Repair potential of the pulp

Evaluation of electric pulp test thresholds and correct probe tip placement site in developing incisors: a clinical study in 1200 teeth

PURPOSE

Although electric pulp tests (EPT) may play a valuable diagnostic role in traumatized immature permanent teeth, the EPT threshold values which can be used as reference are not known. The aim of this study was to determine the average range of EPT threshold values in healthy permanent incisors according to their stage of root development.

METHODS

A total of 1200 permanent incisors were examined in 273 children (142 girls, 131 boys) aged 6-12 years. Panoramic radiographs were used to group teeth according to the stage of root development. A digitest II pulp vitality tester (Parkell, Inc, Edgewood, NY) was used along with toothpaste as the conducting medium to determine sensibility on three different sites (incisal, middle and cervical third).

RESULTS

In all teeth, mean EPT values showed a tendency to decrease along with advanced root development. Irrespective of the stage of root development, the lowest EPT values were obtained when measurements were made on the incisal third of the crown (p < 0.001). Mandibular incisors had lower mean response thresholds than their maxillary counterparts.

CONCLUSION

The present findings provide reference EPT threshold values according to stage of tooth development to monitor the post traumatic pulp status of permanent incisors.

Preserving the vitality of teeth adjacent to a large radicular cyst in periapical microsurgery: a case report with 4-year follow-up

Background

Radicular cysts may enlarge considerably, cause extensive bone destruction, and jeopardize the integrity of the associated vital teeth. The different treatment approaches are aimed mainly at eliminating the cystic epithelial membrane while reducing the risk of injury to vital structures. Contrary to other treatment modalities, preapical surgery offers an unequivocal single occasion resolution for the patient. However, it has been associated with higher risk of collateral damages.

Case presentation

A patient presented with a large radicular cyst originating from a maxillary lateral incisor. The adjacent central and canine teeth initially failed to exhibit responses to sensibility tests but showed signs of vitality. Microsurgical management was aimed at enucleating the cystic membrane while maintaining adjacent teeth vitality. Upon careful and controlled cyst enucleation under the dental operating microscope, the neurovascular bundle of one of the involved teeth was visualized and its integrity was maintained throughout the procedure.

Results

The procedure was successful and follow up recalls revealed recovery of normal sensibility of tooth 11 and 13 with complete bone regeneration around their apices.

Conclusion

Within the limitation of the present case report, we demonstrated that complete excision of large periapical cyst can be performed without sacrificing the vitality of the adjacent teeth, by preserving the integrity of their neurovascular supply through controlled microsurgical enucleation, and by a potential apical vascular repair ensuing unintended injury. Diagnosing the pulp vitality of non-offending teeth whose apices protrude into the cystic lumen is a complex process and can be misleading. Pressure from the growing cyst can inhibit vital teeth responses to neural-based sensibility tests leading to false negative results. Thus, in such cases, the use of blood perfusion-based vitality testing is recommended for correct initial diagnosis.

Oral health in patients with Marfan syndrome

INTRODUCTION

The role of this study is to highlight a correlation between patients with Marfan syndrome and oral health status by evaluating and reviewing the relevant scientific literature. The syndrome is characterized by an abnormal production of the fibrillin1 protein. The manifestations of Marfan syndrome affect organs that contain connective tissue such as the skeletal system, the eyes, the heart and the blood vessels, the lungs and the fibrous membranes that cover the brain and the spine. The facial bony and soft structures can therefore be affected, influencing the stage of tooth formation and the structure of the teeth, we also want to analyze in this study, the periodontal complications and the management of the latter, with the use of surgical techniques that include the use of biomaterials.

MATERIALS AND METHODS

A comprehensive review of the literature was conducted according to PRISMA guidelines. After a careful analysis of the work obtained by two independent academics, there have been 18. All data from the studies were compared and many of these highlighted the presence of abnormalities in the oral district.

RESULTS

The studies taken into consideration a whole series of oral manifestations related to the Marfan syndrome. Oral mucosa, periodontal, dental abnormalities, bone abnormalities or joint dysfunction are frequently involved in patients affected by this disease.

CONCLUSIONS

All the research have given positive results in terms of dental or oral anomalies. This information may be essential to limit and intervene early improving the oral health of syndromic patients.

Pulp canal obliteration after traumatic injuries in permanent teeth - scientific fact or fiction?

Pulp canal obliteration (PCO) is a frequent finding associated with pulpal revascularization after luxation injuries of young permanent teeth. The underlying mechanisms of PCO are still unclear, and no experimental scientific evidence is available, except the results of a single histopathological study. The lack of sound knowledge concerning this process gives rise to controversies, including the most suitable denomination. More than a mere semantic question, the denomination is an important issue, because it reflects the nature of this process, and directly impacts the treatment plan decision. The hypothesis that accelerated dentin deposition is related to the loss of neural control over odontoblastic secretory activity is well accepted, but demands further supportive studies. PCO is seen radiographically as a rapid narrowing of pulp canal space, whereas common clinical features are yellow crown discoloration and a lower or non-response to sensibility tests. Late development of pulp necrosis and periapical disease are rare complications after PCO, rendering prophylactic endodontic intervention useless. Indeed, yellowish or gray crown discoloration may pose a challenge to clinicians, and may demand endodontic intervention to help restore aesthetics. This literature review was conducted to discuss currently available information concerning PCO after traumatic dental injuries (TDI), and was gathered according to three topics: I) physiopathology of PCO after TDI; II) frequency and predictors of pulpal healing induced by PCO; and III) clinical findings related to PCO. Review articles, original studies and case reports were included aiming to support clinical decisions during the follow-up of teeth with PCO, and highlight future research strategies.

