Biomedical subjects

K E Kahnberg

Publications and source records attributed to K E Kahnberg.

At least 19 recordsLinked to original sources

PubMed2004

10-year follow-up of onlay bone grafts and implants in severely resorbed maxillae.

Thirty patients with extremely resorbed maxillae had reconstructive bone grafts from the ala iliaca and endosseous implants in a one-stage procedure. The first ten patients constituted a development group and the following 20 patients a routine group. The marginal bone level and implants success rate was evaluated in a prospective long-term follow-up for a minimum of 10 years (10-13 years). Clinical and radiographic examinations were performed at 6 months and then annually up to 5 years. The final examinations were performed at the 10-year follow-up. The bridges were removed at every clinical examination. Marginal bone loss was seen up to the 3-year examination, where it averaged 4.6 mm in the routine group. Between the 3- and 10-year follow-up no significant change was registered. The initial bone loss was probably due to the design of the 3.6 mm conical unthreaded marginal part of the implant. The implant success rate was 83.1% in the routine group. Failures mostly occurred during the first 2 years (14 out of 20). A substantial amount of bone can be gained in patients with extremely resorbed maxillae, when treated with bone graft according to the procedure described in this study.

Adult↗

PubMed2002

Bone graft remodelling and implant success rate in the treatment of the severely resorbed maxilla: a 5-year longitudinal study.

A total of 30 patients, 10 in a developmental group and 20 in a routine group, with extremely resorbed maxillae were treated with bone grafting from the hip and implant placement in a one-stage procedure. All patients were followed for a minimum of 5 years and were examined regarding the long-term success rate of the implants and marginal bone level. The implant success rate was 74.6% for the whole patient group and 85.8% for the routine group, after 5 years. The marginal bone along the implant surface decreased continuously, up to 3 years and thereafter the bone level stabilized. In the routine group, changes in bone graft dimensions over time were also evaluated by computerized tomography. The mean height of the bone graft postoperatively at all implant sites was 8.3 mm. The total mean bone height, including bone graft and residual alveolar crest, was 12.4 mm. After 5 years the total bone height had decreased to a mean of 10 mm. The mean width of the bone graft was 12 mm postoperatively and 8.7 mm at the 5-year examination. A substantial amount of bone can be gained in patients with extremely resorbed maxillae, when treated with bone graft according to the procedure described in this study.

Adult↗

PubMed2001

Sinus lifting procedure. I. One-stage surgery with bone transplant and implants.

A prospective study of one-stage surgery with intrasinus bone transplant and implants has been performed in 26 patients (13 males and 13 females). The aim of the study was to evaluate the success rate with the one-stage sinus lifting procedure in patients with a need for bony augmentation of the alveolar process. Fifteen patients were partially dentate and 11 edentulous. The mean height of the alveolar ridge was 2.5 mm preoperatively (range 1-5.5 mm). 126 fixtures were inserted, 93 in grafted bone and 33 in alveolar bone. Twenty-two patients have been followed for three years, 21 for four years and 11 for five years. The clinical overall survival rate was 69.6% although only 61.2% in grafted bone. Ten of the patients had varying degree of sinusitis post-fixture installation. At the end of the study, 23 patients had permanent bridges. The survival rate was low for inlay supported implants when the one-stage surgical technique was applied. Two-stage surgery may be a safer method.

Adult↗

PubMed2001

The adaptation of implant-supported superstructures to the alveolar crest: a follow-up of 49 cases.

A prospective clinical and radiographic study has been carried out in 49 patients with a total of 252 implants. In a mixture of 17 edentulous mandibles, 20 edentulous maxillas, nine partial edentulous cases, and three single-tooth cases, prosthetic treatments were aimed at getting as close an adaptation as possible between gingival tissues and superstructure. The shortest possible abutments were used, and the implants were surgically positioned subcrestally. The results during a 5-year follow-up showed a success rate of 98.9% for fixtures in the lower jaw and 96.3% for the upper jaw with a total success rate of 97.3%. The marginal bone reduction during five years with closely adapted superstructures was 0.11 mm in the mandible and 1.1 mm in the maxilla. Our results support the use of close gingivally adapted superstructures, although oral hygiene controls and instructions are regularly advisable.

Aged↗

PubMed2001

Effects of implant design and surface on bone regeneration and implant stability: an experimental study in the dog mandible.

