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Other flap designs that have been previously indicated
include a semilunar incision but the access offered is poor
and there is often significant scarring. Relieving incision(s)
will reduce the tension on the flap; these should be vertical
so as to maintain maximum blood supply to the flap. Care
should be taken to place these in a position where there is
unlikely to be significant tension (e.g. away from root eminences and away from a bony defect). Only use what is
necessary to gain adequate access and reduce postoperative
discomfort to the patient. Incisions should be carried out
with a sharp blade (e.g. Swann–Morton 11, 15, 15c, 69
micro blades); this author’s preference is for a microblade
preserving the incisive papillae and a separate 15c to make
the relieving incisions. When crossing the gingival margin,
incisions should be made at 90° so that closure results in
minimal scarring and gingival recession.
Elevation of the flap should start at the attached gingiva
using a periosteal elevator, e.g. Buser type on the vertical
relieving incision, then progress laterally (undermining elevation) to prevent damage to the flap margins associated
with the cervical areas of the teeth. Once reflected, the flap
should be retracted, taking care to place and maintain the
retractor on bone so as not to compress, damage or compromise the blood supply of the flap. Such damage may lead to
excessive postoperative swelling or discomfort.
Bone Removal
Where there is a large bony defect, loss of the cortical plate
may make access to the root tip straightforward. In many
instances, a round, sterile, water-cooled surgical bur may
need to be used to create a small osteotomy site by removing
bone overlying the root. These osteotomy sites can also be
created using ultrasonics, e.g. Piezosurgery (Mectron, IT),
which are designed to cause less trauma to the bone and
soft tissues. Care must be taken when creating the osteotomy site not to damage adjacent tooth roots or other
anatomical structures.
Once access to the root end has been achieved, it is necessary to curette any granulation tissue or in some cases cyst
lining from the defect. If the lesion is tethered to the underside of the mucoperiosteal flap then this should be carefully
dissected away with a sharp blade taking care not to cut
through the full thickness of the reflected flap. Where possible such tissue should be sent for histological examination. It is not necessary to remove every last remnant of soft
tissue and care should be taken when curetting adjacent to
anatomical structures such as the mental foramen, incisive
nerve or maxillary sinus.
Root End Resection
The root ends may be resected with high-speed crown/
endo-z type burs as long as they are used in a surgical airdriven handpiece where the air is directed away from the
bone, e.g. Impact Air 45 (Palisades Dental LLC, USA).
Failure to do so may result in a surgical emphysema. Alternatively, the root end may be resected using piezosurgery or
using a water-cooled fissure bur. Resections should be carried out using appropriate sterile water or saline coolant.
Any of these techniques can be used to cut back or section
through the root end. In general, about 3 mm of root
should be removed as this will result in removal of accessory canals forming part of the apical delta (Fig. 2.27). The
2 • Endodontics
3 mm
Gutta
percha
Fig. 2.27 There is frequently branching of the root canal in the apical
third; these are areas for biofilm to remain untouched during canal
preparation and be source of recurrent infection. Removal and resection of the final 3 mm preserves root length while removing a large
proportion of the branching. Any granulomatous or cyst-like material
is removed, 3 mm of preparation is carried out with ultrasonics down
the long axis of the tooth; the root end filling with a bio-comparable
material provides a good apical seal.
Root end filling
77
3 mm
resection should also go right through the root but care
should be taken to avoid adjacent teeth or other anatomical
structures. Ideally the resection should be at 90° to the long
axis of the tooth keeping any bevel to a minimum in order
to avoid excessive exposure of dentine tubules. In multirooted teeth, it may be possible to resect an entire root,
particularly where there has been a vertical root fracture
maintaining the remaining roots and still providing a stable
platform onto which a restoration may be placed.
Haemostasis
It is important that the periradicular surgical site be kept
dry whilst the retrograde obturation material is placed
both to improve vision and allow appropriate handling of
the material. This may necessitate packing the cavity with
local anaesthetic impregnated gauze, use of styptic agents,
e.g. sterile ferric sulphate or other haemostatic adjuncts,
e.g. collagen sponge, Surgicel, bone wax or calcium sulphate. The choice of material depends upon individual
preference, but care must be taken to remove all remnants
(except some collagen-based products and calcium sulphate, which are resorbable) as, if left, they will act as a
foreign body and delay healing.
