Accessory Canals Research Articles

An Analysis of Accessory Canals in the Furcation Areas of Human Mandibular Molar Teeth Using the Microfocus X-ray CT System

An Analysis of Accessory Canals in the Furcation Areas of Human Mandibular Molar Teeth Using the Microfocus X-ray CT System

Accessory urethral canal in the male

Accessory urethral canal in the male

Timeliness and effectiveness in the surgical management of persistent post‐treatment periapical pathosis

Common problems that cause persistent post‐treatment periapical pathosis include infection remaining in the apical inaccessible areas, extraradicular infection including apically extruded dentine debris with bacteria present in dentinal tubules, radicular true cysts, foreign body reactions, inadequate non‐surgical root canal treatment with or without iatrogenically altered root canal morphology, and vertical root fractures. Inadequate root canal treatment may be corrected non‐surgically, while more complex problems may require surgical intervention. The important factors that warrant a successful surgery include good quality of the orthograde root canal treatment, deep retrograde preparation of the apical canal, and carefully cleaning and filling of the exposed isthmuses and accessory canals. Ideally, apical surgery and orthograde retreatment are performed simultaneously. In a recent study, 97% of the lesions including large ones of >10 mm in diameter healed completely within 1 year after surgical intervention. Of the teeth that showed ‘complete healing’ at 4 years more than 85% already ‘completely healed’ at 2 years; thus, the endodontic post‐treatment disease might be treated surgically or non‐surgically within 2 years after the previous treatment.

Apical Anatomy in Mesial and Mesiobuccal Roots of Permanent First Molars

The purpose of this in vitro study was to investigate the canal configuration types, and the prevalence and location of anatomical variations in the mesiobuccal (MB) and mesial roots of permanent maxillary and mandibular first molars after instrumentation. The number and the type of canals were determined before instrumentation using conventional methods. All root canals from the 47 MB roots and 42 mesial roots were then instrumented to size #30 with ProFile .04 taper rotary instruments in a crown-down method and then filled with a single gutta-percha cone and sealer. Transverse 1 mm-thick cross-sections at 2, 3, 4, and 5 mm from the apex were obtained, stained and examined using a stereomicroscope. The canal configuration types and the prevalence and location of isthmi and accessory canals in roots with two canals were evaluated. The prevalence of two canals was 80.8% in the maxillary MB roots and 95.2% in the mandibular mesial roots. There were six types of canal configurations in the instrumented root apices. The prevalence of anatomical variations was highest at the apical 4 mm level, and was more frequent in mandibular first molars, and in roots with Weine type III canal. χ 2 test showed that the prevalence of the anatomical variations was statistically higher in the maxillary MB roots with Weine type III canals than in those with Weine type II canals (p < 0.05). Different canal configurations were often found at different levels in the same root. The results indicate that anatomical variations persist following instrumentation of roots with two canals in first molars. These anatomical variations should be considered during surgical or nonsurgical endodontic procedures of the permanent first molars.

Microbial status of apical root canal system of human mandibular first molars with primary apical periodontitis after “one-visit” endodontic treatment

