, and biomaterial replacement was examined. MATERIAL AND METHODS: The phycogenic material (fluorohydroxyapatite) made from calcium-encrusted sea algae was used for the sinus lifts. Twenty-four procedures were carried out (one-stage and two-stage equally) and 45 titanium stepped-screw implants were placed. The patients were followed for 12-23 months. In intervals of 6, 9, 12, or 15 months after the sinus lift, 24 graft specimens were taken with a trephine bur. These specimens were examined histomorphometrically. RESULTS: The grafting material was gradually resorbed and replaced by newly formed bone. Between the sixth and 15th month after the sinus lift, the percentage of newly formed bone grew linearly (from 15.5+/-9.6% to 40.8+/-15.3%) and the percentage of bone substitute decreased linearly (from 34.5+/-8.6% to 13+/-9.6%). After 15 months, the density of trabeculae in grafted bone corresponded to cancellous bone of good quality; however, the bone substitute was not completely resorbed during this period. No significant difference between the quality of the newly formed bone in the cases of the one- and two-stage sinus lifts was found. CONCLUSION: Sinus lift carried out with phycogenic bone substitute was shown to be an effective method with limited invasiveness and a high survival rate of implants (97.8%).

One-stage maxillary sinus grafting using a modified surgical concept.

This modified surgical procedure that permits an implantation simultaneously with sinus floor elevation procedure even when the original bone is very thin. The surgical technique and its benefits were described and discussed.

Can we predict maxillary sinus mucosa perforation?

This study was carried out to evaluate the prevalence of sinus mucosa perforation occurred during maxillary sinus mucosa elevation surgery, its relation to objective conditions and to the causative medical history, and its influence on postoperative sinusitis, as well. One hundred and forty-six sinus lift procedures have been evaluated in 118 patients. The prevalence of the sinus mucosa perforation was evaluated and subdivided into four groups according to its size and way of treatment. No relation was observed between the perforation and the presence of sinus septa, smoking, radiographic thickening and cyst-like lesions of the maxillary sinus, and previous sinus allergy (P < 0.05). Despite of high prevalence of the perforation of the mucosa (56.16%), no signs of bone graft infection or maxillary sinusitis were noted in any of our patient.

Evaluation of stability of titanium and hydroxyapatite-coated osseointegrated dental implants: a pilot study.

An endosseous implant is described as osseointegrated when it is immobile in function. Objective measures of stability testing have been described. The Periotest is a commercially available device that is used for this purpose. This study was designed to measure stability of endosseous implants placed in the mandible. Implants were placed in the mandibular canine or first premolar area to support an overdenture prosthesis. Stability was evaluated through the use of a Periotest device at the time of implant placement and following one year of functional loading. Implant designs were either a screw-shaped titanium alloy or a hydroxyapatite-coated cylinder. A total of 54 implants were placed, 37 were titanium screw-shaped implants, while the remaining 17 were hydroxyapatite cylinders. Initial measurements of stability showed no difference due to implant type. Following one year of functional loading, titanium screw-shaped implants were more stable than hydroxyapatite implants (P < 0.05). The difference in implant rigidity following a period of functional loading may be an indication of a difference in osseointegration between the two implants used in this study.

Maxillary sinus augmentation with deproteinized bovine bone (Bio-Oss) and Impladent dental implant system. Part II. Evaluation of deprotienized bovine bone (Bio-Oss) and implant surface.

The objective of this clinical study was to determine the predictability of endosseous implant placed in a maxillary sinus augmented with deproteinized bovine bone (Bio-Oss). A total of 185 implants (109 titanium and 76 hydroxyapatite-coated) were placed in 77 patients representing 92 sinuses either a one- or two-stage surgical technique. A mixture of venous patient's blood and Bio-Oss was used alone within 20 sinuses (Group 1), or in combination with autogenous bone within 72 sinuses (Group 2). Thirty-nine implants were placed in Group 1 and 147 implants were inserted in Group 2. The grafted sinuses were evaluated clinically and radiographically at second stage surgery. According to certain criteria, of the implants placed, only two titanium implants (1.08%) failed with 98.91% implant survival. There was no statistically variable difference for the use of hydroxyapatite-coated or titanium implants. The two failed implants were from Group 2. No clinical benefit has been achieved from the combination with autogenous bone (P<0.05). All the grafted sinuses were sufficient to place dental implants of at least 12 mm length (100% graft success). The results of this short-term study support the hypothesis that Bio-Oss can be a suitable material for sinus augmentation.

Evaluation of the accuracy of panoramic radiograph in the definition of maxillary sinus septa.

The purpose of this study was to determine the accuracy of panoramic radiography in identification of maxillary sinus septa. Out of 68 sinuses were radiographically examined using both panoramic and computerized tomographic radiographs (CT scan). Using CT scan, 24 (35.9%) out of 68 cases maxillae showed at least one septum, 22 sinuses (32.3%) showed one septum, whereas two sinuses (2.9%) exhibited two septa. Panoramic radiograph led to a false diagnosis regarding the presence or absence of sinus septa in 18 of 68 sinuses (26.5%). On the other hand, they gave negative diagnosis of sinus septa in 12 of 24 septa (50%). There was fully agreement between the two methods (positive septa) only in 12 of 24 septa (50%). We cannot depend on panoramic radiograph for the detection of sinus septa because it can lead to false or negative results.

Maxillary sinus augmentation using deproteinized bovine bone (Bio-Oss) and Impladent Dental Implant System. Part I. Comparison between one-stage and two-stage procedure.

This study was undertaken to compare implant survival after one- or two-stage sinus augmentation. Ninety-two maxillary sinuses in 77 patients were augmented with deproteinized bovine bone (Bio-Oss). These sinuses were sub-divided into two groups: Group 1 (n = 49) was operated on with a one-stage procedure, and Group 2 (n = 43) with a two-stage operation. A hundred and eighty-five implants were inserted in these augmented sinuses. Clinical and radiographical evaluations were performed and recorded according to certain criteria. The follow-up period was ranging from 16 to 44 months. Out of the implants inserted using the one-stage procedure, all survived. Two implants failed in the two-stage procedure group (98.91% implant survival). This study showed that no statistically significance was observed between the two surgical techniques (P < 0.05). Therefore, the authors concluded the type of surgical procedure (one- or two-stage) has no effect on implant survival.