Root End Preparation
Root end preparations are now almost universally carried
out using small contra-angled ultrasonic tips (Fig. 2.28);
the removal of softened gutta-percha from the root end
preparation allows debridement of the canal space and
then compaction of material inside the canal. The preparation can be examined using a miniature retro-mirror. Historically, preparations were performed with small round or
inverted cone burs, either in a straight or a miniature handpiece. The benefit of using ultrasonics over conventional
handpieces is that preparation can take place down the
long axis of the tooth removing gutta-percha and also
cleaning any previously uninstrumented parts of the canal.
Using traditional techniques, preparations were often orientated lingually/palatally with poor shape and ultimately
a poor apical seal; primarily as a result of limited access this
78
A B
Master Dentistry
Fig. 2.28 Examples of fine ultrasonic tips that are used to prepare the
resected root end. The cutting tip is diamond coated and is approximately 3 mm in length; the shafts are angled to allow easier access into
small osteotomy sites.
occasionally resulted in a palatal perforation. Fine ultrasonic tips must be used at an appropriate power setting in
order to minimise the risk of root cracking or tip fracture.
Several designs are available, with different angles for easier
access to posterior regions of the mouth. In addition, narrow designs are available for running out isthmus areas,
which are now considered to be a previously unrecognised
reason for failure in multirooted teeth.
Root End Filling Materials
Calcium silicate bioceramic cements such as MTA are considered to be the root end filling material of choice. MTA
has excellent biocompatibility, is notably alkaline on setting
with excellent osteoinductive properties, it seals well and is
sufficiently radio-opaque to be visible radiographically. Historic approaches used amalgam as the retrograde filling
material and may still be seen radiographically on a number of cases; failures with amalgam were seen as a result of
its much poorer sealing ability, corrosion and aesthetic
problems of staining and tattooing of the soft tissues.
Other materials that have proven success include super
ethoxybenzoic acid (EBA) and intermediate restorative material (IRM). Due to the moisture control needed, glass ionomer cements and composite resins are more challenging to
use; therefore calcium silicate materials are used as the first
line option. Care needs to be taken when placing the retro
filling that the root end and prepared cavity are adequately
isolated and dry. Materials should be mixed according to the
manufacturer’s instructions, and care taken to avoid excess
material out with the retro cavity. There are newer premixed calcium silicates in putty form that are becoming
increasingly popular due to their handling characteristics.
Micro-apical placement (MAP) systems are available akin
to a small amalgam carrier and are very helpful in placing
many of these materials into a prepared cavity; once placed
the material should then be compacted coronally. Ideally, a
radiograph should be taken prior to suturing to ensure that
the retro preparation and filling are adequate (Fig. 2.29).
Debridement and Closure
The surgical area should be thoroughly debrided and then
rinsed with sterile water or saline, and the flap should then
be compressed for about 3 minutes prior to suturing. In
general, small, size 5/0 interrupted non-resorbable monofilament sutures will prove adequate for most situations.
Suture removal should be performed 3–5 days later; in
some cases with good primary closure this can be done as
soon as 48 hours postsurgery.
It is usual for a patient to have some discomfort and
swelling postoperatively. This, however, is normally minimal and can be controlled using analgesics. The area can be
kept clean by continuing the chlorhexidine mouthwash
until suture removal allows improved toothbrush access.
Corrective Surgery
Corrective surgery may be required to seal a perforation
or resect a root. The position of the perforation is of paramount importance in determining whether it is surgically
accessible; parallax radiographs will help to determine
the site. Perforations in the apical third of the root may be
handled by removal of the apex and sealing the canal
with a retro grade filling. Ideally, perforations resulting
from post crowns should have the offending post removed
and a new one placed within the root canal. Surgical correction then resembles the placement of a retro grade
filling in the side of the root. If the post is not removed, it
must be cut back sufficiently to allow an adequate margin
for finishing the retro filling. Many perforations are now
managed by internal perforation repair with MTA, precluding the need for surgery.
Surgical root resection may be indicated on multirooted
teeth that have not responded to treatment or have a
Fig. 2.29 Shows retrograde obturations of UR1, UL1 with MTA putty to
around 3 mm in length. There has been good bony healing up to the
root end restorations (image taken at 1-year follow-up).
2 • Endodontics
79
hopeless periodontal prognosis. Other reasons for root resection include extensive resorption and root fracture in a
multirooted tooth.
