Factors in the psychosocial work environment of staff are associated with satisfaction with care among older persons receiving home care services.

Older persons in Sweden are increasingly encouraged to continue living at home and, if necessary, be supported by home care services (HCS). Studies have examined whether the work environment of staff has an impact on the experiences and well-being of older persons in residential care facilities, but few have examined such associations in HCS. This study examined associations between home care staff's perceptions of their psychosocial work environment and satisfaction with care among older people receiving HCS. The setting was 16 HCS work units. Two surveys were conducted, one on psychosocial working conditions of staff, one on satisfaction of older persons receiving HCS. For each work unit, data on individual satisfaction were matched to average values concerning psychosocial work conditions. Outcomes analysed with linear regressions were overall satisfaction and indices regarding assessment of performance of services, contact with staff and sense of security. The index for treatment by staff was analysed with ordered logistic regressions. Cluster correlated-standard error clustering on work units was used. Results showed that good working conditions were important for satisfaction with care, specifically overall satisfaction, treatment by staff and sense of security. The most important psychosocial work factors were work group climate, sense of mastery, job control, overall job strain, frustrated empathy, balancing competing needs, balancing emotional involvement and lack of recognition. Receiving more HCS hours was associated with stronger relationships between working conditions and satisfaction with care, especially with overall satisfaction and treatment by staff as outcomes. Managers and policymakers for home care need to acknowledge that the working conditions of home care staff are crucial for the satisfaction of older persons receiving HCS, particularly those receiving many HCS hours. Psychosocial work factors together with job strain factors are areas to focus on in order to improve working conditions for staff and outcomes for older persons.

The Association Between Psychosocial Work Environment and Satisfaction With Old Age Care Among Care Recipients.

This study examines the association between nursing assistants' perceptions of their psychosocial work environment and satisfaction among older people receiving care in nursing homes and home care. Cross-sectional surveys were conducted among people receiving care (N = 1,535) and nursing assistants (N = 1,132) in 45 nursing homes and 21 home care units within municipal old-age care. Better psychosocial work environment was related to higher satisfaction in old-age care among the recipients. Significant and stronger associations were more common in nursing homes than in home care. Perception of mastery and positive challenges at work were associated with higher recipient satisfaction both in home care and in nursing homes: social climate, perception of group work, perception of mastery, and positive challenges at work only in nursing homes. Findings suggest that recipient satisfaction may be increased by improving the psychosocial work environment for nursing assistants, both in nursing homes and in home care.

The Impact of Leadership and Psychosocial Work Environment on Recipient Satisfaction in Nursing Homes and Home Care.

This study examines the association between nursing assistants' assessment of leadership, their psychosocial work environment, and satisfaction among older people receiving care in nursing homes and home care. Cross-sectional surveys were conducted with nursing assistants (n = 1,132) and people receiving care (n = 1,535) in 45 nursing homes and 21 home care units. Direct leadership was associated with the psychosocial work environment in nursing homes and home care. Furthermore, better leadership was related to higher satisfaction among nursing assistants and older people in nursing homes. Thus, indirect leadership had no effect on recipients' satisfaction in either nursing homes or home care. The path analysis showed an indirect effect between leadership factors and recipient satisfaction. The findings suggest that the psychosocial work environment of nursing assistants and recipient satisfaction in nursing homes can be increased by improving leadership.

Leadership and the psychosocial work environment in old age care.

