Prospects for new vaccines

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Evaluation and restoration of endodontically treated posterior teeth

The increasing acceptance and utilization of endodontic therapy for the preservation of broken-down posterior teeth presents the practitioner with many difficult restoration problems. If 25% or more of the coronal tooth structure is lost, some form of artificial dentin augmentation is required to provide adequate support and retention for the final restoration. Criteria to be used in the prerestorative evaluation of endodontically treated teeth are presented. Various methods and techniques to protect the remaining toth structure from fracture and to provide support and retention for the final restoration are described.

Efficiency in clinical trials of caries preventive agents and methods

The idea sequence of tests required to establish a caries prophylactic agent or procedure on a public health basis is described and a clear distinction is drawn between an experimental clinical trial, carried out under ideal conditions, and a community clinical trial carried out under real life conditions. Because of the artificial nature of an experimental clinical trial there are strict limitations placed on its objectives and the inferences that can be drawn from its results. Bearing these limitations in mind and using the data collected during a 3-year trial of a fluoride mouthrinse, two methods of improving the efficiency of experimental clinical trials of caries prophylactic agents are considered. Firstly, a reduction in length is suggested either by planning the trial to run for a shorter period in the first place or, alternatively, by stopping the trial when the criteria for success have been satisfied. Secondly, it is proposed that the number of subjects participating in the trial be reduced by excluding those whose contributions to the aims of the trial are likely to be low.

Associations between the total fluoride content of dental plaque and individual caries experience in Australian children

Individual caries experience (DMFT) and the total fluoride content of dental plaque were determined for 72 schoolchildren, aged 9.7-13.0 years, lifelong residents in one of three New South Wales towns, where the fluoride levels of the reticulated water supplies were: Katoomba, less than 0.1 parts/10(6); Sydney, 1.0 parts/10(6) for 4 years; and Yass, 1.0 parts/10(6) for 16 years, prior to sampling. The mean fluoride content of plaque in Sydney (22.6, s.d. = +/- 16.8 parts/10(6)) and Yass (25.6, s.d. = +/- 16.4 parts/10(6)) differed significantly (t = 2.27, P less than 0.05 and t = 3.30, P less than 0.02, respectively) from that in Katoomba (13.5, s.d. = +/- 8.3 parts/10(6)). Significant inverse associations were demonstrated between total plaque fluoride and individual caries experience (DMFT) in Sydney (r = -0.45, P less than 0.025) and overall (r = -0.28, P less than 0.010). Inverse trends were established between plaque quantity (dry weight of plaque collected) and fluoride levels. No associations could be demonstrated between fluoride treatment (dentifrice, tablets or topical application) and plaque fluoride, DMFT or plaque quantity.

Electrical stimulation of teeth

The technical problems of stimulating intact teeth in clinical diagnosis and in pain research are discussed. Bipolar stimulation has no advantage over monopolar stimulation for most applications. A 100 V constant current stimulator is suitable for monopolar stimulation of healthy teeth with a large electrode at about threshold intensity, but, for monopolar stimulation up to 150 micronA and for bipolar stimulation, very much higher voltages are required and no suitable instrument is available. Circuits are given for isolated 100 V and 1kV constant current stimulators.

A 2-year retrospective study of demand for dental care from Scottish school leavers

After leaving school young adults in the United Kingdom are no longer eligible to receive care from the School Dental Service. Patients who have previously been treated by the Service are obliged to seek care elsewhere. The aim of the study was to see how effectively a group of Scottish school leavers coped with the change. The study population was 912 school leavers. The method depended upon a retrospective study of clinical records relating to the year before leaving school and the following year. During the last year at school, 48% of the subjects received treatment from three sources: 30% were treated by a general practitioner, 19% by the school service and 2% by the hospital service. During the 2nd year of the study, 69% of those who had earlier been treated by a general practitioner again requested dental care compared with only 40% of those who had earlier been treated by the school service and 30% of those who had not sought dental care during their last year at school. Recommendations are made for encouraging an increased demand for care from those who have formerly been treated by the school service.

