Pulpal Reactions Research Articles

Iatrogenic pulpal reactions to orthodontic extrusion

A careful review of the literature reveals an absence of studies about the reactions of dental pulp to orthodontic extrusion. The purpose of the present research investigation is to study the pulpal reactions and the sequence of histologic events in human dental pulp after orthodontic extrusion. The sample consisted of 36 intact maxillary first premolars of young adult orthodontic subjects. The mean age of the subjects was 18 years. Eighteen maxillary first premolars were extruded, under controlled conditions with the aid of fixed edgewise orthodontic appliances, for either 1, 2, or 4 weeks. The contralateral maxillary first premolars were not extruded and were used as controls. Immediately after removal of the appliances, all the maxillary first premolars were extracted. The pulps were histologically examined in a double-blind experiment. The results obtained from this study indicate that certain characteristic pulpal reactions arise from orthodontic extrusion. These reactions involve circulatory disturbances with congested and dilated blood vessels, odontoblastic degeneration, vacuolization and edema of the pulp tissues, and (by the fourth week) manifestation of fibrotic changes. It is speculated that the vacuolization of the pulp tissues (which occurred after the application of extrusive orthodontic forces in young adult subjects) resulted from a prolapse of the pulp, made possible by the relatively wide apical foramina. However, the odontoblastic degeneration is most probably the result of a compromised blood supply. The authors believe that this study constitutes a building block for establishing a more complete biologic foundation for orthodontic tooth movement. Further studies are suggested to reach more definitive conclusions.

Biological Evaluation of Glyceryl Methacrylate Solution in Dogs

The pulp reactions to a dentin bonding system including dentin priming with an aqueous solution of 35% glyceryl methacrylate (GM) were examined by observing the pathological change in the pulp of dog teeth restored by the combination of enamel etching with phosphoric acid gel, dentin cleaning with neutralized EDTA solution, dentin priming with the GM solution, and a chemically activated composite mediated by a commercial dentin bonding agent. It is concluded that it is possible to effectively use GM, because no serious irritation was observed in the tested specimens, although slight regressive change was seen in the early stages after restoration.

Pulpal reactions in rat incisors to Caridex™

This study examined the in vivo effects of Caridex, a chemomechanical caries removal system, on rat pulpal tissue. Rat incisors were opened and the pulps exposed to Caridex or physiological saline and sealed with calcium hydroxide. After various time periods, teeth were extracted and examined by light microscopy. Histological evaluation revealed an almost identical response in both test and control teeth which consisted of a transient inflammatory reaction and a limited necrosis in adjacent pulp tissue. Within seven days, formation of hard tissue matrix was seen below the necrotic area and on pulpal walls. It was suggested that the high pH of Caridex may have contributed to the necrotizing effect of calcium hydroxide in adjacent pulp tissue and the formation of hard tissue matrix. Additionally, the solution is most probably bactericidal. The results suggest that the system can be used as a caries removal agent on humans without unfavourable side effects on the dental pulp.

Cellular reactions in pulpal and periodontal tissues after periodontal wound debridement

Periodontal wounds in monkeys were prepared with a bur followed by the application of microbially contaminated cotton pellets. 3 weeks later, the wounds were debrided by scaling followed by etching with citric acid or by treatment with carbonate/peroxidate. The cellular reactions in the periodontal tissues and in the pulp 4, 11, 25, 39 and 53 days after treatment were followed with light microscopy. The marginal periodontium showed heavy inflammatory reactions immediately after treatment, regardless of the debridement procedure. 25 days after debridement, a long epithelial junction had been formed. The apical part of the epithelium deviated from the root surface into the connective tissue, delineating a heavily inflamed part of the connective tissue. After 39 to 53 days, most of the experimental wounds were covered by an epithelial lining. The pulpal reactions were generally limited to a production of irregular dentin on the pulpal wall facing the periodontal wound. It was concluded that the marginal healing pattern following various chemical treatments to the root surface followed, in all essential aspects, conventional treatment with scaling and root planing.