AIMS AND OBJECTIVES: To study leadership factors and their associations with psychosocial work environmental among nursing assistants who are engaged in old age care and to analyse (i) differences in the assessment of leadership factors and the assessment of psychosocial work environmental in nursing homes and home help services and (ii) the association between the psychosocial work environment and factors that are related to leadership in nursing homes and home help services. BACKGROUND: Leadership factors are an important element of the psychosocial work environment in old age care. The physical distance between leaders and nursing assistants is larger in home help services than in nursing homes. Therefore, it is important to study leadership separately in nursing homes and home help services. DESIGN: Assessments from 844 nursing assistants in nursing homes and 288 in home help services (45 nursing homes and 21 home help service units) were analysed. METHODS: The data were analysed using linear regression. Age, gender, number of staff at the unit, number of years at the current working unit and educational level were controlled in Model 1. Summarised indexes that were based on all independent variables except the main independent variable were additionally controlled in Model 2. RESULTS: Psychosocial work environment was related to leadership factors, but stronger associations occurred more frequently in nursing homes than in home help services. Empowering leadership, support from superiors, the primacy of human resources and control over decisions were associated with higher assessments on all the variables that were related to the psychosocial work environment in both the nursing homes and home help services. CONCLUSIONS: Organisational differences in conducting leadership in old age care must be considered. Some leadership characteristics are better prerequisites for creating and maintaining a positive psychosocial work environment for nursing assistants in nursing homes and home help services. IMPLICATIONS FOR PRACTICE: Due to the differences in organisational settings, it is important to consider the differences in prerequisites in conducting leadership. To influence nursing assistants' performance and to increase quality in old age care in the long term, appropriate leadership is necessary.

The influence of stiffness of implant-abutment connection on load-deflection ratios of a screw-retained stiff cantilever beam. 3-D measurements in vitro.

AIM: The purpose of this in vitro study was to investigate the influence of degree of stiffness of implant-abutment connection of a Brånemark implant system on load- deflection ratios in three dimensions of the beam-end of a screw-retained stiff cantilever beam when subjected to vertically directed loads. MATERIAL AND METHODS: Two different implant-abutment connections were tested; welded and screw-retained. One of the abutments (EsthetiCone 2.0; Nobel Biocare AB) was screwed with a torque force of 20 N cm and then laser welded around its entire periphery to one of two Brånemark implants (welded unit). This unit and the other implant were tightly screwed into each of two pre-threaded holes in a steel plate so that the implants became submerged in the plate. The remaining abutment was thereafter screwed to its implant with a torque force of 20 N cm (screw-retained unit). A cantilevered gold beam of 6 mm height and width comprising a gold cylinder (Nobel Biocare AB) was attached to each abutment with a slotted, flat headed, prosthetic gold screw (torque force 10 N cm). A force transducer, synchronized with a 3-D motion analysis system, was glued on the upper surface of each beam-end 19.4 mm from the implant, to register the loads transferred from a specially built loading device. The beam-ends were stepwise subjected to vertically directed loads from 14.9 to 40.3 N and the vertical and horizontal deflections of the beam-ends were registered with the 3-D motion analysis system. RESULTS: For load 14.9-40.3 N the vertical (z-axis) deflections of the beam-end were for the welded implant-abutment connection reduced with 18-46% compared with the screw-retained unit. After maximal loading (40.3 N) the horizontal counter-clockwise rotation of the beam around the screw joints (y-axis rotations) was reduced with 61% for the welded connection. The horizontal movements of the beam-end along the x-axis (x-axis deflections) were reduced with 49% at maximal loading. CONCLUSION: It was concluded that increased implant-abutment stiffness will substantially reduce both vertical and horizontal deflections of a screw-retained stiff cantilever beam subjected to vertically directed loads.

A novel type of dental tube implant for areas with limited bone height. Clinical and radiographic data from three patients with 5-year follow-up.

BACKGROUND: Alternative implant designs may reduce the need for complicated and costly bone augmentation procedures in situations with limited bone height. PURPOSE: Wide dental tube implants have been manufactured and tested in three patients and followed for 5 years to evaluate if such implants are capable to support fixed prosthetic constructions with good prognosis in areas with limited bone height. MATERIALS AND METHODS: Four machined-tube implants with a height of 6 mm, an outer diameter of 7.4 mm, and an inner diameter of 6.0 mm were placed in three patients. After a healing period of 3 months, ceramometal suprastructures were constructed to supply the implants. Annual clinical and radiographical follow-ups were done up to 5 years. At the 5-year follow-up, all three patients were examined with a cone beam computed tomography technique. RESULTS: All implants and the suprastructures were clinically stable after 5 years. In one patient, vertical bone loss and a 6-mm deep pocket appeared after 1 year. The pocket has remained throughout the observation period and has been regularly debrided and kept it free from clinical signs of inflammation. In the other two patients, the soft tissue surrounding the implants was in good health with no or only slight inflammation throughout all observations. Pocket probing revealed no or slight bleeding and pocket depths amounting to less than 3 mm. CONCLUSION: It was shown that this new type of implant will function excellent during follow-up times of several years. Further studies should be done to explore in more detail indications for such implants.

