Edwin A. McGlumphy

Clinical Accuracy of 3 Different Types of Computed Tomography-Derived Stereolithographic Surgical Guides in Implant Placement

PURPOSE Presurgical planning is essential to achieve esthetic and functional implants. The goal of this clinical study was to determine the angular and linear deviations at the implant neck and apex between planned and placed implants using stereolithographic (SLA) surgical guides. PATIENTS AND METHODS A total of 110 implants were placed using SLA surgical guides generated from computed tomography (CT). All patients used the radiographic templates during CT scanning. After obtaining 3-dimensional CT scans, each implant insertion was simulated on the CT images. SLA surgical guides using a rapid prototyping method including a laser beam were used during implant insertion. A new CT scan was made for each patient after implant insertion. Special software was used to match images of the planned and placed implants, and their positions and axes were compared. RESULTS The mean angular deviation of all placed implants was 4.1 degrees+/-2.3 degrees, whereas mean linear deviation was 1.11+/-0.7 mm at the implant neck and 1.41+/-0.9 mm at the implant apex compared with the planned implants. The angular deviations of the placed implants compared with the planned implants were 2.91 degrees+/-1.3 degrees, 4.63 degrees+/-2.6 degrees, and 4.51 degrees+/-2.1 degrees for the tooth-supported, bone-supported, and mucosa-supported SLA surgical guides, respectively. CONCLUSION The results of this study suggested that stereolithographic surgical guides using CT data may be reliable in implant placement, and tooth-supported SLA surgical guides were more accurate than bone- or mucosa-supported SLA surgical guides.

Influence of bone density on implant stability parameters and implant success: a retrospective clinical study

BackgroundThe aim of the present clinical study was to determine the local bone density in dental implant recipient sites using computerized tomography (CT) and to investigate the influence of local bone density on implant stability parameters and implant success.MethodsA total of 300 implants were placed in 111 patients between 2003 and 2005. The bone density in each implant recipient site was determined using CT. Insertion torque and resonance frequency analysis were used as implant stability parameters. The peak insertion torque values were recorded with OsseoCare machine. The resonance frequency analysis measurements were performed with Osstell instrument immediately after implant placement, 6, and 12 months later.ResultsOf 300 implants placed, 20 were lost, meaning a survival rate of %. 93.3 after three years (average 3.7 ± 0.7 years). The mean bone density, insertion torque and RFA recordings of all 300 implants were 620 ± 251 HU, 36.1 ± 8 Ncm, and 65.7 ± 9 ISQ at implant placement respectively; which indicated statistically significant correlations between bone density and insertion torque values (p < 0.001), bone density and ISQ values (p < 0.001), and insertion torque and ISQ values (p < 0.001). The mean bone density, insertion torque and RFA values were 645 ± 240 HU, 37.2 ± 7 Ncm, and 67.1 ± 7 ISQ for 280 successful implants at implant placement, while corresponding values were 267 ± 47 HU, 21.8 ± 4 Ncm, and 46.5 ± 4 ISQ for 20 failed implants; which indicated statistically significant differences for each parameter (p < 0.001).ConclusionCT is a useful tool to determine the bone density in the implant recipient sites, and the local bone density has a prevailing influence on primary implant stability, which is an important determinant for implant success.

Biomechanical aspects of primary implant stability: a human cadaver study.