Effect of toothbrushing with chlorhexidine gel on salivary microflora, oral hygiene, and caries

The effect of daily toothbrushing with 0.5% chlorhexidine-containing gel for 12 months was evaluated in a double-blind study in 37 dental students. The active gel did not markedly influence plaque formation, gingival conditions, or caries as compared with placebo gel treatment. Salivary bacterial counts were performed on subgroups of six subjects using chlorhexidine gel and on six using placebo gel. No differences in the effect of treatment on the microorganisms studied in the two subgroups could be detected except for S. sanguis. The percentage of this species decrease in the placebo group and increased in the chlorhexidine group. The difference became significant after 2 weeks. A tendency to a greater reduction of S. mutans noted in the chlorhexidine group was most marked in individuals who had high initial counts of this species. The proportion of S. sanguis, which could grow on chlorhexidinei-containing mitis salivarius medium, increased and after 12 months of chlorhexidine treatment averaged 34% of cultivable S. sanguis compared with 0.002% prior to treatment. The number of less sensitive S. sanguis decreased in the 12 months following termination of treatment. There was no observed tendency for the selection or proliferation of other streptococci, gram-negative rods, yeasts, or staphylococci.

Comparison of dextranases for their possible use in eliminating dental plaque

Dextranases produced by P lilacinum NRRL 896 and NRRL 895 and by P funiculosum NRRL 1768 were studied for their possible incorporation into a dental plaque elimination system. The following properties of the enzymes were compared: effect of the pH level on the activity and the stability of the enzymes on the acid side of the pH range; molecular weight; affinity to Sephadex G-25 which served as a model for insoluble dextran in plaques; and the extent of hydrolytic action on dextrans containing alpha-1,3, alpha-1,4 and alpha-1,6 bonds in various proportions. The enzyme of P funiculosum NRRL 1768 certainly has its limitations as a plaque-degrading enzyme, for example, diminished activity at a high pH level and lack of activity on alpha-1,3 bonds. However, from our studies, and from a survey of the relevant literature with respect to the aforementioned properties in other dextranases, the enzyme of P funiculosum NRRL 1768 emerges as a suitable choice for incorporation as dextranase, possibly together with other enzymes, into an enzymatic dental plaque elimination system.

Abnormal tooth tissue in human odontodysplasia

The affected teeth in this case of odontodysplasia exhibited abnormal hypoplastic enamel, abnormal dentin containing extensive interglobular regions and completely lacking a peritubular matrix, and an abnormal irregular tissue consisting of highly calcified and partially fused granules located within the dentin of the tooth tips. Electron micrographs of the irregular tissue showed that the granules consisted of crystallites densely and radically packed in a noncollagenous amorphous matrix. Granules were surrounded by a slightly calcified, irregularly arranged, collagenous matrix. The irregular tissue formed in the pulp of the tooth tip befofe and independently of the dentin. It was at least partially formed by pulpal calcification. Abnormal dentin matrix was formed by odontoblasts which were less differentiated than normal. Odontodysplastic teeth showed abnormal differentiation of odontoblasts and ameloblasts resulting in defective enamel and dentin and, in extreme cases, in extensive pulpal calcification.

Atrophic lesions of the tongue: a prevalence study among 175 diabetic patients

Central papillary atrophy and other anomalies of the tongue were studied among 175 diabetic outpatients attending the Tygerberg Hospital. Atrophic lesions of the tongue were found in 26.9% of the patients and 91.7% of these lesions were central papillary atrophy. The degree of control of the diabetes as measured by plasma glucose and urine analyses was not related to the frequency of central papillary atrophy. The prevalence of central papillary atrophy in diabetics was found to be much higher than that of central papillary atrophy and median rhomboid glossitis found in previous investigations among other populations. It is suggested that patients with central papillary atrophy should be screened to rule out diabetes mellitus as the underlying cause. Double central fissures, producing well demarcated triangular areas with their bases at the "sulcus terminalis", were seen in nine instances (5.1%). Four of these areas were associated with central papillary atrophy; the remaining five were covered by non-atrophic mucosa with filiform and fungiform papillae.

