Investigation to Predict Primary Implant Stability Using Frictional Resistance Torque of Tap Drilling

Objectives

The purpose of this experimental study was to investigate the correlation between the frictional resistance torque of tap drilling prior to implant placement and the primary stability after implant placement.

Material and Methods

Solid rigid polyurethane bone blocks of four different densities were used in this study. A computerized surgical implant motor device was utilized to measure the frictional resistance torque of tap drilling. After the tap torque was measured, the dental implants were inserted at the prepared sites. During the implantation, the insertion torque was recorded, and resonance frequency analysis was performed, the value of which was calculated as the implant stability quotient. Thereafter, the correlation between the tap torque and the primary stability of the implant was evaluated and compared with the standard drilling protocol.

Results

A significant positive correlation was found between the tap torque and insertion torque (Pearson's r = 0.88, P < 0.0001). Similarly, there was a positive correlation between the tap torque and implant stability quotient (Pearson's r = 0.69, P < 0.0001).

Conclusions

These results suggest that measurement of the frictional resistance torque of tap drilling prior to implant placement could provide helpful information for implant primary stability.

Inflammatory infiltrate, microvessel density, vascular endothelial growth factor, nitric oxide synthase, and proliferative activity in soft tissues below intraorally welded titanium bars

BACKGROUND

The aim of the present study is a comparative evaluation of inflammatory infiltrate, microvessel density, vascular endothelial growth factor, nitric oxide synthase, and proliferative activity in soft tissues below intraorally welded titanium bars.

METHODS

Twenty-two patients participated in this study. All patients carried immediately loaded one-stage titanium implants splinted with intraorally welded titanium bars. Each patient underwent two gingival biopsies, a control biopsy harvested from an area of mucosa 5 mm away from the titanium bar and a test biopsy from the mucosa below the titanium bar, which were histologically and immunohistochemically processed.

RESULTS

No fractures or radiographically detectable alterations of the welded frameworks were present. In all the cases examined, the average of the modified plaque index was 1, no suppuration or bleeding on probing was present, and probing depth was < or =3 mm. However, the immunohistochemical analysis revealed some differences. The inflammatory infiltrate was mostly present in test sites and its extension was much larger than in control sites. Statistically significant differences were found in microvessel density and Ki-67 expression among control and test groups (P <0.0001). The high intensity of vascular endothelial growth factor, nitric oxide synthase 1, and nitric oxide synthase 3 expression were mainly detected in the test group, whereas the low intensities were mostly expressed in controls, with statistically significant differences (P <0.0001).

CONCLUSIONS

In the present study, the immunohistochemical analysis shows that the tissues below the titanium bars underwent a higher rate of inflammatory and reparative processes. However, further long-term studies, where clinical and immunohistochemical data are collected in parallel, should be conducted for a better understanding of the expression pattern of inflammation markers.

Damping factor for monitoring the bone interface at dental implants

OBJECTIVES

The aim of this study is to investigate whether the damping of osseointegrated implants, as measured quantitatively with the Osstell equipment, is related to the fractal dimension of peri-implant bone.

MATERIAL AND METHODS

Fifty-five maxillary implants in function for 3 years before the present study were investigated. Two Osstell measurements were obtained for each implant with the transducer oriented first palatally and then distally. Using the half-power bandwidth method, the damping was calculated from the frequency/amplitude plot obtained from the Osstell. Damping data were then related to the fractal dimension of peri-implant bone. Fractal dimensions were calculated using a box-counting algorithm on digitally processed intra-oral radiographs of the implants. A Spearman's test was used to verify the correlation between damping and fractal dimension values.

RESULTS

All the implants were clinically stable and free from symptoms. The mean ISQ was 63 for the palatal orientation and 71 for the distal orientation. The mean fractal dimension was 1.47; the mean damping value for palatal orientation was 12.3%, while that for the distal orientation was 8.2%. No significant correlation was found.

CONCLUSIONS

Damping values, measured at peri-implant bone, were found not to be related to a radiographic parameter of trabecular bone pattern like the fractal dimension. The clinical implication would be that Osstell graphs displaying distinct or more rounded peaks might both indicate a stable implant as long as the associated implant stability quotients are in the range of satisfactory values proposed in the literature.

Early versus late loading of unsplinted TiUnite surface implants supporting mandibular overdentures: a 2-year report from a prospective study

The aim of this study was to evaluate the clinical performance of the implants supporting mandibular overdentures, and to investigate the prosthodontic outcomes of the mandibular implant overdentures. Twenty edentulous patients participated in this study. Forty implants were placed in the canine areas of the mandibles of all patients using the 1-stage approach. New maxillary complete dentures and the mandibular implant overdentures were delivered to 10 patients in the test group 1 week after surgery, while new maxillary and mandibular complete prostheses were delivered to 10 patients in the control group. These conventional mandibular prostheses were converted to mandibular implant overdentures 3 months after surgery. No implants were lost neither in test nor in control group. The average ISQ values between the two groups were not statistically significant during 2 years (P > 0.05). The average marginal bone resorptions were 0.4 and 0.5 mm for the test and the control group after 2 years. The number of appointments required for the prosthodontic maintenance of the mandibular implant overdentures in the first year was higher than that in the second year, which was statistically significant(P < 0.001). The results of the study suggest that the 1-week early loading approach does not adversely influence the clinical performance of the implants supporting mandibular overdentures.

Evaluation of two different resonance frequency devices to detect implant stability: a clinical trial

BACKGROUND

Resonance frequency analysis (RFA) provides a non-invasive assessment of implant stability. The established RFA device uses electronic technology, whereas a recently developed device uses magnetic technology. The goal of this clinical trial was to evaluate the ability of the magnetic RFA device to detect changes in stability during early healing following implant placement and to determine whether the implant stability quotient (ISQ) values obtained correlated with those made with the electronic device.

