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PubMed2001

Replacement therapy and the immediate post-extraction dental implant.

Immediate postextraction implant placement often deals with two major problems: maintaining the initial stability of the implant(s) and preventing soft tissue ingrowth during the healing period. Both problems may lead to the loss of the implant(s). The objective of this clinical study was to evaluate the effectiveness, reliability, and placement of single-stage implants in extraction sockets in combination with a synthetic bone substitute. Hopeless teeth were extracted and one-stage cylindrical screw implants, hollow and solid, were inserted together with a composite polymer without using a membrane. Rehabilitation was performed three to six months postoperatively by placement of different types of prostheses. Excellent initial results were confirmed by the follow-up of 7 to 10 years. The hollow screw-type showed a higher failure rate when compared with the solid screw-type. One-stage implant osseointegration in extraction sockets is enhanced if used with this synthetic graft material, and the simplicity of the method does not jeopardize outcome and predictability. It provides the patient with the benefits of implant-supported restorations in a simple, quick, cost-effective, and secure manner.

Adult↗
PubMed2001

Inadequate implant angulation resulting from oroantral fistula: case report.

Successful implant surgery is largely dependent on good treatment planning and careful surgery. A complete treatment plan must encompass both surgical and prosthetic considerations for the implant restoration. Some compromised implants are restorable, and the result can be acceptable if they can be adjusted into a more ideal position. The goals of the segmental osteotomy are the preservation of a healthy dental unit, the creation of a more ideal environment for dental restoration and occlusal reconstruction, the optimization of cost effectiveness, and the minimization of edentulous space. The purpose of this study is to present the segmental maxillary osteotomy to reposition the alveolar segment with its implant that was in a highly compromised situation.

Alveolar Process↗
PubMed2002

A prospective multicenter clinical investigation of a bone quality-based dental implant system.

This article reports the 5-year interim results of an independently monitored, prospective, multicenter clinical trial of a bone quality-based implant design. At six study centers, 495 implants were placed in 151 cases with an average follow-up period of 1.6 years (range: 1.0-3.6 years) after prosthesis delivery. The majority of the implants were placed in D2 or D3 bone to support fixed partial dentures or implant-supported overdentures. Using strict success criteria, there were three implant failures, resulting in a cumulative 99.5% success rate according to Kaplan-Meier survival analysis. Radiographic analysis revealed a mean bone loss of 0.06 mm at 1 year and a bone gain of 0.04 mm at 2 years after prosthesis loading. There were no statistical differences in the results by center, implant type, bone density, area of the mouth, or prosthesis type. The results of this 5-year study revealed a high success rate and limited crestal bone loss in all bone densities by the use of an implant specifically designed for the varying biomechanical conditions and bone quality associated with the human maxilla and mandible.

Alveolar Bone Loss↗
PubMed2002

SwissPlus Implant System, Part 2: Prosthodontic aspects and intersystem comparisons.

Incompatibility between implant systems and the increasing complexity of esthetic restorative options frequently require dentists to obtain special training in the selection and use of prosthetic components. SwissPlus System implants have been designed to simplify restorative procedures by eliminating many ancillary restorative components. The implants are packaged on a fixture mount that also functions as a transfer and as an abutment for cemented restorations. For multiple-unit, screw-retained restorations, the prosthesis can be splinted directly to the top of the implant without an intermediate abutment. Overdenture attachments, straight, angled, screw-receiving, and custom-cast abutments complete the restorative system. This paper presents an overview of the SwissPlus System's prosthodontic aspects. Test data also illustrate intersystem compatibility and differences between SwissPlus System implants and ITI syn-Octa implants.

Dental Abutments↗
PubMed2004

In vitro evaluation of horizontal implant micromovement in bone specimen with contact endoscopy.

Primary stability of dental implants is mandatory for their osseointegration. A method is described that allows objective measurements of implant displacement in bone sites during lateral loading. Ten samples of bovine bone (2 cm x 2 cm) with bone type II, III, and IV according to Lekholm and Zarb were used for the experiment. Ten Semados dental implants of 15-mm length and 3.75-mm diameter were placed. All implants were loaded with lateral forces of 5, 10, 20, and 30 N through 8-mm abutments for 2 seconds each. Lateral displacement was observed by means of contact endoscopy. Micromovement was detected with the help of a transmitter strip attached to the abutment. Endoscopic images were processed digitally and microdisplacement was calculated relative to the reference body (microscrew) placed adjacent to the implant. Micromovement observed varied with the force applied. Lateral force of 5 N resulted in a mean displacement of 39 microm; for 30 N, the mean displacement was 157 microm. Bone type also influenced the amount of movement. Contact endoscopy represents a new method for direct observation of implant movement relative to the bone surface in vitro. In combination with support immersion technique, contact endoscopy could be used as an office procedure to evaluate intraoperatively implant stability during functional loading.