To assess the in vivo intracanal microbial status of apical root canal system of mesial roots of human mandibular first molars with primary apical periodontitis immediately after one-visit endodontic treatment. The residual intracanal infection was confirmed by correlative light and transmission electron microscopy. Sixteen diseased mesial roots of mandibular first molars were treated endodontically, each in one visit. Mesio-buccal canals were instrumented using stainless steel hand files and mesio-lingual canals with a nickel-titanium rotary system. The canals were irrigated with 5.25% sodium hypochlorite (NaOCl) during the instrumentation procedures, rinsed with 10 mL of 17% ethylenediamine tetraacetic acid (EDTA), and obturated with gutta-percha and zinc oxide eugenol cement. Thereafter, the apical portion of the root of each tooth was removed by flap-surgery. The specimens were fixed, decalcified, subdivided in horizontal plane, embedded in plastic, processed, and evaluated by correlative light and transmission electron microscopy. Fourteen of the 16 endodontically treated teeth revealed residual intracanal infection after instrumentation, antimicrobial irrigation, and obturation. The microbes were located in inaccessible recesses and diverticula of instrumented main canals, the intercanal isthmus, and accessory canals, mostly as biofilms. The results show (1) the anatomical complexity of the root canal system of mandibular first molar roots and (2) the organization of the flora as biofilms in inaccessible areas of the canal system that cannot be removed by contemporary instruments and irrigation alone in one-visit treatment. These findings demonstrate the importance of stringent application of all nonantibiotic chemo-mechanical measures to treat teeth with infected and necrotic root canals so as to disrupt the biofilms and reduce the intraradicular microbial load to the lowest possible level so as to expect a highly favorable long-term prognosis of the root canal treatment.

Endodontics: Part 8 Filling the root canal system

The purpose of the obturation phase of a root filling is two-fold; to prevent microorganisms from re-entering the root canal system, and to isolate any microorganisms that may remain within the tooth from nutrients in tissue fluids. The seal at the apical end of the root canal is achieved by a well-fitting gutta-percha master point, and accessory points, although heated techniques may result in a better seal. The seal at the coronal end is achieved by the application of a layer of resin-modified glass ionomer cement as accessory canals may lead from the floor of the pulp chamber to the furcation area. It must always be remembered that success will only be achieved if the root canal system has been as thoroughly debrided as possible of infected material.

Homology between the recessus lateralis and cephalic sensory canals, with the proposition of additional synapomorphies for the Clupeiformes and the Clupeoidei

The recessus lateralis, a complex structure in the otic region of the skull that is probably associated with detection and analysis of small vibrational pressures and displacements, is widely recognized as a synapomorphy of the Clupeiformes. The Clupeiformes includes the Denticipitoidei, with one living species, Denticeps clupeoides, and the Clupeoidei, with about 360 living species commonly known as herrings and anchovies. Comparisons between details of the recessus lateralis of the Clupeoidei and Denticipitoidei, and the sensory cephalic canals of other teleosts, lead to hypotheses of a series of transformations of the cephalic sensory canals. Treating that complex as a single binary ‘presence vs. absence’ character as was traditional practice obscures important phylogenetically informative variation. Specific synapomorphies in that system exist for the Clupeiformes and the Clupeoidei. Hypothesized synapomorphies in the recessus lateralis for the Clupeiformes are the presence of a dilated internal temporal sensory canal in the pterotic, a postorbital branch of the supraorbital sensory canal located in a bony groove in the lateral wing of the frontal, and the terminal portions of preopercular and infraorbital sensory canals closely positioned. Hypothesized synapomorphies for the Clupeoidei are the presence of a postorbital branch of the supraorbital sensory canal located deep within the body of the lateral wing of the frontal, with the distal portion of that branch totally internal on the cranium, and the expanded distal portion of the postorbital branch of the supraorbital sensory canal. The homology of the sinus temporalis of Clupeoidei, and of the dermosphenotic of both Denticeps and the Clupeoidei, with those of other teleosts is also considered. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 141, 257‐270. ADDITIONAL KEYWORDS: accessory temporal canal ‐ basal teleosts ‐ character complex ‐ Denticipitoidei ‐ dermosphenotics ‐ sinus temporalis.

