Tooth morphology and
pulpal access cavities
Restorative dentistry
Endodontics I.
8.3.2021
Basic terminology
Basic terminology
• Periodontium
• Dentin tubules
• Endodont – morphological and functional connection of pulp and
dentin
Root canal doesn’t run in straight line, usually its mesially curved. It
can split in branches, not rounded diameter.
Morphology of the root apex
• http://theendoacademy.com/wp-content/uploads/2013/04/apex-LargeType-001-620x604.jpg
Morphology of the root apex
Preparation of access cavity
• Opening of pulp chamber and removing its roof -> creating access
cavity.
Access cavity preparation
• Removing of caries.
• Preserving remaining hard dental tissues.
• Remove roof of pulp chamber.
• Removing of all content from pulp chamber.
• Localization of entrances toroot canal system.
• Straight-line access to root canal.
Access opening – guidelines
• X-ray intraoral
• Illumination and magnification
• Micromotor
• Burs
• Endo probe
• Ultrasound tips
Proper intraoral X-ray
Illumination and magnification
Preparation of access cavity
• Mikromotor max. 40000 RPM.
• Sharp and sterile burs.
• Round diamond bur, dia trepan, round bur.
• Batt bur – safe ended burs – non-active tip.
– perfect for removing roof of pulp chamber
Batt bur and dia trepan
Localization of root canal orifices
• Endodontic probe
• Microopener
• Ultrasound tips
Ultrasound preparation
• Precise preparation under control of sight.
• Ideal for removal of pulp stones, calcifications, smoothening walls.
Opening access - frontal teeth
• In the middle of the palatal surface we will start preparation of
opening access, size up to ½ of predicted size.
• In ENAMEL we use diamond burs, angle 90° to the surface.
• In DENTIN we use standart round bur, paralell with long axis of the
tooth.
• Penetration into pulp chambre – probe.
• Extension of opening access to incizal edge.
Failures during access cavity preparation
Opening access - distal teeth
• In ENAMEL we use diamond burs, angle 90° to the
surface.
• In DENTIN we use standart round bur, rotations
max. 40 000 per minute. Perpendicular to oclusal
surface.
• Entrance to pulp chambre can be verified by using
probe.
Opening access is localized on line between vestibular and oral cusp.
For lower premolars the opening access must respect lingual inclination
of crown.
For molars the correct starting location is on the central groove halfway
between the mesial and distal boundaries.
• Completly remove roof of
pulp chamber.
• Straight line access into
root canal.
Failures during access cavity preparation
Localization of root canal orifices
• Knowledge of morphology.
• Diagnostic X-ray.
• Magnification and illumination
• Equipment
Guidelines for localization orifices of root
canals
• Centrality: The floor of the pulp chamber is always located in the center of the
tooth at the level of the CEJ.
• Symmetry: Except for the maxillary molars, canal orifices are equidistant from a
line drawn in a mesiodistal direction through the center of the pulp chamber
floor. Except for the maxillary molars, canal orifices lie on a line perpendicular to
a line drawn in a mesiodistal direction across the center of the pulp chamber
floor.
• Color change: The pulp chamber floor is always darker in color than the walls.
• Orifice location: The orifices of the root canals are always located at the junction
of the walls and the floor; the orifices of the root canals are always located at the
angles in the floor-wall junction; and the orifices of the root canals are always
located at the terminus of the roots’ developmental fusion lines.
• More than 95% of the teeth these investigators examined conformed to these
spatial relationships.
Naked eye vs. microscope
Maxillary central incisor
• The access cavity has triangular
outline.
• 1 root – 1 root canal
Maxillary central incisor
Length of tooth 23,5mm
Length of crown 10,5mm
Length of root 13mm
Width of crown 8,5mm
Width of cervical area 7mm
Maxillary lateral incisor
• The access cavity is triangular
and reproduces the shape of
the endodontic space.
• 1 root – 1 root canal
In 53% cases we can find distal
curvature in the apical third of the root.
Maxillary lateral incisor
Length of tooth 22mm
Length of crown 9mm
Length of root 13mm
Width of crown 6,5mm
Width of cervical area 5mm
Maxillary canine
• The access cavity of the pulp
chamber has an oval shape, going
from the cusp to the cingulum of
the coronal cervical one-third.
• 1 root – 1 root canal.
Maxillary canine
Length of tooth 27 mm
Length of crown 10 mm
Length of root 17 mm
Width of crown 7,5 mm
Width of cervical area 7mm
Maxillary first premolar
• Vestibular and palatal pulp horn.