Deflections of an implant-supported cantilever beam subjected to vertically directed loads: in vitro measurements in three dimensions using an optoelectronic method. I. Experimental set-up.

AIM: The aim of this in vitro study was to develop and test an experimental set-up consisting of a video camera and computer-based optoelectronic motion analysis system, synchronized with a loading device, for studying load-dependent deflections in three dimensions of single implant-supported cantilever beams. MATERIAL AND METHODS: One Brånemark System implant was tightly screwed into a steel plate so that the entire implant became submerged. An abutment was attached to the implant and a cast 22-mm-long cantilever gold alloy beam incorporating a prefabricated gold cylinder was attached to the abutment with a prosthetic gold screw. A force transducer was glued on the upper surface of the beam end with its centre 19.4 mm from the centre of the implant abutment gold cylinder unit to register the applied load. A specially designed loading device was used to apply increasing vertical loads of the beam end via the transducer. The motion analysis system was synchronized with the transducer to enable measurements of three-dimensional positional changes of the beam end related to known loads. RESULTS: Vertical loads from 15.7 to 40.4 N were applied resulting in vertical positional changes of the beam end ranging from 40.8 to 225.2 µm (z-axis). The corresponding horizontal changes perpendicular to the long axis of the beam (y-axis) due to counterclockwise horizontal rotation of the beam around the abutment- and prosthetic cylinder threads varied from 7.4 to 77.4 µm. This rotation changed the position of the beam end from 11.9 to 49.3 µm along the x-axis of the coordinate system toward the supporting implant. CONCLUSION: It was possible to arrange an experimental set-up for optoelectronic 3-D measurements within such a limited measurement volume that would permit satisfactory registrations of small load-dependent deflections of the prosthetic beam and implant components.

Marginal bone level changes at dental implants after 5 years in function: a meta-analysis.

BACKGROUND: It is important that peri-implant bone breakdown caused by, for example, undue load and/or peri-implantitis, is prevented or minimized. Some continuous loss of marginal bone is generally accepted, but the question remains as to what extent it must occur. PURPOSE: The purpose of this study was to compile and compare data on peri-implant marginal bone level changes from prospective studies that have registered the peri-implant marginal bone level radiographically at the time of prosthetic loading, and after 5 years of follow-up for implant systems currently available on the market. MATERIALS AND METHODS: A literature search was carried out to identify prospective studies on peri-implant marginal bone level changes around dental implants. To be included in a meta-analysis, the implant systems should have been subjected to at least two independent studies. Copycats without documentation were not accepted. RESULTS: Forty prospective studies that presented with a 5-year data were identified. Three implant systems met the inclusion criteria of having at least two independent studies; Astra Tech Dental Implant System® (Astra Tech AB, Mölndal, Sweden), Brånemark System (Nobel Biocare AB, Göteborg, Sweden), and Straumann Dental Implant System (Institute Straumann AG, Basel, Switzerland). The pooled mean marginal bone level change amounted to -0.24 mm (95% CI -0.345, -0.135) for the Astra Tech Dental Implant System, 0.75 mm (95% CI -0.802, -0.693) for the Brånemark System, and 0.48 mm (95% CI -0.598, -0.360) for the Straumann Dental Implant System over 5 years, with a statistically significant difference (p < .01) between the systems. CONCLUSIONS: The identified implant systems showed an annual bone loss below or much below what hitherto has been set up as a limit for success. A careful documentation of marginal bone level changes should be mandatory for all implant systems before being marketed. It is also time for revision of existing success criteria to refine the basis for clinical quality judgment of implant treatment.