BACKGROUND: Previous experimental studies have shown a higher degree of bone-implant contact for surface-enlarged implants compared with machined implants. Yet, there is insufficient evidence that such implants show higher stability and an increased survival rate. PURPOSE: The purpose of this investigation was to study the integration and stability of grit-blasted implants with retention elements on the implant neck, with and without marginal bone defects, compared with machined implants without retention elements. MATERIALS AND METHODS: After tooth extraction of the mandibular premolars in six dogs, two grit-blasted, partly microthreaded Astra Tech implants and one standard Brånemark implant were bilaterally placed in each dog. On one side, 3 x 3 mm large buccal defects were created, to expose three to four implant threads. The contralateral side served as control, and no defects were made. The animals were sacrificed after 4 months of healing. Implant stability was measured using resonance frequency analysis at implant installation and after 4 months of healing. Histologic and histomorphometric evaluation was made after 4 months of healing. RESULTS: Resonance frequency analysis indicated that all implants in the test and control groups were osseointegrated after 4 months, with a tendency toward higher implant stability for the Astra Tech implants. There was a statistically significant higher increase in resonance frequency for the Astra test implants compared with their corresponding controls. Histology and histomorphometry showed well-integrated implants with varying degrees of bone repair at the defect sites. The greater bone-implant contact for the Astra implants was statistically significant. No significant difference between the implants in amount of bone filling the threads was recorded. CONCLUSIONS: The Astra Tech implants tested showed a higher degree of bone-implant contact and higher level of bone regenerated at defect sites compared with the Brånemark implants. Resonance frequency analysis demonstrated a significantly higher increase in the Astra test implants compared with their control groups than did the Brånemark test implants versus their controls.

Alveolar Bone Loss↗

PubMed2000

Healing of titanium implants in onlay bone grafts: an experimental rabbit model.

An experimental rabbit bone graft model for the study of bone formation and remodeling around titanium implants is described. A 2.5-cm long radius bone segment served as an onlay graft. Two commercially pure (c.p.) titanium implants were inserted into the bone graft prior to fixation to the inferior border of the mandibular base with osteosynthesis titanium screws. Each animal was operated twice, allowing follow-up periods of 6 weeks on one side and 6 months on the contralateral side. In order to study bone remodeling by means of fluoroscopy the animals received single injections of tetracyclin and alizarine complexone 2 weeks and 1 week, respectively, prior to sacrifice by perfusion fixation with glutaraldehyde. The bone and implants were excized en bloc, postfixed and embedded in plastic resin. Stained and unstained thin ground sections as well as microradiographed thick sections were produced for light microscopic morphometry and fluoroscopy. After 6 weeks, osteoclastic/osteoblastic activity was primarily observed in the graft-recipient contact area and in the intracortical compartment of the graft bone. New bone formation observed on the implant surface originated from the recipient site. The bone formation was evident also in the implant-graft interface. At 6 weeks the average bone fill of the implant threads was 28.4% which increased to 36.4% after 6 months as measured by morphometry. An average of 17.6% bony contact was measured after 6 weeks which increased to 29.7% 6 months after surgery. The graft bone had reduced in size from an average of 39.5% after 6 weeks down to 24.8% after 6 months (P \lt 0.05). It is concluded that the described experimental model can serve as a useful method for the study of implant healing in onlay grafts.

Journal Article↗

PubMed1999

Effects of barrier membranes on bone resorption and implant stability in onlay bone grafts. An experimental study.

The objective of the present report was to study the effects of barrier membranes on bone resorption and implant stability in a rabbit onlay bone graft model, using resonance frequency analysis, coordinate measurements on plaster models, removal torque measurements and histology. Disc-shaped bone grafts were harvested from the calvarium and placed with titanium implants in the proximal tibial metaphyses of 9 rabbits. On one side (test) the bone graft/implant was covered by an e-PTFE barrier, while the contralateral side was not covered by a membrane and served as control. Three animals were sacrificed after 8 weeks for histology. In 6 animals the membranes were removed after 8 weeks and the animals were followed for an additional period of 16 weeks. Implant stability and bone height around the implants was assessed for the test and control sides at Day 0 and 8, 16 and 24 weeks postoperatively. Removal torque tests were performed after 24 weeks. The results showed an increase in volume of the bone graft on the test side as long as the barrier membrane was in place. However, after removal of the membrane at 8 weeks the resorption rate was higher on the test side compared to the control side, resulting in a similar bone height after 24 weeks. There were no statistically significant differences in implant stability between the test and control sides at any time point, as measured with resonance frequency analysis. Additionally, no statistically significant differences were found between the test and control sides after 24 weeks, using removal torque measurements, coordinate measurements and histomorphometric evaluation. Thus, in this experimental model, the use of non-resorbable barrier membranes did not improve the stability of implants simultaneously placed with onlay bone grafts. Moreover, extensive resorption of the grafted bone was seen after barrier removal, which resulted in similar bone graft volume for the test and control sides at the end of the observation period.

Animals↗

PubMed1999

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.

Aged↗

PubMed1998

Stability assessments and histology of titanium implants placed simultaneously with autogenous onlay bone in the rabbit tibia.