Extraction With Subsequent Replantation
Atraumatic extraction with intentional replantation is a
recognised technique that can offer good success rates in
cases where there is an experienced operator. The procedure
Self-Assessment: Questions
MULTIPLE CHOICE QUESTIONS (TRUE/FALSE)
1. The following are important factors in restoring an endodontically treated tooth:
a. Preserving as much coronal tooth substance as
possible
b. Creating a ferrule effect
c. Removing all coronal dentine
d. Providing a wide post
e. Producing a long post without compromising apical
seal
2. Efficiency of irrigation is affected by:
a. Depth of needle penetration
b. Coronal pre-enlargement
c. Frequency of use
d. Volume and type of irrigant
e. Temperature of irrigant
3. Major causes of failure in root canal therapy are:
a. Placing small instruments through the foramen
b. Presence of bacteria remaining within the root canal
c. Presence of small amounts of filling material in the
periradicular tissues
d. Presence of necrotic material within the canal system
e. Loss of coronal seal and reinfection of a cleaned
canal system
4. Rotary nickel–titanium instruments:
a. Require a patent canal prior to use
b. Are used for canal negotiation
c. Can be used round any curvatures
d. Are used for canal enlargement
e. Should be used with a light touch
5. The following are features of irreversible pulpitis:
a. Response lasts for minutes to hours
b. Pain may develop spontaneously
c. Heat may be more significant in the later stages
d. Pain does not linger after stimulus
e. All of the above
6. An ideal access cavity should:
a. Provide unimpeded access to the root canal system
b. Have convergent walls
c. Be only large enough to allow files in to canals
d. Provide straight-line access to each canal orifice
e. Eliminate the pulp chamber roof in its entirety
7. Coronal pre-enlargement:
a. Is always necessary
b. Blocks the canal
c. Reduces the bacterial count coronally
d. Decreases the effect of irrigation
e. Enhances apical tactile feedback
involves extracting the tooth as atraumatically as possible
for example using a periotome or extractor device, the
root is handled carefully and root resection or repair
carried out swiftly before replanting the tooth. The
tooth will require splinting in the same way as for a
traumatic injury. This procedure may be indicated when a
conventional orthograde or surgical approach is not possible or advisable.
8. Periradicular surgery is indicated:
a. For all endodontic failures
b. When it is not possible to treat the root canal system
by conventional means
c. To clean the root canal system
d. To obtain tissue for a biopsy
e. As an investigative procedure
9. Ultrasonic root end preparation:
a. Is an improvement over steel burs
b. May cause root cracking
c. Should be used dry
d. Enables preparation up the long axis of the root
e. Needs more space for access
10. The following are features of reversible pulpitis:
a. Pain lingers after application of stimulus
b. Pain is difficult to localise
c. Tooth is tender to percussion
d. Pain does not linger after stimulus is removed
e. Normal appearance on a radiograph
11. A patency file:
a. Should be small and flexible
b. Is used to deliberately enlarge the foramen
c. Helps to eliminate apical blockage
d. Should be used vigorously
e. Is a generally accepted technique
12. Root canal filling materials should:
a. Be easy to insert into the canal
b. Absorb moisture
c. Expand on setting
d. Be difficult to remove
e. Not stain the tooth
13. The following are accepted obturation techniques:
a. Silver points
b. Laterally condensed gutta-percha
c. Continuous wave
d. Carrier devices
e. Single point gutta-percha
14. Fractured instruments may be avoided by:
a. Not precurving them
b. Not sterilising them
c. Jumping between different sizes of instruments
d. Discarding damaged instruments
e. Not forcing instruments
15. Root canal blockage:
a. May be caused by dentine chips
b. May lead to perforation
c. May be reduced by use of a lubricant
d. Is increased if the coronal two-thirds is prepared first
e. Is avoidable
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Master Dentistry
SINGLE BEST ANSWER QUESTIONS
1. A 23-year-old patient attends having fallen over whilst
drunk the night before, there was no loss of consciousness or soft tissue trauma. Your examination reveals a
complex crown root fracture of the upper left central
incisor tooth and less extensive fractures. Which radiographs should be your first line images?