Soft tissue-anchored transcutaneous port attached to an intestinal tube for long-term gastroduodenal infusion of levodopa/carbidopa in Parkinson disease.

PURPOSE: To report experiences with a transcutaneous soft tissue-anchored titanium port (T-port) attached to an intestinal tube for gastroduodenal infusion of levodopa/carbidopa in patients with Parkinson disease, and to describe and analyze complications related to the T-port, gastrostomy technique, and intestinal tube placement. MATERIALS AND METHODS: The T-port implantation and gastrostomy were done under local anesthesia in 15 patients (mean age, 64 years; range, 52-74 y). An intestinal tube (10 F) was attached to the T-port for duodenal/jejunal access. Three versions of the T-port have been tested (generations I-III). RESULTS: Our experience with T-ports covers 34.5 patient-years (mean, 2.3 y per patient). Maximum duration of use was 4.9 years. The major complications were perforation of the skin by the straight flange (three of five generation I ports), local infections (12 of 15 patients) resulting from leakage of levodopa/carbidopa (five of 11 generation II ports), problems with T-fasteners, and poor hygiene. Hypergranulation tissue was often seen as a result of local inflammation/infection resulting from levodopa/carbidopa leakage, poor hygiene, and/or an overly mobile T-port. The last version of the T-port (generation III), with more optimized implantation and gastrostomy techniques, seemed to considerably improve the results. CONCLUSIONS: The initial experience with the T-port system reveals that it may be a useful alternative to presently used gastrojejunostomy tubes. Several improvements of the T-port and placement technique were made. The T-port offers a potential advantage compared with standard techniques from an aesthetic point of view.

Surgical guided tissue regeneration treatment of advanced periodontal defects: a 5-year follow-up study.

OBJECTIVES: To study the 5-year outcome of combined use of guided tissue regeneration (GTR) barriers and bovine bone in advanced periodontal defects. MATERIAL AND METHODS: In each of 24 patients, one defect was surgically exposed, debrided, filled with bovine bone, and covered with a bioresorbable barrier. Re-examinations were made after 1, 3, and 5 years. RESULTS: Average full-mouth plaque scores (FMPS) were 14.5% at baseline and 10.7%, 9.8%, and 18.9% after 1, 3, and 5 years, respectively. Mean probing pocket depth (PPD) was 10.0 mm at baseline. Mean PPD reduction was 5.2 mm after 1 year, 5.6 mm after 3 years, and 5.3 mm after 5 years. Mean gingival recession was 1.0 mm after 1 year, 1.6 mm after 3 years, and 1.3 mm after 5 years. Mean gain in clinical attachment level (CAL) was 4.2 mm at the 1-year, 4.1 mm at the 3-year, and 4.3 mm at the 5-year examination. Smoking significantly influenced CAL change at all re-examinations. FMPS were significantly correlated with radiographic defect depth at the 5-year examination and CAL with smoking and FMPS at the 3-year examination. CONCLUSION: Advanced periodontal defects can be successfully treated with the combined use of GTR barriers and bovine bone to substantially reduce PPD and achieve a stable, long-term gain of CAL.

Effect of three different dental health preventive programmes on young adult individuals: a randomized, blinded, parallel group, controlled evaluation of oral hygiene behaviour on plaque and gingivitis.