Relationship of Radiologic and Histologic Signs of Inflammation in Human Root-filled Teeth

The aim of this study was to determine the relationship between histologic and radiologic signs of inflammation in human root-filled teeth. In addition, other factors with possible importance for apical inflammation were assessed. Fifty-three block sections of root-filled teeth were gathered from human cadavers. The blocks were radiographically exposed, sectioned, and stained with hematoxylin and eosin. Histologic sections were categorized as inflamed or uninflamed. Radiographically, the roots were assigned as apical lucency, widened periodontal ligament (PDL), or no lucency. Presence and contents of accessory canals were recorded (empty, tissue, or filling material). Statistical analysis was performed with the Chi-square test. All roots had accessory canals; 12 showed tissue remnants, and the others were empty. Of the cases, 49% were histologically uninflamed at the apex, and 52% appeared radiographically intact. The odds ratio of finding a histologically inflamed apex with radiologic lucency versus a radiographically intact apex was 9.2 (p = 0.002). The odds ratio of finding a histologically uninflamed apex with a radiologically tight coronal seal versus an unacceptable seal was 3.7 (p = 0.053). It may be concluded that there are relationships between radiologic and histologic signs of inflammation in human root canal-treated teeth. There appears to be a tendency that the radiologically determined quality of the coronal seal has an impact on the histologic state of the root-filled tooth. No relationship was detected between unfilled lateral or accessory canals and the status of inflammation at the periapex (51% inflamed, 49% uninflamed).

A SEM investigation of accessory foramina in the furcation areas of primary molars.

The purpose of this study was to determine the prevalence and anatomic characteristics of accessory foramina in the external and internal furcation areas of primary molars. Sixty human primary molars were divided into two equal groups. The teeth of the experimental group showed in previous radiographic examination the presence of a radiolucency area confined to the inter-radicular region, while the teeth of the control group had no sign of pulpal inflammation in the clinical and/or radiographic examination. The specimens were observed by scanning electron microscope (SEM). The external furcation area (EFA) showed a higher prevalence of accessory foramina than the internal furcation area (IFA) (P<0.05). However, the comparison between the two groups did not show statistically significant difference (P>0.05). The presence of accessory canals should not be considered the only reason for inter-radicular pathological bone resorption following pulpal necrosis in deciduous molars.

The Cochlear Aqueduct De Aquaeductibus Auris Humanae: Part II

The Cochlear Aqueduct (CA) is a narrow bony canal connecting the cochlear with the posterior cranial fossa in the subarachnoidal space. Narrow in the otic segment, it widens in the vicinity of the petrous bone aperture. The CA contains loose connective tissue making up the periotic duct that in turn derives from primitive extroflexion of the subarachnoidal space. Alongside the CA runs an accessory canal containing the inferior cochlear vein which flows into the inferior petrosal sinus. CT investigations of the petrous bones routinely evidence the CA while the medial aperture is detected at MR. This article describes the typical appearances and provides an in-depth review of the most important studies into CA morphological variability and the possible functional implications. The CA arises in the basal coil of the scala timpani. The isthmus of the duct, located in the otic capsule and not always visible, measures between 0.05 and 0.35 mm. The canal widens funnel-like to 2 – 7 mm as it reaches the superior edge of the jugular foramen. Overall length varies between 9 and 17 mm. In contrast, neonate CA is shorter, straighter and patent. With age, patency is progressively reduced even to the point of obliteration. It has been postulated that the CA provides a direct link between CSF and perilymph in the presence of both normal labyrinth and malformations. While some studies suggest that CA patency sustains conditions involving labyrinthine hypertension, others report complete CA obliteration, thereby excluding any connection between the two districts. An enlarged, patent CA, as evidenced in Mondini type dysplasias, has been considered to enable retrograde flow of CSF into the vestibule and the spread of infection from one compartment to the other and/or induce perilymphatic hydrops with consequent loss of hearing and lesions of the window and possible cerebrospinal fluid otorrhea. More probably, however, the pathway of communication between CSF and perilymph spaces is the fundus of the internal auditory canal. Abnormally dilated CA that may be classified as a true malformation is extremely rare and has been reported in only one case as an isolated anatomic finding. As a result, it has been suggested that the yardstick for diagnosing dilated CA on CT be a diameter of more than 2 mm along the whole duct, from the cochlear end to the posterior fossa. There are also a few documented cases of the CA provide a route for infection between the two spaces. Finally, some cases of tumours invading the CA have been described in which the first clinical signs were cochlear-vestibular symptoms. These findings suggest that even if not a routinely finding, the CA may in certain cases connect the subarachnoidal space and the perilymph and thus affect auditory vestibular function. Better understanding of CA anatomy, morphological variations and their possible functional significance is therefore required since assessment of the cochlear aqueduct should be part of routine imaging diagnostics to investigate labyrinthine disorders.

