I.B. Bender

The interrelationship of pulp and periodontal disease

Abstract In order to ascertain whether or not a relationship exists between periodontal and pulpal lesions, eighty-five teeth with periodontal lesions were examined histologically. Prior to extraction, subjective symptoms and the results of clinical tests were recorded. In addition, a medical and dental history was elicited. In many teeth a profusion of lateral and accessory canals and foramina were found, especially in the bifurcation and trifurcation regions of molars. Where the roots were fused with cementum, accessory canals were frequently seen. The pulps of only five teeth (6 per cent) were found to be uninvolved. Atrophic pulps were found in twenty-three teeth (27 per cent). The pulps were inflamed in forty-two teeth (49 per cent) and totally necrotic in fifteen teeth (18 per cent). These observations appeared to indicate that periodontal lesions produced a degenerative effect on the pulps of the involved teeth. In order to separate the effects of caries or operative procedures in the pulps of those teeth with periodontal involvements, we examined thirty-two periodontally involved teeth in which there was no evidence of caries or restorations. Among this group, twelve teeth (37 per cent) had pulps exhibiting various degrees of atrophy and twelve teeth (37 per cent) had inflammatory pulp lesions. In three teeth the pulps were completely necrotic. Further analyses indicated that pulps subjected to a combination of pulp and periodontal irritants showed a greater incidence of inflammatory reactions than those subjected to operative procedures alone. Pulp lesions were found to have an effect on the severity of the periodontal lesion. Inflammation of the periodontal membranes from inflamed and necrotic pulps was readily spread through lateral canals and accessory foramina, especially in molars. Also, extensive apical granulomas caused resorption of the crest of the interradicular alveolar ridge. Thus, retention of these teeth could be accomplished only through combined endodontic and periodontal therapy. Pain in periodontally involved teeth was also investigated. Atrophy or inflammation of the pulp was responsible for the greatest incidence of pain. The pain incidence appeared to increase when caries or restorations were present. Thermal responses in teeth with periodontal lesions increased significantly when the pulps were found to be inflamed, but there was no correlation between the type of pulp inflammation and a specific thermal test. The patients complaints relating to pain on thermal stimuli were not found to be reliable indicators of the state of the pulp in periodontally involved teeth.

Endodontic success—A reappraisal of criteria

Abstract An attempt has been made to correlate clinical, histologic, and roentgenographic observations of endodontically treated teeth in order to focus attention on the inadequacies of the roentgenogram as the sole criterion of treatment success. Definitions and interpretations of success vary among clinicians, and most often the roentgenogram is used as the sole criterion of success. Clinical observations, such as the persistence of pain, swelling, and the development of a fistula, are seldom included as additional criteria. Roentgenographic interpretations of radiolucencies present many fallibilities. These are usually produced by differences in vertical and horizontal angulation of the roentgen beam. Systemic and local constitutional disorders often simulate periapical radiolucencies that are not of endodontic origin. Periodontal disease often causes roentgenographic lesions that are mistaken for evidence of endodontic treatment failure. These lesions develop either before or after endodontic treatment. Differences in the length of observation time used for the evaluation of success can produce variations in the rates of success or failure. Using the roentgenogram as the only criterion of success in cases in which no radiolucency developed in teeth without a region of rarefaction, we observed a success rate of 92.7 per cent in 1,200 cases within a period of 6 months. After a period of 2 years the success rate was 88.7 per cent in 500 cases. This difference was statistically significant. In cases of teeth with radiolucencies in which a decrease in the size of the area was viewed as an indication of success, there was no difference between a 6 month (75 per cent) and a 2 year (77 per cent) follow-up. When complete bone regeneration, as visualized on the roentgenogram, was used as the standard of success, our success rate was 39.2 per cent in 365 teeth after an observation period of 2 to 10 years. Failures as manifested by roentgenographic evidence usually will occur within 2 years, whereas the clinical symptoms of pain, swelling, and development of a fistula will occur during treatment or within the first few months after treatment. The teeth of patients with persistent pain during or immediately after treatment are often resected or extracted. This group is seldom included in the analysis of endodontic failures. Histologic sections of teeth, with and without areas of rarefaction, that were extracted because of pain occasionally revealed the presence of undisclosed accessory or lateral canals. However, pain was also present in a similar number of cases in which there were no accessory canals. Furthermore, necrotic tissue was observed in many of these canals with no clinical symptoms of pain. In endodontically treated teeth with periapical radiolucencies, there is a definite correlation with histologic findings, whereas no such correlation exists in teeth without periapical radiolucencies. This lack of correlation is especially true in the case of teeth with necrotic pulps. Histologic evidence of chronic inflammation in the periapical tissues of teeth with normal roentgenographic findings has been observed invariably in both animal and human teeth with necrotic pulps. Cysts and granulomas developed in the periapical region following pulp extirpation in a number of cases that did not exhibit radiolucent areas before or after treatment. Most of the histologic sections of periapical tissues of teeth with areas of rarefaction revealed granulomas and cysts in equal distribution. Scar tissue in the periapical region was found in only two of 100 specimens examined after treatment. The small incidence of cases with scar tissue in the periapical area does not justify the conclusion that healing occurs with scar tissue formation merely because an area appears smaller on a follow-up roentgenogram. We have observed that large areas of radiolucency can also contain fibrous tissue following endodontic therapy in a similar percentage of cases. Large, small, arrested, or reduced areas of rarefaction all contain the same inflammatory cells. Most radiolucencies, whatever their size may be, are either granulomas or cysts. We have proposed a hypothesis to show how a cystic lesion can heal following a nonsurgical or conservative endodontic procedure, and we have offered new and more realistic criteria of successful endodontic therapy, based on clinical, histologic, and roentgenographic evaluation.

