Invasive cervical resorption: a case report

Invasive cervical resorption (ICR) is a relatively uncommon form of external resorption, which may occur in any tooth in the permanent dentition. Characterized by its cervical location and invasive nature, this resorptive process leads to progressive and usually destructive loss of the tooth structure, the clinical features of which often resemble internal resorption ("pink tooth"). This article describes a case report of ICR and its management. The salient features were a large resorptive defect and localized fibrous in-growth located almost wholly on the cervicolabial aspect of the maxillary incisor crown involving the enamel and dentin.     

Clinical, radiologic, and histopathologic features of invasive cervical resorption.

Invasive cervical resorption is a relatively uncommon form of external root resorption. There may be no external signs, and the resorptive condition is often detected by routine radiographic examination. Where the lesion is visible, the clinical features vary from a small defect at the gingival margin to a pink coronal discoloration of the tooth crown resulting in ultimate cavitation of the overlying enamel. The condition is usually painless unless pulpal or periodontal infection supervenes. Radiographic features of lesions vary from well-delineated to irregularly bordered mottled radiolucencies, and these can be confused with dental caries. A characteristic radiopaque line generally separates the image of the lesion from that of the root canal, because the pulp remains protected by a thin layer of predentin until late in the process. Histopathologically, the lesions contain fibrovascular tissue with resorbing classic cells adjacent to the dentin surface. More advanced lesions display fibro-osseous characteristics with deposition of ectopic bonelike calcifications both within the resorbing tissue and directly on the dentin surface. Secondary invasion of microorganisms into the pulp or periodontal ligament space will elicit a normal inflammatory response.     

Treatment of invasive cervical resorption with sandwich technique using mineral trioxide aggregate: a case report

This article presents two cases of large invasive cervical resorption (ICR) with maintenance of pulp vitality after treatment with mineral trioxide aggregate (MTA) in a sandwich technique.Invasive cervical resorption is a relatively uncommon but aggressive form of external resorption, primarily caused by dental trauma or injury of the cervical periodontal attachment. The resorptive process does not penetrate into the root canal, and the pulp is not involved in the first phase of the resorption. This feature differentiates external resorption from internal resorption. In most cases, invasive cervical resorption is found during routine radiographic or clinical examination. Different materials have been proposed for the treatment of external cervical resorption. Therapy can be effective when it 1) removes the etiological factors and 2) interrupts the progressive resorption mechanism.The key learning points of this article are the following: treatment strategy to arrest the cervical resorption process and to prevent further resorption without changing pulpal vitality and successful seal of invasive cervical resorption defect using MTA with a sandwich technique.     

The effect of simulated intrapulpal pressure on bond strength to enamel and dentine

The purpose of this study was to evaluate the effect of simulated intrapulpal pressure on the shear bond strength (SBS) of a self-etching bonding system (Clearfil Liner Bond II) to both enamel and dentine surfaces. Forty-two caries-free human molar teeth were randomly assigned to two equal groups (n=21). One group of 21 teeth was connected to a special pulpal pressure machine, which is developed to simulate in vivo conditions. The buccal and lingual surfaces of the teeth were prepared with a diamond wheel to create flat dentine and enamel surfaces. A self-etching bonding system was then applied under pulpal pressure and 2.5 mm diameter composite cylinders were bonded to the prepared surfaces. The samples were then stored in distilled water at room temperature for 24 h under pulpal pressure before SBS was tested. The second restored group was used as a control and the teeth were not connected to the pulpal pressure apparatus during material application and test procedures. They were stored for 24 h in distilled water at room temperature before the SBS test. Fracture analysis of the enamel and dentinal surfaces was performed using a stereomicroscope. Shear bond strength values to dentine was significantly reduced with pulpal pressure (P < 0.001). However, in the enamel, SBS was increased (P < 0.001). In the control group, the SBS values to dentine and enamel did not show any significant difference (P > 0.05). Based on these results, it can be concluded that further analysis of enamel histology and bonding mechanisms are needed.     

