Clinical application of a new cone-beam computerized tomography system to assess multiple two-dimensional images for the preoperative treatment planning of maxillary implants: case reports

Accurate assessment of the location of the maxillary sinuses, incisive canal, and nasal cavity, as well as the height, width, and angulation of bone is essential for implant treatment planning. The purpose of this study was to introduce the clinical application of a cone-beam computerized tomography system (Ortho-CT) to assess multiple two-dimensional (2D) images for the preoperative treatment planning of maxillary implants. To evaluate the multiple 2D images scanned using the Ortho-CT system the maxillary region placed with radiopaque template in the maxilla. Ortho-CT images provided useful information for evaluating the morphology of the maxilla, for locating the incisive canal, maxillary sinuses, nasal cavity, and for showing the relationship of the template to the bone. It is concluded that the Ortho-CT system is a useful aid for diagnosis and treatment planning for maxillary implant treatment.

Implant treatment in combination with lateral augmentation of the alveolar process: a 3-year prospective study

BACKGROUND

In patients in whom the height of the alveolar process is adequate but the crest is too narrow to host an implant, lateral augmentation is required. Such augmentations have mostly been performed using autogenous bone blocks secured to the buccal surface. An alternative to autogenous bone may be bovine hydroxyapatite (Bio-Oss, Geistlich Pharma AG, Wolhusen, Switzerland) or other bone substitutes.

PURPOSE

The aim of this study was to evaluate the clinical and radiographic outcome of dental implants inserted after lateral augmentation of too narrow alveolar processes with a combination of bovine hydroxyapatite (Bio-Oss) and autogenous bone.

METHODS

Thirty patients (14 males and 16 females) with a mean age of 41.6 years fulfilled the inclusion criteria. Twenty-nine augmentation sites with a total of 74 implants could be followed for 3 years.

RESULTS

Three implants were lost; these were lost before loading (at the abutment operation). The survival rate was 95.9%. The mean marginal bone loss during the 3-year observation period was 0.3 +/- 0.2 mm.

CONCLUSIONS

A 50/50 combination of Bio-Oss and autogenous bone chips stabilized with Tisseel (Baxter AG/Duo Quick AG, Vienna, Austria) was useful for lateral augmentation of the alveolar crest. Lateral grafts with Bio-Oss, autogenous bone, and Tisseel made it possible to achieve good implant stability and high implant survival results. The bone level changes adjacent to the implants were the same as in nongrafted cases.

A Technique for Standardized Evaluation of Soft and Hard Peri-Implant Tissues in Partially Edentulous Patients

BACKGROUND

There is a growing need to evaluate the esthetics of implant-supported crowns and bridges. An important tool for such an evaluation is standardized assessment of the soft and hard peri-implant tissue levels.

METHODS

A simple acrylic device has been developed for reliable and reproducible assessment of soft and hard peri-implant tissues using standardized color slides and standardized dental x-rays. With this device, changes in both the soft and hard tissues around implant-supported crowns can be evaluated as a function of time. The reproducibility of the technique was tested on color slides as well as on dental x-rays in a series of implant-supported crowns and their neighboring teeth.

RESULTS

The reproducibility of this technique was excellent. The measuring errors for repeated measurements of the soft and hard tissues were 0.14 +/- 0.02 mm and 0.13 +/- 0.01 mm, respectively.

CONCLUSIONS

The device is a reliable tool to assess changes in both soft and hard tissues around crowns and implants over time. Likewise, it is suggested that this technique also can be used to objectively assess soft and hard tissue changes around natural teeth with or without prosthetic restorations.

The supplementary role of panoramic radiographs in diagnosis and prevention of life-threatening systemic health condition. Case report

A 71-year-old white male had a routine panoramic radiograph taken for oral health reasons. Positive carotid calcifications findings on the radiograph were in agreement with significant carotid stenosis as determined by duplex ultrasonic examination. If the occasion arises, the authors advocate that a routine panoramic radiograph examination include an assessment of the region of the carotid system for presence of carotid calcifications in all adult patients.