Proximo-occlusal composite restorations in primary molars: Marginal adaptation, bacterial penetration, and pulpal reactions

Marginal adaptation and bacterial penetration were studied in 32 primary molars filled with composite resin in shallow class II cavities. The restorations had served in the mouth for 3 years (mean, 3 years and 4 months; range, 8 months to 6 years and 4 months). Ground sections of the retrieved teeth were evaluated with polarized light microscopy and demineralized sections with light microscopy. Clinically excellent restorations, free from bacteria, were found in 25%. Gaps were recorded in 42%, under- or over-contouring and porosities in 95%, caries in the cervical area in 58%. Bacteria were observed subjacent to the fillings in 75% and in the dentin tubules in 61%. Pupal necrosis was found in 7 of 16 teeth. Marginal discoloration, visible crevice, or color mismatch was associated with marginal defects, bacterial leakage, and pulpal reactions.

Human pulp reactions to resin restorations performed with different acid-etch restorative procedures

Fifty-eight experimental resin restorations were performed in intact, human premolars, using different leakage-reducing restorative procedures. These were conventional acid-etching and acid-etching followed by cavity treatment with an intermediary layer of low-viscous resin or the dentin adhesive NPG-GMA/ethanol. The teeth were extracted after 4 months and examined for pulpal inflammation/necrosis (I), reduction of odontoblasts (OR), and formation of tertiary dentin (TD). By the general linear model procedure, 91%, 34%, and 56% of the variations in I, OR, and TD, respectively, could be explained by variations in the experimental conditions. The significant independent variables were jaw, stage of root formation, width of pulp, width of cavity, marginal leakage, bacteria in the cavity, bacteria in the exposed dentinal tubules, and the restorative procedure. With regard to the restorative procedure the analyses showed that application of low-viscous resin increased the pulpal reactions OR and I, whereas cavity treatment with NPG-GMA/ethanol had no adverse biologic effect.

Dentin and osteodentin matrix formation in apicoectomized replanted incisors in cats.

The reestablishment and rate of osteodentin and dentin matrix formation in 27 apicoectomized replanted and 20 control incisors in cats were studied after Procion H8-BS vital staining. In control teeth the pattern of matrix formation differed in the various pulpal zones, with a higher rate of matrix formed toward apical areas, most dominantly in maxillary incisors. Osteodentin formation could be traced after a lag period of more than 10 days after replantation. Thirty and 60 days postoperatively osteodentin matrix was found in the total pulpal length in 83% and 73% of the teeth, respectively. A common finding was a tubular osteodentin matrix in the pulpal apical third in the replanted teeth. Tubular osteodentin matrix was, however, present most incisally in some teeth 60 days postoperatively. Internal resorption corresponding to outer cervical lesions dominated the pulpal reactions in the maxillary replanted teeth after 60 days. It is concluded that under the present experimental conditions the pulp tissue possesses a high healing potential and that the osteodentin formation reflects the pulpal healing pattern after replantation traumas. The results also indicate that successful pulpal healing depends on unexposed dentinal tubules.

Nd: YAGレーザーによるラット生活歯髄切断法における歯髄の組織学的変化

Nd: YAGレーザーによるラット生活歯髄切断法における歯髄の組織学的変化

The sealing properties of temporary filling materials

R ecent articles suggest that many of the reported pulpal reactions to restorative materials may have been the result of microleakage of bacterial products around the restorations instead of the direct effect of the materials.‘-’ In such studies negative controls usually included cavities restored with zinc oxide-eugenol (ZOE) because it demonstrated little microleakage.6s7 However, Browne and Tobias,” in a review of the literature, suggested that the modest pulpal response reported beneath ZOE restorations may be the result of the antimicrobial properties of ZOE instead of its superior sealing qualities. Thus the sealing properties of ZOE and other temporary fillings warrant careful evaluation if investigators wish to use appropriate negative controls, namely, materials that seal perfectly. This study quantitatively evaluated the sealing properties of regular and reinforced ZOE, gutta-percha (GP), Cavit-G, (Premier Dental Products Co., Norristown, Pa.) and polycarboxylate cement placed in class I cavities prepared in extracted human third molars, by using the fluid filtration method described by Derkson et al.9 The results demonstrate the importance of the materials and their powder-to-liquid ratios in achieving a good seal between the filling materials and the cavity wall.