Wet versus dry enamel ablation by Er:YAG laser

The purpose of this study was to observe tooth structure and pulpal temperature changes in extracted human teeth subjected to a pulsed Er:YAG (2.94 microns) laser. Two teeth were irradiated while dry and three teeth while moistened by a fine water mist. When the dry teeth were irradiated, there was minimal enamel ablation. SEM of the resulting surface showed rounded fragments of enamel rods, enamel melting, cracks, and smooth-edged voids. Intrapulpal temperature measured by thermal sensor rose more than 27 degrees C. When the laser application on the teeth was pulsed with a constant fine water mist, enamel and dentin were efficiently ablated. SEM of the resulting surfaces showed fissures and conical craters with sharp enamel projections remaining. Intrapulpal temperatures rose an average of 4 degrees C. These results indicate that pulsed Er:YAG (2.94 microns) used with a water mist removes enamel and dentin without producing significant pulpal temperature changes.     

Identifying early osteoclastic resorptive lesions in feline teeth: a model for understanding the origin of multiple idiopathic root resorption

Background and Objective:  Domestic cats commonly suffer from external osteoclastic tooth resorption, a disease with many similarities to human multiple idiopathic root resorption. In both diseases, it is unclear whether anatomical features of the tooth surface are associated with a predisposition for resorptive lesions. The aim of the present study was to investigate the origin and progression of early feline osteoclastic resorptive lesions in teeth exhibiting no clinical signs of disease.
Material and Methods:  The entire surfaces of 138 teeth from 13 adult cats were analysed using back-scattered electron microscopy. The distribution of lesions was assessed by tooth type, location and between individuals.
Results:  Seventy-three (53%) teeth showed at least one resorptive lesion. Eleven (85%) cats had lesions, and there was a significant association between increasing age and incidence of resorptive lesions. The highest frequency occurred in mandibular molars (82%). On average, there were 3.5 lesions per tooth. Fifty-two (38%) teeth featured resorptive lesions at the cemento–enamel junction. Twenty-three per cent of teeth with resorptive lesions showed evidence of repair of lesions that was limited to the root surface. There was no evidence of repair of resorptive lesions at the cemento–enamel junction.
Conclusion:  Resorption is prevalent without evidence of clinical disease, and occured at younger ages than previously reported. It can initiate anywhere on the root surface, but lack of repair of lesions at the cemento–enamel junction indicates that mechanisms of replacement are absent or compromised in this region. Whereas resorption of the root may undergo repair, resorption at the cervix may progress to clinically evident lesions.     

SEM-morphology in dentinogenesis imperfecta type II: microscopic anatomy and efficacy of a dentine bonding system.

AIM: Dentinogenesis Imperfecta is a hereditary defect consisting of opalescent teeth composed of irregularly formed and undermineralised dentin that obliterates the coronal and root pulpal chambers. The aim of this study was to examine the morphology of permanent human enamel, dentine and the dentine-enamel junction, in individuals affected by Dentinogenesis Imperfecta type II in undercalcified sections using scanning electron microscope (SEM) to compare the findings to the normal morphology, and to study the efficacy of modern bonding system to dentine and enamel DI type II affected. MATERIALS AND METHODS: Four third molars extracted from two 19 year-old subjects (one patient affected by Dentinogenesis Imperfecta type II) were included in resin, two divided in slices with a air-cooled diamond disc, and two used to study the characterisation of the resin-dentin interface. The sections of the teeth were examined by means of SEM. The slices were finished up with abrasive paper (400, 600, 1000, and 2000), the half surfaces obtained were etched with 37% phosphoric acid and then joined up to the stubs for SEM analysis. SEM Stereoscan 440 Leica with magnifications of 20X, 100X, 250X, 1000X, 2000X, 3000X was used. As control group were used four third molars with normal anatomy. RESULTS: This study shows that the permanent enamel from patients with DI exhibits few structural changes. No relationships were found between enamel morphology and the DI type II. Enamel appeared to be regularly mineralised. The major findings were anomalies in the dentine-enamel junction, locally a lower degree of mineralisation and an undulating morphology. The dentine showed absence of tubules. CONCLUSION: This study confirms that the problem with teeth affected by DI type II is the defect in dentine and weakness in the way the enamel is attached to the dentine. The adhesive system tested is not able to create a real hybrid layer in dentine DI type II affected and seems to be less effective than on normal substrates.     