Analysis of Variance↗
PubMed2005

Finite element analyses of two antirotational designs of implant fixtures.

The purpose of this study was to compare the effect of cyclic compressive forces on loosening of the abutment retaining screw of dental implant fixtures with two different antirotational designs using the finite element analysis. A three-dimensional model of externally hexed and trichannel dental implant fixtures with their corresponding abutments and retaining screws was developed. Comparison between the two designs was carried out using finite element analysis. The results revealed that the externally hexed design has significantly higher overall stress, contact stress, and deflection compared with the trichannel design. The trichannel antirotational design has the least potential for fracture of the implant/abutment assembly in addition to its capability for preventing rotation of the prosthesis and loosening of the screw.

Dental Abutments↗
PubMed2005

Analysis of changes in implant screws subject to occlusal loading: a preliminary analysis.

Loosening of the abutment screw can present a problem for the stability of the implant-supported crown or prosthesis. The purpose of this study was to understand the parameters of screw loosening, using an in vitro model, including loss of torque, screw head rotation, changes in screw dimension, and distortion of the implant-abutment joint. Implants (4 x 10 mm) were potted in autopolymerizing blocks. Abutments were placed with screws tightened with a 35-Ncm torque and standardized crowns fabricated. There were 3 implant systems used: Nobel Biocare USA, Inc. (Yorba Linda, CA), 3i Implant Innovations, Inc. (Palm Beach Gardens, FL), and Bio-Lok International, Inc. (Deerfield Beach, FL). Seven samples were tested for each system. Samples were loaded with 300-N loads for 50,000 cycles at 1 Hz. Torque turn audits were performed at 10,000, 25,000, and 50,000 cycles. At the conclusion of the loading, counterclockwise rotation of the abutment screw was measured. The screws were retrieved and measurements made compared with the controls. Finally, 1 sample from each group was embedded in resin, sectioned longitudinally, and examined under the standard error of the mean. The Nobel Biocare system showed a 9.4-Ncm loss of torque from the loading protocol. This result was accompanied by a counterclockwise rotation of 7 degrees and a 200-ìm elongation of the screw. Finally, there was compression and distortion of the longitudinally sectioned joint architecture observed with the standard error of the mean. From the 3i and Bio-Lok International groups, no loss of torque, counterclockwise rotation, or lengthening of the screws was observed. Intimate adaptation of the joint without distortion was seen in the longitudinal sections. Screw loosening appears to follow specific parameters that include counterclockwise rotation, lengthening of the screw, and distortion of the screw joint. This process is likely associated with both the physical properties of the screw as well as its configuration.

Bone Screws↗
PubMed2006

A finite element analysis of ferrule design on restoration resistance and distribution of stress within a root.

AIM: To analyse the effect of ferrule height upon the mechanical resistance and stress distribution within a root to explain variations in the pattern of root fracture. METHODOLOGY: An extracted, intact, caries free, maxillary right central incisor was scanned by laser and then reconstructed on a computer to produce a model of the tooth and associated periodontal ligament. A simulated post/core/crown restoration was constructed on conventional tooth preparations with various ferrules. The crown was loaded with a simulated 500 N force and the simulated displacement of components and the tensile and compressive stress within the tooth structure were recorded. RESULTS: Without a ferrule preparation, the simulated crown tilted to the labial and rotated distally. With increasing ferrule height the displacement and rotation of the crown reduced in conventional and crown-lengthening models with maximum reduction occurring when the ferrule height reached 1.5 mm. In ferrule models, higher levels of tensile stress developed in internal (by a factor of 8) and mid-root palatal (by a factor of 90) dentine at the cervical margin of the preparation. With an increase in ferrule height, the area of tensile stress within the palatal mid-dentine expanded towards the cervical margin. Similar patterns and stress values were recorded for the crown-lengthening models. CONCLUSION: The study confirms that a ferrule increases the mechanical resistance of a post/core/crown restoration. However a ferrule creates a larger area of palatal dentine under tensile stress that may be a favourable condition for a crack to develop. Crown-lengthening did not alter the levels or pattern of stress within compared with conventional ferrule preparations.

Computer Simulation↗
PubMed1990

Implants and infections with special reference to oral bacteria.

Osseointegration or bony anchorage of oral implants was first described by Brånemark and coworkers. This type of connection between the titanium oxide layer and the bone gives stable long-term results for the implants in function. Fibrous tissue interphase between implant and bone will allow mobility which will gradually increase and cause implant failure. The microbiota around stable versus failing implants seem to parallel the patterns around healthy versus diseased natural teeth. Infections most often develop around failing implants. This may create mostly localized, but sometimes even widespread serious infection problems. Metastatic infectious problems related to endo-prosthesis replacing joints and cardiovascular structures are briefly discussed in connection with bacteremia caused by oral infections in general and surgical procedures.

