THE mild form of dens invaginatus, wherein the

THE SILENT KILLER CAUGHT WHITE
HANDED

ABSTRACT

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Palatogingival
groove (PGG) is a developmental anomaly in the maxillary anterior teeth quite
notorious for causing combined periodontic-endodontic lesions. Due to its
inconspicuous occurrence, variable morphology and extent on the root surface,
they promote adherence of plaque and bacteria to levels significant enough to
induce bony destruction adjacent to the teeth with no carious or traumatic
history. Here in this report, a 17-year-old female patient complained of pain
and mobility in maxillary left lateral incisor along with pus discharge for the
past 3 to 4 weeks. Clinical examination confirmed a perio-endo lesion due to
palatogingival groove with respect to left lateral incisor. Endodontic treatment
was completed, followed by surgical exploration of defect after 6 weeks. The
defect was filled with synthetic
osteoconductive bone graft material; sinus tract was excised
followed by odontoplasty of the groove. The combined endodontic – periodontal therapeutic
approach was successful in resolving the pathology with complete healing seen
both clinically and radiographically.

Keywords –
Palatogingival groove, developmental anomaly, lateral incisor,
interdisciplinary approach, bone graft.

INTRODUCTION

According  to the Glossary of Endodontic terms, palatogingival
groove (PGG) is defined as ‘a developmental anomaly in a root that, when
present, is usually found on the lingual surface of maxillary incisor teeth’.(Glossary
Of Endodontic Terms) The term was coined by Lee et al. long back in 1968 (lee
et al) but then other terms like palato radicular groove, disto lingual groove,
corono radicular groove, radiculo lingual groove and syndesmocoronoradicular
groove have been described in literature.2,3add aticle2 It displays a broad
spectrum of morphologic variations with regard to extent, depth and complexity
with distal and mid?palatal surfaces being the most commonly affected Table
1.3,11

Although
there are conflicting speculations concerning etiology which still remains a
mystery, a variety of theories have been put forward. Embryologically, some
authors believe it to be an infolding of enamel organ and the Herwig’s epithelial
sheath before the calcification phase simulating a mild form of dens invaginatus,
wherein the invagination results in a circular opening.8 Others proclaim it
to be an attempt of a tooth to form a supernumerary root.9Recently, A genetic
link also have been proposed by Ennes and Lara 
1 who suggested that a alteration of the genetic mechanisms may
account for the occurrence of groove.

Clinically,
PGG is seen as a V?shaped notch with altered or interrupted cemento?enamel
junction (CEJ). It originates in the region of the cingulum and extends
apically parallel to the long axis of the tooth for a varying distance.10 It
is quite challenging to pinpoint the groove on radiographs due to its
superimposition over the pulp canal space; nevertheless, a series of radiographs
with different horizontal projections can disclose a palatogingival groove as a
radiolucent para pulpal line.12

The
simple occurrence of a palatogingival groove does not point out pathology. In
majority of cases where the epithelial attachment is intact across the groove,
the tooth and the periodontium remain healthy. However on the other hand, if
the attachment is breached, it acts as an suitable milieu for accumulation of plaque
and calculus concealed from the efforts of cleansing thereby predisposing the
tooth to severe localized periodontal destruction. 11 Sometimes the pocket
extends so deep almost up to the apex leading to combined perio-endo lesion. Occasionally
pulpal involvement can communicate to this funnel shaped groove via the
accessory foramina or exposed dentinal tubules. As a result, it turn out to be
difficult to distinguish whether the endodontic or periodontic lesion is primary
in the combined lesion.14

The
prognosis depends on the extent of groove, timely detection and treatment of
defect. Numerous therapeutic options for the management of radicular groove
include curettage of the affected tissues, 15 exclusion of shallow grooves by
saucerization with a round bur16 or sealing deep grooves with a variety of
materials like composite, Glass?ionomer cement or Biodentine17.The therapy is
successful  as long as the infection in
the accessory canal and depth of the groove is efficiently eliminated or
sealed. Surgical intervention is often required in an attempt to achieve new
attachment, if the groove extends beyond the middle?third of the root apex.(art
8) Presented here is a case of PGG in maxillary left lateral incisor treated
successfully with interdisciplinary approach that included a endodontic therapy,
flap procedure with removal of the granulation tissue and careful scaling and root
planning, followed by use of synthetic bone graft to correct the defect.