METHODS

RFA assessments were performed using electronic- and magnetic-based devices on 34 non-submerged titanium dental implants in 17 patients. Each patient received two implants in the posterior maxilla or mandible. Implant stability was measured at placement and weekly until week 6, when implants received provisional crowns, and at 12 weeks, when definitive crowns were cemented. During each visit, measurements were taken three times and averaged to obtain a single representative ISQ for each device.

RESULTS

At placement, the mean ISQ obtained with the electronic device was 61.9 (95% confidence interval [CI], 59.4 to 64.3); it increased to 63.2 (95% CI, 61.2 to 65.2) at 12 weeks. With the magnetic device, the mean ISQs were 70.6 (95% CI, 68.4 to 72.8) and 75.9 (95% CI, 74.2 to 77.7), respectively. Both devices indicated a pattern of decreased mean stability from 1 to 3 weeks post-placement, small fluctuations in mean ISQ from 3 to 6 weeks, and significantly increased mean stability from 6 to 12 weeks. For the complete set of implant measures across all weeks, the paired electronic and magnetic ISQ values correlated significantly (r = 0.52; P <0.001).

CONCLUSIONS

This study demonstrates that changes in implant stability measured with the newer magnetic device correlate well with those found with the electronic device. Both devices confirmed the initial decreases in implant stability that occur following placement and identified an increase in stability during the first 6 weeks of functional loading.

Resonance frequency analysis in relation to jawbone characteristics and during early healing of implant installation

OBJECTIVES

To monitor resonance frequency analysis (RFA) in relation to the jawbone characteristics and during the early phases of healing and incorporation of Straumann dental implants with an SLA surface.

MATERIAL AND METHODS

17 Straumann 4.1 mm implants (10 mm) and 7 Straumann 4.8 mm implants (10 mm) were installed and ISQ determined at baseline and after 1, 2, 3, 4, 5, 6, 8 and 12 weeks. Central bone cores were analyzed from the 4.1 mm implants using micro CT for bone volume density (BVD) and bone trabecular connectivity (BTC).

RESULTS

Pocket probing depths ranged from 2-4 mm and bleeding on probing from 5-20%. At baseline, BVD varied between 24% and 65% and BTC between 4.9 and 25.4 for the 4.1 mm implants. Baseline ISQ varied between 55 and 74 with a mean of 61.4. No significant correlations were found between BVD or BTC and ISQ Values. For the 4.8 mm diameter implants baseline ISQ values ranged from 57-70 with a mean of 63.3. Over the healing period ISQ values increased at 1 week and decreased after 2-3 weeks. After 4 weeks ISQ values, again increased slightly, no significant differences were noted over time. One implant (4.1 mm) lost stability at 3 weeks. Its ISQ value had dropped from 68 to 45. However the latter value was determined after the clinical diagnosis of instability.

CONCLUSION

ISQ values of 57-70 represented homeostasis and implant stability. However no predictive value for loosing implant stability can be attributed to RFA since the decrease occurred after the fact.

Influence of Transducer Orientation on OsstellTMStability Measurements of Osseointegrated Implants

BACKGROUND

Resonance frequency (RF) analysis is frequently used to monitor implant stability in patients. The influence of transducer orientation on RF of implants placed in jawbone has not been evaluated.

PURPOSE

The aim of this study was to evaluate to what extent transducer orientation influences RF. The second aim was to evaluate if measurements taken with any particular orientation would best relate to marginal bone levels.

MATERIALS AND METHODS

Nine patients edentulous in the upper jaw received 55 implants 3 years before this study. They underwent clinical and radiographic evaluation. Using Osstell (Integration Diagnostics AB, Göteborg, Sweden), four RF measurements were made for each implant. Measurements were obtained with the transducer cantilever placed buccally (B), distally (D), palatally (P), and mesially (M).

RESULTS

All implants were clinically stable. Significant differences resulted between the measurements perpendicular to the bony crest (B, P) and the parallel ones (M, D). A tendency of negative correlation was found between marginal bone levels and implant stability quotient (ISQ) measurements; however, this correlation was not statistically significant.

CONCLUSIONS

In conclusion, when measuring the RF of dental implants using the Osstell, it has to be taken into account that the transducer orientation influences the measurement. It seems therefore advisable to standardize the orientation. Moreover, although there was a tendency, any statistical significant correlation between ISQ values and marginal bone levels could not be established.

Stability and marginal bone level measurements of unsplinted implants used for mandibular overdentures: a 1-year randomized prospective clinical study comparing early and conventional loading protocols

OBJECTIVES

The aim of this study was to compare the performance of two non-splinted implants used as retention for a mandibular overdenture when applying conventional or early loading protocols.

MATERIAL AND METHODS

Twenty edentulous patients were treated with two unsplinted and non-submerged implants (15 mm long, TiUnite RP, Brånemark System) in the anterior mandible. The patients were randomly allotted into two groups: (i) test group (Group A), in which the overdenture was connected 1 week after surgery, and (ii) control group (Group B), in which the overdenture was connected after 12 weeks of healing. Resonance frequency analyses (RFA) for implant stability measurements were performed at implant surgery and after 1, 3, 6, 9 and 12 months. Marginal bone levels were evaluated at implant surgery and after 6 and 12 months.

RESULTS

No implant from either group was lost and all implants showed less than 1 mm of marginal bone resorption during the first year. The mean implant stability quotient (ISQ) values at implant surgery were 76.2+/-2.8 for Group A and 75.6+/-4.5 for Group B. The 12-month measurements showed 76.4+/-2.5 ISQ and 76.4+/-2.8 ISQ for Groups A and B, respectively. There were no statistically significant changes between or within the groups with time. There were no differences in marginal bone loss, which was on average 0.3 mm for both groups after 1 year.