Bleaching options for pulp-calcified teeth: case history reports

The aim of this article is to review some essential aspects of anterior tooth calcification and its esthetic treatment. Furthermore, three cases including different and successful bleaching strategies are reported.

Pattern of transmission of laser light through carious molar teeth

AIMS

The aims of this study were to investigate the pattern of transmission of laser light through carious human molar teeth, and to examine the effect on light transmission of reactions to caries in the dentine.

METHODOLOGY

Sectioned carious human molars were examined whilst illuminated from their external surfaces by a helium-neon laser probe of 0.5 mm diameter. The pattern of light transmission was observed and selected specimens were photographed. The passage of light through the surrounding dentine toward the pulp space was investigated by confocal microscopy. Further carious and restored teeth were illuminated from three buccal and three lingual sites to establish the probability of light being able to reach the coronal pulp space.

RESULTS

For all 31 teeth examined, it was possible to illuminate the pulp space from a position on the buccal side. The presence of intracoronal restorations did not necessarily prevent light transmission to the pulp. Confocal microscopy demonstrated conduction of light within dystrophic deposits of irregular secondary dentine.

CONCLUSIONS

The presence of carious lesions or restorations in molar teeth does not necessarily interfere with transmission of laser light to the pulp space. Light is conducted within irregular secondary dentine. With appropriate probe placement, assessments of pulp health in diseased posterior teeth may be possible using laser Doppler flowmetry.

Treatment of crown fractures with pulp exposure

Thirty permanent incisors with vital pulps and complicated crown fractures were treated by a partial pulpotomy (Cvek technique). This consisted of amputation of 1 to 2 mm of the exposed pulp, placement of calcium hydroxide powder, and a temporary restoration. Clinical and radiographic assessment of the hard tissue barrier was done after 3 months and again after 1 to 8 years. The treatment was successful in all incisors. No differences were found in stage of root development, size of exposure, and length of time exposed. In conclusion, the partial pulpotomy technique is a successful and permanent treatment for crown fractures with pulp exposure regardless of the size of exposure, the maturity of the root, or the interval between accident and dental treatment.

Unusual pattern of pulp canal obliteration following luxation injury

Pulp canal obliteration can occur as a result of tooth injury. A case report is presented in which a 6-yr-old patient developed partial pulp canal obliteration of a maxillary central incisor 9 months after luxation injury. The mineralization created unusual canal morphology which presented some difficulty in endodontic treatment of the tooth.

Healing of the guinea pig incisor after partial pulp removal

A histological and microradiographical study was made of eruption and healing of guinea pig lower incisors after endodontic treatment compared with intact incisors. One incisor per animal was cut perpendicularly at the level of the gingiva. One third to one half of the pulp was removed. The experimental periods were 0, 4, 7, 16, 21 and 31 days. Unstained, HE or Brown and Brenn stained sections were studied microscopically. Some teeth were sectioned undecalcified and studied microradiographically. In intact incisors the dentin matrix deposition and mineralization were described. In the dentin, incisally to the pulp proper, narrow canals, the walls of which consisted of mineralized material, were found opening at the occlusal surface. Histologically, in the treated teeth, a beginning of cell-rich fibrodentin deposition at the original dentin wall was present at Day 4. At Day 7 a substantial walling off of the pulp is achieved by cell-rich and some cell-poor fibrodentin. After 16 days large amounts of cell-rich and cell-poor fibrodentin were covered by some tertiary dentin. After 31 days the amount of tertiary dentin was larger than after 16 days and also covered the incisal part of the root canal walls. Further apically some vasodentin and newly formed normal, secondary, dentin was observed. In course of this period the cells of the cell-rich and cell-poor fibrodentin first showed necrobiosis, then necrosis. The cell-rich fibrodentin appeared not fully mineralized. All blood vessels and strands of soft tissue which ran in canals in the fibrodentin came to a dead end. Thus the root canal was fully obturated. Although the teeth appeared (nearly) normal to the naked eye and radiographically after 31 days, histologically they were not. Large amounts of fibrodentin still being present incisally which showed the dual potential of the guinea pig pulp to produce both fibrodentin and orthodentin.