A technique for making a diagnostic and surgical template

Implant-supported restorations can restore function and esthetics provided that the implants are placed in the predetermined location and properly angulated. This article describes the fabrication of a diagnostic template incorporating a silicone radiopaque marker as a guide for achieving 3-dimensional evaluation of bone without artifacts using computed tomography. The diagnostic template may be easily transformed into a surgical template by removing the silicone marker.

Implant Stability, Tissue Conditions, and Patient Self-Evaluation after Treatment with Osseointegrated Implants in the Posterior Mandible

BACKGROUND

Implant treatment in the posterior mandible is considered challenging because of bone resorption and the presence of the inferior alveolar nerve, which may result in the use of short implants.

PURPOSE

To evaluate implant stability, tissue conditions, and patient opinion after treatment with implant-supported bridges in the posterior mandible.

MATERIALS AND METHODS

Thirty-four patients treated with implant-supported bridges in the posterior mandible according to a two-stage protocol were clinically and radiographically examined and interviewed after a mean functional time of 3.9 years. One hundred five Brånemark implants (Nobel Biocare AB, Gothenburg, Sweden) were placed in premolar and molar regions to support 40 bridges. Twenty-eight implants were placed anterior to the mental foramen, and 77 implants were placed posterior to the mental foramen. Bridges were supported either by two or by three implants. After 2 to 6 years, the bridges were removed to analyze the resonance frequency of the implants with the use of a special instrument (Osstell instrument, Integration Diagnostics AB, Gothenburg, Sweden), and an implant stability quotient (ISQ) was recorded for each implant.

RESULTS

One implant was lost. An ISQ range of 59 to 90 (mean, 70.05) expressed stability of fully integrated implants in the posterior mandible. Significantly higher (p < .024) ISQ values were found in implants in three-implant bridges when compared with implants in two-implant bridges. There were no differences in ISQ values between molars/premolars, implant types, implant widths, implant lengths, anchoring depth, or uni- or bilateral mandibular bridges. Good mucosal health in the periimplant soft tissue and minor bone resorption around the implants were observed. Patients were generally very satisfied with the treatment outcome.

CONCLUSIONS

High implant stability can be reached in the posterior mandible. The implants were more stable in three-implant bridges than in two-implant bridges. The patients were highly satisfied with the treatment, and few complications were seen.

Jaw muscles in older overdenture patients

OBJECTIVE

To determine, using computer tomography (CT), whether the retention of a small number of teeth in the older adult used to support overdentures could affect the cross-sectional area (CSA) and X-ray density of two jaw closing muscles.

DESIGN

Cross-sectional study of a group of older patients subdivided into dentate, edentulous and those wearing overdentures supported by two to five teeth.

SUBJECTS

The sample consisted of 24 subjects aged 55-68 years.

OUTCOME MEASURES

CSA and X-ray density of two jaw closing muscles, masseter and medial pterygoid were measured and evaluated using CT.

RESULTS

There were no significant differences between left and right jaw muscles, but the CSA of the masseter muscles were significantly larger than the medial pterygoid muscles. The CSA of the masseter and medial pterygoid muscles was significantly smaller in edentulous subjects compared with dentate subjects but no significant difference was observed between subjects wearing overdentures and those with a natural dentition. No significant differences were observed with the X-ray density between different muscles or dental states.

CONCLUSION

The retention of a small number of teeth in the older adult used to support overdentures appears to sustain the CSA of two jaw closing muscles and therefore could enhance these patients' masticatory ability compared with those who were edentulous.

Bone regeneration by bodily tooth movement: dental computed tomography examination of a patient

A 32-year-old man was examined with computed tomography before and after orthodontic treatment, and alveolar bone levels at the edentulous spaces were assessed. When the computed tomography scans were compared, 2.2 to 5.2 mm of additional craniocaudal alveolar bone remodeling by bodily tooth movement was found in the space-opening region. Bodily movement was achieved with single- and crossed-lever-arm mechanics. Root resorption measuring 1 to 4 mm was observed at the mandibular anterior region, where teeth were used for anchorage to upright the molars.

