A scanning electron microscope study of monkey maturation-stage ameloblasts

The maturation-stage enamel organs of Macaca arctoides and Macaca mulatta were examined in order to determine whether the cells were similar to those of the continuously erupting rat incisor. Tooth buds of the permanent dentition were fixed in formaldehyde-glutaraldehyde and post-fixed in OsO4. The enamel organs were separated from the enamel during dehydration, critical-point-dried, metal-coated, and examined in a scanning electron microscope. The results showed that there were few differences in the morphology of maturation-stage ameloblasts of these primates compared with those of other species reported in the literature. The apical plasma membranes were either smooth- or ruffle-ended, while the later membranes had maze, microvillous, or ridge configurations, also seen in rats, and an additional configuration of interdigitating bulbous extensions. The blood vessels of the papillary layer in monkeys were about 7 micron in diameter, considerably larger than those of the rat.     

Dental caries and oral hygiene status of school children in Davangere related to their socio-economic levels: an epidemiological study

Dental caries and periodontal disease, the most commonly seen disease show striking geographic variation, socio-economic patterns and severity of distribution all over the world. Hence, an attempt has been made to determine the relationship of oral health status with socio-economic status in Davangere town. A total of 2007 children of 13 to 14 years age belonging to both sexes were examined. Type III examination was carried out during the survey. DMFcaries Index and Oral Hygiene Index was used to assess caries experience and oral hygiene status. Prasad's classification was used to know the social classification of the children. It was concluded that dental caries experience and oral hygiene status of children are strongly correlated to socio-economic status.     

Upper removable appliance or Jones Jig for distalizing first molars? A randomized clinical trial

Aim – To compare the effectiveness of two intra‐oral methods of distalizing upper first permanent molars: an upper removable appliance (URA) and a Jones Jig. Sample – Twelve patients were randomly allocated to URA treatment and 11 patients to a Jones Jig. Methods – Upper study models were collected at the start of treatment and after 6 months of appliance wear. The amount of distal movement, tipping and rotation of the upper first permanent molars and mesial movement of the upper first permanent premolars was measured using a reflex metrograph. Results – There were no statistically significant differences between the two treatment methods for any of the outcome measures (P < 0.05). Distal movement obtained by both appliances was approximately 1 mm. Conclusions – The amount of distal movement obtained with both appliances was small and no differences were shown in the amount of molar tooth movement. It is suggested that there is no advantage in using the Jones Jig as a non‐compliance appliance.     

The effect of disc thickness and trauma on disc surface friction in the porcine temporomandibular joint

The pathomechanics of osteoarthritis in the human temporomandibular joint (TMJ) are unknown. Compromised lubrication is a potential factor, but, lubrication within even the normal TMJ is not understood completely. Weeping lubrication is a concept that may be applicable to the TMJ. A characteristic of weeping lubrication is a slow increase in friction during static loading. The rate of increase in friction is related to the rate of lateral movement of synovial fluid away from the loading area. The TMJ disc is expected to be the main source of TMJ lubrication. This study tested two variables, disc thickness and magnitude of trauma to the disc, as factors that can affect the rate of flow of synovial fluid and thus alter lubrication of the disc surfaces. To test these variables, TMJ disc surface friction was measured before and after an impulse load. Before the impulse load, all discs demonstrated a gradual increase in friction during light static loading. The rate of increase in friction was inversely related to the disc thickness (R(2)=0.75). After an impulse load of known magnitude and peak force, disc surface friction was higher. The magnitude of this surface friction was correlated with the magnitude of the impulsive blow (R(2)=0.89) and the area of surface damage (R(2)=0.85). Disc thickness was a significant factor in determining the minimal impulse needed to produce higher surface friction (R(2)=0.99). These results confirm that disc thickness and trauma to the disc affect surface friction in the TMJ, and therefore may be important factors in compromised lubrication and the development of osteoarthritis.     

Ridge augmentation using mandibular tori

A 19-year-old female was referred by her dental practitioner for the restoration of missing maxillary lateral incisors and canines. Ridge augmentation was required. This was undertaken using mandibular tori as the sites for harvesting bone. The grafting was successful and the spaces were subsequently restored using resin-bonded bridgework. The case reports that mandibular tori provide a local and convenient source of bone for ridge augmentation procedures.     

Effects of audiovisual distraction during dental prophylaxis

BACKGROUND: Fear and anxiety often inhibit patients from seeking dental care. Audiovisual, or A/V, distraction techniques have been shown to reduce patient anxiety and pain during dental procedures. The authors investigated the effects of a virtual image A/V eyeglass system on patients' anxiety and pain. METHODS: Twenty-seven routine dental prophylaxis patients participated and completed the Dental Fear Survey and the Fear of Pain Questionnaire-III before treatment. In random order, the clinician scaled and polished two quadrants in subjects while they watched and listened to a standard video using the A/V eyeglasses and two quadrants while they did not. A posttreatment questionnaire was administered to both the patient and the clinician. RESULTS: Subjects reported less anxiety and discomfort when using the A/V eyeglass system than when they did not. Most subjects preferred to use the A/V equipment rather than receive traditional treatment. The clinician experienced no significant technical interference during the use of the A/V device. The use of the A/V eyeglasses led to decreased treatment time in the first one-half of the procedure. The system appeared to lead to some decreases in the physiological parameters over the course of treatment, with the highest systolic blood pressure occurring after the condition with no use of A/V eyeglasses. CONCLUSIONS: A virtual image A/V system is beneficial in the reduction of fear, pain and procedure time for most dental prophylaxis patients. CLINICAL IMPLICATIONS: Use of screening questionnaires may be helpful for identifying anxious patients. An A/V device may be beneficial to the clinician and the mildly or moderately anxious patient.     