CASE REPORT

A
17?year?old female patient reported to the Department of Periodontics, Dr. R
Ahmed Dental College and Hospital, Kolkata with a chief complaint of pain, swelling
and mobility of upper left front tooth along with purulent discharge for the
past 3 to 4 weeks. Medical history was noncontributory. Dental history did not disclose
any previous trauma and the patient also did not report any past episodes of
severe pain or swelling with respect to the concerned tooth.

 Clinical Examination showed an intraoral draining
sinus pointing on the labial gingiva between the left lateral incisor and
canine. The tooth was non-carious with no change in the color or texture. A
localized circumscribed swelling of the marginal gingiva was seen in the
palatal aspect, which appeared cyanotic. It overlay a notch that in all likelihood
though concealed appeared to continue as a groove onto the lingual surface. The
overall oral hygiene status of the patient was good however a periodontal
pocket of 10 mm
in depth was recorded in the midpalatal aspect of root of 22 Figure 1. The
tooth was tender on percussion. Thermal and electric pulp testing revealed the
associated tooth to be non-vital in comparison to adjacent teeth which elicited
normal response. In addition to it, intraoral peri-apical radiograph of the
tooth showed a lateral and periapical radiolucency. The findings were
indicative of retrograde pulpitis secondary to periodontal lesion and hence a
diagnosis of pulp necrosis with chronic apical periodontitis with draining
sinus was established.

A
multidisciplinary approach with combination of endodontic and periodontal
treatment was planned for this tooth. In the first/endodontic phase of therapy,
working length was established and chemomechanical preparation was performed in
a step back manner. The canal was cleaned and shaped with stainless steel
K-files (Dentsply- Maillefer, Switzerland) along with copious irrigation with 2.0%
sodium hypochlorite solution. Calcium hydroxide (RC Cal, Prime Dental Products,
India) was packed into the canal as an intracanal medicament and the access
cavity temporarily sealed with intermediate restorative material (Cavitemp,Ammdent,Punjab,India).
A week later, the swelling had reduced in size and the groove was now more evident.
Repeated irrigation of the canal was performed using 5.2% NaClO and Ca(OH)2
placed into the canal for another 1 week. On subsequent visit, after a final
rinse with normal saline, the canal was thoroughly dried with paper points and
obturated with gutta percha (Dentsply- Maillefer, Switzerland) and Calcium
hydroxide sealer (Apexit plus, Ivoclar vivadent, Switzerland). After 4 weeks
interval, the patient was asymptomatic with healing of intraoral sinus tract.

Extension
of the groove onto the root surface along with the presence of probing pocket depth
of 10 mm mandated a surgical intervention as second phase of therapy.
Pre-surgical scrub of both intraoral and extraoral tissues on and around the
surgical site was done with betadine. Local anesthesia was achieved after
administering 2% lignocaine with 1:80,000 adrenaline following which a
triangular flap was raised on the labial surface of lateral incisor. Vertical
releasing incision was given on the distal line angle of canine keeping esthetics
as prime concern. The sinus tract was excised. A full thickness mucoperiosteal
flap was raised on the palatal aspect to expose a bony defect extending
apically along the palatogingival groove (Figure 3a). Thorough debridement of
granulation tissue was performed by meticulous scaling and root planning using
Gracey curettes number 1/2 and 5/6 (Hu-Friedy Manufacturing Co., Chicago, IL).
A complete through and through bucco lingual bone defect was seen as shown in
figure. Subsequently the groove was eliminated by saucerization with round bur.
The bone defect was later filled with synthetic osteoconductive bone graft
substitute consisting of Beta-Tricalcium phosphate (B-OstIN TP Granules,
Particle size 0.355 to .500 mm, Basic Healthcare, India). Finally the flap was
approximated and sutured using 4-0 silk suture and periodontal dressing was
placed. Necessary post-surgical instructions were given. A course of
antibiotics and analgesics (Amoxicillin trihydrate 500mg, metronidazole 400mg,
and ibuprofen 400mg three times a day) was prescribed for 5 days along with
antacid (Omeprazole 20mg once a day). The patient was directed to use
Chlorhexidine mouth rinse (0.2%) for 3 weeks. Sutures were removed after 10
days as the healing was observed to be satisfactory. The patient was put on
maintenance therapy initially for three months and later recalled after six
months for follow up. At 3 months, gingiva appeared healthy and probing depth
further reduced to 4 mm which continued to remain at the same level. Radiographic
evidence showed excellent healing in the periradicular area (Figure 4b).