Immediate non-occlusal loading vs. early loading in partially edentulous patients

Immediate loading of dental implants can reduce treatment time and management concerns, thus increasing patient acceptance. This paper reports the authors' preliminary experience with partially edentulous patients having received non-occlusally loaded provisional restorations within 24 hours of surgery, compared to patients treated according to an early loading protocol. The present data suggest that implant supported fixed partial prostheses can be immediately non-occlusally loaded and restored with a predictability similar to early loaded implants.

Tuned aperture computed tomography (TACT[reg ]) for cross-sectional implant site assessment in the posterior mandible

PURPOSE

This study was designed to optimize a new radiographic modality known as tuned aperture computed tomography (TACT) for cross-sectional imaging of implant sites in human dry mandibles.

MATERIALS AND METHODS

Five imaging modalities were compared for image quality and measurement accuracy: (1) conventional hypocycloidal tomograms, (2) TACT images reconstructed using the average method produced using a linear x-ray source movement, (3) TACT images reconstructed using the average method produced using a multidirectional x-ray source movement, (4) minimally reconstructed TACT images without a fiducial marker at the site of interest, and (5) minimally reconstructed TACT images with a fiducial marker at the site of interest.

RESULTS

The extended Mantel-Haenszel mean score statistic was used to investigate the influence of modality on subjective image quality. A statistically significant difference for certain types of TACT images and multidirectional tomography (P < 0.0001) was observed. Linear TACT and multmin TACT were rated as significantly better than other image modalities (P < 0.0009), whereas multidirectional tomography was rated as being significantly worse than other radiographic modalities (P < 0.0001). For the quantitative assessment, data were normalized and analyzed statistically through a paired-comparisons t test. For each modality, the accuracy for maximum height and height was significantly different from ground truth (P < 0.05).

CONCLUSION

The qualitative data suggest that visibility of structures important to the choice of implant location and dimension were seen better with certain TACT methods. Quantitative differences from ground truth (actual measurements of the bone-absolute truth) were clinically negligible. TACT appears to offer the potential of superior image quality over the status quo.

Early loading of nonsubmerged titanium implants with a sandblasted and acid-etched (SLA) surface: 3-year results of a prospective study in partially edentulous patients

PURPOSE

The aim of this study was to evaluate the success rate of ITI implants with the SLA surface that were loaded after 6 weeks of healing.

MATERIALS AND METHODS

In this prospective cohort study, a total of 104 implants were placed in posterior sites of 51 partially edentulous patients exhibiting bone densities of Class 1, 2, or 3. After a healing period of 6 weeks, all implants were functionally loaded with cemented crowns or fixed partial dentures. The patients were recalled at 3, 12, 24, and 36 months for clinical and radiographic examination.

RESULTS

One implant failed to integrate during healing, and 1 implant was lost to follow-up and considered a dropout. The remaining 102 implants showed favorable clinical and radiographic findings and were considered successfully integrated at the 3-year examination. This resulted in a 3-year success rate of 99.03%.

DISCUSSION

The peri-implant soft tissues were stable over time, as evidenced by no changes in the mean probing depths and the mean attachment levels during the follow-up period. None of the radiographs exhibited signs of continuous peri-implant radiolucency, which confirmed ankylotic stability of all 102 implants. The radiographic evaluation of the bone level at the implant indicated stability of the bone crest levels.

CONCLUSION

The results of this prospective study demonstrated that early loading of ITI implants with the SLA surface after an unloaded healing period of 6 weeks provided successful tissue integration with high predictability, and that successful tissue integration was well maintained up to 3 years of follow-up in this study population.

Early function of splinted implants in maxillas and posterior mandibles using Brånemark system machined-surface implants: an 18-month prospective clinical multicenter study

BACKGROUND

There are limited clinical data available for immediately or early loaded implants placed in posterior mandibles and maxillas. This is probably because bone density often is low in these areas, making it difficult to establish good initial implant stability. By eliminating countersinking and using slightly tapered implants (Brånemark System , Mk IV, Nobel Biocare AB, Gothenburg, Sweden), however, high initial implant stability might be achieved in these regions.