BACKGROUND The quality of bone is an important factor in the successful implant treatment, and it is evident that higher implant failure is more likely in poor quality of bone. The primary stability of oral implants related to resistance to micromotion during healing is influenced by bone quality, surgical technique, and implant design. PURPOSES The aims of this biomechanical study were to explore the effect of bone quality on initial intraosseous stability of implants, and to determine the correlations between the bone quality and implant stability parameters. MATERIALS AND METHODS Twenty-four implants (Neoss Ltd., Mölnlycke, Sweden) were placed into anterior and posterior regions of three human cadaver mandibles. The bone densities of implant recipient sites were preoperatively determined using computerized tomography (CT) in Hounsfield unit (HU). The maximum insertion torque values were recorded, and primary implant stability measurements were noninvasively performed by means of resonance frequency analysis (RFA). RESULTS The bone density values ranged from -267 HU to 553 HU. It was found that mean bone density, insertion torque, and RFA values were 113 +/- 270 HU, 41.9 +/- 5 Ncm, and 70 +/- 7 implant stability quotient (ISQ), respectively. Statistically significant correlations were found between bone density and insertion torque values (r = 0.690, p < .001); bone density and ISQ values (r = 0.557, p < .05); and insertion torque and ISQ values (r = 0.853, p < .001). CONCLUSION CT is a useful tool to assess bone quantity and quality in implant recipient sites, and bone density has a prevailing effect on implant stability at placement.

Two Alternative Surgical Techniques for Enhancing Primary Implant Stability in the Posterior Maxilla: A Clinical Study Including Bone Density, Insertion Torque, and Resonance Frequency Analysis Data

BACKGROUND The primary stability of dental implants associated with resistance to micromotion during healing is affected by surgical technique and implant design, which are important especially in the soft bone, where implant failures are more likely. PURPOSES This study was designed to compare the parameters associated with implant insertion using two different methods of enhancing implant primary stability and to identify any relationship between these parameters at implant insertion. MATERIALS AND METHODS A total of 60 implants were placed in the maxillary posterior regions of 22 patients. The bone densities at the implant sites were recorded using a computerized tomography machine in Hounsfield unit (HU). The maximum insertion torque data were recorded with the Osseocare (Nobel Biocare AB, Göteborg, Sweden) equipment, while resonance frequency analysis (RFA) measurements were taken using an Osstell (Integration Diagnostics AB, Göteborg, Sweden) machine at implant surgery. Comparisons including HU, Ncm, and implant stability quotient were made between two control groups (C1 and C2), and corresponding four test groups (T1-T4) using thinner drills to enhance primary implant stability. RESULTS Two implants were lost, meaning an overall implant survival rate of 96.6% after 3 +/- 1 years. When compared to control groups, significantly higher mean maximum insertion torque and RFA values were found for corresponding test groups. In addition, strong correlations were observed between the bone density and insertion torque, and implant stability values at implant placement. CONCLUSION The results of this study suggest that using thinner drills for implant placement in the maxillary posterior region where bone quality is poor may improve the primary implant stability, which helps clinicians to obtain higher implant survival rates.

Should edentulous patients be constrained to removable complete dentures? The use of dental implants to improve the quality of life for edentulous patients.

BACKGROUND Nowadays, there is some speculation among dental educators that the need for complete dentures will significantly decrease in the future and that training in their provision should be removed from the dental curriculum. OBJECTIVE To sensitise the reader to the functional shortcomings of complete denture therapy in the edentulous patient and present restorative options including implants to improve edentulous quality of life in these patients. METHODS Information retrieval followed a systematic approach using PubMed. English articles published from 1964 to 2008, in which the masticatory performance of patients with implant-supported dentures was assessed by objective methods and compared with performance with conventional dentures, were included. RESULTS National epidemiological survey data suggested that the adult population in need of one or two complete dentures will increase from 35.4 million adults in 2000 to 37.9 million adults in 2020. Clinical studies have showed that the ratings of general satisfaction were significantly better in the patients treated with implant overdentures post-delivery compared with the complete denture users. In addition, the implant group gave significantly higher ratings on comfort, stability and ability to chew. Furthermore, patients who received mandibular implant overdentures had significantly fewer oral health-related quality of life problems than did the conventional group. CONCLUSION Implant-supported dentures including either complete overdentures or a hybrid prosthesis significantly improve the quality of life for edentulous patients compared with conventional removable complete dentures. Therefore, the contemporary dental practitioner should consider other options as well as conventional removable complete dentures to restore edentulous patients.