Biologic aspects of endodontics: Part III. Periapical tissue reactions to root canal instrumentation☆

Abstract The pulps of twenty-seven human teeth and twenty-four Macaca rhesus monkey teeth were extirpated. The root canals of twelve human and twelve monkey teeth were then instrumented short of the apices. In fifteen human teeth and in twelve monkey teeth, the root canals were instrumented beyond the apices into the surrounding periodontal ligament and alveolar bone. The reactions of the apical pulp stumps and periapical tissues were studied at various time intervals from immediately to 1 year after the endodontic procedures were performed. It was found that the tissue reactions following instrumentation short of the apex were milder than those reactions which followed instrumentation beyond the apex. Where the remaining pulp stump retained its vitality, complete repair occurred. However, if the pulp stump became necrotic, periapical inflammation persisted. Periapical granulomas developed and persisted following instrumentation beyond the apex. In many lesions, cell rests of Malassez proliferated and there was a profuse growth of stratified squamous epithelium.

To culture or not to culture

Abstract The results of root canal therapy in 2,335 teeth after 6 months and 706 teeth after 2 years were studied statistically in an attempt to uncover a significant relationship between success of repair in teeth with and without areas of rarefaction, positive or negative cultures, method of filling canals, and other variables. 1. 1. Repair was successful in 82 per cent of the teeth in all categories. 2. 2. Among the root canals of teeth which in the previous visit had yielded a negative culture, 16.6 per cent yielded positive cultures immediately prior to filling of the canal. 3. 3. On the basis of roentgenographic evidence alone, the prognosis for successful repair was less favorable in teeth with areas of rarefaction, regardless of the bacteriologic status of the root canal (88.8 per cent success in teeth without areas of rarefaction, 77 per cent success in teeth with such areas). 4. 4. There was no statistically significant difference between success of repair in teeth yielding positive or negative cultures prior to filling. 5. 5. The lateral-condensation methods of filling canals yielded slightly better results than the single-cone method, but the difference was not statistically significant in all groups. 6. 6. Overfilling of the root canal gave the worst percentage of success (69 per cent), and canals filled flush with the apex showed the best results (87.4 per cent success). 7. 7. A 2 year follow-up gives a more significant evaluation of success than a 6 month follow-up in teeth without areas of rarefaction. In teeth with areas of rarefaction a 6 month follow-up period is as reliable as a follow-up period of 1 to 2 years after treatment for evaluation of success. 8. 8. Differences in successful results may be due to an individual investigators technique of debridement and pus evacuation, filling, and diagnosis, as well as other factors, but are not based on culture results. 9. 9. Differences in degree of success in this study were dependent upon roentgenographic interpretation and not on other clinical factors.