AIM: To evaluate, in young adults, the effect of different preventive programmes on oral hygiene and to determine whether the variables investigated are predictors of gingival health. MATERIAL AND METHODS: This randomized, blinded, parallel, controlled clinical study examined the effectiveness of three dental health programmes. Four hundred subjects aged 20-27 years, 211 males and 189 females, participated in the study. They were recruited from a Public Dental Service clinic and from a private dental practice in Jönköping, Sweden. The effect of the programmes on plaque and gingivitis was evaluated over a 3-year period. The programmes included activities that were adapted for individuals as well as for groups. The plaque indices (PLI) and gingival indices (GI) were used to evaluate the programmes. RESULTS: All programmes resulted in a decrease in PLI and GI. The greatest decrease was found in the group that was followed-up every 2 months. Professional tooth cleaning was non-significant for the clinical result. Gingival health at baseline, participation in any of the test programmes, and knowledge of the dental diseases caries, gingivitis or periodontitis were significant predictors of good gingival health. CONCLUSIONS: The study confirms the efficacy of three different preventive programmes in reducing supragingival plaque and gingival inflammation. Professional tooth cleaning provided no clinical benefit beyond that derived from individual and group-based health education.

Bone morphology and vascularization of untreated and guided bone augmentation-treated rabbit calvaria: evaluation of an augmentation model.

OBJECTIVES: Cranial vault is widely used in experimental models on membranous bone healing in general, guided bone augmentation (GBA) studies being one example. To our knowledge, however, few studies on the characteristics of the untreated calvaria regarding bone density, vessel topography, and their intra/interindividual variations and associations are available. The aims of this investigation were to (1) map the large vessel topography of the skull vault, (2) describe the parietal bones of the adult rabbit histologically and morphometrically, and (3) histologically compare untreated parietal bone with parietal bone that had been treated with a GBA device. MATERIAL AND METHODS: Ten adult untreated rabbits were microangiographed. General anesthesia was induced and the mediastinum was opened. Heparin and lidocaine were injected in the aorta followed by perfusion with India ink. After death, en bloc biopsies of the skull vault including the overlying soft tissues and dura mater were taken. The specimens were cleared with the Spalteholtz technique, microscopically examined, and digitally imaged. Thereafter, circular biopsies were harvested to obtain decalcified sections. In addition, sections from 14 GBA-treated rabbit skulls (of the same race, sex and age as the untreated animals) served as reference specimens for comparison. Histomorphometric examinations were carried out. RESULTS: In the cleared specimens, all parietal bones were found to be supplied by one major branch of the meningeal artery. From each of these, separate branches supplied the dura wherein a fine vessel network covered the bone. No major vessels were found in the supracalvarial soft tissue. Numerous fine vessels were found within the periosteum and dura entering the cortical plates. The decalcified sections of the parietal bones revealed an outer and inner cortical plate enveloping a diploic space containing bone trabeculae, marrow tissue and larger sinusoids. Hollow connections were frequently found in both the outer and inner cortical plates in both the untreated and the GBA-treated specimens. These connections contained marrow tissue that extended to the periosteum and the dura. The morphometric measurements revealed similar proportions of cortical, trabecular, and marrow areas in the right and left untreated bones. The area of the outer cortical plate was significantly larger than the area of the inner cortical plate. Bone density was similar in the right and left untreated and GBA-treated specimens, as was the frequency and width of hollow connections through the cortical bone plates. CONCLUSIONS: The symmetry between the left and right parietal bones concerning the large vessel topography and the histomorphometric parameters assessed was high. Hollow connections in the cortical plates were frequently found. The bilateral use of the parietal bones is suggested to be reliable in experimental GBA models regarding the blood supply and bone quality.

Soft-tissue-anchored transcutaneous port for long-term percutaneous transhepatic biliary drainage.