Bacterial Infections↗
PubMed2006

The vibratory characteristics of obturators with different bulb height and form designs.

The aim of the present study was to investigate whether the vibratory characteristics of obturator prostheses are affected by bulb design, i.e.: the hollow or buccal flange type, and different lateral and medial bulb heights. Buccal flange and hollow bulb obturator prostheses were fabricated with two different lateral bulb wall heights and two different medial bulb wall heights. Ultimately, eight obturator prostheses were prepared for evaluation of their vibratory characteristics. The frequency-response functions were recorded on an FFT analyzer to identify their vibratory characteristics. A transient response simulation was carried out in which an impact was applied to the non-defect side. The decay rate, damping time and maximum amplitude of the retainers were statistically analysed by anova with Scheffé's test (P < 0.05). The decay rate of every buccal flange type was higher and damping time was shorter than those of every hollow type, except between a pair with low lateral and low medial bulb walls. The maximum amplitude values of four obturators with low medial bulb walls were significantly lower than those of four obturators with high medial walls. The buccal flange obturator prosthesis with high lateral and low medial walls showed the maximum decay rate and the minimum amplitude of the retainers on molars. Vibration analysis suggests that a buccal flange obturator prosthesis with high lateral and low medial walls is preferable.

Analysis of Variance↗
PubMed2006

A comparison between insertion torque and resonance frequency in the assessment of torque capacity and primary stability of Brånemark system implants.

The aim of this study was to determine primary stability and insertion torque of Brånemark System implants placed in the anterior mandible, and to evaluate a possible correlation between primary stability and insertion torque. Thirty edentulous patients were treated with 60 Brånemark System implants using a one-stage technique. The insertion torque values of all implants were recorded with the Osseocare equipment. Immediately after implant placement, each implant was connected to the transducer of an Osstell machine to measure the primary implant stability. The average insertion torque and resonance frequency values were 41.5 +/- 5.8 and 74.1 +/- 3.8 for 30 implants. The correlation between insertion torque and resonance frequency values indicated a statistical significance (P < 0.001). The difference between mean insertion torque values for female and male patients was statistically significant (P < 0.001). No significant difference (P > 0.05) was found between younger and older patients with mean insertion torque values of 43.1 +/- 4.7 and 40.1 +/- 6.5 respectively. The results of this study showed a strong correlation between the primary stability and insertion torque values of Brånemark System TiUnite MKIII implants at the time of implant placement.

Age Factors↗
PubMed2006

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.

Adult↗
PubMed1993

In vitro consistency of the Periotest instrument.

PURPOSE: The consistency of measuring the damping characteristics using the Periotest (Siemens AG, Bensheim, Germany) was studied. MATERIALS AND METHODS: Periotest values (PTV) of three rods embedded in various depths of impression material were recorded by seven dentists. RESULTS: There is no statistically significant difference among the subjects in measuring PTV of any of the three rods. However, the variation in the occlusal-gingival position of impact resulted in statistically significant different PTV measurements of each of the three rods. Assessment of mobility of the same objects using a clinical criterion was found to be less consistent as the mobility of the object increased. CONCLUSION: In vitro PTV measurements are consistent provided that the position of impact is controlled.

Analysis of Variance↗
PubMed1993

Mechanical properties of metal connectors soldered by gas torch versus an infrared technique.

PURPOSE: The ultimate tensile strength and percentage elongation of solder joints of three alloy systems were tested. MATERIALS AND METHODS: Solder joints were formed using either an infrared soldering machine or gas-oxygen torch. Intact solder materials were used as controls. RESULTS: There were no significant differences in percentage elongation among different treatment methods of the solders or among various solder materials. All intact solder materials possessed significantly higher ultimate tensile strength than the joints made with either method. For high-noble and noble alloy solders, there were no significant differences in ultimate tensile strength of joints made with either method. For base metal alloy solder, the ultimate tensile strength of joints made with the infrared technique was significantly higher than that made with the gas-oxygen torch technique. CONCLUSIONS: The infrared technique can be used as an alternative to the gas-torch technique for soldering high-noble and noble alloys. It is superior to the gas-torch technique for soldering a cobalt-chromium alloy.

Analysis of Variance↗
PubMed1993

A measurement of torque values obtained with hand-held drivers in a simulated clinical setting.