Retention and effectiveness of a chemically polymerized pit and fissure sealant after 12 months

The aim of the present study was to evaluate the retention and effectiveness of a bis-GMA type of fissure sealant which polymerizes after conventional mixing of the two catalyst/activator components (Concise Enamel Bond System). Unilateral sealing of homologous pairs of permanent first molars was carried out by a dental hygienist. Of the 451 sealed sites sealant was present in 73%, partly missing in 8%, and completely missing in 18% after 1 year. The effectiveness of the treatment in preventing occlusal caries was highly significant and the caries reduction was found to be about 70%. A strong relationship between status of sealant and occlusal decay was demonstrated. The shortcomings of the half-mouth design when evaluating sealants as a caries-preventive measure in public dental health programs are discussed.

Sensory and reflex responses to tooth pulp stimulation in man

Experiments have been carried out to investigate whether all tooth pulp afferent nerves are capable of producing pain. Monopolar and bipolar stimuli were applied to teeth in human subjects and sensory thresholds determined. EMGs were recorded from the masseter and the anterior digastric muscles. With stimuli up to three times the sensory threshold, no response could be detected in the digastric but at, or just above, the sensory threshold, inhibitory effects were produced in masseter muscle. The latency of the muscle response with bipolar stimulation was 18-22 msec. There was no evidence of stimulus spread to nerves outside the teeth. Bipolar and monopolar stimulation both produced the same sensation but this was not described as painful. It is concluded that some pulpal afferent nerves may not be capable of producing pain, and that the sensory and reflex responses at threshold were probably produced by the same fibres.

Surgical repair of tusk injury (pulpectomy) in an adult, male forest elephant (Loxodonta cyclotis)

A 15-year-old male forest elephant housed in a zoo sustained a fracture of the right tusk that was 10 cm inside the cheek pouch, thus exposing the tusk canal. Treatment of the cavity by packing, topical application of antibiotics, and administration of various antiseptic preparations failed; however, the tusk grew. To treat the infected, growing tusks's root canal or pulp, surgery--comparable to a pulpectomy in man--was performed with successful results.

Improvement in lacrimal and salivary secretions after alkali therapy in Sjøgren's syndrome with renal tubular acidosis

A patient with Sjøgren's syndrome developed renal tubular acidosis which led to systemic acidosis and potassium depletion. Treatment with Shohl's solution and potassium supplements was followed by subjective improvement in tear flow, salivary flow, and by disappearance of bronchitic symptoms. Detailed objective assessments were then made during the next year, twice on treatment and twice without. These confirmed the subjective impression of improvement.

Time lapse by diagnosis of oral cancer

This survey comprised thirty-four patients who were suffering from malignant tumors of the oral cavity diagnosed in a 12-year period in the Department of Oral Surgery, Royal Dental College, Aarhus, Denmark. The categories of tumors were as follows: carcinomas (twenty-seven), osteosarcomas (four), reticulum-cell sarcomas (two), and lymphosarcomas (one). Special emphasis is placed upon the calculation of two time factors, i.e., the time that elapsed from when the symptoms were first noticed until the patient consulted a physician or dentist, and the period during which the patient was under professional care up to the time at which a final diagnosis was made. The first of these periods was found to be, on an average, 4.9 months; the second period averaged 5.6 months. The most common complaints were swelling and pain, two symptoms with which the physician or surgeon often are confronted. This may be a possible reason for a relatively late diagnosis in the case of several malignant tumors. A frequently very suspect symptom, such as a persistent ulceration, was found in only thirteen of twenty-seven cases of carcinoma, whereas another symptom in the same category, disturbances in sensibility, was noted in only three cases. Because of the short observation period in some cases, no correlation between the two time factors and the prognosis was attempted. Despite the inadequacy, it may be concluded that the period of 5.6 months which in this material was found to elapse between the first consultation and the actual time of diagnosis was far too long. All lesions that do not respond to adequate therapy in 14 days should be suspected of being malignant, and the patient should be referred to a specialist for proper diagnosis.