CONCLUSION

Although a limited number of patients were followed for 1 year only, the results of the present study indicate that early loading of two unsplinted 15 mm long implants with an overdenture does not negatively affect implant stability or marginal bone conditions when compared with implants subjected to 12 weeks of healing before loading.

A 2-Year Clinical Report of Patients Treated With Two Loading Protocols for Mandibular Overdentures: Early Versus Conventional Loading

BACKGROUND

The original Brånemark protocol for dental implant treatment was based on submerged healing prior to loading. In recent years, immediate/early functional loading has been reported to be possible with high success for various indications including two splinted mandibular implants supporting an overdenture. However, there are a limited number of studies regarding the early loading protocol for two unsplinted mandibular implants supporting an overdenture.

METHODS

A total of 26 edentulous patients were treated with two unsplinted dental implants supporting mandibular overdentures. All implants were placed in the canine regions of each mandible according to the one-stage surgery. For the test group, overdentures were connected 1 week after surgery, and for the control group, overdentures were connected 3 months after surgery. Peri-implant parameters were recorded 1, 6, 12, 18, and 24 months after surgery. Marginal bone levels were evaluated at implant placement and after 6, 12, 18, and 24 months. Clinical stability measurements were performed at surgery, and after 3, 6, 12, 18, and 24 months.

RESULTS

No implant from either group was lost during 2 years. Clinical peri-implant parameters, clinical implant stability measurements, and marginal bone resorptions showed no statistically significant differences between the two groups during 24 months.

CONCLUSION

The results of this clinical trial suggest that the early loading approach of two dental implants supporting a mandibular overdenture does not jeopardize peri-implant soft tissue health, marginal bone resorption, and implant stability.

Validity and clinical significance of biomechanical testing of implant/bone interface

PURPOSE

The aim of this paper was to review the clinical literature on the Resonance frequency analysis (RFA) and Periotest techniques in order to assess the validity and prognostic value of each technique to detect implants at risk for failure.

MATERIAL AND METHODS

A search was made using the PubMed database to find clinical studies using the RFA and/or Periotest techniques.

RESULTS

A limited number of clinical reports were found. No randomized-controlled clinical trials or prospective cohort studies could be found for validity testing of the techniques. Consequently, only a narrative review was prepared to cover general aspects of the techniques, factors influencing measurements and the clinical relevance of the techniques.

CONCLUSIONS

Factors such as bone density, upper or lower jaw, abutment length and supracrestal implant length seem to influence both RFA and Periotest measurements. Data suggest that high RFA and low Periotest values indicate successfully integrated implants and that low/decreasing RFA and high/increasing Periotest values may be signs of ongoing disintegration and/or marginal bone loss. However, single readings using any of the techniques are of limited clinical value. The prognostic value of the RFA and Periotest techniques in predicting loss of implant stability has yet to be established in prospective clinical studies.

A numerical approach to resonance frequency analysis for the investigation of oral implant osseointegration

Experimental devices based on vibration testing are employed as non-destructive procedures for evaluating implants osseointegration. Their behaviour was evaluated considering the outcome of numerical analysis. The purpose was to use the finite element method for assessing the ability of frequency analysis in detecting the degree of oral implant osseointegration. A three-dimensional model of a mandible was obtained from tomographic survey. A single implant was considered in canine region. Two configurations were analysed, with and without a mass linked to the implant as a cantilever, reproducing experimental devices. Simulation consisted of analysing the response to impulse forces for different osseointegration levels, thus evaluating the biomechanical efficiency of the implant-bone compound. A good correlation between frequency response and osseointegration level was obtained. This was carried out by providing an impulse excitation of the implant that resulted in a vibration pattern. Within the limit of finite element analysis, the outcomes showed that numerical investigation provides understanding the behaviour of testing devices based on frequency measurements, confirming the potential of vibrations technique as non-invasive analysis for osseointegration process.

Clinical and radiological results of patients treated with two loading protocols for mandibular overdentures on Branemark implants

OBJECTIVE

The aim of this study was to evaluate clinical and radiological outcomes of the unsplinted implants supporting mandibular overdenture when applying conventional or early loading protocols.

MATERIAL AND METHODS

Twenty-six edentulous patients were treated with two unsplinted Brånemark System implants supporting mandibular overdenture. There was a test group, in which the overdenture was connected 1 week after surgery, and a control group, in which the overdenture was connected 3 months after surgery. Peri-implant parameters were recorded 1, 6, and 12 months after surgery. Clinical stability measurements were performed at surgery, and after 3, 6, and 12 months. Marginal bone levels were evaluated at implant surgery, after 6, and after 12 months.

RESULTS

No implant from either group was lost. Clinical peri-implant parameters, clinical stability measurements, and marginal bone resorptions showed no statistically significant differences between two groups during 12 months.

CONCLUSION

The results of this study suggest that one-week of early loading protocol of two Brånemark implants supporting mandibular overdenture does not compromise implant stability, marginal bone loss, and peri-implant soft-tissue health.

Simplified Methods of Implant Treatment in the Edentulous Lower Jaw: A 3-Year Follow-Up Report of a Controlled Prospective Study of One-Stage versus Two-Stage Surgery and Early Loading

BACKGROUND

Interest in the use of one-stage surgery and immediate loading of oral implants has lately been increasing.

PURPOSE

The aim of this study was to compare the 3-year results of one-stage surgery versus two-stage surgery, early loading versus loading after a 3-month healing period, and the use of one-piece implants versus the use of two-piece implants.

MATERIALS AND METHODS

The study included 108 patients with edentulous mandibles. Each patient was treated with four Brånemark System implants (Nobel Biocare AB, Göteborg, Sweden) and with full fixed prostheses. Patients were consecutively treated and were distributed in four groups: group A (one-stage surgery), group B (control group with two-stage surgery), group C (one-piece implants), and group D (early loading). In groups A and B Brånemark Standard implants and standard abutments were used. In group C the conical one-piece Brånemark implant was used, and in group D the patients had Brånemark System Mk III implants together with multiunit abutments. All patients were observed for 3 years.