Fabricating complete dentures with CAD/CAM technology

Conventional complete denture prosthetics require several appointments to register the maxillomandibular relationship and evaluate the esthetics. The fabrication of milled complete dental prostheses with digital scanning technology may decrease the number of appointments. The step-by-step method necessary to obtain impressions, maxillomandibular relation records, and anterior tooth position with an anatomic measuring device is described. The technique allows the generation of a virtual denture, which is milled to exact specifications without the use of conventional stone casts, flasking, or processing techniques.

A comparison of the stress transfer characteristics of a dental implant with a rigid or a resilient internal element

It has been suggested that there is a unique set of problems associated with joining an implant and a natural tooth with a fixed partial denture. The manufacturer of the IMZ implant system claims that this procedure can be accomplished successfully because of the planned stress-distributing characteristics of their resin internal (intramobile) element. This study compared the difference in the stress patterns generated in photoelastic plastic by an IMZ implant with a resilient or a rigid internal element. Under a standardized cantilever load, the stress patterns were photographed in the field of a circular polariscope. The total stress areas were calculated and a statistical comparison performed. The static load conditions of the model demonstrated no statistical difference between the area of stress pattern generated by an IMZ implant with or without a resilient internal element. Moreover, a single load produced the same deflection of the cantilever beam regardless of which element was interposed.

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

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

Load to failure of different zirconia abutments for an internal hexagon implant

STATEMENT OF PROBLEM Various zirconia abutment designs are available to restore implant systems. Fracture resistance is one of the criteria involved in selecting among these options. PURPOSE The purpose of this in vitro study was to measure and compare load to failure for 5 zirconia abutments for an internally hexagon implant. MATERIAL AND METHODS Five 4.1×11.5-mm Zimmer tapered screw-vent implants were individually secured in a loading apparatus, and 3 specimens of each of the 5 different abutments (Zimmer Contour with a Ti ring, anatomic-contour Atlantis-Zr, anatomic-contour Inclusive-Zr, anatomic-contour Astra Tech ZirDesign, Legacy Straight Contoured abutment with Ti core) (N=15) were loaded at a 30-degree angle until the implant abutment complex failed. Data for load to failure were compared with analysis of variance and a Tukey-Kramer post hoc test (α=.05). RESULTS The custom anatomic-contour abutment (Inclusive) showed the lowest load to fracture, and the stock anatomic-contour (AstraTech ZirDesign) the second lowest load to fracture. These were significantly lower than all other abutments (P<.05). The highest overall fracture strength was of a zirconia abutment with a titanium core-hexagon (Legacy Straight Contoured), which was significantly greater than all other abutments (P<.05). Anatomic-contour zirconia abutments fractured at an average of 275 N compared with the average fracture load of 842 N for zirconia abutments with titanium component (P<.05). CONCLUSION The stock zirconia abutment with a titanium ring and the zirconia abutment with a titanium core-hexagon (Legacy Straight Contoured) had significantly greater fracture resistance than that of any of the 1-piece anatomic-contour zirconia abutments tested.

Is there a lower threshold value of bone density for early loading protocols of dental implants

This clinical study aimed to determine the bone density in dental implant recipient sites using computerized tomography (CT) and to establish a lower threshold value of bone density for early loading protocols. The study group was composed of 100 early loaded implants in 42 patients. A total of four groups were established according to the loading time and implant sites. The bone density of each recipient site for implant placement was determined using CT. The maximum insertion torque values were recorded with torque controlling machine. Implant stability measurements were performed with resonance frequency analyser. The bone density values varied from 528 to 1231 HU. It was found that mean bone density, insertion torque and resonance frequency analysis values were 887 +/- 180 HU, 41.2 +/- 6 Ncm, and 73.7 +/- 4 ISQ, respectively. Strong correlations were found between these three parameters. CT may be a useful tool for assessing the bone density of recipient areas before implant placement, and the early loading of dental implants may be possible in the implant sites where bone density is over 528 HU.