PURPOSE: A transcutaneous port (T-port) has been developed allowing easy exchange of a catheter, which was fixed inside the device, using the Seldinger technique. The objective of the study was to test the T-port in patients who had percutaneous transhepatic biliary drainage (PTBD). METHODS: The T-port, made of titanium, was implanted using local anesthesia in 11 patients (mean age 65 years, range 52-85 years) with biliary duct obstruction (7 malignant and 4 benign strictures). The subcutaneous part of the T-port consisted of a flange with several perforations allowing ingrowth of connective tissue. The T-port allowed catheter sizes of 10 and 12 Fr. RESULTS: All wounds healed uneventfully and were followed by a stable period without signs of pronounced inflammation or infection. It was easy to open the port and to exchange the drainage tube. The patient's quality of life was considerably improved even though several patients had problems with repeated bile leakage due to frequent recurrent obstructions of the tubes. The ports were implanted for a mean time of 9 months (range 2-21 months). Histologic examination in four cases showed that the port was well integrated into the soft tissue. Tilting of the T-port in two cases led to perforation of the skin by the subcutaneous part of the ports, which were removed after 7 and 8 months. CONCLUSION: The T-port served as an excellent external access to the biliary ducts. The drainage tubes were well fixed within the ports. The quality of life of the patients was considerably improved. Together with improved aesthetic appearance they found it easier to conduct normal daily activities and personal care. However, the problem of recurrent catheter obstruction remained unsolved.

Placement of autogeneic bone chips or bovine bone mineral in guided bone augmentation: a rabbit skull study.

PURPOSE: Our primary aim was to use a rabbit guided bone augmentation model to evaluate whether use of autogeneic bone grafts or bovine bone mineral (BBM) combined with a space-making barrier enhances bone augmentation compared with a barrier alone. MATERIALS AND METHODS: Sixteen rabbits were studied. In each rabbit, 2 titanium cylinders, each with 1 titanium lid, were placed subcutaneously in perforated slits made in the cortical bones, with their open ends facing the parietal bones. One cylinder was left empty and the other was filled with either autogeneic skull bone chips or BBM. Bone labels were injected after 4 and 11 weeks. After 12 weeks, the animals were sacrificed to obtain ground sections for histology and histomorphometry. RESULTS: Significantly more tissue was augmented in the 2 test groups than in the control group. Most of the autografts were resorbed, leaving only minute amounts in the upper third of the cylinders. Slender new bone trabeculae were distributed mainly from the contiguous bone plate that had no contact with the remaining graft material. In the BBM group, most of the BBM remained evenly distributed in the cylinder. In the upper third of the cylinder, the BBM was surrounded by soft connective tissue, while in the lower two thirds, mainly mineralized bone enclosed the BBM. Equal amounts of mineralized bone were found in both test groups. Comparisons of contact between bone and BBM on one hand and bone and bone cylinder wall on the other revealed that the greatest bone contact was with the BBM in the lower third of the cylinder. In the middle and upper third of the cylinder, bone-BBM contact and bone-cylinder wall contact were similar. Fluorescent label intensity was higher in the autograft group than in the BBM group. In all 3 groups the intensity of the early label was similar to that of the late label, indicating that the graft materials do not seem to retard mineralization. DISCUSSION: BBM was found to promote as much new bone as did autogeneic bone. In addition, BBM appears to have at least the same osteoconductive properties as titanium, provided BBM is contained in a stable environment. CONCLUSIONS: Placement of autogeneic bone or BBM in conjunction with a stiff space-making barrier generated more tissue than a barrier only. In this model, autogeneic bone chips and BBM augmented similar amounts of new mineralized bone.

The effect of different dental health programmes on young adult individuals. A longitudinal evaluation of knowledge and behaviour including cost aspects.

The goal of this study was to report the long-term effect of different dental health programmes on young adult individuals' knowledge and behaviour relative to oral health. Over a 3 years period, the effect of three different dental health programmes on caries, gingivitis/periodontitis, and knowledge and behaviour concerning oral health in 400 Swedish young adults was evaluated. During the following 2 years, additional prophylactic measures--now based on the individual's symptoms and the prophylaxis previously received--were conducted and evaluated. Five years later still one follow-up was made. The evaluations were based on clinical and radiographic examinations and on a questionnaire survey whose purpose was to study the short- and long-term effects of the different preventive measures, including cost aspects. At the end of the 3 years period, the three test groups exhibited better knowledge and significantly improved behaviour compared with the control group concerning approximal cleaning, from approximately 50% of the individuals at the baseline examination to approximately 90% at the end of the period. Improvement was observed as early as the first year. There were no differences between the test groups. The intensified, individual-related prophylaxis carried out in the following 2 years did not significantly increase knowledge in the test groups; a significant increase in approximal cleaning, however, was found in the control group during this time. At the 10-year follow-up, the individuals' knowledge was undiminished while behaviour concerning approximal cleaning had sunk from 90% to approximately 70% of the individuals. A slight behavioural change concerning number of snacks was found in the course of the study with a shift towards fewer snacks per day. In conclusion, it can be said that simple prophylactic models have an effect on and maintain young adult individuals' knowledge and behaviour concerning oral health and that new knowledge is remembered for long periods of time while changes in behaviour are maintained less well. Moreover, it was found that the scope of the prophylactic programme measured in time and cost had little effect on the long-term result.