PURPOSE

The aim of this study was to investigate the possibility of early application of implant function in oral locations where the bone density is often low, namely the maxilla and posterior mandible.

MATERIALS AND METHODS

Thirty-one patients were included consecutively in the study, and 36 edentulous areas in maxillas and posterior mandibles were treated. All patients were nonsmokers in good general health. Bruxism and uncontrolled periodontal disease were exclusion criteria. One hundred twenty-four machined-surface implants were placed using an insertion torque of at least 40 Ncm. Temporary prostheses with narrow occlusal platforms, flat cusps, and light occlusal contacts were generally placed within 1 week and not exceeding 20 days from implant placement.

RESULTS

Of the 124 implants installed, 4 failed, 1 in each of four patients, giving an overall survival rate of 96.8% after 18 months. Two implants failed in maxillas and two in mandibles. One implant in a maxilla and one in a mandible were lost in an early stage, and the other two were lost a few months after placement. The prostheses' survival was 100%.

CONCLUSIONS

This study shows that early implant function rehabilitation in maxillas and posterior mandibles is viable using the present clinical protocol. The results are comparable with those of conventional two-stage protocols.

Immediate and early function of Brånemark System implants placed in the esthetic zone: a 1-year prospective clinical multicenter study

BACKGROUND

Immediate/early implant function means great benefits for patients and therapists because treatment time and cost can be substantially reduced. This concept has become an accepted alternative for complete arch fixed restorations in the mandible, and clinical documentation is emerging for other indications.

PURPOSE

The purpose of this prospective clinical multicenter study was to evaluate the outcome of implants placed in incisor, canine, and premolar regions in maxillas or mandibles. Implants were loaded with provisional crowns and bridges on the same day or within a few days and were followed up for 1 year during function.

MATERIALS AND METHODS

Four centers treated 76 patients each in need of an implant-retained prosthesis in the anterior and premolar regions in the maxilla or mandible. A total of 116 titanium implants with machined surfaces (Brånemark System , Nobel Biocare AB, Gothenburg, Sweden) were placed: 74 in maxillas and 42 in mandibles. Eighty-seven prostheses were made, of which 63 were single crowns and 24 were bridges (supported by 53 splinted implants). Twenty-two implants in 14 patients were placed in fresh extraction sites. The goal with the preparation and insertion technique was to achieve good primary implant stability and a minimum implant insertion torque of 30 Ncm before the implant was completely seated. The occlusion was adjusted to eliminate direct contact with the provisional prostheses. After 6 months, the patients received their permanent prostheses. Sixty-seven patients were followed for 1 year.

RESULTS

Five implants were lost in five patients, three in the maxilla and two in the mandible. Four of the lost implants were single-tooth replacements and one was splinted. The cumulative survival rate (CSR) was 95.7% for all implants after 1 year and 93.7% and 98.1% for single-tooth and splinted implants, respectively. There were no implant losses in the extraction sites.

CONCLUSIONS

The CSR of 96% at 1 year indicates that immediate function of Brånemark System implants placed in incisor to premolar regions in both jaws is a viable concept. More failures occurred with single-tooth replacements (6.3%) than with splinted implants (1.9%).

Clinical bone densitometric evaluation of the mandible in removable denture wearers dependent on the morphology of the mandibular cortex

STATEMENT OF PROBLEM

Wide normal variations have been found in the structure and density of the human skeleton, as well as of the mandible.

PURPOSE

The objective of this study was to determine whether the mandibular bone mineral density is correlated with the classification of the structure of the inferior cortex on panoramic radiographs in complete and removable partial denture wearers.

MATERIALS AND METHODS

The mandibular cortical index of 136 randomly selected complete and removable partial denture wearers was evaluated via panoramic radiographs. The criteria for the mandibular cortical index were as follow: category 1, sharp endosteal margin of the inferior cortex; category 2, semilunar defects; and category 3, thick cortical residues on endosteal margin. Forty male patients (mean age 72.7; range 56 to 84 years) and 96 female patients (mean age 69.7; range 48 to 86 years) participated. With a copper stepwedge and DenEx 2001 computer program, the mandibular bone mineral density was investigated densitometrically on dental panoramic radiographs. Four experienced observers and 6 general dental practitioners made the observations on all panoramic radiographs. All bone mineral density values were expressed in equivalents of the actual stepwedge thickness. An independent t test (alpha =.05) was used.