PURPOSE: This study measures the amount of torque that can be applied to the heads of implant screws via hand-held drivers and wrenches in a simulated clinical setting. MATERIALS AND METHODS: Sixty second-year dental students applied their maximum controlled torque to the head of a hex instrument attached to a Tonichi torque gauge mounted in a mannequin. The torque values obtained were recorded, and a mean torque value was calculated RESULTS; The mean torque value obtained in this study was 11.55 N.cm. CONCLUSIONS: Small-diameter, 10 N.cm gold screws can be adequately tightened with manufacturer-supplied instrumentation. Larger screws requiring more than 10 N.cm of torque cannot be tightened manually using currently available hand-held screwdrivers and hand wrenches.

Dental Implants↗
PubMed1995

Partial denture framework design for bone-grafted mandibles restored with osseointegrated implants.

Unilateral osseous reconstruction of a dentate mandible after tumor ablation may be restored with implants and a removable partial denture. Often the remaining dentition is in a "straight line" that does not allow cross-arch stabilization of the framework. Framework design incorporating existing unilateral lingual or buccal retention in the natural dentition and unilateral implant attachments affords a stable, retentive definitive prosthesis for this patient population.

Acrylic Resins↗
PubMed1995

Effect of dynamic loading methods on cement film thickness in vitro.

PURPOSE: Reduced cement flm thicknesses can improve crown seating and decrease marginal discrepancies. Improved marginal adaptation has the potential to reduce plaque accumulation, periodontal disease, and cement dissolution. Studies have indicated that dynamic seating methods can reduce seating discrepancies associated with zinc phosphate and resin cements. However, other types of cements and other dynamic techniques have not yet been studied or compared, nor has the mechanism for improved seating been fully explained. Therefore, the purpose of this study was to investigate the effect of a variety of loading methods on the film thicknesses of current types of crown and fixed partial denture cements compressed between glass plates. MATERIALS AND METHODS: This study investigated the effect of three dynamic loading methods on film thickness of six representative fixed prosthodontic cements. These included zinc phosphate, resin-modified glass ionomer, encapsulated glass ionomer, adhesive composite resin, composite resin, and polycarboxylate. The method was derived from American Dental Association specifications for cement film thickness. In control groups, the cements were placed between two glass glass plates and statically loaded with a 15-kg weight. The test groups were initially similarly loaded, and then for 30 seconds further subjected to simulated repeated patient opening and closing, vibrations from an electromallet, or an ultrasonic device. RESULTS: Mean film thicknesses ranged from 7.4 micrometers for polycarboxylate / ultrasound up to 40.3 micrometers for composite resin / static. Two-way analysis of variance revealed that the effects of material type and cementation method and their interaction all significantly affected film thickness (P < .0001). Multiple range analysis showed that dynamic methods were generally superior to static loading and that the ultrasonic method was the best overall. CONCLUSIONS: The different dynamic loading methods all significantly decreased cement film thicknesses between glass plates. The ultrasonic method was the most effective. The type of cement used also influenced film thickness. Composite resins were more affected than other materials.

Analysis of Variance↗
PubMed1997

Evaluation of stresses and forces in selected I-bars using the finite element method.

PURPOSE: Three-dimensional models of half-round, tapered and full-round, untapered I-bar clasps of varying configurations and material properties were constructed. The purpose of this study was to examine the stresses and reaction forces produced within each model upon deflection to 0.01 in (0.254 mm), 0.02 in (0.508 mm), and 0.03 in (0.762 mm) at 1 mm from the tip using the finite element method. MATERIALS AND METHODS: Three-dimensional computer models of half-round and full-round clasps were constructed using solid eight-node brick elements. The half-round, tapered I-bar clasp model was 2.4 and 1.4 mm in diameter at the base and tip, respectively. The full-round, untapered I-bar clasp model was 1 mm in diameter. Three design groups were created for each clasp form. Group A had 25% of the total length in the straight anchor end of the I-bar clasp, B had 35%, and C had 50%. All models were 31 mm in length and had a radius of curvature of 5 mm. Different material properties were incorporated into the models. Each model was deflected at a point 1 mm from the tip to 0.01 in (0.254 mm), 0.02 in (0.508 mm), and 0.03 in (0.762 mm). RESULTS: The stresses and forces produced as a result of the deflection applied to each clasp were viewed and displayed graphically. The maximum von Mises stresses in megapascals and the reaction force in newtons (N) were recorded. Stresses varied in each clasp in the range of 0 to 154.3 MPa for the half-round, tapered I-bar clasp models, and 0 to 100.9 MPa for the full-round I-bar clasp models at 0.01-in deflection. Reaction force measured near the tip of the clasp models was between 1.60 N and 6.31 N for the half-round, and between 0.22 N to 2.13 N for the full-round I-bar clasp models. For all clasps studied, as the deflection increased, the location of stress within each group remained the same regardless of the material properties; however, the stress and force values increased linearly. CONCLUSIONS: The location of maximum stress varied with the length of the anchor portion of the clasps studied. Maximum stresses were located on the flat side of the half-round, tapered I-bar clasp model.

Color↗