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In the present study the psychophysical detection threshold levels for mechanical stimulation of 32 prosthetic limbs were determined. Prosthetic limbs were anchored to the bone by means of an implant (n=17) or supported by a socket enclosing the amputation stump (n=15). Detection threshold levels were assessed for pressure and vibratory stimulation of the prosthesis and the limb at the contralateral side (control). Following vibratory stimulation, thresholds were increased on an avarage 20% for socket prostheses, but approached those of the control for bone-anchored prostheses. For pressure stimulation, thresholds were increased up to 60% for socket prostheses and 40% for bone-anchored prostheses compared to the control. While bone-anchored prostheses yielded significantly lower threshold levels than socket prostheses, there was no significant difference between both treatments regarding pressure stimulation. Results were applicable to both upper and lower limb amputees. It could be concluded that detection thresholds for pressure and especially vibratory stimulation of prosthetic limbs were generally higher than for control limbs. The outcome was related to the prosthetic limb design with bone-anchored prostheses yielding better perception than socket prostheses.

Background:A double‐blind, randomized, parallel, comparative study was designed to evaluate the long‐term safety and efficacy of subgingivally administered minocycline ointment versus a vehicle control. Methods:One hundred four patients (104) with moderate to severe adult periodontitis (34 to 64 years of age; mean 46 years) were enrolled in the study. Following scaling and root planing, patients were randomized to receive either 2% minocycline ointment or a matched vehicle control. Study medication was administered directly into the periodontal pocket with a specially designed, graduated, disposable applicator at baseline; week 2; and at months 1, 3, 6, 9, and 12. Scaling and root planing was repeated at months 6 and 12. Standard clinical variables including probing depth and attachment level) were evaluated at baseline and at months 1, 3, 6, 9, 12, and 15. Microbiological sampling using DNA probes was done at baseline; at week 2; and at months 1, 3, 6, 9, 12, and 15. Results:Both treatment groups showed significant and clinically relevant reductions in the numbers of each of the 7 microorganisms measured during the entire 15‐month study period. When differences were detected, sites treated with minocycline ointment always produced statistically significantly greater reductions than sites which received the vehicle control. For initial pockets ≥5 mm, a mean reduction in probing depth of 1.9 mm was seen in the test sites, versus 1.2 mm in the control sites. Sites with a baseline probing depth ≥7 mm and bleeding index >2 showed an average of 2.5 mm reduction with minocycline versus 1.5 mm with the vehicle. Gains in attachment (0.9 mm and 1.1 mm) were observed in minocycline‐treated sites, with baseline probing depth ≥5 mm and ≥ 7 mm, respectively, compared with 0.5 mm and 0.7 mm gain at control sites. Subgingival administration of minocycline ointment was well tolerated. Conclusions:Overall, the results demonstrate that repeated subgingival administration of minocycline ointment in the treatment of adult periodontitis is safe and leads to significant adjunctive improvement after subgingival instrumentation in both clinical and microbiologic variables over a 15‐month period.J Periodontol 1999;70:657‐667.

The importance of visual cues in a positioning task was established by performing experiments in which the visual feedback display was varied. Thirty subjects had to maintain a constant jaw or finger position coinciding with the target level provided on an oscilloscope screen. A linear variable displacement transducer recorded, amplified, and digitized the position signals. Spectral analysis and calculation of the median frequency detected possible shifts in the power spectrum. Positioning accuracy was evaluated by means of the root-mean-square (RMS) error, which calculated the deviation from the target position. The median frequency of the finger tremor spectrum increased after withdrawal of visual feedback display, when eyes were either open or closed. Increased power in the low-frequency range of the finger signal was observed when delays were introduced in the feedback display. For jaw-closing muscles, the median frequency was not significantly altered when a delayed visual display was introduced or when the visual feedback display was abolished. Furthermore, RMS errors for finger positioning increased significantly in the 0.25-, 0.50-, and 1.00-s delayed display condition. Jaw-positioning errors significantly increased only after introduction of a 1.00-s delayed display. Results of a supplementary experimental set-up indicated a significant improvement of finger-positioning performance during 4 min of training, whereas no such effect was established for jaw positioning. These findings indicate that modification or withdrawal of visual feedback affects finger positioning more than jaw positioning. The spectral composition of a jaw position signal is not visually determined.