RESULTS

Of the 432 inserted implants, 24 were lost. Survival rates in the three experimental groups ranged from 93.2 to 93.3% whereas the survival rate in group B (the control group with two-stage surgery) was 97.5%. The differences between the groups were not statistically significant. The changes in marginal bone level were measured from fixture insertion to the final follow-up at 3 years. The bone loss in group D (early loading) was significantly less than in group B (the control group) whereas there were no differences in marginal bone change between the other groups.

CONCLUSIONS

Early loading seemed to give good results in the anterior part of the mandible. The survival rate of the early-loaded implants did not significantly differ from that of implants inserted with the conventional two-stage procedure, but the mean marginal bone loss around the surviving implants was less with early loading.

Implant Stability Measurements for Implants Placed at the Time of Extraction: A Cohort, Prospective Clinical Trial

BACKGROUND

Studies indicate that implants placed at the time of extraction have high success rates. Implants must be stable at the time of insertion. Presently there are no data indicating the degree of implant stability when implants are placed at the time of extraction. This study evaluated changes in stability of implants from implant placement to abutment connection utilizing resonance frequency analysis (RFA). The unit of measurement was the international stability quotient (ISQ).

METHODS

Prior to treatment, patients were given medical history and dental evaluations. Periapical and panogram radiographs were taken. Fifty-two patients requiring extraction of one or two teeth and implant placement immediately after extraction were enrolled in this study. Under conscious sedation and local anesthesia or local anesthesia alone, teeth were atraumatically removed and the extraction sockets were debrided. A total of 73 dental implants (57 in the maxilla, 16 in the mandible) were placed. Using a one-stage approach, all implants were placed within the patient's alveolar envelope and were never placed directly into extraction sockets. All implants were placed into contained extraction sites. Bone augmentation procedures were not performed. After implant insertion, the RFA electronic transducer was attached to the head of the implant with the retaining screw. The device was attached to a computer designed to register RFA scores in ISQ units. RFA measurements were taken at implant placement and abutment connection. Bone qualities, quantity, implant length and width as well as site of placement were recorded.

RESULTS

The average interval between implant insertion and abutment connection was 5.6 months (SD 2.05). Two implants were lost between implant insertion and 1 year. At 2 to 3 years, the cumulative survival was 97.2%. Resonance frequency measurements at implant placement showed a mean primary stability of 62.0 (SE 1.1; range 43 to 83 ISQ) and a mean secondary stability after 1 year of 64.0 (SE 1.2; range 40 to 98 ISQ) for all implants. The increase was marginally significant (generalized estimating equation z-statistic = 1.79; P value = 0.07).

CONCLUSIONS

Implants placed at the time of extraction and inserted into native bone and not directly into extractions sockets have a high degree of initial stability as evidenced by RFA measurements. Implants with initial high ISQ levels revealed a slight drop in levels over time, while implants with levels lower than 60 had increases in levels between implant insertion and abutment connection. At 2 to 3 years the cumulative survival rate was 97.2%.

Rehabilitation of Edentulous Mandibles by Means of Turned Branemark SystemR Implants after One-Stage Surgery: A 1-Year Retrospective Study of 152 Patients

BACKGROUND

Rehabilitation of the edentulous mandible with oral implants is today predominantly executed with one-stage surgery and early or immediate loading. It is generally claimed that the outcome is similar to that of the classic two-stage technique.

PURPOSE

The aim of the present investigation was to retrospectively evaluate the 1-year results of one-stage surgery and early loading performed in edentulous mandibles in a large group of patients. The outcome was compared with that of a study, from the same clinic (control), that used the two-stage surgical technique in edentulous mandibles and whose data were well controlled.

MATERIALS AND METHODS

The study included 152 individuals with 750 turned Brånemark System implants of various designs placed in edentulous mandibles by means of one-stage surgery. The prosthetic procedure was commenced at a mean of 13 days after the surgical intervention. Intraoral apical radiography was performed at the time of prosthesis placement and at the 1-year annual checkup. Comparison of failure rates between the test and the control groups was made by means of the chi-square test.

RESULTS

A total of 18 implants in 12 patients in the study group were found to be mobile up to and including the first annual checkup, equivalent to a 1-year implant cumulative survival rate (CSR) of 97.5%. The corresponding CSR for the control group was 99.7%. Differences between the two groups in regard to implant survival reached significant levels when analyzed with the chi-square test (p < .05). No such significant difference was seen on the patient level (p > .05). Because of implant failures one prosthesis in the study group was remade. The mean marginal bone resorption during the first year of function was 0.4 mm in both groups.

CONCLUSIONS

The present investigation showed a high but (compared with the classic two-stage technique) somewhat lower CSR after 1 year for the one-stage technique. More prosthetic adjustments due to implant failures were observed in the study group, and the results emphasize the need for large study samples in order to statistically verify small differences between various treatment techniques.

Bone Formation at Titanium Implants Prepared with Iso- and Anisotropic Surfaces of Similar Roughness: An in Vivo Study

BACKGROUND

Implant surface topography influences the bone response after implantation. However, the importance of surface orientation is not known.

PURPOSE

The aim of this study was to investigate the bone tissue response and the stability of titanium implants prepared with isotropic and anisotropic surfaces of similar roughness.

MATERIALS AND METHODS

A total of 18 implants were divided into two groups and were inserted into the femurs of nine rabbits for 12 weeks. Confocal laser scanning microscopy was used for the topographic description to verify that the two different surfaces were modified as intended. The stability of the implants was recorded by resonance frequency (RF) measurements at insertion and at time of removal, after which the implants were evaluated histomorphometrically.

RESULTS

RF measurements showed that implant stability increased with time. However, there was no significant difference between the two different surface modifications at insertion and after 12 weeks. The histomorphometric comparison revealed no statistically significant differences in regard to either bone-to-metal contact or bone area inside the threads.

