PEDIATRIC DENTISTRY/Copyright © 1989 byThe American Academy of Pediatric Dentistry

Volume ] 1, Number 3

The prevalence of furcation foramina in primary molarsD. Ringelstein, BDSc W. Kirn Seow, BDS, MDSc, PhD, FRACDS

Abstract

Accessory canals in the furcation region of primary molarsprovide pulpal-periodontal communications which haveimportant clinical implications. This study of 75 extractedprimary molars using dye penetration under vacuum suctionshowed that 42.7% have foramina loca ted within the fu rcationregion. There were no significant differences in the prevalencebetween the first and second primary molars. However, in thesecond primary molar series most of these foramina werelocated on the root surfaces within the furcation region, ratherthan in the immediate area of root division. The highprevalence of accessory canals in the furcation region ofprimary teeth indicates the need for greater clinicalconsideration during endodontic° and periodontalmanagement.

The furcation area of a molar tooth, whichencompasses the region around the division of the roots,is of special significance in the primary dentition due toits close anatomical relationship with the follicle of thesuccedaneous permanent molar. Accessory canals inthe furcation area are clinically important for severalreasons. Infection in the pulp can spread through thesecanals to affect the interradicular bone before involvingperapical tissues (Winter 1962; Myers et al. 1987). addition, medicaments placed in pulp can enterfurcation bone through these canals. These accessorycanals also provide communication of the pulp withperiodontal tissues, often being the cause of deepperiodontal pockets associated with nonvital teeth(Seltzer et al. 1963). Although the clinical implications these communication canals are well recognized, therehas been little research showing their existence or theanatomical location of these furcal foramina,particularly in primary teeth. This study was performedto determine the prevalence and location of accessorycanals in the furcation region of extracted primarymolars.

Materials and Methods

Selection of teeth

Seventy-five extracted primary molars, which hadbeen stored previously in 2% formalin, were selected atrandom. Although the reasons for the extractions wereunknown, they were carefully selected by the criteriathat root resorption did not involve more than a third ofthe apical aspect of any root. In addition, teeth showingsurface defects in the furcation region also wereeliminated.

Preparation of teeth

The teeth were prepared according to the method ofGutmann (1978), with slight modifications. They werefirst placed in a solution of 2.5% sodium hypochloritefor surface cleansing for 20 min followed by rinsing withtap water. An occlusal endodontic access cavity wasprepared in each tooth, followed by standardendodontic techniques of pulp tissue removal usingspoon excavators and broaches. Care was taken not toscrape the floor of the pulp chamber. The teeth werestored in 3% hydrogen peroxide for I week, the solutionbeing changed every two days. This technique destroystissue attachment to the tooth, allowing for easydebridement but not causing decalcification (Hibbardand Ireland 1957). The teeth were rinsed in tap water for20 min, then immersed in 95% alcohol for 24 hr to fix thetissues. Finally, they were dried thoroughly usingcompressed air before being placed in a vacuum suctionsystem for dye penetration of the pulp system.

Dye penetration under vacuum suctionA tube was modified from a 3 cm by I cm rubber teat

(Ansell International, Dandenong, Victoria, Australia).One end was placed around the crown of each tooth (Fig1) to achieve a tight seal. The other end was sealedaround a plastic tube modified from a 1 cm disposablepipette tip (Monoject Scientific, Sherwood, St. Louis,MO, USA), and the joint was secured using a piece of0.18 mm wire tie (Fig 1). The plastic tube was locatedcentrally in a 4 cm diameter rubber stopper designed to

198 FURCATION FORAMINA IN PRIMARY MOLARS: RINGELSTEIN AND SEOW

Fig 1. Primary molar toothassembled for dye penetrationof the root canals. A rubber teatholds securely at one end toachieve a tight seal. The otherend of the teat is sealed arounda plastic tube through which thedye is inserted. A wire tie is usedto seal this section securely. Redsticky wax is applied to theapices of the tooth.

fit a 2 L flask attached toa vacuum pump (Fig 2).Red sticky wax wasapplied to the apical one-third of each root to sealthe apical foramen (Fig3). A drop of Safranin8

dye (red) (Sigma Chem-ical Co., St. Louis, MO,USA) was intro-duceddown the tube into thepulp chamber using afine disposable glasspipette. Extreme carewas taken to ensure thatno spillage of dyeoccurred onto the ex-ternal aspects of thetooth. A vacuum pres-sure of 550 mbar merc-ury was applied to theexternal root surfaces fora maximum of 5 min. Assoon as the vacuum wasapplied, the furcationarea of each tooth was

observed carefully for the appearance of any redstaining. As soon as red staining was noted, the toothwas removed so that markings on the cemental surfacesremained discrete.