Interrelationships between orthodontics and periodontics

At the present time, periodontists have no evidence to indicate that orthodontic treatment in the child will either enhance or detract from the periodontal health of the patient or that it will increase or decrease the longevity of the teeth. Many periodontists believe that much orthodontic treatment is undertaken on an esthetic or empirical basis. Proper emphasis on plaque control procedures prior to initial banding, altered and reinforced during the entire period of orthodontic treatment, may well minimize the inflammatory lesion often found during therapy. Gingival, periodontal, and mucogingival problems should be treated as soon as they are diagnosed. Limiting our orthodontic objectives in adult patients because of the possibility of inducing supporting alveolar bone loss and other problems that did not previously exist may be a worthwhile compromise. Orthodontic movement in periodontally healthy adults, and especially in those with periodontally involved teeth, constitutes a problem distinct from routine orthodontics. When periodontal disease has already produced significant destruction of supporting tissue and secondary occlusal trauma is a complicating factor, orthodontic treatment may possibly serve as another mode of treatment to reestablish the correct occlusal plane and alter bony deformities. Various methods can be used to try and place teeth into better bone. One should make certain that teeth are being moved into a greater volume of bone. The bite plane is of great value in allowing continuous eruption of the teeth and their supporting structures and in eliminating additional trauma by enabling the teeth to move into their correct cusp-fossa relationships unimpeded by the inclined planes of the opposing teeth. Since little is known about the interrelationships between orthodontic treatment and periodontal health and disease, there is still a great deal to learn. In spite of this lack of knowledge, the general practitioners and the various specialists of dentistry, each seeking a rationale for his preventive and therapeutic procedures, subject the patient to treatment based on concepts of the occlusion which have yet to be corroborated. In addition to the need for research in this field, a common language between the periodontist and the orthodontist must be established to eliminate the existing communications barrier. Once basic principles can be determined, elucidated, and applied correctly, the movement of teeth in periodontal cases will be limited only by the imagination of the operator.

Inhibition of rat dental caries by dextranase from a strain of Spicaria violacea

Dextranase AD17 obtained from a culture liquor of a strain of Spicaria violacea was assessed for its ability to inhibit the development of dental caries in conventional Sprague-Dawley rats which had been infected with one of the Streptococcus mutans strains. MT6R (serotype c), OMZ 176R (d), or MT-703R (e). These experiments showed that caries was significantly inhibited when rats were given cariogenic diets No. 2000 and drinking water containing AD17 at a concentration of 10 units/g, as compared to control rats not given dextranase. The inhibitory effects of AD17 were more prominent in smooth surface caries than in total caries. AD17 had a tendency to retard both the establishment of inoculated S. mutans and plaque deposition on tooth surfaces. However, S. mutans could be implanted in the rat oral cavity after repeated inoculation of the bacteria, even in the presence of AD17. These results suggest that the anticaries activity of AD17 is due to not only inhibition of adherence of S. mutans cells on tooth surfaces but also to physiochemical changes of dental plaque formed under the enzymatic action of AD17. Preliminary histophatological examination showed that AD17 had no significant toxicity in rats.

Relationship between the width of the occlusal table and pressures under dentures during function

The effect of altering the width of the occlusal table was studied on one edentulous subject. A maxillary denture was designed to accept four interchangeable posterior occlusal segments, differing only in the buccolingual dimension of the occlusal table. The opposing mandibular denture contained pressure transducers that made contact at selected sites along the residual ridge. Pressures developed during function between the denture base and the ridge mucosa were analyzed.

A laboratory method for assessment of dentrifrice abrasivity

This is the report of the Laboratory Abrasion Committee of the American Dental Association (ADA) Dentifrice Program relative to specific methods to measure the in vitro abrasivity of dentifrices. This method was used in two collaborative studies with six participating laboratories. These studies were designed by the ADA Dentifrice Program Statistical Committee and their interpretations form a basis for recommendations on the use of the method. This laboratory method is recommended for use in dentifrice development and may provide some basis for expectations in normal dentifrice use.