CONCLUSION

Titanium implants prepared with isotropic and anisotropic surfaces of similar roughness integrate similarly to bone during the 3 months after implantation.

Predicting osseointegration by means of implant primary stability

The purpose of the present clinical study was (1) to evaluate the Osstell as a diagnostic tool capable of differentiating between stable and mobile ITI implants, (2) to evaluate a cut-off threshold implant stability quotient (ISQ) value obtained at implant placement (ISQitv) that might be predictive of osseointegration, (3) to compare the predictive ISQitv of immediately loaded (IL) implants and implants loaded after 3 months (DL). Two patient groups were enrolled, 18 patients received 63 IL implants and 18 patients were treated with 43 DL implants. The ISQ was recorded at implant placement, after 1, 2, 4, 6, 8, 10 and 12 weeks. All implants passed the 1-year loading control. Two implants failed, one DL implant with ISQ at placement (ISQi) of 48 and one IL implant with ISQi of 53. The resonance-frequency analysis (RFA) method was not a reliable diagnostic tool to identify mobile implants. However, implant stability could be reliably determined for implants displaying an ISQ> or =47. After 1 year of loading, all DL implants with an ISQi> or =49 and all IL implants with an ISQi> or =54 achieved and maintained osseointegration. By the end of 3 months, implants with ISQi<60 had an increase of stability. Implants with ISQi 60-69 had their stability decrease during 8 weeks before returning to their initial values. Implants with ISQ>69 had their stability decrease during the first 4 weeks before remaining stable. Although preliminary, these data might orient the practitioner to choose among various loading protocols and to selectively monitor implants during the healing phase.

Implant stability measurement of delayed and immediately loaded implants during healing.. A clinical resonance-frequency analysis study with sandblasted-and-etched ITI implants

The purpose of the present study was (1) to measure the primary stability of ITI implants placed in both jaws and determine the factors that affect the implant stability quotient (ISQ) determined by the resonance frequency method and (2) to monitor implant stability during the first 3 months of healing and evaluate any difference between immediately loaded (IL) implants and standard delayed loaded (DL) implants. The IL and DL groups consisted of 18 patients/63 implants and 18 patients/43 implants. IL implants were loaded after 2 days; DL implants were left to heal according to the one-stage procedure. The ISQ was recorded with an Osstell apparatus (Integration Diagnostics AB, Gothenburg, Sweden) at implant placement, after 1, 2, 4, 6, 8, 10 and 12 weeks. Primary stability was affected by the jaw and the bone type. The ISQ was higher in the mandible (59.8+/-6.7) than the maxilla (55.0+/-6.8). The ISQ was significantly higher in type I bone (62.8+/-7.2) than in type III bone (56.0+/-7.8). The implant position, implant length, implant diameter and implant deepening (esthetic plus implants) did not affect primary stability. After 3 months, the gain in stability was higher in the mandible than in the maxilla. The influence of bone type was leveled off and bone quality did not affect implant stability. The resonance-frequency analysis method did not reveal any difference in implant stability between the IL and DL implants over the healing period. Implant stability remained constant or increased slightly during the first 4-6 weeks and then increased more markedly. One DL and IL implant failed; both were 8 mm long placed in type III bone. At the 1-year control, the survival rate of the IL and the DL implants was 98.4% and 97.7%, respectively. This study showed no difference in implant stability between the IL and DL procedures over the first 3 months. IL short-span bridges placed in the posterior region and full arch rehabilitation of the maxilla with ITI sandblasted-and-etched implants were highly predictable.

Provisional Implants: A Clinical Prospective Study in 45 Patients, from Implant Placement to Delivery of the Final Bridge

BACKGROUND

Protocols for submerged healing of dental implants often require the patient to have no teeth until suture removal and to wear a removable prosthesis during the remaining healing period. This may be inconvenient for the patient, and healing may be influenced negatively by the removable prosthesis.

PURPOSE

The aim of the present prospective clinical study was to evaluate the use of provisional implants (PIs) to provide patients with a provisional fixed bridge during the healing of permanent implants.

MATERIALS AND METHODS

Twenty female and 25 male patients were consecutively included in the study. The 45 patients were treated for either partial (16 patients) or total (29 patients) edentulism in the maxilla. The permanent implants were placed first; as many PIs as possible were then installed between the permanent implants. After suturing, impressions from which to manufacture provisional bridges (to be cemented to the PIs) were taken. The patients were monitored with clinical and radiographic follow-up from implant placement to delivery of the final prosthesis.

RESULTS

Five (2.2%) of the 230 permanent Brånemark System implants (Nobel Biocare AB, Gothenburg, Sweden) did not integrate. None of the failures could be related to the presence of PIs between the permanent implants. Seven PIs failed during the observation period. In addition, 17 (9%) of the 192 PIs showed mobility at the second-stage surgery although they had supported the provisional bridges without clinical symptoms. Forty-four of 45 patients showed stabile PI bridges at the time of second-stage surgery.

CONCLUSION

Based on our experiences we concluded that provisional implants can be successfully used to provide patients with a fixed provisional bridge during the healing of permanent implants.

Resonance frequency analysis of implants subjected to immediate or early functional occlusal loading. Successful vs. failing implants

OBJECTIVES

The objective of this study was to analyze the development of implant stability by repeated resonance frequency analysis (RFA) measurements during 1 year in 23 patients treated according to an immediate/early-loading protocol. The objective was also to evaluate the possible differences between failing and successful implants.

MATERIAL AND METHODS

Eighty-one Brånemark System implants were placed in 23 patients for immediate/early-occlusal loading in all jaw regions. Thirty of the implants were placed in extraction sockets and 62 were subjected to GBR procedures. Apart from clinical and radiographic examinations, the patients were followed with RFA at placement, prosthesis connection and after 1-3, 6 and 12 months. Statistical analyses were carried out to study the possible differences between implants that failed during the study period and implants that remained successful.