Statistical AnalysisThe Chi-square test was used for statistical analysis

of the data.

ResultsPrevalence of foramina in the furcation region

It is important to define the anatomical areas understudy. The "furcation" has been defined as the arealimited to the immediate region where the roots sepa-rate, while the "furcation region" encompasses the ac-tual furcation of each tooth plus an area 4 mmdown the internal aspect of the root surfaces(Gutmann 1978). Using these definitions, wefirst surveyed the prevalence of foramina inthe furcation region of 75 primary molars.Overall, there were 32 teeth showing presenceof foramina in the furcation region, giving aprevalence of 42.7% (Table 1). This prevalencevaried slightly among the different teeth sur-veyed (Table 1). As shown in Table 1, theprevalence of foramina in the furcation regionranged from 33.3% in the mandibular first pri-

Fig 2. The vacuum suction apparatus for dye penetration of rootcanals.

mary molar to 40.0% inthe mandibular secondmolar, 48.0% in the max-illary second primarymolar, and 50.0% in themaxillary first primarymolar. The differences inprevalence among thedifferent molars is notstatistically significant (P>0.1).

Location of furcationforamina

It is of interest toanalyze the location ofthe foramina. Table 2(page 200) shows thedistribution of the for-amina in the furcation region of the molars. As shown inTable 2, there were no significant differences in thelocation of the foramina (P > 0.1) in both maxillary andmandibular first primary molars. In contrast, in both the

TABLE 1. Prevalence of Foramina in Furcation Region'of PrimaryFirst and Second Molars

Fig 3. Accessory foramenlocalized in the furcation of amandibular primary first molar.

First Primary MolarMax. Mand.

(N = W) (N = W)

No. withFurcalForamina

Percentage

5

50.0%

3

33.3%

Second Primary MolarMax. Mand.

(N = 25) (N = 30)

1248.0%

1240.0%

Total(N = 75)

3242.7%

The difference in prevalence of furcal foramina among the different molars isnot statistically significant (P > 0.01)

PEDIATRIC DENTISTRY: SEPTEMBER, 1989 ~ VOLUME 11, NUMBER 3 199

TABLE 2. Analysis of Location of Foramina in Furcation Region inPrimary Molars

Tooth

Location of ForaminaFurcation

Furcation* region' P value

First Primary MolarMax. (N = 5)Mand. (N = 3)

Second Primary MolarMax. (N = 12)Mand. (N = 12)

2 (40.0%)2 (66.7%)

3 (25.0%)2 (16.6%)

3 (60.0%)1 (33.3%)

9 (75.0%)10 (83.4%)

>0.1>0.1

< 0.001< 0.001

* Furcation encompasses the immediate root division region.1 Furcation region includes the internal aspect of the root from root division

area down to approximately 4 mm of root length.

maxillary and mandibular second primary molars therewere greater percentages of foramina located in thefurcation regions compared to the furcation itself (75.0vs. 25.0% in the case of the maxillary second primarymolar, and 83.4 vs. 16.6% in the case of the mandibularsecond primary molar). These differences werestatistically significant (P < 0.001). Figure 3 shows aprimary mandibular first molar with a foramen in thefurcation, as indicated by the discrete stained spot. Incontrast, Figure 4 shows a foramen in the furcationregion of a primary mandibular second molar.

Roots showing foramina in furcation regionIt may be clinically relevant to identify the roots in

furcation region showing foramina in the primarymolars. Table 3 shows the roots involved in themandibular primary molars. The most commonlyinvolved root in these teeth was the distal root (45.5%),followed by the mesial root (36.3%), and theinvolvement of both mesial and distal roots (18.2%).However, these differences were not statistically

significant (P > 0.1).Table 4 shows a similaranalysis of the rootsinvolved in the maxil-lary molars. The mesio-buccal root is mostinvolved frequently(41.7%), with another41.7% showing thepresence of foramina inboth mesiobuccal andpalatal roots. Only 16.6%showed the presence offoramina in the disto-buccal root alone, and noteeth had foramina on

Fig 4. Accessory foramen noted the palatal root alone,in the furcat ion region of a It is of interest to notem a n d i b u l a r p r i m a r y second that all thg foraminamolar.

appeared as discrete areas of staining.Diffusion of the dye through dentinal tubuleswas not a problem.