Electrothermal debracketing. Part I. An in vitro study

The contemporary techniques of bracket removal require shearing or compression forces. The force necessary to separate the bracket from the tooth is sufficient to cause deformation of the bracket and, in some cases, is capable of damaging the tooth. An alternative to conventional bracket removal is electrothermic debracketing (ETD). ETD is the technique of removing bonded brackets from enamel surfaces with a cordless battery device that generates heat. The heat is transferred to the bracket by a blade that is placed in the bracket slot. The bracket is firmly held by a thumb-activated lock-on arm of the ETD unit. When the heat applied to the bracket is transferred to and deforms the adhesive-bracket interface, the bracket can be gently lifted from the enamel surface without distortion of the bracket or excessive force to the underlying enamel. Part I of this study measured the in vitro rise in temperature at the pulpal wall when ETD is used. These data are correlated with established primate threshold temperatures that have been reported to cause pulpal pathosis. All ETD procedures in the sample elicited pulpal wall temperatures that were significantly below the primate baseline. When water spray was used in conjunction with ETD, the mean ultimate increase in pulpal wall temperature was less than 1 degree C.     

Pulpal response to pyruvic acid.

Etching of enamel surfaces produces a marked increase in the bond strength of dental materials to tooth structure. The results of recent studies have indicated that pyruvic acid may be used in preference to phosphoric acid, because of its milder etching effect on enamel surfaces, without adversely affecting the bond strength. The pulpal responses elicited by 10% pyruvic acid applied for 90 seconds to freshly prepared cavities in monkey teeth, were examined after 4, 14 and 42 days. The differences between some of the ariteria used to evaluate the pulpal responses in acid-treated and control teeth at the three post-operative time intervals were statistically significant. These results suggest that exposed dentin should be protected with a lining before etching adjacent enamel surfaces with 10% pyruvic acid.     

Pulpal response to pyruvic acid

Abstract. Etching of enamel surfaces produces a marked increase in the bond strength of dental materials to tooth structure. The results of recent studies have indicated that pyruvic acid may be used in preference to phosphoric acid, because of its milder etching effect on enamel surfaces, without adversely affecting the bond strength. The pulpal responses elicited by 10 % pyruvic acid applied for 90 seconds to freshly prepared cavities in monkey teeth, were examined after 4, 14 and 42 days. The differences between some of the criteria used to evaluate the pulpal responses in acid-treated and control teeth at the three postoperative time intervals were statistically significant. These results suggest that exposed dentin should be protected with a lining before etching adjacent enamel surfaces with 10 % pyruvic acid.     

Multiple idiopathic cervical resorption: case report and discussion of management options

AIM: To present a case of cervical root resorption affecting all teeth and resulting in multiple tooth loss. SUMMARY: A healthy 33-year-old Chinese male, with no contributory medical or family/social history, presented with generalized cervical root resorption. Lesions varied in severity amongst teeth and even involved an impacted third molar. All cervical root surfaces were affected and lesions often extended coronally, undermining enamel. CBCT demonstrated that the lesions were more extensive and more widely distributed than was seen using conventional radiography. Bone extended into many resorptive defects but without clinical evidence of ankylosis. Periodontal probing, pulp testing, percussion sound and mobility were within normal limits. Key learning points ? Aetiology of the generalized idiopathic cervical root resorption is uncertain. ? Management is complex, and options have included surgical exposure and restoration of affected sites, extraction and submergence of affected roots. ? A staged approach involving early intervention with restoration of resorptive defects, followed by progressive extraction and replacement with implant-supported prostheses is recommended.     