A. Full maxilla CBCT
B. Periapical UL1
C. Parallax views of all upper anteriors
D. Vertical bitewing
E. Limited field CBCT
2. A 35-year-old patient attends with mesio-occlusal caries
affecting an upper first molar; during your caries removal there is a small pulpal exposure (2 mm); you
clear the periphery and isolate the tooth. Following disinfection with sodium hypochlorite, the most appropriate treatment is:
A. An indirect pulp cap with calcium hydroxide
B. A direct pulp cap with a calcium silicate cement
C. A partial pulpotomy with calcium hydroxide
D. A coronal pulpotomy with calcium silicate
E. A pulpectomy and root canal treatment
3. A 34-year-old patient complains of pain from a lower
left molar tooth; the onset of pain is following hot or cold
drinks and lingers for a few minutes; the pain is poorly
localised. There is no need for analgesics. A periapical
radiograph suggests secondary caries beneath a large
restoration and the periodontal membrane space appears normal. The most likely diagnosis is:
A. Asymptomatic irreversible pulpitis with normal api-
cal tissues
B. Irreversible pulpitis with normal apical tissues
C. Normal pulp with symptomatic apical periodontitis
D. Reversible pulpitis with normal apical tissues
E. Reversible pulpitis with symptomatic apical peri-
odontitis
4. A 45-year-old patient complains of pain on biting from
an upper first premolar; there are no other symptoms.
History reveals that a large MOD amalgam restoration
was placed recently; the tooth is TTP but only on the
palatal cusp; it responds normally to pulp testing. There
are no radiographic findings other than the deep MOD
restoration. The most likely diagnosis is:
A. Cracked tooth
B. Pulp necrosis, symptomatic apical periodontitis
C. Pulp necrosis, acute apical abscess
D. Irreversible pulpitis, asymptomatic apical periodontitis
E. Reversible pulpitis, normal apical tissues
5. A 56-year-old patient attends complaining of pain from
a lower molar tooth; clinical examination reveals deep
probing depths around the distal root with associated
suppuration. The tooth is TTP but not mobile and nonresponsive to pulp testing. A periapical radiograph reveals a deep restoration, there is ‘J’ shaped radiolucency
that extends distally from the periapex of the distal root
and a smaller apical radiolucency around the mesial
roots. BPE codes reveal some increased periodontal
probing depths elsewhere in the mouth. What is the
most likely diagnosis?
A. A true combined periodontal–endodontic lesion
B. Localised periodontitis, Stage 4, Grade C
C. Normal pulp, periodontal abscess
D. Pulp necrosis, symptomatic apical periodontitis
E. Pulp necrosis, chronic apical abscess
6. A 30-year-old patient complains of a ‘lump on the gum’
adjacent to an upper premolar. The swelling has been
present ‘on and off ’ for almost a year and gentle pressure
leads to discharge of pus from the gingival margin. The
patient is periodontally healthy but there is an isolated
area of deep probing (10 mm) in a single site where the
discharge is coming from. Radiographically bone levels
are good but there is a periapical radiolucency. What is
the most likely diagnosis?
A. Localised periodontitis, Stage 4, Grade C
B. Pulp necrosis, acute apical abscess
C. Pulp necrosis, chronic apical abscess
D. Pulp necrosis, condensing osteitis
E. Symptomatic irreversible pulpitis, symptomatic api-
cal periodontitis
7. A 25-year-old patient attends for obturation of an upper
incisor; you have previously performed initial access,
extirpation and canal shaping and cleaning at the last
visit. The patient reported pain for 3 days following the
last visit which has improved but the tooth is still tender
to bite on. In addition to the previously initiated therapy,
what is the most likely periapical diagnosis?
A. Acute apical abscess
B. Normal apical tissues
C. Chronic apical abscess
D. Symptomatic apical periodontitis
E. Asymptomatic apical periodontitis
PICTURE QUESTIONS
1. This 25-year-old patient attends with a discoloured upper right central incisor; the patient sustained previous
facial injuries after being hit by a horse when they were
a child. You are considering elective root canal treatment
and non-vital bleaching. The tooth has not previously
been accessed. Describe the radiographic appearance of
the tooth.
2 • Endodontics
81
3. This 32-year-old patient presents with pain from a discharging buccal sinus adjacent between the upper right
canine and upper right lateral incisor teeth. The GP
point inserted travels from the sinus tract opening to the
upper right central incisor. The UR4, UR3, UR2, UR1,
UL1 all appear to be heavily restored and have existing
root canal treatments with pathology noted around
UR3, UR2, UR1. Describe the treatment planning approach for these teeth.
2. This 23-year-old patient has a history of an impacted canine that has been removed from the palate. The lateral
incisor has an all ceramic crown to camouflage the peg
shaped tooth; the tooth has subsequently become nonvital. Describe why this tooth may be challenging to carry
out root canal treatment on and what interoperative
techniques can be used to overcome these challenges.
4. This 50-year-old female patient attends complaining of
multiple dental abscesses; they have two children each
of whom is under the care of a paediatric dentist for
similar problems affecting the primary dentition. The
patient is fit and well and has no other medical problems. The teeth clinically appear relatively sound and
moderately restored, the crowns are bulbous and the
root canals in many of the teeth appear indistinct or
obliterated. What is the most likely cause and what
treatment may be offered?