DiscussionAccessory canals on root surfaces may be

considered developmental aberrationscaused by the persistence of abnormallyplaced blood vessels that leave gaps in theHertwig's sheath (Scott and Symons 1982).Although accessory canals may occuranywhere along the root surface, those in thefurcation areas of molars pose the mostdifficult complications in clinical dentistry.

Most of the previous work investigating the furcationregion of teeth has centered on permanent molars. Inthese teeth, a wide range of prevalence figures havebeen noted, probably due to differing sensitivity of thetechniques employed. Using dye penetration methodsimilar to that of the present study, Gutmann found that24.5% of 102 permanent molars showed patentaccessory canals leading from the floor of the pulpchannels to the furcation (Gutmann 1978). However, ahigher prevalence of 40% was noted by Vertucci andWilliams (1974) in their visual examination of 100mandibular first permanent molars using a dissectingmicroscope. The highest prevalence (59%) was noted byLowman et al. in 1973 using a combination ofradiopaque dye system and radiography on 46permanent molars.

In sharp contrast, other investigators employingchiefly radiographic methods have found no lateral

TABLE 3. Type of Root Showing Foramina in FurcationRegion* in Mandibular Primary Molars

No. of teeth with ForaminaRoot CN = U)

Distal AloneMesial AloneDistal and Mesial

5 (45.5%)4 (36.3%)2 (18.2%)

* These foramina are located on the internal aspect of the rootwithin 4 mm from the center of the true furcation area.

The differences in the results are not statistically significant (P >0.1).

TABLE 4. Type of Root Showing Foramina in FurcationRegion* in Maxillary Primary Molars

No. of Teeth With ForaminaRoot Surface (N = 12)

Mesiobuccal AloneDistobuccal AlonePalatal AloneMesiobuccal and Palatal

5 (41.7%)2 (16.6%)05 (41.7%)

* These foramina are located on the internal aspects of the rootwithin 4 mm from the center of the true furcation area.

200 FURCATION FORAMINA IN PRIMARY MOLARS: RINCELSTEIN AND SEOW

canals coming from the pulp chamber of multirootedteeth (Pineda and Kuttler 1972; De Deus 1975; Hession1977). This probably is due to low sensitivity of thetechnique employed in these studies for the detection ofaccessory canals.

Although permanent molars have been wellinvestigated, there is a paucity of information regardingthe presence of accessory canals in the furcation regionof primary molars. Interest in this anatomical part of thetooth was aroused first from clinical observations thatmany necrotic primary molars show bone loss in thefurcation area (Winter 1962; Myers et al. 1987),suggesting possible channels of communicationbetween the pulp and periodontal bone in this region ofthe root. To demonstrate this, Winter (1962) used a dyeperfusion system to study by direct observation theprevalence of patent accessory canals in the furcationregion. He reported that 29% of 100 primary molarspossessed accessory canals leading to the interradicularroot surface, with the opening of these canals foundprincipally on the middle third of the root surface. Theabove results were confirmed by Moss et al. (1965) in histological study which found that 20% had accessorycanals entering the pulp chamber in the region of thefurcation of the roots. However, both these studies weredone on primary molars which were extracted forinterradicular abscesses diagnosed from radiographs,so the results may be biased.

Our present study using randomly selected primarymolars shows a much higher prevalence (42.7%) accessory canals in the furcation region of primarymolars. Although some of the canals may not be patentin the healthy in vivo state due to connective tissue seals,they represent potential channels which may be openedduring pathological changes in the pulp.

There is important clinical significance of thesecanals. First, infection of the pulp can spread easily tothe interradicular bone via these furcationcommunications. This problem was addressed bySeltzer and co-workers in 1963, as well as by Winter in1962 who located furcation accessory canals in 29% ofprimary molar teeth showing interradicular abscesses.These interradicular abscesses tend to drain through theperiodontal ligament and are an important cause ofperiodontal pockets in the primary dentition.

Second, during the pulpotomy procedure it ispossible that excess medicament solutions placed in thepulp chamber may enter these accessory canals andinvolve the alveolar bone. Many of these medicaments,such as formocresol, possess strong inflammatorypotential (Seow and Thong 1986) and if allowed contact bone, may cause painful osteitis. Therefore, it is

advisable to localize pulpotomy medicaments to theamputated root stump rather than spreading it over theentire pulpal floor, where there is a high possibility ofdiffusion of the medicaments through accessory canalsinto the bone.