RESULTS

Nine implants failed (11.2%) during the 1 year of loading. RFA showed a distinct different pattern between the implants that remained stable and the implants that were lost. The implants that failed during the course of the study showed a significantly lower stability already after 1 month.

CONCLUSION

Within the limitations of this study, it is concluded that failing implants show a continuous decrease of stability until failure. Low RFA levels after 1 and 2 months seem to indicate an increased risk for future failure. This information may be used to avoid implant failure in the future by unloading implants with decreasing degree of stability with time as diagnosed with the RFA technique.

Simplified Methods of Implant Treatment in the Edentulous Lower Jaw. Part II: Early Loading

BACKGROUND

Most implant treatment is performed with a two-stage surgical procedure. A disadvantage of these implant treatments is that they are time-consuming.

PURPOSE

The aim of the present study was to evaluate the results of early loading in the edentulous mandible and to compare those results with treatment results of one-stage surgery followed by a healing period and with two-stage surgery.

MATERIAL AND METHODS

The material comprises four treatment groups with a total of 108 patients with edentulous lower jaws and 432 implants. All patients were treated with Brånemark implants (Nobel Biocare AB, Gothenburg, Sweden) with a turned surface and fixed prostheses in the lower jaw, supported by four implants. The patients in group A were treated with a one-stage procedure, a two-piece implant, and a 3-month healing period before loading. Group B (control group) had a two-stage procedure, a two-piece implant, and a 3-month healing period. Group C had a one-stage procedure, a one-piece implant, and a 3-month healing period. Group D was treated with a one-stage surgical procedure, a two-piece implant, and early loading (within 3 weeks). All patients were provided with a Procera Implant Bridge (Nobel Biocare) with a framework made by computer-assisted milling of one piece of pure titanium. All patients have been followed up for 1 year.

RESULTS

The survival rates were 93.2 to 93.3% in the experimental groups and 97.5% in the control group. The difference was not statistically significant. The measurements of the marginal bone level demonstrated a mean bone loss of 0.8 mm between fixture insertion and the 1-year examination in patients with early loading (group D) whereas the bone loss in patients who underwent a healing period before loading was 1.3 to 1.6 mm. The difference between the control group and the group with early loading was significant.

CONCLUSIONS

Survival rates for patients treated with a one-stage procedure were lower than survival rates for patients treated according to a "classical concept," but the differences were not statistically significant. There was no difference between treatment results with one-piece and two-piece implants. The implant loss in patients with early loading was probably caused by overloading, and careful supervision of occlusal loading is recommended. Early loading gave significantly less marginal bone loss when compared with two-stage surgery.

Early Functional Loading of Unsplinted Roughened Surface Implants with Mandibular Overdentures 2 Weeks after Surgery

BACKGROUND

Before early functional loading of unsplinted implants with mandibular overdentures can become widespread, more clinical studies are needed to investigate the success of the approach.

PURPOSE

To evaluate the success rates of two types of roughened titanium surface implants with early 2-week functional loading of paired mandibular interforaminal implants with overdentures.

MATERIALS AND METHODS

Random allocation divided 24 strictly selected edentulous participants into two groups, with each group to receive a different implant system (ITI Dental Implant System, Straumann AG, Waldenburg, Switzerland; or Southern Implant System, Southern Implants, Irene, South Africa). Two implants were placed in the anterior mandible of all participants using one-stage standardized surgical procedures. Previously constructed conventional mandibular dentures (opposing maxillary complete dentures) were temporarily relined and worn by the participants for the first 2 weeks; participants used a soft diet. Two weeks after implant surgery and following some mucosal healing, the mandibular dentures had the tissue conditioner removed and the appropriate matrices included for an unsplinted prosthodontic design.

RESULTS

No implant from either group was lost. Resonance frequency analysis (RFA) indicated higher primary stability at surgery for the Southern group than for the ITI group, with a statistically significant difference between the groups throughout the study period. The drop in RF values between surgery and 6 weeks was significant and was greater for the Southern group. RFA also indicated stabilized osseointegration between 6 to 12 and 12 to 52 weeks, with no participant showing any decrease in those values over time. Participants with type 3 bone showed a significant improvement in RF values between 12 and 52 weeks, eventually matching those of participants with type 2 bone. There were no significant differences in marginal bone loss, periimplant parameters, or prosthodontic maintenance between the groups over the study period.

CONCLUSIONS

Using only strict patient selection criteria, 1-year follow-up data indicate that early functional loading of ITI and Southern implants with mandibular two-implant overdentures is possible as early as 2 weeks after implant surgery.

Early loading of maxillary fixed cross-arch dental prostheses supported by six or eight oxidized titanium implants: results after 1 year of loading, case series

BACKGROUND

Recent reports have demonstrated that immediate/early loading of dental implants is a clinically feasible concept with results similar to those for two-stage procedures, at least in good bone qualities. However, documentation of the outcome of immediate/early loading in the totally edentulous maxilla is scarce.

PURPOSE

The present investigation was undertaken to evaluate the outcome over 1 year of oxidized titanium implants when loaded with a fixed full-arch bridge in the maxilla 1 to 9 days after implant placement.

MATERIALS AND METHODS

Ten patients with totally edentulous maxillas were treated with 61 oxidized titanium implants, and a provisional fixed bridge was delivered after 1 to 9 days (mean 2.5 d). Nine patients had six implants and one patient had eight implants supporting the bridge. The provisional bridge was replaced with a permanent bridge after 2 to 7 months (mean 4.1 mo) of loading. Resonance frequency analysis (RFA) for implant stability measurements was made at implant placement in eight patients and in conjunction with permanent bridge connection in five patients. The patients were followed up for 1 year with clinical and radiographic examinations.