82
Master Dentistry
the most likely causes of this persistent swelling, the
stages involved in carrying out an apicectomy and
the follow-up regime for this patient.
5. A 42-year-old patient attends with persistent swelling
overlying the apices of their upper right central and lateral incisor teeth. These teeth have been root canal
treated on a number of occasions without improvement
in symptoms. An apicectomy has been carried out and
the image shown is immediately postoperative. Outline
Self-Assessment: Answers
MULTIPLE CHOICE ANSWERS
1. a. True. It is essential that sound coronal tooth tissue is
retained as this enables the tooth to be restored as
strongly as possible. See (b, e).
b. True. Retention of coronal dentine allows a collar to be
placed around the remaining tooth structure. This ferrule effect strengthens the remaining tooth structure.
c. False. Removing coronal dentine unnecessarily weak-
ens the tooth, makes it more difficult to create a ferrule
and produces a shorter post. See (e).
d. False. Wide posts weaken roots.
6. A 60-year-old patient attends with pain above an upper
left central incisor tooth. Clinically the margins appear
intact and despite historical Stage 2 grade B periodontal
disease it is currently stable. Radiographic view shows a
mesiodens, a post-crowned tooth with no obvious root
canal treatment beyond the post. Describe the treatment
strategies available to this patient.
SHORT NOTES QUESTIONS
Write short notes on:
1. reactionary and reparative dentine
2. pulp sensitivity tests
3. cracked tooth syndrome
4. balanced forces
5. the accuracy of electronic apex locators
e. True. A long post is more retentive than a short one.
Leaving coronal dentine enables a longer post to be
provided. It is essential however that the apical seal is
not disturbed. After post preparation, 3–5 mm of
root filling should remain.
2. a. True. It is important to get deep needle penetration;
this can only be achieved if the canal is large enough.
Irrigant solution does not travel much further apically
than the needle tip.
b. True. Early radicular access increases the space avail-
able for needle penetration and irrigant exchange.
2 • Endodontics
83
c. True. It is important to refresh irrigating solutions
frequently as this removes debris and ensures an
active solution.
d. True. A larger volume of irrigant has an increased
flushing effect. Sodium hypochlorite has been shown
to be more effective than water or local anaesthetic as
it will kill bacteria and dissolve pulp remnants.
e. True. Increasing the temperature of irrigating solu-
tions increases their reactivity and makes them more
efficient.
3. a. False. Small instruments placed through the foramen
do not increase the likelihood of failure. It is important, however, not to overenlarge the foramen or
cause damage to the periradicular tissues by using
large instruments in such a manner.
b. True. Successful endodontics involves removing as
many bacteria as possible from the root canal system.
The more bacteria that remain, the greater the likelihood of failure.
c. False. Small amounts of filling material outside the
root cause localised inflammation, which may be detectable histologically; it is not, however, a major
contributing factor to failure and does not usually
cause clinical symptoms.
d. True. Any necrotic tissue remaining within the canal
acts as a continuing irritant.
e. True. Loss of coronal seal allows reinfection of the
root canal system and is a major cause of failure.
4. a. True. Rotary nickel–titanium instruments require a
patent canal as they should be used for canal enlargement, not negotiation.
b. False. Using rotary nickel–titanium instruments to
negotiate canals increases the risk of fracture.
c. False. Rotary nickel–titanium instruments may be
used around gradual curvatures; however, sharp
curves and recurvatures put extra stress on the
instruments and can lead to fracture.
d. True. See (a).
e. True. If too much force is used in an attempt to drive
a rotary nickel–titanium file down a canal, there is
an increased risk of binding and file fracture.
5. a. True. Pain from irreversible pulpitis is long lasting
and may be severe.
b. True. Pain may develop spontaneously, while lying
down or wake the patient at night.
c. True. Heat frequently becomes a more significant
feature in the later stages when in fact cold may act
as a relieving factor.
d. False. Pain usually lingers after the stimulus is re-
moved.
e. False. See above.
6. a. True. It is important that the access is large enough
to allow canal identification and easy placement of
instruments.
b. False. The walls should be divergent to enable good
visualisation and support of a temporary dressing.
c. False. The access should be large enough to allow
unimpeded access of files into canals. This may
mean offsetting it to enable straight-line coronal
access.
d. True. The file handle should stand upright in the
canal when straight-line access has been achieved.
e. True. This allows canal orifices to be identified.