DISCUSSION –

PGG,
a rare developmental anomaly that begins near the tooth cingulum, extends from
the cementoenamel junction (CEJ) along the root in apical direction for varying
depth and length. Interestingly, the evidence of PGG dates back to prehistoric
and medieval eras between 2500 and 1000 BC.It was first described by Black in
1908 as a radicular groove. Half a century later, a radicular invagination of a
maxillary lateral incisor in a Chinese female was reported by Oehlers.6 However
it was Lee et al. in 1968 who proposed the term PGG to describe a groove in the
palatal aspect of lateral incisor and associated it with localized
periodontitis.3

Incidence

Occurrence
rates for PGG vary from study to study. Rate of affliction was seen to be
higher in lateral incisors (4.4-5.6%) in comparison to central incisors
(0.28-3.4%).1 The first large survey that included 625 extracted maxillary
lateral incisors, conducted by Everett et al., showed a prevalence of less than
2% with 0.5% of PGG extending into the apical area.8  3,168 extracted maxillary incisors were
surveyed by Kogon et al. who reported a total prevalence rate of 4.6% (central
incisors – 5.6 % and lateral incisors -3.4%) wherein 58% extended more than 5
mm from the CEJ and about half of the grooves terminated on the root.9 Conversely
studies by Storrer et al. and Al-Rasheed et al. reported higher prevalence rates
of 9.58% and 10.3% respectively (12,13) Similarly Iqbal et al. stated a
prevalence rate of 10% (6.75% as a coronal groove and 3.25% as an apical groove)
after clinically examining 200 patients. They also found bilateralism in 57.5%
of cases.1 Hou et al. reported a prevalence rate of 18.1% .14 This discrepancy
in prevalence rates may perhaps be due to different diagnostic criteria or
examination techniques (e.g., clinical examination vs. survey of extracted
teeth) or owing to ethnic/racial disparities, which would advocate a genetic liaison.15
Studies with larger samples representing the entire population are required to
obtain more precise prevalence rates.

Classification

S.No

CRITERIA

AUTHOR & YEAR

CLASSIFICATION

1.

Location of
groove

Kogon SL
1986

Distal
Mesial
Midpalatal

2.

Degree of
invagination of the groove towards the pulp cavity

Kogon SL
 1986

Shallow/flat
( 1
mm)
Closed tube

3.

Extent of groove

Goon WW et al
1991

Mild: Gentle
depressions of the coronal enamel that terminate at or immediately after
crossing the CEJ Moderate: the grooves extend some distance apically along
the root surface in the form of a shallow or fissured defect Complex: Deeply
invaginated defects that involve the entire length of the root or that
separate an accessory root from the main root trunk

4

Complexity of
groove

Goon WW et al
1991

Simple grooves
– do not communicate with the pulp and represent only a minor infolding of
the Hertwig’s epithelial root sheath.
Complicated
grooves communicate with the pulp cavity either laterally or apically owing
to their severe depth and extent on the root.

5

Degree of
severity based on microcomputed tomography studies

Gu YC
2011

Type I: the
groove is short (not beyond the coronal third of the root
Type II: the
groove is long (beyond the coronal third of the root) but shallow,
corresponding to a normal or simple root canal
Type III: the
groove is long (beyond the coronal third of the root) and deep, corresponding
to a complex root canal system

 

The
clinically significance of this structural variation is that it serves as an
ideal niche for plaque and microorganisms initiating focal periodontitis.
Nevertheless not all grooved teeth will present a breakdown of the epithelial
attachment, but the presence of the anomaly constitutes a risk factor of which
the dentist should be mindful. An endodontic or periodontal disease or combined
lesion can occur due to PGG resulting in diverse symptoms, including no symptoms
even with advanced lesions32. Most often patients complain of acue 22,29 or dull
intermittent pain 27,28 mobile teeth,30-32 purulent discharge,29-31,33 and/or
gingival swelling.22 Pulp vitality may be retained or lost. Clinically, one can
find a funnel shaped groove often obscured by accumulation of plaque and
calculus, along with loss of epithelial attachment, pocket formation, and
bleeding on probing. Accessory foramina or dentinal tubules along the grooves
have been regarded as the possible pathway between the pulp canal and the
groove.18,26

Radiographically,
a teardrop-like or pear shaped radiolucency can be observed with apical
periodontal widening. As stated earlier, a radiolucent parapulpal line can be
observed extending along the length of the root or it can be obscured due to
superimposition over the root canal.8 Furthermore, the course and extent of the
groove can be delineated by radiographing a gutta-percha cone traced through
the sulcus.34 Recently, cone beam-computed tomography (CBCT) can provide three
dimensional, accurate information that might aid to assess and chalk out
treatment plan.39 However, owing to the amount of radiation exposure the
patients receive, the use of CBCT should be limited to cases where conventional
imaging fails to provide required information.