The odontogenic keratocyst. A clinicopathologic study of 312 cases. Part I. Clinical features

An analysis was made of the clinical features of 312 acceptable cases of odontogenic keratocysts from the files of the Department of Oral Pathology, Indiana University School of Dentistry. A total of 5.1 per cent of the keratocysts were from patients with the basal-cell nevus syndrome and 5.8 per cent were from patients with multiple keratocysts but with no other features of the syndrome. There was a wide age range, with a peak incidence in the second and third decades of life. The mandible: maxilla ratio was 2:1, with the mandibular third molar area and ramus being the most common sites. Dentigerous cyst was the most frequent clinical as well as histologic diagnosis for the majority of the keratocysts in this study. The primordial cyst comprised the greatest percentage of keratocysts (44.4 per cent). A total of 50.3 per cent of the patients were symptomatic before seeking treatment, the most common finding being intraoral drainage and swelling. Their radiographic appearance was quite variable, although they frequently resembled ameloblastoma. These cysts may be very aggressive clinically. They have a relatively high recurrence rate, as previously reported in the literature, in comparison with other types of odontogenic cyst. The findings in this study support the theory that the histologic appearance of an odontogenic keratocyst may be assumed by any of the odontogenic or nonodontogenic cysts.

Pyruvic acid as an etching agent

Phosphoric acid at different concentrations has been extensively used as an etching agent to improve bonding of dental materials to enamel surfaces. Recently attention has been drawn to the possible use of polyfunctional organic acids as conditioning agents. The object of this investigation was to determine the optimal concentration of pyruvic acid as an etching agent. A commercial composite resin with an intermediary bonding system supplied with 37% H3PO4 as an etching agent was used as the control system. In addition, a comparative study was carried out to evaluate 37% H3PO4, 20% lactic acid and the optimal concentration of pyruvic acid as conditioning solutions. Etching enamel surfaces with 10% pyruvic acid resulted in the optimal tensile bond strength of the resin to etched enamel surfaces. The use of 10% pyruvic acid did not adversely affect the bond strength of the resin system when compared to enamel surfaces etched with 37% H3PO4 for the same time period. Significantly lower tensile bond strengths were recorded on enamel surfaces etched with 20% lactic acid. The rate and depth of etching obtained with 37% H3PO4 can be considerably reduced by using 10% pyruvic acid as the conditioning agent.

Sealing quality of polycarboxylate cements when compared to amalgam as retrofilling material

Four hundred roots were uniformly prepared for retrofilling. One hundred of these were retrofilled with amalgam and served as controls for the study. The polycarboxylate cements--Durelon, PCA, and Poly C--were each used as retro-filling material for 100 roots. After immersion in 2 per cent aqueous methylene blue for 7 days, the roots were sectioned in 1 to 2 mm. increments to determine the depth of dye penetration. The depth of dye penetration was used as a measure of their sealing effectiveness. The groups were compared statistically by means of a t test. All cements were significantly different from amalgam. All cements performed inferiorly to amalgam, an already accepted retrofilling material.

Evaluation of a dehydrated test strip,Microstix -Candida for detection of Candida-induced denture stomatitis

The outgrowth of yeast from the fitting surface of the maxillary denture and the palatal mucosa was estimated in 63 denture wearers by means of smears and by culture on Microstix-Candida (M-C). There was a significant relationship between the concentration of yeasts as assessed by smears and by M-C. There were confluent spots on M-C, indicating large numbers of yeast cells, in 81% of 37 denture wearers with a positive microscopic diagnosis for Candida-induced denture stomatitis, whereas there were confluent spots on M-C in only one of 26 denture wearers with a negative microscopic diagnosis for infection. It is concluded that the M-C test seems to have sufficient diagnostic sensitivity to be an alternative to the smear for establishing the diagnosis of Candida-induced denture stomatitis.

Effectiveness of fissure sealant 3 years after application

Findings 3 years after the application of a fissure sealant revealed that of the 166 sealed permanent first molars, 7.8% of the sealants were missing or partly missing, 14.5% were in fair condition, and 77.8% had remained in good condition. During the 3-year test period, 7.8% of the sealed permanent molars had become carious, while 63.3% of the respective control teeth had decayed. The teeth which had sealants in good condition showed no caries, whereas 92.3% of the teeth which had sealants missing or partly missing showed carious fissures. The net gain in the study was 104, and the percentage effectiveness of the method was 88.1%. The treatment effect was found to be very significant when analyzed on the basis of homologous paired test-control teeth (P less than 0.001). The sealing of pits and fissures was found to have a positive treatment effect on 60.2% of the subjects when evaluated on an individual basis (0.1 less than P less than 0.05).