Commonly the roof of the pulp chamber is not completely removed over the orifice of the second mesiobuccal canal in upper molars.
7. a. False. Pre-enlargement is not necessary in medium
to large root canals.
b. False. Debris is produced during pre-enlargement;
however, correct use of irrigation and a small file to
disturb the dentine chips will prevent blockage.
c. True. Pre-enlargement removes dentine coronally
that is infected with bacteria.
d. False. Pre-enlargement improves irrigation because
there is improved access for the needle.
e. True. Pre-enlargement removes coronal dentine,
which may restrict the passage of a file deeper into
the root canal.
8. a. False. Root canal retreatment is the preferred option
in the majority of cases.
b. True. It may not be possible to treat the root canal
by conventional means if a very large post is present, the root canal is blocked by a fractured root
canal instrument or the apical third anatomy has
been destroyed by overinstrumentation.
c. False. Periradicular surgery aims to remove the api-
cal 3 mm and clean a further 3 mm of canal system
but is no substitute for conventional cleaning and
shaping procedures.
d. True. The collection of biopsy material at the time
of surgery is an important part of the procedure.
e. True. Surgery offers the opportunity to look for root
fractures or perforations.
9. a. True. The introduction of ultrasonic techniques has
been a major advancement in endodontic surgery.
b. True. Care needs to be taken to use ultrasonic vibra-
tion at the lowest effective power. If it is used at too
high a power, for long periods or in thin roots, then
fracture may occur.
c. False. Ultrasonic vibration produces heat. Water
spray cools the tip as well as removing debris.
d. True. One of the major problems of instrumenta-
tion with steel burs was that it was not possible to
get the retro-preparation in the long access of the
root.
e. False. Ultrasonic tips are much smaller than con-
ventional burs and handpieces; therefore, less space
is required.
10. a. False. Pain from reversible pulpitis is short lasting.
b. True. The pulp does not contain proprioceptive re-
ceptors; consequently pain is difficult to localise
until the inflammation involves the periodontium.
c. False. See (b).
d. True. See (a).
e. True. The inflammation is contained within the
tooth; therefore, there are no changes to be seen in
the periodontium.
11. a. True. Small flexible files help to prevent blockage
without overenlarging the foramen.
b. False. The purpose of a patency file is to clear the
foramen, not enlarge it.
c. True. This is the main purpose of the patency file.
d. False. A patency file should be used with a gentle
touch to avoid overenlargement of the foramen.
84
Master Dentistry
e. True. Maintaining patency is important to ensure
that there is adequate exchange of irrigant and disinfectant around the apical terminus.
12. a. True. Ease of handling is an important property.
b. False. Root canal filling materials should not absorb
moisture as this could lead to expansion or contamination.
c. False. Expansion on setting could predispose to root
fracture.
d. False. It is important to be able to remove root filling
materials easily for ease of retreatment and post
space preparation.
e. True. This is important, as staining of tooth struc-
ture leads to an unaesthetic appearance for the patient.
13. a. False. Silver points do not seal the canal laterally or
coronally and may cause staining.
b. True. Lateral condensation is a well-recognised
technique as it seals the root canal laterally and
coronally.
c. True. Continuous wave is a simplified version of verti-
cal condensation of gutta-percha and has the potential to seal lateral canals as well as the main canal
system.
d. True. Such devices have been shown to provide an
adequate canal seal. Popular examples include
Thermafil and 3D GP.
e. False. A poorly fitting single gutta-percha cone will
not seal the root canal laterally or coronally.
14. a. False. A correctly curved instrument should not
have any sharp bends in it; these would increase
stress in the instrument. Therefore, it will not
predispose the file to fracture.
b. False. Sterilising instruments is an essential part
of root canal therapy; it does not weaken them.
However, root canal instruments should not be
re-used.
c. False. Jumping between different sizes of instru-
ment is not recommended; they should be used in
an ordered sequence.
d. True. A good quality-control programme is an
essential part of endodontic therapy.
e. True. Root canal instruments should never be
forced as they can break.
15. a. True. Irrigation and recapitulation with a small file
will help to reduce blockage as a result of dentine
chips.
b. True. Attempts to get past a root canal blockage
may result in the file going offline and perforating
the root.
c. True. Lubrication helps to keep debris in solution
and emulsifies pulp tissue in vital cases.
d. False. Coronal two-thirds enlargement improves ir-
rigation and, therefore, helps reduce the incidence
of canal blockage.
e. True. Canal blockage is avoidable if sufficient care is
taken in canal preparation.