Pulpal reactions following experimental acute trauma of concussion type on immature dog teeth.

Abstract The pulpal reactions of 14 immature incisors of two dogs were histopathologically evaluated 45 days after experimental mechanical blows that did not, as shown by post‐traumatic clinical examination, cause fracture, displacement or loosening of the teeth. The more significant pulpal reactions in all specimens were the coagulation necrosis of the coronal pulp and the hyalinization of the central region of the radicular pulp. Dystrophic calcifications within coronal or radicular necrotic tissue, and absence of inflammatory infiltration were also observed in all traumatized teeth.

Pulpal response to topical application of citric acid to root dentin.

Abstract The purpose of the present study was to investigate the pulpal reactions to citric acid (pH 1.0) applied for 3 min to exposed root dentin. We used 48 roots of 24 maxillary and mandibular third and fourth permanent premolars from dogs divided equally into experimental (citric acid) and control (saline) roots. Following surgical exposure of the buccal root surface and the removal of the cementum with a Gracey curette, citric acid or saline was applied on the exposed dentin. The pulpal reactions were histologically evaluated 1, 7 and 15 days postoperatively using hematoxylineosin stained sections. Results obtained from 43 specimens showed no difference in the pulpal response at any of the observation intervals between citric acid and saline‐treated teeth.

Monkey pulp reactions to cavities treated with Gluma Dentin Bond and restored with a microfilled composite.

Deep buccal cavities were cut in 72 incisors and canines in six young monkeys. The cavities were restored as follows: Group One: acid etching of the enamel followed by an intermediate layer of unfilled resin and a light-cured microfilled composite. Group Two: acid etching of the enamel followed by treatment of the dentin with Gluma Cleanser and Gluma Bond. The cavities were restored as in Group One. Group Three: same procedure as in Group Two except for application of a calcium hydroxide cement on the pulpal wall prior to acid etching. Pulp reactions, presence and location of bacteria were studied after 8 and 90 days. A significant association between presence of bacteria and moderate to severe inflammatory reactions were observed. Bacteria were only found in a very few cavities pretreated with Gluma Dentin Bond. In general, slight inflammatory changes prevailed in Groups Two and Three. When the pulpal wall was extremely thin a toxic effect of Gluma Dentin Bond was observed.

Tissue response to dental caries.

Abstract Caries still represents the most widespread human disease. The pulp tissue sequelae of den tin caries are of utmost importance, because prevention of pulpal damage considerably reduces the need for extensive restorations and endodontic therapy. There is, however, considerable disagreement in the literature regarding how early the pulpal response to caries can be detected. The material in this article, gathered from the author's and his coauthors' earlier investigations, deals with pulp reactions from initial caries to increasingly extensive caries; caries in combination with attrition; the effect of carious den tin in experimental cavities of intact dentin; the effect of medicaments, restorative procedures and materials, and indirect pulp capping in the treatment of deep caries; microbiologic aspects of dentin caries; diagnosis criteria for treatment; light and electron microscopic study of teeth with carious exposure; periodontal disease and root caries in the geriatric population; pulp biopsies of teeth with periapical lesions, and the breakdown of the remaining pulp and its periapical sequelae. Pulpal reactions to initial caries detected as early as bacteria reach the dentinal tubules arc also discussed. As in medium and deep caries, this can be reversible following the removal of the infected dentin, except for irritation dentin and calcifications on the canal walls or free in the lumen. Bacteria remaining in dentinal tubules combined with iatrogenesis may be the reason for pulpal disintegration under deep restorations. Indirect pulp capping is not an acceptable procedure. Pain (or lack thereof) is not a predictable indicator of the inflammatory stage of the pulp. Root caries must be treated early to prevent pulpal destruction. Vital pulp tissue can be found in the roots of teeth with periapical radiolucencies that will ultimately show the presence of bacteria.