Root resorption by ameloblastomas and cysts of the jaws

Radiographs of 122 cases of a series of nonmalignant simple jaw cysts and ameloblastomas were examined and the frequency of resorption of adjacent tooth roots compared. The ameloblastomas proved to have a root resorptive potential far greater than the cystic lesions considered. Certain statistically significant differences were observed in the root resorption related to the cystic lesions. The dentigerous cyst showed a tendency to resorb roots (55%), whereas in this study no resorption was observed in primordial cysts. These differences may aid the clinician in the preoperative differential diagnosis. It is suggested that the capacity of the dentigerous cyst for root resorption may be the result of its origin from the dental follicle, which is associated with resorption of the roots of primary teeth during normal tooth succession.

Droperidol/fentanyl, diazepam/pentazocine: a comparison

Anaesthesia with a combination of diazepam and pentazocine is compared with the well established technique of neuroleptanaesthesia using droperidol and fentanyl. The former compared favourably, producing similar cardiovascular stability, rapid recovery of conciousness and postoperative analgesia.

The antilingula as an anatomic landmark in oral surgery

The antilingula is a highly variable anatomic landmark and in most instances is situated considerably anteriorly and superiorly to the inferior dental foramen. However, a cut made between 5 and 10 mm. distal to the antilingula is within a statistically safe area, in over 72 per cent of cases, to avoid encroaching upon the inferior alveolar foramen.

How many tastes are there for low concentration "sweet" and "sour" stimuli? - Threshold implications

Ascending series of solutions of sucrose, glucose, and citric acid were tasted and detection and recognition thresholds were noted; subjects were also required to determine the number of taste sensations that occurred and their sequence of occurrence. It was found that subjects varied in their reports of the number of taste changes and hence potential criteria for detection and recognition. Even among those subjects who reported the same number of criteria there was little consistency as to which were actually chosen for detection and recognition. Some subjects even used an intensity change rather than a quality change to signal a threshold. They criterion can thus be seen to be a potential variable in threshold measurement, and criterion-free measures of sensitivity are recommended. Taste quality descriptions were also studied and a high proportion of novel descriptions was noted; it was hypothesised that this was due to the fact that subjects were not primed with traditional descriptive terms during the instructions.

Miliary tuberculosis presenting with multifocal oral lesions

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Traumatization of teeth and gingiva related to habitual tooth cleaning procedures

Traumatization of oral hard and soft tissues connected with mechanical oral hygiene procedures has been reported in the dental literature. Definitions, classifications and localization of such lesions are listed, and in vivo and in vitro experiments within the field are reviewed. Existing literature suggests that hard tissue lesions are mainly due to abrasives in dentifrices, whereas gingival lesions may be caused by toothbrushing per se. Factual knowledge about the prevalence, severity and clinical significance, as well as relevant and reliable experiments, is scarce and further research on these topics seems to be indicated.

Chairtime needed for an incremental dental care program for schoolchildren in Israel

Chairtime needed to provide initial treatment to 80 children, 6 1/2 to 7 1/2 years of age, in an incremental care program was recorded. An average of 8.2 carious teeth with 14.0 carous surfaces required treatment. The clinical and radiographic examinations were concluded earlier and were not included in the chairtime recorded. One year after completion of the initial treatment, 51 of these children were reexamined to determine the maintenance treatment needs. These were found to be approximately one-third of the initial treatment needs. The average chairtime required for initial treatment was 2 hours and 37 min. It was estimated that for complete treatment, including examination and preventive measures, 3 hours per child would be required for initial treatment and 1 hour for maintenance care each following year.

A survey of accredited dental technology education programs in the United States

A study was made of current educational methods and prosthetic technology used in the accredited dental technology education programs in the United States. Some of the results have been compared with the findings of a similar study in Britain and several differences have been noted. The results of this study and of the British one refer to accredited educational programs and do not necessarily reflect the procedures used in dental practice or in commercial dental laboratories.