SINGLE BEST ANSWER QUESTION ANSWERS
1. Answer C. Parallax views are particularly helpful. A
single PA would not provide any information about the
involvement of adjacent teeth and may not capture a
root fracture. A limited field CBCT may be indicated but
only after initial plain film radiography and if diagnosis
or management would be affected.
2. C
3. B
4. A
5. A
6. C
7. D
PICTURE QUESTIONS ANSWERS
1. There has been pulp chamber obliteration in the mid
third of the root most likely as a result of dental trauma,
the dentine deposition is likely to be irregular in nature
and it is often possible to bypass the apparent blockage.
The canal appears wide coronally (consistent with the
age of trauma) and patent beyond the blockage and
amenable to root canal treatment.
2. The coronal access may be difficult through an all ceramic crown; the morphology of the crown may be different to the underlying anatomy. The canal has significant curvature in its apical third and there is a higher
risk of canal transportation, ledging and instrument
fracture. Careful straight-line access is required, ideally
with good light magnification. Initial glide path should
be developed with precurved flexible stainless steel instruments or NiTi glide path files to reduce the risk of
transportation. Superflexible heat-treated NiTi rotary or
reciprocatory instruments will allow canal preparation
at reduced risk of procedural error
3. Initially the patient’s pain should be relived, the UR1
should have the existing RCT removed as a priority, disinfected with sodium hypochlorite and then dressed
with a non-setting calcium hydroxide. Then, teeth
planned for re-RCT should have any existing restorations removed, caries removed and each assessed for
restorability. Working composite cores are helpful.
Gutta-percha can be removed with hand or rotary instruments with or without the use of solvent. Re-RCT
can be carried out prior to placement of cores 6 fibre
posts prior to preparation for new crowns. The status of
the remaining upper anteriors on the left side should
also be considered.
4. This patient has dentinogenesis imperfecta (without osteogenesis imperfecta), as do their children. Further investigation in the form of a CBCT scan is indicated as to
whether or not the teeth with chronic apical abscesses
are amenable to either orthograde or retrograde endodontics. A larger volume scan could be justified as
there is strong likelihood of multiple dental abscesses in
other areas of the mouth. If not possible then this can be
used to plan for replacement with dental implants.
5. This is most likely a periapical granuloma or infected
odontogenic cyst. Stages for apicectomy – consent, local
anaesthetic, raising of mucoperiosteal flap, osteotomy
site, curettage of the lesion, root end resection, root end
filling, irrigation, compression of flap, sutures, post-op
advice (bleeding, diet, analgesics, emergency contact
information) and specimen sent for histopathology.
Review should be for suture removal, and at 1 year.
2 • Endodontics
85
6. The challenge here is removal of what is a very long
post; this would involve sectioning the crown and either
trying to vibrate using ultrasonics, pull out the post or
alternatively trephine around it with a Masserann kit.
Orthograde root canal treatment could then be carried
out followed by post-crown restoration. Surgery is an
option but would potentially leave the tooth in a weakened state. Removal of the ideal 3 mm of root end would
leave little space for a root end filling and would leave the
tooth with a limited amount of bone support. Extraction
and RBB or implant are also possible treatment options.
SHORT NOTES ANSWERS
1. Reactionary and reparative dentine are both types of
tertiary dentine, as distinct from physiological secondary
dentine. Reactionary dentine is a response to a mild noxious stimulus; reparative dentine is deposited directly
beneath the path of the injured dentinal tubules as a
response to strong noxious stimuli.
2. Pulp sensitivity tests can be divided into thermal and
electrical. Their purpose is to identify the offending
tooth, although it is usual to start with a tooth expected
to respond within normal limits in order to establish a
baseline. Thermal tests are usually the most useful as
they give an indication as to whether the pulp is alive
and how healthy it is. Cold tests include EndoIce or ethyl
chloride spray on a cotton pledget, ice or dry ice; hot
tests include hot gutta-percha or hot water. Electric pulp
tests are less useful as, although they provide an indication as to whether there is vital nerve tissue in the tooth,
they do not give an indication of different levels of degeneration.
3. Cracked tooth syndrome is an increasingly common
clinical problem and can be very difficult to diagnose in
its early stages. Pain is usually short lasting but can be
very sharp, especially on release of the biting pressure. A
plastic bite stick (tooth sleuth) may be used over individual cusps in an effort to find the offending one. Lower
second molars and upper premolars are frequently affected. Extensively cracked teeth require extraction; if
the crack is less severe, then extracoronal restoration
may prevent further progression.