Strips of teflon and cellulose acetate were glued to the upper lateral incisors of human volunteers in a split mouth, double blind study on the influence of the substratum surface free energy (s.f.e.) on supragingival dental plaque accumulation during a three day period of no oral hygiene. Plaque accumulation, microbial composition of the plaque and s.f.e. of the microorganisms were determined and compared to plaque developed on natural enamel surfaces. Significantly less microorganisms colonised the polymer surfaces (p < 0.002). Streptococcus sanguis I was the predominant microorganism found in enamel samples, comprising about one-third of the total microflora, whereas it was recovered infrequently and in lower numbers from the polymeric surfaces, which predominantly contained Streptococcus sanguis II. Only on cellulose acetate sometimes high numbers of Streptococcus mitis and Streptococcus morbillorum were detected. The mean s.f.e. of the total plaque flora was lowest on teflon (84.5 mJ m-2) followed by cellulose acetate (86.0 mJm-2), whereas enamel harboured a microflora with a significantly higher mean s.f.e. (930 mJ m-2; p < 0.05). Also within the same bacterial species lower s.f.e. strains were isolated from the polymer surfaces compared to enamel. The results conform to a previously postulated model in which the interfacial free energy is the driving force for adhesion of microorganisms to solid surfaces.

Oral malodor affects a largeproportion of the population and may be the cause of a significant social and psychological handicap. This pilot study aimed to examine whether a 1‐stage full‐mouth disinfection in periodontitis patients (scaling and root planing of all pockets within 24 hours together with the application of chlorhexidine to all intra‐oral niches followed by chlorhexidine mouth rinsing for 2 months) resulted in a significant improvement in malodor when compared to a fractionated periodontal therapy (consecutive root planings per quadrant, at a 1 to 2 week interval). The baseline and outcome data concerning oral malodor were linked to the presence of tongue coating and to its roughness (fissures). Twenty‐four patients with severe periodontitis were randomly allocated to test and control groups. At baseline and after 1 and 2 months, the concentration of volatile sulfur compounds (VSC) in the mouth was measured and organoleptic ratings (expired air and total mouth air) were given. Plaque samples were collected from the dorsum of the tongue to calculate the number of colony forming units (CFU) per ml (anaerobic culturing) as well as the number of pigmented CFU/ml. Both the baseline organoleptic ratings and the VSC scores correlated well with the presence of tongue coating but not with the tongue roughness. Because a correlation between tongue coating and its microbial load could not be detected, it was hypothesized that the tongue coating per se, and not the bacteria, might be responsible for the malodor. The 1‐stage full‐mouth disinfection resulted in a faster and additional reduction in the organoleptic ratings of the oral malodor, even after 2 months. This might be explained by the improved periodontal outcome and/or the more significant reduction in the CFU/ml of pigmented species. In contrast to the organoleptic ratings, which were significantly reduced in both treatment groups (when compared to baseline), the VSC levels remained unchanged. This pilot study indicates that a 1‐stage full‐mouth disinfection has, in comparison to a standard periodontal therapy, additional beneficial effects in the treatment of oral malodor. J Periodontol 1998;69:374–382.

1. In anaesthetized cats the left maxillary and mandibular canine and incisor teeth were extracted. Nine weeks later the animals were anaesthetized again and titanium implants were placed into the edentulous ridge of the maxilla and mandible. 2. Terminal experiments were performed between 9 weeks and 10 months after inserting the implants. Recordings were made from the trigeminal ganglia and peripheral nerves of anaesthetized cats. Neurones were identified which responded to forces applied to the maxillary teeth but none was found which responded to forces applied to the implant. 3. The responses of motor units in the temporalis muscle were studied in response to ramp‐plateau forces applied to the maxillary canine tooth and maxillary implant using peristimulus time histograms and cumulative sum (cusum) analysis. A small amount of inhibition of the motor units was observed in response to the applied forces to the implant. However, the inhibition was much more profound when similar forces were applied to the tooth. 4. The results confirm that when forces are applied to a tooth, periodontal mechanoreceptors are stimulated which evoke reflex inhibitions to motor units in the jaw‐closing muscles. However, there is evidence that mechanoreceptors situated distant to the periodontium can also evoke such reflexes. 5. The results are discussed in relation to the overall functional role of periodontal mechanoreceptors in the reflexes of mastication.

Summary The efficacy and safety of ciramadol (Cir) as an analgesic in relieving moderate to severe pain after oral surgery has been studied in 79 patients randomly assigned to receive single oral doses of Cir 15, 30 or 60 mg, codeine 60 mg or placebo. During the 6-hour observation period, the three ciramadol-treated groups indicated greater pain relief than the codeine 60 mg or placebo groups. In general, Cir 60 mg was significantly more effective than codeine 60 mg, and all doses of Cir were superior to placebo. The proportion of patients in each Cir group reporting adverse experiences was significantly higher than in either the placebo or codeine groups. The experimental system proved very effective in demonstrating analgesic potency of Cir. The very high incidence of side-effects in the three ciramadol-treated groups makes it unfit for further clinical use in ambulant patients.