Biologic aspects of endodontics

Abstract The apical portions of the roots of sixty-four nonperiodontally involved and forty-two periodontally involved upper central and lateral incisors were examined histologically for the purpose of studying their anatomic and morphologic characteristics. Observations were made of the blood and nerve supply to, and the morphologic characteristics of, the apical pulp tissue. In addition, the following features were noted: 1. 1. Accessory and/or lateral canals were observed in 34 per cent of the teeth. 2. 2. Denticles were noted in the root canals of 15 per cent of the teeth. 3. 3. Cell rests of Malassez were detected in the periodontal ligament in 70 per cent of the cases. 4. 4. Resorptions of the cementum, externally and within the root canal, were commonly observed (62 per cent) in nonperiodontally involved teeth. Resorptions were noted in every case of periodontally involved teeth. 5. 5. A thick layer of cementum generally was present around the root apex. The most frequently encountered cementum thickness was in the range of 0.21 to 0.30 mm. 6. 6. The diameter of the root canal was usually smallest at the cementodentinal junction, but there were variations, especially in periodontally involved teeth. The implications of some of these findings in terms of endodontic therapy have been discussed.

Intentional replantation of endodontically treated teeth.

This article reports 31 cases of intentional replantation with an overall success rate of 80.6% with six recorded failures. Survival times varied from 1 day to 22 years. A second mandibular molar that failed after 3 weeks was replanted successfully a second time with no signs of failure after a 46-month follow-up period. Two cases of intentional replantation of deciduous molars are also reported. We suggest that intentional replantation reduces adverse outcomes and should be considered as another treatment modality and not as a procedure of last resort. This procedure is recommended as the treatment of choice in the following instances: for lower second molars, for single-rooted teeth, and lower first molars when there is difficulty in accessibility to perform apical surgery; when the mental foramen is superimposed over the apex of the premolars; when the molar apex is in proximity to the mandibular canal; when patients object to periradicular surgery; when failures occur after apical surgery, or when surgery would create a periodontal pocket as a result of extensive bone removal. Periradicular surgery with a retroseal is more advantageous for first molars when roots are more curved, widespread, and are more prone to fracture compared with second molars whose roots are more tapered and close together.

Cognitive dissonance in endodontics

Cognitive dissonance is the existence of views, attitudes, or beliefs which are inconsistent or incompatible with one another but, nonetheless, are held simultaneously by the same person. In a penetrating article, Edwin G. Boring (1), Edgar Pierce Professor of Psychology Emeritus at Harvard University, has documented the existence of cognitive dissonance among scientists who, after all, he said, turn out to be human. One of the graphic examples offered is the persistence of smoking, despite evidence that it is hazardous to life itself. To rationalize, the smoker must change his cognition, thereby minimizing the scare about lung cancer, suppress or ignore the dissonance, or change his behavior by giving up smoking. Is cognitive dissonance present in endodontics? It is our belief that, as scientific evidence accumulates, a greater and greater dissonance is emerging in both the theory and the practice of endodontics. At least, this is true for us, and we would like to share our dissonance with others in the scientific community who perhaps have similar but unexpressed views. It has long been held that if the three basic principles—the so-called “endodontic triad”—are followed faithfully, the end result of endodontic treatment must be successful (2). These three “principles” are (a) thorough debridement of the root canal, (b) sterilization of the root canal, and (c) complete obturation of the root canal. Put down as a simple formula, it would be a! b! c endodontic success. In endodontic therapy, the a ! b ! c formula for success has been taught in most dental schools as the only sure way to achieve a lasting and permanent result. Deviations from this formula are almost certain to result in failure. So far, no dissonance. However, some dissonance begins to creep in when the dental student or general practitioner (or even the experienced endodontist, for that matter) follows the a ! b ! c formula and failure ensues (Fig. 1). Usually, the dissonance is resolved quickly by the rationalization that, somehow, there has been a break in adherence to the a! b ! c formula. For example, maybe a small amount of necrotic tissue was left in the root canal and somehow escaped being removed, or perhaps the negative culture obtained was a false negative and there were some microorganisms lurking in hidden recesses just waiting for the opportunity to emerge and “vent their spleens” on the periapical tissues after treatment was completed. Perhaps the canal was not completely obturated and there were minute voids between the root filling and the dentinal wall, or perhaps the canal was overfilled and the filling material was irritating. The possibilities are numerous. Conversely, dissonance also arises when, through intention or neglect, the formula is not followed and success results anyway (Fig. 2). How can this be explained rationally? The cognitive dissonance rears its ugly head when we examine each part of the triad, as we shall now do.