A disc-shaped bone graft was harvested from the calvarium in ten rabbits and anchored as an onlay bone graft, using a titanium implant, at the proximal tibial metaphysis. The contralateral tibia served as the control, where an implant was placed without a graft with the implant head at a height corresponding to the thickness of the graft on the test side. Resonance frequency measurements were performed 4, 8, 16 and 24 weeks postoperatively and removal torque measurements were performed at 24 weeks. A statistically significant higher implant stability, as assessed by resonance frequency measurements (RFM), was measured from 4 weeks throughout the 24-week period. The mean peak removal torque for the test implants was 50.4+/-10.0 Ncm and 30.0+/-6.9 Ncm for the control implants, which was a statistically significant difference. Histologically, the grafted bone was well incorporated and morphometry revealed more bone around the test implants. Calculations of shear stresses indicated that the grafted bone had similar biomechanical properties to the cortical bone of the recipient site. It is concluded that the integration of titanium implants in autogenous onlay bone grafts results in an increased biomechanical support of the implant. The use of RFM may also serve as a useful instrument for noninvasive monitoring of implant stability in vivo.

Animals↗

PubMed1998

An experimental rabbit model for studying the healing of onlay bone grafts.

An experimental rabbit model for studying the incorporation of onlay bone grafts is described. Bone grafts from radius served as the graft and were positioned beneath the mandibular basis. Six rabbits were used in the study and healing periods of 6 weeks and 6 months were used. Each animal was operated twice and in this way the grafts could be followed for six weeks on one side and for 6 months on the contralateral side of the mandible. Healing of the bone graft with bony union to the mandibular base with cortical bone in contact with cortical bone was encouraging. Remodelling of the graft was observed after 6 weeks but was even more pronounced after 6 months. After 6 weeks osteoclastic/osteoblastic activity was primarily observed in the graft-recipient contact area and in the intracortical compartment of the grafted bone. The resorption was most pronounced in the borderlines of the graft. It is concluded that the described experimental model can serve as a useful method for the study of onlay bone graft healing and interaction between implants and bone transplants.

Animals↗

PubMed1997

Correction of maxillofacial asymmetry using orthognathic surgical methods.

A total of 20 patients with varying degrees of facial asymmetry were followed clinically and radiographically for at least 18 months after undergoing surgical correction. In 12 of the patients, the cause of asymmetry was hemifacial microsomia of varying severity. Infection of the TMJ in early childhood and irradiation damage were other causes of facial growth disturbance. Bimaxillary osteotomy was carried out in all cases and was often combined with resection of the coronoid process in order to lengthen the ramus. A postoperative jaw exercise programme has proved important as a means of maintaining or increasing mouth-opening capacity. The facial asymmetry cases are not easy to correct and are not always in line with expectations. However, they are an important part of maxillofacial reconstructive surgery.

Adolescent↗

PubMed1997

Diskectomy in temporomandibular joints with internal derangement: a follow-up study.

OBJECTIVE: To follow up a series of patients treated consecutively who had undergone a diskectomy 2 years previously because of persistent pain and disk displacement in the temporomandibular joint. STUDY DESIGN: Sixteen subjects rated their current symptoms during 1 week and were systematically examined for signs of temporomandibular disorders clinically and radiographically by independent observers. RESULTS: Subjectively, all subjects were satisfied with the operation. Five rated their current pain as significant during masticatory function. Some signs of temporomandibular disorders, usually related to function, were registered in all subjects. Postoperative mandibular movements were improved but still below normal range. Signs and symptoms correlated significantly. Surgical complications were nonexistent, but radiographic changes were extensive. Erosion and flattening of the condyle were common. CONCLUSIONS: It was verified that subjects with persistent pain and disk displacement benefit subjectively and clinically from diskectomy. The radiographic outcomes appear less encouraging. Only prospective, randomized, and controlled studies can eventually clarify the effectiveness of diskectomy in relieving pain caused by displacements in the temporomandibular joint.

Adult↗

PubMed1997

Structural alterations in the TMJ disk in patients surgically treated for internal derangements (ADD).

Twenty-eight patients with temporomandibular dysfunction problem have been subjected to diskectomy unilaterally. The diagnosis was in 23 patients ADD (anterior disk displacement) without reduction and in another five ADD with reduction. The disk was removed in total according to a routine procedure. Surgical observation of a firm connection between the inferior surface of the disk and the condylar head was noted in eighteen patients. The disk tissue was orientated on a cork sheet according to its position in the fossa and subjected to histological examination. Histopathological analysis showed that the posterior attachment was a considerable part of the specimen in 12 out of 28 disks. Splitting of the disk was confined to the inferior surface. Chondrocytes were found close to the inferior surface. Surface irregularities, tags, were noticed on the inferior surface in thirteen cases. However, cellular signs of inflammation were found in the retrodiskal tissue in eight cases.