Pulpal reactions to a dentin bonding agent: Dentin adhesit

Pulpal reactions to a dentin bonding agent, Dentin Adhesit, were studied in 27 teeth of two monkeys. The investigation was carried out as a “usage test” in freshly prepared cervical cavities in conjunction with a composite resin (Heliosit). Life was used as a control liner. At the intermediate period (35 days), the teeth exhibited a subodontoblastic inflammatory reaction and little apposition of new dentin. The long-term specimens (74 days) showed recovery of the pulp, with minimal inflammation present in only a few teeth, and reparative dentin formation under practically all experimental and control cavities.

An investigation of pulp capillaries and tight junctions between odontoblasts in cats

The relative roles of capillaries and odontoblasts in the process of dentinogenesis and in pulp reactions to trauma and pathology are not clear. Contributing to the problem is the paucity of information on odontoblast--capillary relationships and tight junctions between odontoblasts. Using light microscopy the capillaries have now been examined in semithin transverse sections of perfusion fixed teeth at different positions in the long axis from the apical foramina to the pulp horns. Odontoblastic capillaries were prominent in the coronal and middle regions of canines and present at the same levels of incisors. In the pulp horns and just coronal to the pulp horns capillaries were all subodontoblastic but near the apex there were also a few odontoblastic capillary profiles. Transmission electron microscopy on ultrathin sections revealed that a high proportion of middle and coronal odontoblastic capillary profiles were fenestrated but subodontoblastic profiles coronal to the pulp horns were the most fenestrated. In a search for tight junctions in ultrathin sections some typical strands were observed between odontoblasts. The difficult of obtaining the latter evidence was explained by the cellular arrangement of the odontoblasts which differed markedly from an ideal parallel, apically coplanar arrangement. The results question the possibility that there is a direct exchange of materials between pulp capillaries and dentine in teeth of limited growth and provide a baseline for future experiments to test the permeability of the odontoblast layer.

Pulpal reactions to glutaraldehyde and paraformaldehyde pulpotomy dressings in monkey primary teeth.

Abstract Pulpotomy was performed in primary teeth of 4 vervet monkeys to compare the effect of an experimental dressing containing glutaraldehyde (GL) to a similar formula with paraformaldehyde (PF). Forty teeth were examined histologically 2 weeks to 5 months post‐operatively. In the PF group, calcifications were more frequently observed and the central core of tissue in the root canal was heavily laden with debris. Pathologic apical resorption and lesions were more frequent. The pulp in the apical third of the root canal was usually uninflamed in the GL group and peripheral calcifications were seldom observed in it. Reaction to GL seemed, therefore, more favorable clinically. Defects were not observed in the permanent teeth that erupted following shedding or extraction of the experimental primary ones of either group.

Bonding of enamel-dentin crown fractures with GLUMA and resin.

Abstract A procedure is described whereby enamel‐dentin fragments can be bonded to the remaining tooth substance. The tooth and tooth fragment are conditioned with EDTA and GLUMA® and then bonded together with a light‐cured composite resin. Results based on the restoration of 76 complicated and uncomplicated crown fractures of permanent incisors with up to 2 years' observation indicate that teeth bonded with GLUMA® can withstand normal chewing forces. Long‐term studies on the retention of bonded fragments, color stability and pulpal reaction to bonding are now in progress.

Pulpal responses to amalgam restorations in cavities with and without smear layer removal.

A conventional low copper amalgam was placed in cavities with and without smear layer removal and the amalgam restorations were covered with a resin overlay. The restored teeth were retrieved at 2, 28 and 56 days postoperatively in order to test for leakage and then pulpal reactions. More inflammation was seen in the teeth from which the smear layer had been removed. Abscesses were present in 6 teeth at 28 days but only one was associated with demonstrable bacteria. This study does not support smear layer removal before insertion of low copper amalgam restorations.