Clinical and radiographic appearance of proximal carious lesions at the time of operative treatment in young permanent teeth

Clinical tissue changes were recorded during restorative treatment of proximal carious lesions of young premolars and molars. 60 proximal surfaces with radiolucencies in the inner half of the enamel or the outer half of the dentin were treated. The extent and character of the tissue changes were documented with photographs taken during drilling and evaluated after magnification. The maximum extent for each lesion was correlated to the extent of the radiographically observed lesion. The results showed that 70% of the restored surfaces were associated with a breakdown of the enamel surface. When the radiolucency did not extend deeper than into the inner half of the enamel, cavities were found in 61%; for lesions with a radiolucency extending into the outer half of the dentin the percentage was 78%. In the majority of cases the cavity was limited to the enamel. In all cases discoloration was observed in the enamel. The dentin was soft and discolored in 83%. Severe damage of tooth substance was found in 12% of the teeth.     

Clinical and radiographic appearance of proximal carious lesions at the time of operative treatment in young permanent teeth

Clinical tissue changes were recorded during restorative treatment of proximal carious lesions of young premolars and molars. 60 proximal surfaces with radiolucencies in the inner half of the enamel or the outer half of the dentin were treated. The extent and character of the tissue changes were documented with photographs taken during drilling and evaluated after magnification. The maximum extent for each lesion was correlated to the extent of the radiographically observed lesion. The results showed that 70% of the restored surfaces were associated with a breakdown of the enamel surface. When the radiolucency did not extend deeper than into the inner half of the enamel, cavities were found in 61%; for lesions with a radiolucency extending into the outer half of the dentin the percentage was 78%. In the majority of cases the cavity was limited to the enamel. In all cases discoloration was observed in the enamel. The dentin was soft and discolored in 83%. Severe damage of tooth substance was found in 12% of the teeth.     

Amelogenesis imperfecta: a scanning electron microscopic and histopathologic study

Amelogenesis imperfecta (AI) is a hereditary defect in enamel formation affecting both primary and permanent dentition. Scanning electron microscopic investigation is one of the most effective methods in diagnosing and identifying the type of amelogenesis imperfecta. The aim of this study was to investigate the ultrastructure of different types of amelogenesis imperfecta enamel. The primary teeth of three children with AI aged 4, 10 and 11-years-old were studied by scanning electron microscopy and irregular enamel, irregularities in enamel crystallites, hypoplastic areas on the enamel surface were seen. Histopathological evaluation revealed predentin areas with irregular canaliculi between normal dentin and internal resorption areas in the pulp tissue. Conclusively, in amelogenesis imperfecta, enamel tissue is mostly affected besides minor defects in dentinal and pulpal tissue.     

Fluoride bioactive glass paste improves bond durability and remineralizes tooth structure prior to adhesive restoration

ObjectiveThe current study aimed at examining a fluoride containing bioactive glass (BiominF®) paste as a temporary filling material capable of remineralizing the demineralized enamel or dentin, and its ability to decrease a simulated dentinal fluids pressure on the resin/dentin interface, without affecting the shear bond strength of a universal bonding agent to enamel and dentin.Methods60 premolars were utilized for the acid resistance, trans-microradiography (TMR) and shear bond strength (SBS) experiments. Enamel and dentin discs were demineralized for 4 days to create a subsurface demineralized zone followed by applying BiominF® paste, 1.23% acidulated phosphate fluoride, or a temporary filling material for 24 h.30 extracted human non-carious third molars were utilized for the pulpal pressure experiment in which direct communication to the pulp chamber was created by cutting at a level approximately 1 mm below the cemento-enamel junction while the coronal enamel was ground to expose mid coronal dentin. The dentin surface was exposed to a simulated pulpal pressure. The dentin surfaces had BiominF® paste, an oxalate desensitizing agent, or temporary filling material followed by application of a universal adhesive system.ResultsOne way ANOVA showed that BiominF® paste remineralized effectively the demineralized enamel or dentin, did not affect the bond strength of the enamel and dentin surfaces to the tested adhesive system p < 0.05, and improved the acid resistance of the demineralized enamel and dentin against a secondary erosive challenge. Moreover, BiominF® paste decreased the nanoleakage expression in the dentin/adhesive interface exposed to a simulated pulpal pressure.SignificanceBiominF® paste may serve as a temporary filling material that may improve the longevity of adhesive restorations and help to conserve tooth structures by preserving the demineralized enamel and dentin form cutting during cavity preparation.     