RESULTS

Four implants (6.6%) were lost in one patient after 10 weeks of loading owing to an infection. All other implants were clinically stable with a mean marginal bone loss of 1.3 +/- 0.6 mm after 1 year of loading. RFA showed a mean primary stability of 60.1 +/- 3.6 ISQ (implant stability quotient), which increased to 62.8 +/- 1.6 ISQ after, on average, 4 months.

CONCLUSIONS

The results from this limited study on 10 cases indicate that early loading protocols can be applied for cross-arch dental bridges supported by six to eight implants in the maxilla. However, more clinical trials are needed to establish the long-term predictability of the treatment.

3-year prospective multicenter study on one-stage implant surgery and early loading in the edentulous mandible

BACKGROUND

The long-term success rates achieved in dental implantology suggest that flexibility might well exist within the various implant systems to a degree that an altered protocol (ie, one-stage surgery and immediate or early loading) can be performed under controlled conditions. However, before variations of the protocol can be considered for general use, they must be subjected to critical analysis, particularly with respect to the predictability of osseointegration, alteration of soft tissue barrier, and relative change in bone height around the implants.

PURPOSE

The aim of this prospective multicenter study was to evaluate implant survival and periimplant conditions around endosseous implants placed in a one-stage surgical procedure and early loading.

MATERIALS AND METHODS

A total of 170 implants were placed in 40 patients with mandibular edentulism and were functionally loaded within 6 weeks with overdentures (n = 30) or fixed prostheses (n = 10). All patients and prosthetic constructions were evaluated according to a standardized protocol during 3 years of follow-up. Cumulative implant survival rates were calculated, and implant loss in relation to implant size and bone quality and quantity were evaluated. Furthermore, the protocol included assessment of clinical (plaque and bleeding scores, prosthesis stability) and radiographic parameters.

RESULTS

Over a period of 3 years, the implant survival rate was 93% for both implants and prostheses (fixed or removable). No implants were lost after the first year of loading. The periimplant tissues were in a healthy condition. Mean marginal bone resorption from the time of loading to the 3-year follow-up was 0.41 mm (SD 0.52).

CONCLUSIONS

From this study it may be concluded that early loading results in good implant survival and proper periimplant health in edentulous mandibles.

Stability measurements of osseointegrated implants using Osstell in partially edentulous jaws after 1 year of loading: a pilot study

BACKGROUND

The introduction of resonance frequency analysis (RFA) as a commercially available technique has made it possible to measure implant stability in implant stability quotient (ISQ) units at any time during the course of implant treatment and loading. However, no information on normal ISQ levels can be found in the literature.

PURPOSE

The aim of this pilot study was to measure the stability of clinically successful implants in partially edentulous patients after 1 year of loading and to study the influence of jaw, anterior/posterior position, implant length, and marginal bone level on implant stability.

MATERIALS AND METHODS

Fourteen partially edentulous patients previously treated with 45 implants were subjected to clinical and radiographic evaluations and RFA measurements using Osstell (Integration Diagnostics, Savedalen, Sweden) after 1 year of loading.

RESULTS

All 45 implants were stable, and implant stability levels were in the range of 57 to 82 ISQ units with a mean of 69 +/- 6.5 ISQ after 1 year of loading. Mandibular implants were more stable than were maxillary ones. There were no differences between anterior and posterior implants. No correlation could be found between implant length and stability. Only minor marginal bone resorption was observed.

CONCLUSIONS

The results from this limited material showed that successfully integrated implants have ISQ levels from 57 to 82 ISQ with a mean of 69 ISQ after 1 year of loading. Mandibular implants are more stable than are maxillary ones. High implant stability can be achieved with short implants and placement in posterior regions.

Simplified methods of implant treatment in the edentulous lower jaw. A controlled prospective study. Part I: one-stage versus two-stage surgery

BACKGROUND

The original protocol for Brånemark System implants in the mandible was a two-stage procedure with 3 months healing time. With five or six implants and a cast framework of gold, the treatment is rather expensive, and simplified methods would be desirable.

PURPOSE

The goal of this controlled serial study was to investigate the outcome of a simplified procedure with one-stage surgery, four Brånemark implants, shortened healing time, and a new titanium-acrylic fixed full prosthesis.

MATERIALS AND METHODS

Eighty-two patients were treated in three different groups at two specialist centers. All patients were provided with four implants, loaded with a Procera All-in-One bridge (Nobel Biocare, Gothenburg, Sweden) after 12 weeks. In group A (n = 30), one-stage surgery was combined with two-piece implants. In group B (n = 30), the control group, two-stage surgery and two-piece implants were used. In group C (n = 22), one-stage surgery was combined with one-piece implants. Marginal bone level was rated from radiographs at implant insertion, at baseline, and after 1 year.

RESULTS

The survival rate after 1 year for group A was 93.3%; group B, 97.5%; and group C, 93.2%. The differences were not statistically significant. Between fixture insertion and baseline, the average bone loss for group A was 1.2 mm; group B, 1.3 mm; and group C, 1.3 mm. No complications in the form of bridge loosening or acrylic fractures were recorded during the first year.

CONCLUSIONS

The survival rates and the marginal bone changes did not differ significantly between the one-stage groups and the control group. The survival rate and the marginal bone changes were similar for one-piece and two-piece implants. Four implants were sufficient to support full fixed prostheses in the mandibles. The Procera All-in-One bridges proved to be of high quality, and no complications were experienced. key words: endosseous implants, nonsubmerged implants, one-piece implants, prospective clinical study, submerged implants

Early loading of unsplinted implants supporting mandibular overdentures using a one-stage operative procedure with two different implant systems: a 2-year report

BACKGROUND

Step-wise reduction in loading protocols is necessary to evaluate early loading of implants with mandibular overdentures.

PURPOSE

To compare the success rates of two different dental implant systems following conventional or early loading protocols in patients being rehabilitated with mandibular overdentures.