Vital bleaching: The effects of heat and hydrogen peroxide on pulpal enzymes

Pulpal reactions to bleaching of vital teeth with H2O2 and heat have ranged from reversible inflammation to frank necrosis. Little is known of the effects of such treatments on actual molecular activities in pulpal tissues. This study examines the effects of H2O2 and heat, separately and together, on seven enzymes found in bovine dental pulp. A phosphate buffer extract of calf dental pulps was made immediately after slaughter and maintained at 4°C until used. Enzyme activities examined were alkaline phosphatase, aldolase, glucose 6-phosphate dehydrogenase (G6-PDH), serum glutamic-oxaloacetic transaminase (SGOT), isocitrate dehydrogenase, malate dehydrogenase, and phosphohexose isomerase. Enzyme activities were measured as a percentage of untreated control activities. The heat treatment was as follows: 50°C for 1 to 30 min then recooled to 4°C for assay. H2O2 treatment: H2O2 was added to pulp extract for a final H2O2 concentration of 1.25 to 15%. In combined treatments, the final H2O2 concentration was 2.5, 7.5, and 15% and the heat at 50°C for 7.5, 15, and 30 min, respectively. The sensitivity of the enzymes to H2O2 (in descending order) was G6-PDH, isocitrate dehydrogenase, malate dehydrogenase, alkaline phosphatase, SGOT, aldolase, and phosphohexose isomerase. In the sensitivity to heat test, after 30 min, G6-PDH retained 5% of the original activity, SGOT retained 60%, and all others retained 80% or more. Combined heat and H2O2 treatment, even under the mildest conditions (2.5% H2O2, 7.5 min of heating), totally inhibited G6-PDH and isocitrate dehydrogenase; SGOT was least affected (50% activity). Pulpal enzymes are significantly inhibited by H2O2, in vitro, especially when heated. Pulpal reactions to bleaching of vital teeth with H2O2 and heat have ranged from reversible inflammation to frank necrosis. Little is known of the effects of such treatments on actual molecular activities in pulpal tissues. This study examines the effects of H2O2 and heat, separately and together, on seven enzymes found in bovine dental pulp. A phosphate buffer extract of calf dental pulps was made immediately after slaughter and maintained at 4°C until used. Enzyme activities examined were alkaline phosphatase, aldolase, glucose 6-phosphate dehydrogenase (G6-PDH), serum glutamic-oxaloacetic transaminase (SGOT), isocitrate dehydrogenase, malate dehydrogenase, and phosphohexose isomerase. Enzyme activities were measured as a percentage of untreated control activities. The heat treatment was as follows: 50°C for 1 to 30 min then recooled to 4°C for assay. H2O2 treatment: H2O2 was added to pulp extract for a final H2O2 concentration of 1.25 to 15%. In combined treatments, the final H2O2 concentration was 2.5, 7.5, and 15% and the heat at 50°C for 7.5, 15, and 30 min, respectively. The sensitivity of the enzymes to H2O2 (in descending order) was G6-PDH, isocitrate dehydrogenase, malate dehydrogenase, alkaline phosphatase, SGOT, aldolase, and phosphohexose isomerase. In the sensitivity to heat test, after 30 min, G6-PDH retained 5% of the original activity, SGOT retained 60%, and all others retained 80% or more. Combined heat and H2O2 treatment, even under the mildest conditions (2.5% H2O2, 7.5 min of heating), totally inhibited G6-PDH and isocitrate dehydrogenase; SGOT was least affected (50% activity). Pulpal enzymes are significantly inhibited by H2O2, in vitro, especially when heated.

Histopathological evaluation of the effect of a new dental adhesive resin on dog dental pulp

The pulpal reactions of dog teeth were investigated after full coverage crowns were set with new dental adhesive resins, Super Bond C & B and Panavia EX. Elite Cement 100 and Durelon was used as control. Histopathological changes were examined according to the standard of ADA on 123 adult dog teeth at different periods of time after the setting of crowns. All of the materials satisfied the ADA standard. However, histopathological reactions changed with a lapse of time in a way different for each material. With all materials, acute inflammatory reactions of pulpal were observed after 1-3 days, though the reactions caused by the new resins were less severe than those caused by Elite Cement 100 and Durelon. The acute inflammatory reaction disappeared after 25-35 days except the teeth with Elite Cement 100, and the formation of reparative dentine was observed with all materials. The inflammatory reaction caused by Elite Cement 100 was not ob. served after 50-60 days, and the formation of reparative dentine became less remarkable with all materials. These results suggest that the effects of Super Bond C & B and Panavia EX on dental pulp were less harmful than those of usual setting materials.