Microscopy of resorption of enamel and dentine from the cusp tips of the molar teeth of rats

In 48 first mandibular molar teeth of rats aged 7–16 days, maturing epithelium overlying enamel-free areas (EFAs) was examined by transmission electron microscopy; the enamel at the margins of EFAs was examined by light microscopy and scanning and transmission electron microscopy. The shape and organelle content of EFA epithelial cells varied and changed with increasing age. Some variants closely resembled resorptive ameloblasts and appeared to effect a gradual resorption of the dentine surface of EFAs; others removed whole particles of dentine or rapidly broke down the surface dentine and any enamel present before resorbing them. Groups of ameloblasts at, or near the margins of EFAs, appeared to resorb enamel, resulting either in deep craters, or a reshaping of the enamel margins. The capacity of EFA epithelium and some adjacent ameloblasts to remove the mineral as well as matrix of enamel and dentine, indicates that these cells have marked resorptive function.     

Zinc and strontium analyses by energy dispersive X-ray fluorescence in human permanent teeth

The zinc and strontium content of enamel and dentine from humans aged 9-64 yr was analysed, after systematic sampling, by X-ray fluorescence. Relatively high levels of zinc were found in both hard tissues but there was no significant increase with age. Zinc content decreased significantly from outer to inner enamel and increased significantly again from peripheral to pulpal coronal and root dentine. The strontium content was significantly higher in enamel than in dentine; there was a significant increase with age in enamel but not in dentine. However, outer and inner enamel showed no significant difference in strontium content. Almost similar amounts of strontium were found in coronal and root dentine.     

Pulpal effects of argon: fluoride excimer laser irradiation and acid-etching of rat molar enamel.

The reaction of enamel, dentine and pulpal tissues to exposure from a laser beam has been shown to depend on the type of laser medium used. The objective of this study was to examine the pulpal response in rat molars after external enamel surface treatment with either an Ar:F excimer laser or acid-gel application. Maxillary right molar occlusal surfaces in 22 animals were irradiated (energy density = 45.0 J/cm2). Maxillary left molar occlusal surfaces were treated with 37 per cent phosphoric acid for 30 s. Untreated mandibular right molars served as controls. At two postoperative time periods (1 and 6 weeks), molars were removed, sectioned, stained (H&E) and scored. Data analysis indicated no significant difference between Ar:F irradiation and controls at 1 week. Treatment with laser or acid-etching left a similar degree of pathosis at 1 and 6 weeks. Although the Ar:F excimer laser produced a more exaggerated pulp response than controls at 6 weeks, tissue vitality was maintained. The Ar:F excimer laser may be useful for ablating vital tooth structure since pulpal tissue in rat molars exhibited no damage in response to low-power irradiation.     

The orientation and direction of rods in dental enamel

Enamel rods are commonly accepted as perpendicularly oriented to the tooth surface and this concept has influenced the design of cavity preparations. This investigation studied the orientation and direction of enamel rods at the outer third of the enamel plate. Fifteen human molars were randomly selected and sectioned in the buccolingual, mesiodistal, and coronal directions. Angulations of the rods at the outer surface were measured by use of a protractor superimposed on the micrographs taken by scanning electron microscope. The mean angulation for axial surfaces was 60 degrees. The enamel rods were consistently parallel to the long axis of the tooth with 55-degree mean angulation. The conclusion was that enamel rods are not perpendicular to the surface except at the edge of the cusps and occasionally at the cervical area.