Seventy-five implants were installed in 12 fresh ethanol-treated bovine ribs by use of a torque gauge manometer to measure the force needed to screw the implants fully into the bone. Digital radiographs were taken and a density histogram of the bone at the implant/bone interface was obtained. The damping characteristics of the implant/bone interface were assessed by tapping the abutment with the Periotest (PT) device. Abutments of several lengths screwed at 20 N/cm were used to conduct PT measurements and the PT values (PTVs) were related to the insertion torque force, the bone density, and implant and abutment length. The results indicated that high correlations exist between PTVs and insertion torque force (R value -0.74579), and PTVs and bone density (R value -0.83031). There was also a significant difference (p 0.001) among the PTVs of the different abutment lengths used. Implant length did not demonstrate influence on PTVs (p 0.3847).

The sterile abutments of2‐stageimplants offer a unique model to study intraoral transmission and bacterial colonization patterns in the oral cavity. This study aimed to examine, by means of differential phase contrast microscopy, parameters that influence the intra‐oral colonization of these abutments. In part one, 159 partially edentulous patients were examined to determine the influence on the microbial composition around implants of the following parameters: 1) the relative location of the teeth in relation to the implants; 2) the microbial composition of the subgingival plaque around these teeth; and 3) the frequency of deep pockets around the natural dentition. The results indicate that the subgingival flora around the implants harbored more spirochetes and motile rods when teeth were present in the same jaw (P< 0.05) and/or when the pockets around them harbored a pathogenic flora (P< 0.05). In part two, the impact of periodontitis around the remaining teeth and of probing depth around the implants on the composition of the peri‐implant subgingival flora was investigated. Thirty‐one partially edentulous implant patients were classified according to their periodontal condition into 3 groups: healthy (n = 17), chronic periodontitis (n = 11), and refractory periodontitis (n = 3). The samples from deep pockets (≥ 4 mm) around implants showed significant increases in the total proportion of spirochetes and motile organisms when compared to samples from healthy subjects (1.2%) or in chronic periodontitis patients (21.0%), or to patients suffering from refractory periodontitis (31.5%). For shallow pockets (< 4 mm) significant differences were only detected between subjects with a healthy periodontium (1.0%) or chronic periodontitis (2.4%), and refractory periodontitis cases (19.7%). The present findings confirm the transmission of microorganisms from teeth to implants, and thereby highlight the importance of periodontal health around the natural dentition before as well as after implant installation. J Periodontol 1996;67:986–993.

To establish whether different implant-supported prosthetic reconstructionsinfluence jaw muscle resistance to clenching efforts, sustained submaximal (50%) clenching was performed in two groups of patients who were edentulous in one or both jaws. One group consisted of patients who were rehabilitated by means of an overdenture on two to four implants connected by a bar; the other group consisted of patients who were rehabilitated with an implant-supported fixed prosthesis on four to seven implants in either the maxilla or the mandible. Results indicated that after rehabilitation with implant-supported fixed reconstructions, the myoelectric output level increased over time, which was parallel to a higher bite force level. For the other group, such a time-dependent change in electromyographic amplitude did not occur. On the other hand, power spectrum analysis revealed a significant downward shift of the mean power frequency during sustained clenching after rehabilitation with implant-supported overdentures but not with implant-supported fixed prostheses. The absence of a spectral shift in the latter group probably expressed a fear of biting too hard and fracturing the prosthesis.

Abstract: Stereognosis is the ability to recognise and discriminate forms. Oral stereognostic ability has been studied in different reports. The experimental design of the test is of primary importance as both the method used and the material applied may influence the results dramatically. The form, size and surface characteristics of the test piece, the presentation order, subject-related factors and the method of scoring all have their effect on the results. With regard to subject-related factors, ageing has a negative influence on stereognostic ability; gender is considered of no importance. Another influencing factor is dental status. A healthy natural dentition offers a very good oral stereognostic ability. Edentulous subjects usually show a decreased oral stereognostic ability, depending on the rehabilitation form. A number of questions have been addressed, especially with regard to the perception itself. Receptors mainly involved in oral stereognostic ability are located in various oral structures and form perception results from an association of more than one group of receptors. The following review tries to deal with these questions and attempts to provide clear guidelines for further research on oral stereognosis.