Influence of preimplant surgical intervention and implant placement on bone wound healing.

The aims of the present investigation were to study (1). the influence of preimplant (4 weeks) surgical intervention and (2). the influence of the implant placement per se on bone density and mineralized bone-implant contact (BIC) at implant sites in the rabbit jawbone. The experiment was performed in the edentulous area of the maxillas of 16 adult rabbits. In eight rabbits, the alveolar bone on the left side (test) was surgically exposed and a groove was prepared in the bone crest. Trabecular bone and marrow tissue were removed, and a bioabsorbable barrier membrane was placed to cover the groove. The right side underwent no treatment and served as the control. Four weeks later, a screw-shaped titanium implant was placed transversally through the maxilla, penetrating both the test and the control areas. After another 4 weeks of healing, the animals were killed to obtain ground sections for histomorphometry. Untreated jaws from eight rabbits served as reference specimens. In the rabbits subjected to surgery, the areas (mm2) of both mineralized bone and marrow tissue were similar for test and control (4.9 +/- 1.7 vs. 5.1 +/- 2.2 and 6.3 +/- 5.7 vs. 6.8 +/- 5.7 for bone and marrow, respectively). The BIC (%) for all threads was significantly lower on the test side than on the control side (32.1 +/- 27.7 vs. 47.7 +/- 20.3). The bone density (%) of the total experimental area was similar for test and control (48.5 +/- 12.1 vs. 46.5 +/- 9.3), as was the bone density in the area within the implant thread valleys and their mirror areas (43.0 +/- 13.9 vs. 41.3 +/- 13.5, and 40.2 +/- 11.0 vs. 40.3 +/- 7.2 for thread area and mirror area, respectively). The bone density of the total experimental area in the untreated rabbits was 35.9 +/- 5.2%. This value was significantly lower than the values in the total experimental areas (test and control) of the surgically treated rabbits. Similarly, the density of the reference area in the untreated rabbits was 25.4 +/- 5.3%, which was also significantly lower than the bone density of the periimplant area of the surgically treated rabbits. We conclude that the surgical trauma caused by the placement of implants in the maxilla of rabbits significantly enhanced the bone density of the implant sites. Surgical intervention in the implant sites 4 weeks prior to the implant placements, however, did not further enhance bone density or BIC.

Surgical intervention in enchondral and membranous bone: intraindividual comparisons in the rabbit.

