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Nyaga, JM.  2010.  External and internal root morphology of the first Permanent molars in a Kenyan population. Abstract

Background: A thorough knowledge of dental anatomy and its variability is
critical in clinical dentistry. It is important for the clinician to be familiar with
variations in root morphology for such variations in the roots and canals have
significancein endodontic treatment and restoration of the treated teeth.
Objective: To determine the external and internal root morphology in first
permanentmolars in a Kenyan population.
Study design: This was a cross sectional descriptive study
Study area: The study involved collection of extracted teeth from patients whom
after dental evaluation, a tooth was recommended for extraction in five dental
clinics within Nairobi;- K.N.H.-Dental clinic, U.O.N.-School of Dental Sciences, St
Mary's Hospital Dental clinic, Mbagathi District Hospital Dental clinic and Social
ServicesLeague Dental clinic.
Materials and methods: Maxillary and mandibular first permanent molars were
co~ectedfrom male and female patients aged between 10 and 40 years. The
teeth were collected from individuals who met the inclusion criteria. The teeth
were separated at the collection site based on gender and whether they were
maxillary or mandibular first molars by the researcher and trained research
assistants.After collection, the teeth were further sorted out using the inclusion
criteria.A total of 187 maxillary molars and 189 mandibular molars were studied.
Observationswere done to determine the number of roots, root fusion and the
direction of root curvature. Measurements, using an electronic vernier caliper,
were done to determine the root length in millimetres. A standard clearing
technique was applied to determine the number of canals and the canal
configurations with reference to Vertucci's classification (1984). A data collection
form was used to record the findings for each tooth after examination
Data analysis and presentation: The data collected was entered into a
computer and analyzed using the Statistical Package for Social Sciences (SPSS)
12.1. Computation was done to determine pattern of root fusion, frequency of
root curvature in a certain direction, calculate the mean root length, number of
canals per root, frequency of various canal configurations and gender variations
in the findings. The data was presented in form of frequency tables, pie charts
and bar graphs.
Results: All the maxillary first molars had three roots while mandibular first
molars had two roots. Root fusion was observed in 3.9% of the maxillary first
molars. Root fusion between distobuccal and palatal root was more frequent
(2.8%) than the mesiobuccal and distobuccal roots (1.1%) and gender variation
in root fusion was not statistically significant. Majority of the mesiobuccal roots
63.6% were curved and of the curved, 95% curved distally. In the distobuccal
root, 49.7% of the roots were curved and majority 77.4% curved mesial. Majority
of the palatal roots were straight (65.3%). Of the curved palatal roots, 92.5%
curved in a buccal direction. In the mandibular first molars, 16.3% of the mesial
roots were straight while the rest were curved distally in both genders. Majority of
distal roots were straight. The gender variations in root curvature in both
maxillary and mandibular first permanent molars were not statistically significant.
The mean root length in palatal, mesiobuccal and distobuccal roots was
23.28mm, 20.22mm and 19.67mm respectively. While in the mandibular molars,
the mean root length was 21.97mm and 21.38mm in mesial and distal roots
respectively. Males had longer mean root length compared to females in the first
permanent molars. The gender variation in root lengths was statistically
significant (p=0.001).
Majority of the first permanent molars had 3 canals, 70.1% in maxillary and
56.0% in mandibular first molars. The mesial root of mandibular first molars had
two canals in 96.3% of the teeth in both male and females and type IV canal
configuration was most prevalent in the mandibular mesial root among males and
females. The distal root of mandibular first molar had one canal in 57.7% of the
teeth in males and females. There were significant gender variations in the
number of canals and canal configurations in the distal root. Two canals were
more prevalent in females (53.6%) compared to males (30.4%) and a single
canal was more frequent in males (69.6%) compared to females (46.4%)
(P=0.001). Canal types I, " and IV were the most frequent in mandibular distal
root. The gender variation the frequency of canal types I, " and IV in the distal
root was statistically significant (P=0.001). Most of the palatal (98.9%) and all the
distobuccal roots had one canal Vertucci type I configuration. The mesiobuccal
root had 2 canals in 29.4% of the roots in both males and females. Canal
configurations in mesiobuccal root varied widely. Canal types I, II, IV, V, VI and
VII had frequencies of 65.2%, 12.8%, 14.4%,4.3%,2.7% and 0.5% respectively
in both gender.
Conclusions: The maxillary first molars had three roots while the mandibular
ones had two roots. Root fusion occurred in 3.9% of maxillary first molars.
Palatal and distal root in maxillary and mandibular first molars respectively had
the lowest frequency of curved roots.
In the maxillary first molars, the mean palatal root length was 23.28mm,
mesiobuccal 20.22mm and distobuccal 19.67mm while in mandibular first
permanent molars, mesial root was 21.97 mm and distal 21.38mm.
The mean root lengths were higher in males as compared to females
Most of maxillary first molars 70.1% had three canals while 29.4% had four
canals. Vertucci type I canals configuration was the most prevalent in all roots.
Most of mandibular first molars had three canals 56% while 41% had four canals.
Two canals were more frequent among females 53.6% compared to males
30.4% and Canal types I, II and IV configurations were the most frequent in
mandibular distal root.
• The palatal root of maxillary and distal root of mandibular first permanent molars
are the most suitable for post placement.
• Three dimensional diagnostic techniques are essential in identification of
anatomical features
• Long and short files should be included in the endodontic armamentarium
• More attention should be directed towards searching for and locating the second
canal in the mesiobuccal and distal roots of maxillary and mandibular first molars

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