Abstract: A randomised clinical trial was performed to investigate whether there is a need or advantage to splint two implants in the mandible retaining a hinging overdenture. Furthermore, patient satisfaction was evaluated for different attachment systems retaining the overdenture. Thirty-six edentulous patients were randomised into three groups of equal size and treated with either magnets, ball attachments or straight bars (reference group). After 3 years of observation no implants were lost in any of the groups. Besides, no statistically significant differences were noted for the peri-implant outcome. Although the bar group presented the highest retention force, the general satisfaction of the patients in the three groups did not differ. The patients with bar retentions showed less prosthetic complications of the retention elements but more at the level of the denture-supporting mucosa. Finally, the clinical outcome of all groups confirms that overdenture treatment demands regular controls with limited time intervals.

Statement of problem. The results of the implant overdenture treatment in the maxilla remains inferior to those in the mandible. Different reasons have been alluded to, such as bone quality and quantity, number of implants, as well as the prosthesis design. Purpose.To investigate the latter, a new design for the rehabilitation of the resorbed maxillae was set up. Material and methods. Thirteen patients were selected and provided with four endosseous maxillary implants, splinted with a rigid-cast bar. Results. After a mean loading time of 3 years, six implants were lost; three at abutment and another three shortly after abutment connection, resulting in a cumulative success rate of 88.6% at year 4. A mean marginal bone loss of 0.3 mm was observed within the first year. After the first year, the marginal bone level, the attachment level, and the Periotest scores hardly changed. The main prosthetic complication was the frequent need to renew or to activate the attachments. A strong improvement in patient satisfaction was observed when compared with the old conventional denture. Conclusions. Within the limits of this study, the outcome confirmed that, on a medium-term base, implant-retained hinging overdentures on four implants were promising. (J Prosthet Dent 1998;79:156-64.)

Abstract: The treatment of fully edentulous mandibles by means of implant-supported hinging overdentures has become a routine therapy, although long-term data on the success rate of implants and prostheses are lacking. This longitudinal study examined 207 consecutively treated patients who received, during the past 10 years, 449 Br�nemark implants to retain a mandibular hinging overdenture, mainly on a Dolder bar. Clinical parameters and standardized radiographs taken at every recall visit with an interval of 6–12 months were used to judge the implant rigidity in the jawbone, the marginal bone level, and attachment level changes. The cumulative implant failure rate at 9 years was 3%. After loading, implant loss was concentrated during the first 12 months, with only one failure observed at 22 months. A radiographically determined bone loss of 0.7 mm was observed during the first year. From the second year, a mean annual bone loss of 0.05 mm occurred. The attachment loss, calculated as the sum of probing pocket depth plus the recession, was 0.07 mm/year and paralleled the changes in marginal bone level over time. The rigidity of the implant–bone interface revealed an increase over time, as shown by a decrease in Periotest values. The bar–overdenture complications were related to relining (23%), untightening of the retention clip (10%), and renewal of the prosthesis (7%). When magnets or ball attachments were used, more aftercare was needed. Fracture of the antagonistic full denture occurred in 7% of patients. The present data indicate that the mandibular overdenture therapy on two (Br�nemark) implants is a very reliable and cost-effective treatment, even in a long-term perspective for the fixed full mandibular prosthesis and especially in elderly patients.

Abstract: The long-term success of Brånemark implants has been previously reported. The success rate of the same implants, when associated with autologous grafts, seemed much less predictable. In the present study it is demonstrated that when these implants are installed in conjunction with an autologous corticocancellous hip graft, either onlay or inlay, the cumulative success rate remains at 95% for individual implants in non-smokers. The short extracorporal time might be an explanation. On the other hand, the same approach in patients with congenital defects or who underwent radiotherapy is deceptive. The use of hyperbaric oxygen may dramatically improve these results.

Spectral analysis of the electromyogram, i.e., computation of its power spectrum, has proved useful in studies of muscle fatigue and in studies of the relative contribution of firing rate modulation to force production by muscles (Weytjens & Van Steenberghe, 1984a & b). The models on which the interpretation has been based either do not include realistic assumptions as to motor unit synchronization (Lago & Jones, 1977), or do not make use of the classical definition of the power spectrum of a stationary stochastic process as the Fourier transform of the autocorrelation function (Blinowska et ai, 1980). This paper presents a realistic extension of the Lago and Jones model and then lists equations for the power spectra and the cross-power spectra of two synchronized motor unit action potential trains (Muapts) derived using their relations with the auto- and cross-correlation, respectively (Weytjens & Van Steenberghe, 1984c), from which the effects of motor unit synchronization can easily be understood.