BACKGROUND: The long bones, which are of enchondral origin, are often used in histologic evaluations of dental implants that clinically will be placed in bones of membranous origin. PURPOSE: The aim of this investigation was to study the effect of surgical trauma by multiple drill perforations on both enchondral and membranous bone--the tibial and maxillary bone architecture--8 weeks after surgery. MATERIALS AND METHODS: In eight rabbits the medial metaphyses of both tibiae and the edentulous ridges of both sides in the maxilla were surgically exposed. On the test sides, 25 to 30 holes were drilled through the cortical plate and 5 mm into the medullary space. The contralateral sides underwent no treatment and served as controls. Eight weeks later the animals were killed to obtain transverse ground sections for histomorphometry. A paired analysis of the bone densities of the tibiae and the jaw specimens was made. RESULTS: In general the morphologic appearances of the test and control tibiae were similar. In the control group the anatomy of the medullary space appeared normal, with few bone trabeculae and with abundant marrow tissue. In the test group, areas of resorption were evident on the cortical bone plate that had been perforated 8 weeks previously; also evident were ingrowths of marrow tissue and bone formation. In a few specimens some newly formed bone trabeculae were found in the medullary space, both contiguous to the perforated cortical bone plate and as small islets in the marrow tissue. The mean test and control site values for each parameter were similar, and no statistically significant differences were found. In the maxilla, the bone architecture had altered substantially by way of an increase in the proportion of trabecular bone and a decrease in the proportion of cortical bone. Drilling appeared to have little effect on tibial bone density, which did not significantly differ between test and control sites. Maxillary bone density, however, was significantly greater at the test sites than at the control sites. Comparisons of bone density between tibia and jaw specimens revealed no significant differences either between test sides or between control sides. Thus, the same magnitude of surgical trauma that altered the bone architecture and density of the rabbit maxilla was not found to have altered those of the tibia in the same animal 8 weeks after surgery. The reasons for the differences are discussed in this article. CONCLUSIONS: As observed 8 weeks post surgery, multiple drill perforations were not found to cause significant alterations in the metaphysis of the tibia whereas a considerable change in bone architecture and an increase in bone density were found in the maxilla. Whether this depends on different embryologic origins or reflects morphologic and functional differences in the mature bone demands further study.

Impact of cortical perforations of contiguous donor bone in a guided bone augmentation procedure: an experimental study in the rabbit skull.

BACKGROUND: It has been shown that bone can be augmented beyond the original skeletal envelope by using space-making barriers. Further, it has been suggested that perforation of the contiguous donor bone enhances bone formation in guided bone augmentation procedures. PURPOSE: The goal of the present investigation was to evaluate whether perforations into the donor bone marrow through the cortical plate, located contiguous to an extracalvarial experimental space, influence bone generation into this space with regard to augmented bone tissue volume and bone density 3 months postoperatively. MATERIALS AND METHODS: Two titanium cylinders, each with a titanium lid, were subcutaneously placed with their open ends facing the parietal bones of eight rabbits and secured with miniscrews. The cortical bone plate on the test side was perforated with seven evenly distributed holes, each with a diameter of 1.2 mm, using carbon-steel burs. Together, these perforations corresponded to about one-third of the total experimental bone area. The bone on the control side was left intact, and no bleeding occurred during the placement of the titanium lid. The perforation procedure (test side) resulted in various degrees of blood fill. After 3 months, the animals were sacrificed to obtain ground sections for histology and histomorphometry. RESULTS: The cylinders were found to be partly filled with tissue containing slender bone trabeculae and marrow spaces in abundance. The bone consistently reached a higher level at the inner wall compared with the central part of the cylinders (p = .001). Hollow connections between the experimental space and the skull bone marrow were found in the contiguous outer cortical plate in four of the seven control sites. No statistically significant differences could be demonstrated between the perforated test sites and the control sites regarding augmented tissue volume (64.4 +/- 18.9% vs. 64.9 +/- 22.2%) or bone density, although there was a tendency toward denser bone in the test sites (21.5 +/- 11.1%) versus control sites (14.7 +/- 5.4%). There was no statistical difference regarding relative bone-to-titanium wall contact (27.4 +/- 14.7% for test; 38.6 +/- 25.9% for control). Thickness (height) and density of the skull bone vault were measured in the area beneath and lateral to the cylinders. No significant differences could be observed regarding these parameters between the test and control side. There were no correlations between thickness (height) or density of donor bone versus amount or density of augmented bone. The degree of immediate blood fill could not be shown to correlate with augmented tissue volume or augmented bone density. CONCLUSIONS: In the present model, as observed 3 months postoperatively, cortical perforations of contiguous donor bone or degree of immediate blood fill of an extracalvarial experimental space were not found to enhance augmented tissue volume beyond the skeletal envelope. Although there was a much higher mean value for bone density of augmented bone in the test sites, the large variations failed to show significant intergroup differences.