Diagnosis

The
defect may manifest itself with symptoms of true periodontal disease or as a
true endodontic lesion, or as a combined lesion making diagnosis difficult. Radiolucent
parapulpal lines might aid in diagnosis. However the final diagnosis is done by
detecting a notch in the palatal surface of the crown. Differential diagnosis
includes a crack on the crown, vertical root fracture, dens invaginatus, Tomes’
root etc.,

Discussion
of case

Our
case presented with a Type II palatogingival groove on the distopalatal surface
of left maxillary lateral incisor as it was judged to extend more than
two-thirds the length of the root but was shallow, corresponding to a normal or
simple root canal. The origin of groove on the lingual surface of the crown was
apparent during clinical probing. A deep isolated periodontal pocket (measuring
10mm) strongly suggested a concomitant endodontic and periodontal pathology. The
affected lateral incisor in our case was non-vital; hence immediate measures
were taken to debride and prepare the pulp canals. Conventional lateral
condensation technique was preferred for obturation.

Nevertheless,
treatment cannot be considered absolute unless measures are taken towards eradication
of the anatomical defect.  In 2003,
Kerezoudis et al.40 summarized the treatment interventions needed in cases of
relatively shallow PGG: (i) surgical removal of granulation tissue and
irritants,8 (ii) a gingivectomy and apically positioned flap,3 (iii) surgical
exposure and flattening of the groove by grinding, with or without application
of guided tissue regeneration techniques,44 (iv) positioning a restoration in
the groove,3,7 and (v) orthodontic extrusion of the tooth.12 Amongst the
several known treatment strategies, saucerization or odontoplasty of the groove
is best known to treat simple/shallow grooves. ‘Saucerization’ is one method
for treating the mild form of PGG that involves grinding the groove to the
level of the crestal bone with a rotary cutting and polishing instrument.45

If
the groove extends beyond the apical third of the root, surgical interventions
are required to access the whole groove area and related lesions. For
regeneration of periodontal tissues,

diverse
barrier or graft materials (bone grafts, platelet-rich plasma, and enamel
matrix derivative) have been used, with consideration of the size of the bone
defect and the presence of palatal bone loss. 1) Membrane Attam et al. reported
that a combined technique of bone graft and membrane significantly reduced the
pocket depth compared with cases treated by open flap debridement (Figures 2c
and 2d).35 McClain et al. reported that the attachment level was more
predictable when combined graft/GTR therapy was used.58 Gandhi et al. also
reported the use of synthetic bone graft material in an extensive bone defect
area related to PGG.31

The
treatment approach for teeth with PGG is based on the following three
strategies: (i) complete eradication of microbials, (ii) permanent and thorough
sealing of the root groove that com municates between the root canal and the
periodontium, and (iii) periodontal regeneration and complete healing of the
periodontium.

Prognosis

The
prognosis for a tooth with PGG depends on several factors: the location of the
groove, severity of the accompanying periodontal disease, accessibility to the
defect area, and type of groove (shallow/deep or long/ short).16,62 If the
groove is shallow and terminates before the CEJ (confined to the crown of the
tooth), the prognosis is good. Even in cases initially thought to have poor
prognosis because of the severity and complexity of the disease, several
authors have reported successful treatment outcomes with active and multidirectional
treatment interventions.

Conclusions

Diagnosis
and treatment of palatogingival groove is often dilemmatic and clinically
challenging especially when the clinical presentation increases in severity and
turns complex. Thorough clinical examination of the lingual surface of incisors
should be encouraged as a part of the routine protocol to prevent extensive
involvement in future due to the defect. Deep radicular grooves can predispose
to pulp necrosis and the establishment of combined endodontic periodontal
problems.  If their presence is
suspected, they should be restored either preventively to restrain subsequent
complications; or subjected to regular prophylaxis and the concerned tooth kept
under constant reevaluation. Combined endodontic

And advanced
periodontal regeneration treatment modalities can help us to salvage the
problems associated with this developmental anomaly.