4. Balanced forces is a method of instrument rotation introduced by Roane in 1985. The initial technique involved
rotating the instrument 90° clockwise to set the flutes
and then rotating 180° anticlockwise while maintaining
apical pressure to cut dentine. It is efficient and has been
shown to maintain a central canal position even around
moderate curvatures. It is usual nowadays to use a
slightly less aggressive technique, which involves a 60°
clockwise rotation and 120° anticlockwise rotation with
the apical pressure being just sufficient to prevent the
instrument backing out of the canal.
5. Electronic apex locators are used to help to determine
canal length. They are accurate about 85% of the time;
however, canal length should be confirmed with a radiograph. Problems can occur with the accuracy of
electronic apex locators if the canal is very wet and
there is fluid in the pulp chamber. These may lead to
short circuiting with files in other canals or to metallic
restorations. Further problems may be encountered if
the file size does not closely resemble the width of the
root canal.
Reference
Roane et al. The ‘Balanced Force’ Concept of Instrumentation of Curved
Canals. J Endod. 1985;11:203–211.
3
Conservative Dentistry
CHAPTER OUTLINE
Overview, 86
3.1 Examination, Diagnosis and Treatment
Planning, 86
3.2 Caries, 86
3.3 Resin Bonding, 91
3.4 Materials for Direct Restorations, 92
Overview
This chapter reviews current methods for the restoration
and replacement of teeth using direct and indirect restorations. These contemporary techniques have evolved more or
less simultaneously with developments in dental materials.
The selection, properties, advantages and disadvantages of
various materials are discussed.
3.1 Examination, Diagnosis and Treatment Planning
LEARNING OBJECTIVES
You should:
• describe the relevant anatomy of enamel and dentine
• assess the risk factors for the progression of dental caries
• outline the strategies for caries risk assessment and
management
• describe the principles of cavity preparation and
finalisation
• be familiar with the principles of resin bonding and
adhesive dentistry.
Examination of patients with a view to carrying out conservative procedures should follow the general principles
for dental examination and history taking; treatment
should address the underlying aetiology of the pathological
process (Table 3.1).
RELEVANT ANATOMY
Enamel
Enamel has a rigid and highly crystalline structure, which
confers a hard outer coating to teeth. It has translucent and
opalescent properties important to the appearance of a
tooth. It is largely made up of crystals of hydroxyapatite
(95–98% by mass) which makes enamel prone to acid demineralisation, from both caries and erosion. It is also brittle and liable to cracking, especially when unsupported by
dentine, which provides both resilience and toughness. The
inorganic component comprises 86–95% hydroxyapatite
86
3.5 Tooth Surface Loss, 94
3.6 Indirect Restorations, 95
3.7 Biomechanical Considerations, 98
3.8 Bridges, 107
Self-Assessment: Questions, 110
Self-Assessment: Answers, 113
by volume. The organic component comprises 1–2%, while
water contributes 4–12%. Enamel prisms are the main
structural units and are generally orientated at 90° to the
external surface of the tooth.
Dentine
Dentine comprises 45–50% inorganic hydroxyapatite
crystals, with 30% organic matrix and 25% water by volume. It is vital, moist, flexible and permeable and its colour varies with its value tending to increase with age.
Dentine is slowly deposited throughout a patient’s lifetime; this is referred to as secondary dentine. Tertiary reactionary dentine, which is deposited much more quickly,
has a more irregular structure. It is deposited in response
to chronic low-grade trauma such as attrition, erosion,
abrasion, progressive caries and tooth preparation.
Dentine consists of:
n
intertubular dentine: the primary structural component, comprising hydroxyapatite embedded in a collagen
matrix
n
peritubular dentine: which provides a collagen-free
hypermineralised tubular wall
n
dentinal tubules: filled with odontoblastic processes,
which form the interface between the dentine and the
pulp.
No specific nerve endings lie within the tubules; therefore
dentine sensitivity and its pathological derivative, hypersensitivity, have been hypothesised to arise from fluid movement within the tubules. This is called the hydrodynamic
theory of dentinal sensitivity and explains how certain
stimuli, such as thermal changes and those creating osmotic gradients, can result in painful sensations. Persistent
sensitivity can lead to peripheral nerve sensitisation and, as
a result, relatively low-grade stimuli can elicit an exaggerated painful response.
3.2 Caries
In order to understand the management of dental caries,
we must begin by understanding how the caries process is
initiated and progressed (Fig. 3.1). Caries is a disease of the