• The access preparation for the
maxillary first premolar is oval or
slot shaped.
• P root – 1rc.
• V root – 1rc 95 %, 2rc 5%.
Maxillary first premolar
Length of tooth 22,5 mm
Length of crown 8,5 mm
Length of root 14 mm
Width of crown 7 mm
Width of cervical area 5 mm
Maxillary second premolar
• Vestibular and palatal pulp
horn.
• The access preparation for the
maxillary second premolar is
oval or slot shaped.
Maxillary second premolar
Length of tooth 22,5 mm
Length of crown 8,5 mm
Length of root 14 mm
Width of crown 7 mm
Width of cervical area 5 mm
Maxillary first molar
• The maxillary first molar is the
largest tooth in volume and one of
the most complex in root and canal
anatomy.
• The access cavity has a rhomboid
shape, with the corners
corresponding to the four orifices.
• P root – 1rc (55% B curved).
• DB root – 1rc 96%, 2rc 4%.
• MB root – 1rc 5-40%%, 2rc 95-60%
MB2
• Localised on the line connectin MB a P root canal, under dentin
shoulder.
• Removing shoulder-> US StartX 2.
Maxillary first molar
Length of tooth 20/22mm
Length of crown 7,5mm
Length of root 12/13mm
Width of crown 10mm
Width of cervical area 8mm
Second upper molar
• When 4 canals are present, the
access cavity has a rhomboid shape
• If only 3 canals are present, the
access cavity is a rounded triangle
with the base to the buccal.
• If only 2 canals are present, the
access outline form is oval
• P root – 1rc (37% B curved).
• DB root – 1rc.
• MB root – 1rc 57%, 2rc 23%.
• MB and DB fused – 16%.
Second upper molar
Length of tooth 19/21mm
Length of crown 7mm
Length of root 11/12mm
Width of crown 9mm
Width of cervical area 7mm
Mandibular central and lateral incisor
• High difficulty – small
proportions of tooth
• The external outline form may
be triangular or oval,
extended to incizal edge.
• 1 root – 1 root canal 75%, 2
root canals 25%
Mandibular central incisor
Length of tooth 22 mm
Length of crown 9,5 mm
Length of root 12,5 mm
Width of crown 5 mm
Width of cervical area 3,5 mm
Mandibular lateral incisor
Length of tooth 23,5 mm
Length of crown 9,5 mm
Length of root 14 mm
Width of crown 5,5 mm
Width of cervical area 4 mm
Mandibular canine
• The access cavity for the mandibular
canine is oval or slot shaped.
• 1 root – 1 rc in 94%, 2 rc in 6%
Mandibular canine
Length of tooth 23 mm
Length of crown 10 mm
Length of root 17 mm
Width of crown 7,5 mm
Width of cervical area 5,5 mm
Mandibular first premolar
• Two pulp horns. Lingual
inclination of crown.
• The access preparation is oval or
slot shaped.
• 1 root – 1rc 74%.
Mandibular first premolar
Length of tooth 24,5 mm
Length of crown 8,5 mm
Length of root 14 mm
Width of crown 6 mm
Width of cervical area 5 mm
Mandibular second premolar
• Two pulp horns. Lingual
inclination of crown.
• The access preparation is oval or
slot shaped.
• 1 root – 1rc 97%.
Mandibular second premolar
Length of tooth 24,5 mm
Length of crown 8,5 mm
Length of root 14 mm
Width of crown 7 mm
Width of cervical area 5 mm
Mandibular first molar
• It is often extensively restored, and it
is subjected to heavy occlusal stress.
Consequently, the pulp chamber
frequently has receded or is
calcified.
• The access cavity is typically
trapezoid or rhomboid, regardless of
the number of canals present.
• M root – 1rc 12%, 2rc 87%, 3rc 1%
• D root – 1rc 70%, 2rc 30%.
Mandibular first molar
Length of tooth 21,5mm
Length of crown 7,5mm
Length of root 14mm
Width of crown 11mm
Width of cervical area 9mm
Mandibular second molar
• The access cavity is typically
trapezoid or rhomboid.
• M root – 1kk 27%, 2kk 73%.
• D root – 1kk 92%, 2kk 8%.
Mandibular second molar
Length of tooth 20mm
Length of crown 7mm
Length of root 13mm
Width of crown 10mm
Width of cervical area 8mm
Literature sources
• Cohen Pathways of the Pulp - 10th edition
• Cohen Pathways of the Pulp - 11th edition
• Laser in endodontics