RESULTS

The severity of changes in the mandibular cortex was significantly related to all measured mandibular bone mineral density values (t test: P<.01). Mandibular cortical index category 3 had significantly lower bone mineral density values in all measured regions of interest. Interobserver and intraobserver agreement in mandibular cortical index assessment was excellent.

CONCLUSION

Patients having lower bone mineral density values in the mandible have much more porous cortical layer of the inferior border of the mandible.

Implant-supported fixed cantilever prostheses in partially edentulous arches. A seven-year prospective study

The purpose of the following study was to evaluate the medium- to long-term prognosis of implant-supported cantilever fixed prostheses, and to establish to what degree this is influenced by factors such as length, type of cantilever (mesial or distal), and opposite dentition versus cantilever prostheses. This study was performed on a sample of 38 partially edentulous patients treated between January 1994 and March 2001 with 49 partial cantilever fixed prostheses supported by 100 implants. Marginal bone resorption (MBL) has been studied and used as a reference parameter to define therapeutic success. The MBL measurement was made possible by transposing X-ray images of patients selected on a PC and then using a software program. Statistical analysis was carried out for possible correlation between peri-implant bone resorption and the parameters considered in this study: length and type (mesial or distal) of cantilever and opposite dentition to cantilever prostheses. Seven years after loading cantilever prostheses, the overall cumulative implant survival rate (OCSR) was 97%, and the prostheses success rate is 98%. Mesial cantilever prostheses registered a lower success rate (97.1%) than distal cantilever prostheses (100%). Furthermore, a better prognosis was not observed when the opposite dentition of the prostheses comprised natural teeth, or fixed prostheses on natural teeth, when compared with the cases in which opposite teeth were implant-supported fixed prostheses. The authors concluded that medium-term prognosis of implant-supported cantilever fixed prostheses and traditional implant-supported fixed prostheses was comparable. However, a thorough pre-treatment analysis of risk factors regarding implant-supported prosthesis survival is important.

Morphology and dimensions of the mandibular jaw bone in the interforaminal region in patients requiring implants in the distal areas

This study aimed to analyse variations in the mandibular interforaminal morphology in an attempt to identify potential risks or contraindications for surgery, especially implant installation, in this particular region. A total of 210 spiral computer tomography (CT) examinations of patients requiring endosseous implant installation in the lower jaw were re-evaluated to explore anatomical variations in bone morphology (shape and contour), and to measure parameters concerning height, width and inclination of the bone in the symphyseal atrea. All measurements were performed on the cross-sectional reformatted images mesial to the mental foramina. A lingual concavity (with a depth of 6 +/- 2.6 mm) was observed in 2.4% of the jaws, with a remaining bone height in that area ranging from 4.2 to 11.9 mm. A clearly lingual tilted/inclined morphology was seen in 28.1% of jaws with a mean angle of 67.6 +/- 6.5 degrees, but a relatively constant width (> 8.8 mm). The remaining jaws (69.5%) showed a slight broadening in the caudal direction. The morphologic parameters were influenced neither by age nor by gender. In conclusion, mandibles with a lingual concavity or a severe slope of the lingual cortex might confer increased risks of lingual perforations during trepanation surgery or graft harvesting as well as fenestrations during implant installation. The detection frequency of such variations within the lower jaw seems to advocate a profound dissection of the lingual site and, in the case of some special treatment strategies, additional cross-sectional radiography.