The oral fistula: its diagnosis and treatment.

Abstract 1. 1. A method of tracing a fistulous tract by means of a fine orthodontic wire is described. 2. 2. A differential diagnosis can be made, whether the fistula is of periapical, periodontal, periosteal, or bone involvement. 3. 3. The diagnostic importance of determining the derivation of the fistula in order that proper treatment may be instituted is stressed. 4. 4. Histologic examinations of fistulous tracts do not reveal the presence of epithelial tissue. Only granulation tissue is present. 5. 5. Clinical observations reveal that fistulas close spontaneously after the first or second treatment in an interval of one to two weeks. 6. 6. Surgical intervention is not necessary to eradicate a fistula. 7. 7. Because of the natural drainage created by a fistula, fewer complications (pain or swelling) follow treatment in cases of fistulization.

Some Influences Affecting Repair of the Exposed Pulps of Dogs' Teeth

N UMEROUS investigators have demonstrated that the pulp of human and animal teeth has the ability to repair itself following exposure. Abundant histologic evidence of the stimulatory influence of calcium hydroxide on the formation of secondary dentin is available. The literature on this subject has been extensively reviewed by Euler,4 Nyborg,11 and many others. Other factors and materials influencing the repair of exposed dental pulps have also been investigated. These influences include numerous drugs whose purposes were to stimulate or sterilize or both, blood clotting, removal of greater or lesser amounts of pulp tissue, cautery, and cajolery. Quigley14 has comprehensively reviewed the investigations in these areas. Most investigators have assumed that if a bridge of secondary dentin was produced, the pulp was completely repaired and no subsequent degeneration could or would occur. The purposes of our experiments on the exposed pulps of dogs teeth were to study the influences of drugs, alkalinity, time, and blood clot formation on pulp repair. Besides studying pulp reactions subjacent to the region of exposure and drug placement, observations were also made in the radicular and periapical regions.

Histologic changes in dental pulps of dogs and monkeys following application of pressure, drugs, and microorganisms on prepared cavities

Abstract Irritants were applied to prepared cavities in the teeth of dogs and monkeys, the animals were killed at intervals, and the dental pulps were examined for evidence of histologic change. The degree of damage to the pulp was judged by such criteria as nuclear and cytoplasmic changes in the odontoblasts, altered arrangements of the odontoblasts, disruption of the pulpodentinal membrane, vascular changes, changes in matrix formation and postoperative calcification, formation of granulation tissue, and necrosis. The deeper the cavity cut, the greater the change observed in the pulp. If the layer of dentine between the base of the cavity was thick, it shielded the effect of irritants applied to the cavity. Next to the trauma of cavity cutting itself, the greatest damage to the pulp was caused by application of pressure. Silver nitrate or phenol caused severe damage if applied to deep cavities or if used in combination with other irritants. Bacteria (Streptococcus faecalis) placed on the base of the cavity could penetrate the dentine and reach the deep pulp, particularly if pressure was exerted or if the dentinal tubules were opened wider by application of phenol. In the dog, only the reactions to the irritation of cavity cutting were apparent in pulps examined immediately after treatment, but the effects of the other irritants could be seen in specimens taken fourteen hours after treatment. By the end of one month, the pulps had recovered, to a limited degree, from the effects of all the irritants tested with the exception of phenol. Inflammatory responses seemed to occur sooner in the monkey than in the dog. Studies of the results obtained at two-, three-, and six-month intervals will be reported in a future article.