Pulpal healing after luxation injuries and root fracture in the permanent dentition

Pulpal healing patterns were studied in a clinical material of 637 luxated and 95 root-fractured permanent incisors followed routinely for up to 11 years. It was found that pulpal healing patterns could generally be divided into 3 groups according to the degree of injury sustained by the pulp: little, moderate or severe. Thus after luxation injuries, pulp survival could be without radiographic change (PS), with pulp canal obliteration (PCO) or nonhealing (pulp necrosis (PN]. After root fracture, similar healing patterns could be observed: healing by hard tissue union of fragments (HT), by connective tissue union of fragments (CT) or by nonunion due to interposition of granulation tissue between fragments (GT) resulting from PN of the coronal fragment. In both trauma situations, healing or nonhealing could be determined by type of luxation injury, stage of root development and type of fixation used (forceful application of orthodontic bands vs. passively applied acid-etch fixation). Pulpal healing complications (PN or GT) were based on clinical findings (coronal discoloration, loss of pulpal sensibility) and radiographic findings (resorption processes of the lamina dura at the root apex or at the level of the root fracture). However, in both injury groups the same changes could also be seen to be intermediate steps in the pulpal healing process. Based on findings from these studies, hypotheses for the mechanics of pulpal healing are proposed as well as guidelines for acute and later treatment of dental luxations, root fractures and the diagnosis of healing complications.

The effect of inferior alveolar nerve resection on dentin formation

The purpose of this investigation was to quantitatively evaluate the effects of inferior alveolar nerve resection on dentinal structures of dogs with the use of fluorescent tissue-time markers. After resection of the mandibular right inferior alveolar nerve and an experimental interval of 70 days, dentin formation was determined from serial cross sections through the mandibular canines. Results indicated that denervation did not appear to affect secondary dentin formation in the canine teeth of dogs.

Ultrastructure of the relationship between odontoblast processes and nerve fibres in dentinal tubules of rat molar teeth

Serial ultra-thin sections across tubules were analysed three-dimensionally. There was no difficulty in distinguishing nerve fibres and odontoblast processes. In many tubules, a bundle of naked nerve fibres accompanied the odontoblast process for up to 50 microns located in concavities of the surface of the process (type I relationship). No specialized membrane structures between the plasma membrane of nerves and odontoblast process, such as gap junction or membrane thickening similar to that of synapse, were encountered. In a few tubules, the lamellar cytoplasmic processes of the odontoblast extensively enveloped the terminal part of the nerve fibres (type II relationship). This pattern was found in an animal older than the others in which there were lucent tubules and perhaps arose from peripheral sensory stimuli.

Vital apicoectomy of the teeth: a 1-4 week histopathological study in Macaca mulatta

Several studies have reported devitalization of teeth following surgical procedures in the area of the root apices. The purpose of this investigation was to observe the 1-4-week wound healing pattern in monkey dental tissues following intentional vital apicoectomy (IVA). Two adult Macaca mulatta were used in this study. All of the teeth were surgically transected within the apical one-third with a bur. The soft tissues were then closed. At death, a maxillary and a mandibular quadrant for 1, 2, 3 and 4 weeks following surgery were obtained after vascular perfusion. Each quadrant was demineralized in EDTA, processed, serially sectioned at 7 microns and alternately stained with hematoxylin and eosin, Preece's modified trichome, and McKay's bacterial stains. Examination of sequential IVA cuts showed an initial disruption of the pulpal neurovascular supply resulting in pulpal necrosis. The pulpal tissues underwent a process of replacement with PDL-like connective tissues and deposition of cementum on all cut dentin surfaces of the tooth roots as well as in some of the pulp chambers. No abscesses, external resorption or ankylosis were found.

Intentional vital root transection: a 52-week histopathologic study in Macaca mulatta

Past studies dealing with the vascular supply to surgically mobilized dentoalveolar segments have mentioned occasional encounters with vital root transection and have noted varying degrees of pulpal response to this insult. The purpose of this investigation was to observe the pulpal and periapical responses of monkey dental tissues to intentional vital root transection over a 1-year postoperative period. Four adult Macaca mulatta monkeys were used in this study. All roots were surgically transected within the apical third with a bur. Maxillary and mandibular quadrants for 1, 2, 3, 4, 6, 12, 24, and 52 weeks following surgery were obtained after the animals were killed by perfusion of the left ventricle. The tissue blocks were prepared by routine histologic methods. The results demonstrated a disruption of the normal pulpal architecture, with initial pulpal degeneration and subsequent early replacement by the periodontal ligament tissue. A cellular cemental lining of the root canal occurred in all specimens. The periodontal ligament-like tissue continued to deposit cementum, resulting in almost total obliteration of the root canal and pulp chamber and leaving an intact but much reduced blood supply to the pulp chamber containing periodontal tissues.

Innervation of teeth: qualitative, quantitative, and developmental assessment

Anatomical characteristics of tooth innervation provide insights into functional capabilities as well as limitations of this organ. In this review, innervation will be discussed from two major viewpoints. The first part will present distribution of nerve fibers in the tooth; nerve pathways, both autonomic and sensory, will be discussed mostly from a descriptive standpoint. In the second part, quantitation of neural units along key points of the pathways will be presented at milestones in tooth and organism development and aging.