[Influence of biphosphonates on the integration process of endosseous implants evaluated using single photon emission computerized tomography (SPECT)]

Biphosphonates are a large class of drugs which inhibits the resorbing activity of osteoclasts. The aim of this study was to evaluate the influence of topical application of the biphosphonate alendronate on the integration process of endosseus implants placed in a partially edentulous patient. After incision and elevation of a mucoperiosteal flap and carrying out the osteotomy, 2 SLA implants 10 mm long and 3.5 mm wide were inserted in the area of # 4.5 and 4.6. Before placement of # 4.5, a paste made of grinded tablets of alendronate and Rifocin was applied in the osteotomy. Fifteen days after stage I, an evaluation of the osteoblastic peri-implant activity was carried out using single photon emission computerized tomography. Healing was within normal limits. Four months after stage I, the 2 implants were uncovered and considered clinically and radiographically integrated. The osteoblastic activity was judged similar bet-ween the 2 implants in terms of quality of biological response. Osseous scintigraphy and the achievement of implant osseointegration demonstrate the lack of toxicity of the topical application of the biphosphonate alendronate during the initial osseous healing. However, new experimental studies and clinical trials are necessary to confirm the results obtained.

Effect of mandibular positioning on preimplant site measurement of the mandible in reformatted CT

The purpose of this study was to evaluate the effect of mandibular positioning on measurement of the reformatted cross-sectional image of the mandible in computed tomography (CT) according to the area on the mandible. Five dried mandibles, partially edentulous in the premolar and molar areas, were selected. The inferior border of the mandible was placed at 0-, 5-, 10-, 15-, and 20-degree angles to the CT scanning plane, and CTs were taken. The marked area of the reformatted cross-sectional image taken at each angle was found, and the distance from the most superior border of the mandibular canal to the alveolar crest was measured. As the angle between the CT scanning plane and mandibular plane increased, the distance from the most superior border of the mandibular canal to the alveolar crest also increased. The degree of increase was more pronounced in the posterior portion of the mandible than in the anterior portion of the mandible. As mandibular positional change in the CT gantry can affect the vertical measurement of the reformatted cross-sectional image, a correct guiding plane is necessary to accurately position the jaw to the CT scanning plane.

Mandible and maxilla bone mineral density and threshold analysis studies by pQCT in two edentulous women receiving pamidronate

The mandible and maxilla of two edentulous women, treated during 25 weeks with oral pamidronate, were monitored by peripheral quantitative tomography (pQCT). Whole bone volumetric mineral density failed to show meaningful variations after treatment. However, an analysis of separated cortical and medullar areas disclosed focal bone loss at the right mandible cortex of patient #1 and at the left maxilla cortex of patient #2. These and other bone sub-regions were further studied by clustering the internal sites with a different degree of bone mineral density, resorting to the mineral threshold analysis provided by the system. Where bone loss was detected, it corresponded to increased loss of the most osteopenic sites, while medium and high-density portions tended to remain unchanged within the region. There were no significant variations in all other regions, or alternatively, minor losses at osteopenic sites were compensated by an increase at high-density portions. Hence, the pQCT system allowed monitoring volumetric bone mineral density at particular sites of interest, discriminating variations at portions with a dissimilar degree of bone volume. Further studies should confirm whether pamidronate exerts a protective effect on sub-regions with previous medium and high degrees of bone mineralization, as suggested by our present findings.

Management of an implant case that required retreatment: a case report

The presented case represents how the lack of a preoperative panoramic radiograph or any radiograph contributed to incorrect case planning, poor implant selection, and the careless surgical placement of an implant into or dangerously close to the lower left mental foramen, resulting in a paresthesia of 9 months duration. Two implants were surgically removed and the bone defects were grafted with a mixture of irradiated cancellous bone plus Biogran. One implant was sectioned and intentionally "put to sleep." The case was successfully completed with a lower bar overdenture supported by 4 screw implants placed in alternate sites, opposing a custom fabricated maxillary denture with a lingualized occlusal scheme.

[X-ray study of patients at the stage of preparation for prosthesis by using dental maxillary implants]

The paper deals with the possibilities of using the data of X-ray studies--computed tomography and orthopantomography--in planning the surgical stage of implantation for preprosthetic correction of the upper denture. Examination of 23 patients has yielded the data showing what estimation of the size of an image obtained by the "Denta Scan" programme provides.