Incidence of patent furcal accessory canals in permanent molars of a Turkish population.

To determine the incidence of patent furcal accessory canals in permanent molars of a Turkish population. Two-hundred extracted teeth consisting of 50 maxillary first molars, 50 maxillary second molars, 50 mandibular first molars and 50 mandibular second molars from Turkish patients attending the Oral Surgery Department of the Faculty of Dentistry, Istanbul University, Istanbul, Turkey, were included in the study. After preparation of access cavities and removal of pulp tissue, the teeth were stored in 5.25% sodium hypochlorite for 1 h. Following double-sealing of the access cavities, all tooth surfaces except the furcation regions were covered with nail varnish. The teeth were stored in 0.5% basic fuchsin for 1 week. The teeth were sectioned at the cemento-enamel junction and the presence of patent furcal canals was established by examining the pulp chamber floor with a stereomicroscope (10x) to determine staining. Patent furcal accessory canals were detected in 24% of maxillary first molars, 16% of maxillary second molars, 24% of mandibular first molars, and 20% of mandibular second molars. No statistically significant differences were found between the tooth types. In a Turkish population, the incidence of patent furcal accessory canals on the pulp chamber floor of maxillary and mandibular first and second molars ranged between 16 and 24%.

Obturation of Accessory Canals After Four Different Final Irrigation Regimes

The aim of this study was to evaluate accessory canal obturation after four different final irrigation regimes. Sixty-four extracted human lower premolars were instrumented, divided randomly into four groups, and finally irrigated as follows: no irrigation (NO), distilled water (WA), sodium hypochlorite ([SH] 6%, 20 ml for 15 min), and EDTA (15%, 8 ml for 3 min) combined with the SH regimen (ES). The System B and the Obtura II were used to fill the canals. The teeth were cleared and observed under a digital microscope. Obturation material penetration rates in length into the accessory canals were measured and the following values were obtained: 22.3% in group NO, 21.8% in group WA, 53.5% and 68.1% in groups SH and ES, respectively. Statistically significant differences were found when comparing each of the first two groups (NO and WA) with SH and ES groups (p < 0.05). The use of sodium hypochlorite alone or in combination with EDTA in final irrigation flushes may enhance a better obturation material penetration into the accessory canals.

Nervous branch passing through an accessory canal in the sphenozygomatic suture: the temporal branch of the zygomatic nerve.

A nervous branch which passes through a small canal in the sphenozygomatic suture is sometimes observed during dissection. To examine the origin, course and distribution of this nervous branch, 42 head halves of 21 Japanese cadavers (11 males, 10 females) and 142 head halves of 71 human dry skulls were used. The branch was observed in seven sides (16.7%); it originated from the communication between the lacrimal nerve and the zygomaticotemporal branch of the zygomatic nerve or from the trunk of the zygomatic nerve. In two head halves (4.8%), the branch pierced the anterior part of the temporalis muscle during its course to the skin of the anterior part of the temple. The small canal in the suture was observed in 31 head halves (21.8%) of the dry skulls. Although this nervous branch is inconstantly observed, it should be called the temporal branch of the zygomatic nerve according to the constant positional relationship to the sphenoid and zygomatic bones. According to its origin, course and distribution, this nervous branch may be considered to be influential in zygomatic and retro-orbital pain due to entrapment and tension from the temporalis muscle and/or the narrow bony canal. The French version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00276-002-0027-4.

SEM observations of resected root canal ends following apicoectomy.