Third, the communication of the periodontal tissueswith the pulp affected by furcation canals may suggestthat infections originating from the periodontal tissuestheoretically could reach the pulp. Althoughperiodontal abscesses are uncommon in children, theymay be observed around ill-fitting stainless steelcrowns, orthodontic bands, and impacted foreignbodies. However, the incidence of pulpal necrosisresulting from such periodontal infections is unknown.

In conclusion, the high prevalence of accessorycanals in the furcation region of primary molarssuggests that communications of the pulp withinterradicular bone and periodontal tissues are highlypossible.

Mr. D. Ringelstein was a final-year undergraduate dental student atthe time of the study. Dr. W. Kim Seow is senior lecturer in pediatricdentistry, Department of Social and Preventive Dentistry, DentalSchool, University of Queensland, Turbot Street, Brisbane,Queensland, Australia 4000, Telephone: (07) 233 8044. Allcorrespondence should be sent to Dr. Seow. Reprint requests shouldbe sent to: Dr. W. Kim Seow, Dept. of Pediatric Dentistry, Universityof Queensland Dental School, Turbot St., Brisbane, Queensland 4000Australia.

DeDeus QD: Frequency, location and direction of lateral secondaryand accessory canals. J Endo 1:361-66, 1975.

Gutmann JL: Prevalence, location and patency of accessory canals inthe furcation region of permanent molars. J Periodonto149:21-26,1978.

Hession RW: Endodontic morphology: A radiographic analysis.Oral Surg 44:610-20, 1977.

Hibbard ED, Ireland RL: Morphology of the root canals of theprimary molar teeth. ASDC J Dent Child 24:250-61, 1957.

Lowman JV, Burke RS, Pellan GB: Patent accessory canals: incidenceof molar furcation region. Oral Surg 36:580-84, 1973.

Moss SJ, Addelston H, Goldsmith ED: Histologic study of pulpalfloor of deciduous molars. J Am Dent Assoc 70:372-79, 1965.

Myers DR, Battenhouse MR, Barenia JT, McKinney RV, Singh B.Histopathology of furcation lesions associated with pulpdegeneration in primary molars. Pediatr Dent 9:279-82, 1987.

Pineda F, Kuttler Y: Mesiodistal and buccolingual roentgenographicinvestigation of 7,275 root canals. Oral Surg 33:101-10, 1972.

Scott JH, Symons NB: Introduction to dental anatomy. Edinburgh:Churchill Livingstone, 1982.

PEDIATRIC DENTISTRY: SEPTEMBER, 1989 - VOLUME 11, NUMBER 3 201

Seltzer J, Bender IB, Ziontz M: The interrelationship of pulp andperiodontal disease. Oral Surg 16:1474-90, 1963.

Seow WK, Thong YH: Modulation of polymorphonuclear leukocyteadherence by pulpotomy medicaments: effects of formocresol,glutaraldehyde, eugenol and calcium hydroxide. Pediatr Dent8:16-21, 1986.

Vertucci TJ, Williams RG: Furcation canals in the human mandibularfirst molar. Oral Surg 38:308-14, 1974.

Winter GB: Abscess formation in connection with deciduous molarteeth. Arch Oral Biol 7:373-79, 1962.

Nutritional deficiency - oral manifestations

Many developmental and systemic conditions have oral manifestations, some of which are earlyindicators of disease. The following chart pinpoints oral conditions that may be symptoms of nutritionaldeficiencies. In many instances, early detection can increase patient comfort and well being.

Oral manifestations related to nutritional deficiency

Vitamin A- Hyperplasia of the gingiva- Gingivitis- Periodontitis

Vitamin B12 .(pernicious anemia)- Spongy red-blue (very hemorrhagic) gingiva- Detachment of periodontal fibers- Bone loss- Halitosis- Angular cheilosis

Vitamin D (rickets)- Enamel hypoplasia- Absence of lamina dura- Abnormal alveolar bone patterns

Vitamin K- Gingival bleeding (caused by decreased formation of prothrombin)

Thiamin- Satinlike appearance of tongue and gingiva (caused by atrophy of filiform papillae~beri-beri- Angular cheilosis

Niacin- Fiery red glossitis (devoid of papillae)- Ulcerative gingivitis- Angular cheilosis

Iron- Red painful tongue (atrophy of filiform papillae)- Angular cheilosis- Dysphagia

202 FURCATION FORAMINA IN PRIMARY MOLARS: RINGELSTEIN AND SEOW