MATERIALS AND METHODS

Forty-eight edentulous participants were randomly allocated to two different implant systems: one with a machined titanium implant surface (Sterioss, Nobel Biocare, Yorba Linda, California, USA) and the other with a roughened titanium surface (Southern Implants, Irene, South Africa). For each system, the participants were further divided into control groups, in whom mandibular implant overdentures and their respective matrices were inserted following a standard 12-week healing period, and test groups, in whom a 6-week healing period was followed prior to identical loading. Two unsplinted implants to support implant overdentures were placed in the anterior mandible of all participants, using a standardized one-stage surgical procedure. Mobility tests and marginal bone levels, as well as peri-implant parameters, were evaluated at each baseline and 52 and 104 weeks after surgery.

RESULTS

There was no statistically significant difference in the success rates of the two systems in either control or test groups. At the 2-year evaluation, a success rate was found of 87.5% and 70.8% for the control and test Sterioss groups, respectively, and 83.3% and 100% for the control and test Southern Implants groups were observed. For the Sterioss groups, eight implants were lost at an early stage: seven in the test group and one in the control group. For the Southern Implants control and test groups, no failures were seen at any time interval. There were no significant differences in marginal bone loss, Periotest values, and peri-implant parameters between implant systems or between any of the control or test groups.

CONCLUSIONS

Early loading, with step-wise reductions in loading protocols, of unsplinted machined Sterioss and roughened Southern Implants fixtures with mandibular overdentures is possible for up to 2 years.

One-stage operative procedure using two different implant systems: a prospective study on implant overdentures in the edentulous mandible

BACKGROUND

Evidence-based reports are needed to support the application of a one-stage surgical protocol for unsplinted implants supporting mandibular overdentures.

PURPOSE

To examine the feasibility and success of using two different dental implant systems (originally designed for two-stage operative technique) using a one-stage operative procedure in patients being rehabilitated with implant mandibular overdentures.

MATERIALS AND METHODS

The study sample involved 24 edentulous subjects (aged 55-80 yr) randomly allocated to two different implant systems, one with a machined titanium implant surface (Steri-Oss, Nobel Biocare, Göteborg, Sweden) and the other with a roughened titanium surface (Southern Implants, Ltd., Irene, South Africa). Two unsplinted implants to support implant overdentures were placed in the anterior mandible of all patients, using a standardized one-stage surgical and prosthodontic procedure. Primary stability and bicortical anchorage of the implants was mandatory before healing abutments were connected at the time of implant placement. Implant overdentures and their respective matrices were inserted following a standard 12-week healing period. Data relating to mobility tests, radiographs, and peri-implant parameters were documented at 12, 16, and 52 weeks after surgery.

RESULTS

A success rate of 95.8% for the Steri-Oss and 100% for the Southern Implants was found, without any statistically significant differences in the marginal bone loss. Significant changes in Periotest values were observed for both types between 12 and 52 weeks (p < .001). Minor changes were observed in the peri-implant parameters evaluated.

CONCLUSIONS

These preliminary findings show a successful application of this one-stage approach for unsplinted implants supporting mandibular overdentures with Steri-Oss and Southern Implant Systems.

Systemically administered human growth hormone improves initial implant stability: an experimental study in the rabbit

PURPOSE

This study was an investigation to determine whether human growth hormone (hGH) continuously administered to rabbits may improve implant integration in bone.

MATERIALS AND METHODS

Thirty-two commercially pure titanium (c.p. Ti) implants were inserted in the tibiae of 16 rabbits. Human growth hormone (0.3 U/kg/d) or sodium chloride (NaCl) was administered by subcutaneous pumps. Insulin-like growth factor-1 (IGF-1) levels in blood were measured. Two biomechanical tests were performed: (1) every second week resonance frequency analysis (RFA) was used to investigate implant stability or stiffness at the interface and, after 8 weeks of follow-up, (2) removal torque (a measure of implant integration and stability) was registered. Further evaluation was performed by dual energy x-ray analysis (DEXA), to evaluate bone mineral density, and histomorphometric analysis of tissue-to-implant integration on undecalcified cut and ground sections.

RESULTS

A difference in implant stability was detected with the RFA technique after 2 weeks and 8 weeks in favor of the hGH-treated rabbits. No significant differences were detected with removal torque, DEXA, and histomorphometric measurements. The blood test demonstrated antibody development in the rabbits treated with hGH after 4 weeks.

CONCLUSION

Growth hormone has an initial beneficial effect on implant integration; however, owing to rapid antibody formation, this study did not demonstrate whether this effect remains in the long term.

Implant Stability Measurements Using Resonance Frequency Analysis in the Grafted Maxilla: A Cross-Sectional Pilot Study

BACKGROUND

High failure rates have been presented for implants placed in grafted bone. The bone graft-implant interface constitutes a most complex healing situation, where the time scale for osseointegration and development of implant stability currently is not known.

PURPOSE

The aim of the study was to measure the stability of implants placed in grafted bone after various follow-up periods.

METHODS

Implant stability measurements by means of resonance frequency analysis were performed in 10 patients previously treated with a Le Fort I osteotomy and interpositional bone grafts. The implants were placed 3 to 4 months after the grafting procedure. Sixty-seven Brånemark implants were subjected to resonance frequency analysis measurements at fixture placement and up to 5.5 years after implant surgery. Periapical radiographs were used for assessment of marginal bone levels.

RESULTS

The radiographic examinations showed marginal bone loss with time during the 5.5-year follow-up. The resonance frequencies varied from 5860 to 8440 Hz. When accounting for abutment length and marginal bone level, there was a tendency of increasing resonance frequency with time. Two implants with low resonance frequencies failed during the prosthetic phase.

CONCLUSION

The results indicate an increased implant stability with time, which may reflect bone formation, remodeling, and maturation at the implant interface.