The purpose of this study was to examine the apical foramen of root apices extracted during apicotomies. A total of 25 teeth extracted from 25 patients admitted to the Department of Conservative Dentistry at Tokyo Dental College's Chiba Hospital were used for the study. All patients were between 22 to 56 years of age at the time of the study, and each of the 25 cases was determined clinically on radiographs to be chronic apical suppurative periodontitis. Microsurgery was performed on all cases, and the extracted root apices were then observed using SEM. The results demonstrated a wide opening, greater than 350 microns as measured along the major axis, of the apical foramen in 80% of the cases. Various characteristics indicative of resorption were observed around the apical foramen. These features included those believed to have been caused by overinstrumentation during root canal treatment as well as irregularly shaped areas presumed to be apical lesions that had enlarged and eroded. We observed a high frequency of manifestations of cementum resorption surrounding the root apices of teeth with apical lesions. Furthermore, we concluded that in the majority of cases in the present study, due to the fact that the apical foramen exceeded normal opening dimensions as a result of overinstrumentation during root canal treatment or resorption around the root apex, prolongation of the lesions had occurred in response to direct contact of microbial infectious matter and tissues surrounding the root apex over a large area. The above finding suggested that, in cases in which the apical foramen is destroyed through overinstrumentation larger than #35 or in which the apical foramen opens up to dimensions greater than 350 microns due to pathologic resorption, surgical intervention may be indicated. On the other hand, in 64% of the cases, an accessory canal was observed in the root apical lesion. Based on this observation, the presence of an accessory canal in the root apex may contribute to some degree to the prolongation of the lesion.

Gutta percha obturation techniques

T h e most common cause of endodontic failure has been ascribed to incomplete obturation. Filling a root canal is intended to prevent microorganisms and toxins in the canal, as well as those present in the oral cavity, from passing along the root canal and moving out into the periradicular tissues. Matsumiya and Kitamura both demonstrated that bacteria remain in the deep portions of the endodontic system, even after chemical disinfectants. Healing of the periapical tissues occurs when the nutritional supply to the bacteria is stopped by the sealing properties of obturation. Unfortunately, the endodontic system is complex, including the accessory canals, anastamoses, and apical deltas. The inability to completely obliterate the irregularities of the endodontic system with a filling material and seal the apical delta foramen has been reported to account for nearly 60% of root-canal failures. Fluid percolation into the canal arises indirectly from the blood serum, water-soluble proteins, enzymes, and salts from both the apex and oral cavity. Once in the radicular space, those products undergo degradation and diffuse out to the periapical tissues and act as an irritant, which results in periapical inflammation. Bacteria will result in the producuon of toxic products in the root canal with periapical inflammation. In current endodontic treatment, is said that it is more important what comes out of the canal than what goes into So the emphasis seems to be placed more on cleaning and preparing the endodontic system than on filling it. This does not mean that obturation is less important; rather means that endodontic success depends on meticulous root-canal preparation. For a complete three-dimensional fill, proper instrumentation of the root canal makes a lot easier to facilitate. The objective of obturation of the radicular space is to fill the entire endodontic system and all of its complex anatomic pathways completely and densely with a nonirritating hermetic sealing agent(s), which results in a fluid-tight seal, especially at the apex, but also coronally (to prevent infection from the oral cavity). Success is dependent on the thoroughness of endodontic cavity design, shaping, and cleaning. The thoroughness of debridement and patency of the root-canal system facilitates its successful sealing in the three-dimensional phase. A three-dimensional fill is desired because it: 1) prevents percolation of the periapical exudate into the root-canal space (providing a culture medium for any residual bacteria); 2) prevents microorganisms from entering and reinfecting the root canal; and 3)

The structure of dentine in the apical region of human teeth.