Adult↗

PubMed1996

Autogenous onlay bone grafts fixed with screw implants for the treatment of severely resorbed maxillae. Radiographic evaluation of preoperative bone dimensions, postoperative bone loss, and changes in soft-tissue profile.

Thirty patients with severely resorbed edentulous maxillae underwent combined treatment of iliac bone onlay graft and titanium implants. The patients were followed for 3 years. They were radiographically examined before surgery to evaluate the bone volume at the intended implant sites. Only 13/156 implant sites were suitable for implant insertion. The bone level at the implant surfaces was evaluated after 6 months and 1, 2, and 3 years, respectively. There was a continuing decrease of the bone level throughout the follow-up period with a mean loss of 4.9 mm after 3 years and with no difference between sexes. Twenty-six implants were radiographically examined before removal, and only three of these implant sites showed radiographic signs of failure. The soft-tissue profile was analyzed cephalometrically by the subtraction technique. The upper lip generally moved inward and the apex of the nose and the columella downward and inward. The anterior facial height increased in most of the patients, resulting in a downward and inward change of the lower lip, the mentolabial sulcus, the soft-tissue pogonion, and the soft-tissue gnathion.

Adult↗

PubMed1996

Open reduction of subcondylar fractures. A study of functional rehabilitation.

Open reduction of dislocated subcondylar fractures was carried out in 19 adult patients between 1990 and 1992. A comparison of the results between two groups of patients was made 1 year after trauma. The reference group consisted of patients with the same type of fracture but treated with only intermaxillary fixation (IMF) and moderate jaw exercises after release of IMF. Dysfunction of the masticatory system was noticed in only a few cases of either group. Open reduction with plate osteosynthesis made it possible to avoid IMF in 12 of 19 patients. The results in the two groups did not differ significantly from a functional point of view. There are, however, specific indications for open reduction based on the degree of dislocation and concomitant subjective symptoms.

Adolescent↗

PubMed1996

Radiographic morphology in the temporomandibular joint after diskectomy.

The purpose of the study was to evaluate the radiographic appearance in the temporomandibular joint after diskectomy in patients refractory to conservative treatment. The diskectomies were performed in patients in which the common diagnosis were internal derangement or symptoms of osteoarthrosis. Postoperative radiographs were taken in 25 patients after 1-17 yrs and compared with the preoperative from both the operated and the nonoperated joints. Moderate to severe osteoarthrotic changes were found on the operated side in all but two patients in contrast to on the nonoperated side where such changes were absent in all patients except in one who had minor to moderate changes. The radiographic examinations showed flattening of the condylar head but also irregularities and bone apposition. In almost all patients the fossa showed a sclerotic surface, flattening but only occasionally bone apposition and irregularities. Sclerotic changes were found in about 50% of the patients but erosions only rarely. Similar postsurgical changes were also seen on the articular eminence. A reduced joint space was seen in 18 patients. The postsurgical radiographic changes are the normal out come of diskectomy and do not have clinical significance even though they resemble degenerative joint disease.

Adult↗

PubMed1996

Intra-alveolar transplantation. I. A 10-year follow-up of a method for surgical extrusion of root fractured teeth.

A group of 19 patients where traumatic root fractures were treated with surgical extrusion procedure has been clinically and radiographically followed up for 10 years. Except for one out of 21 intraalveolar transplanted roots all functioned with different kinds of crown restorations and without pathological complications. The surgical extrusion method should thus be a useful tool in the treatment of teeth with cervical root-fractures and also teeth with deep cervical root caries which are difficult to treat conservatively.

Adult↗

PubMed1995

Leucocyte accumulation and leukotriene B4 release in response to polyglactin 910 and expanded polytetrafluoroethylene in hollow chambers in the rat.

The acute inflammatory reaction elicited after implantation of polymer membranes used clinically to promote bone healing and augmentation was studied in a soft tissue titanium chamber model. The two materials compared were non-degradable expanded polytetrafluoroethylene (ePTFE) and degradable polyglactin 910, a copolymer of 90% polyglycolic acid and 10% polylactic acid. The membranes were implanted in the titanium chamber for 24 h and 6 d. The number of leucocytes increased for both materials, whereas the leukotriene B4 (LTB4) content decreased over time. In both groups polymorphonuclear granulocytes predominated. The number of leucocytes was significantly higher in chambers with polyglactin 910 than ePTFE. In contrast, the LTB4 content was higher in chambers with ePTFE than polyglactin 910. No differences in cell viability were observed between the materials tested. This study shows that both degradable and non-degradable polymers elicit a marked influx and activation of inflammatory cells during early healing in soft tissues.

Animals↗