The influence of plaque and/or excessive loading on marginal soft and hard tissue reactions around Brånemark implants: a review of literature and experience

High implant survival rates are published with more than 15 years of observation time. Failures over time are often caused by ongoing marginal bone loss. Therefore, the need for reliable monitoring of the stability of periimplant attachment and/or bone level is extremely important. Marginal bone loss around osseointegrated implants has often been associated with periimplantitis, but clinical observations cannot prove this relationship. Otherwise, the impact of excessive loading on periimplant bone has been shown in animal studies and has been positively related to implant failure in terms of implant mobility and marginal bone loss. Some clinical observations support this hypothesis.     

Microstructural investigations of strain-related collagen mineralization

Distraction osteogenesis in rabbit mandibles after osteotomy can be used as an experimental model to study the microstructural features of mineralization of callus under defined mechanical loads. Our aim was to study the relation between the micromotions in the gap and the resulting features of mineralization of the matrix. We found that assembly of collagen and formation of crystals depended on the magnitude of the mechanical stress applied. At physiological bone strains (2000 microstrains), the callus had collagen type I in a mature bone-like extracellular arrangement, whereas at 20000 microstrains bundles were orientated predominantly towards the tension vector. Maximum loads (200000 microstrains) resulted in disorganized assembly of the collagen. Quantitative energy-dispersive analysis by X-rays confirmed that high strains were associated with substantially lower concentrations of calcium and phosphate. In contrast to bone-like apatitic formation of crystals at physiological strains, significantly fewer but larger crystals were detected by electron diffraction analysis in samples exposed to high strains. We suggest that mechanical stress regulates the assembly and mineralization of collagen during distraction osteogenesis.     

A transcultural perspective on the emotional effect of tooth loss in complete denture wearers

PURPOSE: The purpose of this study was to compare the emotional effects of tooth loss in three edentulous populations. MATERIALS AND METHODS: A questionnaire study involved 142 edentulous subjects undergoing routine prosthodontic care at Guy's, King's and St Thomas's Dental Institute, London; the Dental School, Dundee, Scotland; and the Faculty of Dentistry, University of Hong Kong. Data were analyzed using the chi-squared test. RESULTS: Difficulty in accepting tooth loss was a relatively common experience (44%) in all groups, with almost half feeling that their confidence had been affected. The majority (66%) felt that their choice of food was restricted and that the overall eating experience was less enjoyable, particularly the Hong Kong group. A significant proportion of the participants were concerned about their appearance without dentures, although the trend was less marked in Hong Kong. Forty-three percent felt that they were not adequately prepared for tooth loss, although the Hong Kong group was least concerned. CONCLUSION: In general, the emotional effect of tooth loss was significant in all groups. The restrictions on daily activities were generally greater in the Hong Kong group. However, this group was much less inhibited by denture wearing. The differences observed in the Hong Kong Chinese are most likely due to different cultural values and expectations associated with these aspects of daily living.     

The effect of educational intervention on the adoption of nickel-titanium rotary instrumentation in a Public Dental Service

AIM: To study the influence of two educational programmes on the adoption of nickel-titanium rotary instrumentation (NTRI) amongst general dental practitioners in a short-term as well as a long-term perspective. METHODOLOGY: All dentists employed in the Gothenburg Dental service (n = 148) were enrolled in the study. The clinics in the organization were randomly assigned to one of two educational programmes. In the first programme a 4-h lecture on root canal instrumentation was given. In the second programme the lecture course was supplemented by a 6-h hands-on training session. The short-term effect was measured by a questionnaire distributed 6 months after completed education. The long-term effect was evaluated 4 years later. RESULTS: The overall utilization rate of NTRI increased from 4% to 73%. However, lectures in combination with hands-on training resulted in a better short-term acceptance rate (94%) than if teaching was given only in lecture-format (53%) (P = 0.000). As a consequence, all staff were offered hands-on training. The long-term adoption rate was 88%. Reasons for accepting the new technology usually were found within the 'relative advantage' category. Common reasons for dentists not to adopt NTRI were that they could not get started or that they found no advantage over the old technology. CONCLUSIONS: The short-term adoption of a new technology might be influenced by the design of an introductory educational programme. For clinical procedures, such as root canal instrumentation, the inclusion of hands-on training sessions seems to be important to reach a high acceptance rate.