To study the structure of the apical region of human teeth with emphasis on dentinal tubules and their branches. This descriptive histological study employed demineralized stained sections for light microscopy, demineralized unstained sections for scanning electron microscopy, and undemineralized, acid-etched specimens for confocal tandem scanning microscopy. The apical portion of human teeth showed marked variations in structure, including accessory root canals, areas of resorption and repaired resorptions, occasional attached, embedded and free pulp stones, varied amounts of irregular secondary dentine, and even cementum-like tissue lining the apical root canal wall. The apex often deviated from the long axis of the root canal. Primary dentinal tubules were irregular in direction and density. Some areas were devoid of tubules. The irregular and variable structure of the apical region of human teeth represent special challenges during endodontic therapy. Obturation techniques based on the penetration of adhesives into dentinal tubules are unlikely to be successful and adhesive techniques must depend on impregnation of a hybrid layer.

Fiberoptic Endoscope Usage for Intracanal Visualization

A new method of magnified intracanal visualization using a fiberoptic endoscope has been developed for use in conventional endodontic treatment. The 0.7 mm flexible fiberoptic endoscope allows the endodontist to view canal morphology and biomechanical canal preparations, and helps to identify fractures, accessory canals, and remnant pulpal tissue.

Mandibular and maxillary furcation tunnel preparations – literature review and a case report

The objective of this literature review and subsequent case report is to discuss and illustrate the tunnel preparation procedure as a treatment alternative for furcation-involved molars. Furcation tunnel preparation, i.e., the creation of access for plaque control between periodontally diseased roots, has not been discussed in the literature as comprehensively as root resective therapy, though success rates appear to fall within the same range. A short root trunk and a wide furcation entrance diameter are prerequisites for the indication of the tunnel preparation procedure. Although accessory canals in the furcation area are frequent findings on extracted teeth, endodontic complications have not been reported to be major complications after tunnel preparation. Caries developed at tunneled teeth even under proper maintenance, but did not necessarily lead to the loss of an affected tooth. In the case presented to illustrate the indication for the tunnel preparation procedure, periodontal disease was almost entirely restricted to the furcation sites of molar teeth. Affected teeth were either extracted or left intact and subjected to tunneling procedures. Periodontal health could be established and maintained at both single and double tunnels over a period of 2 years of periodontal supportive therapy.

Mandibular and maxillary furcation tunnel preparations - literature review and a case report

The objective of this literature review and subsequent case report is to discuss and illustrate the tunnel preparation procedure as a treatment alternative for furcation-involved molars.Furcation tunnel preparation, i.e., the creation of access for plaque control between periodontally diseased roots, has not been discussed in the literature as comprehensively as root resective therapy, though success rates appear to fall within the same range. A short root trunk and a wide furcation entrance diameter are prerequisites for the indication of the tunnel preparation procedure. Although accessory canals in the furcation area are frequent findings on extracted teeth, endodontic complications have not been reported to be major complications after tunnel preparation. Caries developed at tunneled teeth even under proper maintenance, but did not necessarily lead to the loss of an affected tooth.In the case presented to illustrate the indication for the tunnel preparation procedure, periodontal disease was almost entirely restricted to the furcation sites of molar teeth. Affected teeth were either extracted or left intact and subjected to tunneling procedures. Periodontal health could be established and maintained at both single and double tunnels over a period of 2 years of periodontal supportive therapy.

An Experimental Animal Model of Split Cord Malformation

In this study, we examined an experimental animal model of split cord malformation (SCM) produced by the surgical induction of a fistula. In Cynopus pyrrhogaster neurulae (stage 18.5 ± 0.5), the neural plate was incised and divided to construct a fistula that mimicked a neurenteric canal. After the procedure, the development of these embryos was examined morphologically and histologically. Following incubation, hemicords, hemicords with their own heminotochords, and dermal sinus were observed in histological sections of embryos with an induced fistula. These abnormalities varied with the length and duration of the fistula, and the induction of this fistula apparently caused the development of this anomaly. The histological findings resembled the findings in human cases. The results of this study support the hypothesis that SCM may originate from an accessory neurenteric canal.