54 J Gandhara Med Dent Sci
July - September 2025
ORIGINAL ARTICLE
:
:
THE ASSESSMENT OF THE DIFFICULTY INDEX OF IMPACTED THIRD MOLAR BASED ON
PEDERSON’S DIFFICULTY INDEX
Muhiyuddin Malik
Karamatullah1, Hammad Wazir2, 3, Tahir Saeed4, Maidah5,
Usman Ul Haq6, Manzoor Khan7
How to cite this article
Karamatullah, Wazir H, Malik M,
Saeed T, Maidah, Haq UU, et al. The
Assessment of the Difficulty Index of
Impacted Third Molar Based on
Pederson’s Difficulty Index . J
Gandhara Med Dent Sci.2025;12(3):54-
Date of Submission: 13-02-2025
Date Revised: 27-05-2025
Date Acceptance: 05-06-2025
1Oral & Maxillofacial Surgeon Health
Department, KPK
2Oral & Maxillofacial Surgeon Health
Department, KPK
3Oral & Maxillofacial Surgeon Health
Department, KPK
4Oral & Maxillofacial Surgeon Health
Department, KPK
5Oral & Maxillofacial Surgeon Health
Department, KPK
6Oral & Maxillofacial Surgeon Health
Department, KPK
Correspondence
7Manzoor Khan, Oral & Maxillofacial
Surgeon Health Department, KPK.
+92-302-8809637
ilyas_khan526@yahoo.com
ABSTRACT
OBJECTIVES
The study aimed to determine the frequency of difficulty indices associated
with impacted mandibular third molars using the Pederson difficulty index
for impacted third molars.
METHODOLOGY
A descriptive cross-sectional study was conducted on 119 patients who
presented at the Department of Oral and Maxillofacial Surgery, Khyber
College of Dentistry, Peshawar, from January to December 2024, with
impacted third molars. A clinical examination of the oral cavity, along with
confirmation via intraoral peri-apical x-rays and orthopantomograms, was
used to assess the molar difficulty index. The difficulty index was further
analysed across different age groups and genders to identify potential effect
modifiers using the Chi-square test. A significance level of p ≤ 0.05 was
considered statistically significant.
RESULTS
The mean age presentation was 33.5±9.12years. Pell and Gregory’s
classification was utilised to assess angulation, depth, and relation with the
ramus. Winters classify impactions according to angulations. The most
common impactions were mesioangular (38 cases, 32%), level A (61 cases,
51%), and class 1 (59 cases, 50%), followed by horizontal (17 cases, 14%),
level B (46 cases, 39%), level 2 (42 cases, 35%). The least common impaction
type was vertical (12 cases, 10%), level C (12 cases, 10%), and level 3 (18
cases, 15%). The Pederson difficulty index was applied to the 119 patients
analysed, revealing that 12 patients (10%) were classified as "very difficult",
26 patients (22%) as "moderately difficult", and 81 patients (68%) as
"slightly difficult".
CONCLUSION
The frequency of difficulty index in removing impacted mandibular third
molars was 10% for very difficult, 22% for moderately difficult, and 68% for
slightly difficult.
KEYWORDS: Molars, Pederson’s Index of Complexity, Trismus
INTRODUCTION
Mandibular third molars represent the most commonly
impacted teeth within the human dentition.1 The
surgical extraction of impacted mandibular third molars
is a frequently conducted minor oral surgical procedure
performed by oral maxillofacial surgeons.2 An
impacted tooth fails to erupt into the dental arch within
the expected timeframe due to factors such as
malposition, lack of space, or physical barriers
obstructing its path of eruption. The indications for
third molar extraction include dental caries,
pericoronitis, cysts, periodontal disease, orthodontic
treatments, tumour formation associated with impacted
third molars, and orthognathic surgery.3 According to
research conducted by Elyse and Rock, mandibular
third molar impaction is found in approximately 73% of
young adults in Europe.4 Typically, mandibular third
molars are expected to erupt between the ages of 17 and
24 years; however, the eruption timing may vary among
different races and genders.5 In males, mandibular third
molars tend to erupt approximately 3-6 months earlier
than in females.6 Additionally, the incidence of third
molar impaction is observed to be higher in females.7
Infections are common in removing the mandibular
third molar following partial or complete removal of
bony impaction. Apart from infection, other
complications include swelling, pain, nerve injuries,
mandibular fracture and space infections. The other
complication is that the fracture of the apical third root
of impacted teeth results in more bone retrieval, leading
to an increased risk of damage to adjacent
structures.8,9,10 Therefore, adequate knowledge
regarding the difficulty index is necessary to reduce
complications and facilitate atraumatic surgical
extraction of impacted mandibular third molars. This
58. https://doi.org/10.37762/jgmds.12-3.
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55J Gandhara Med Dent Sci
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study aims to gather data to evaluate the challenges
encountered and the time required for the surgical
extraction of impacted mandibular third molars.
Additionally, it seeks to determine the optimal timing
for referring patients to oral and maxillofacial surgeons
for effective management. The findings of this research
will help determine whether the surgery should be
conducted in a dental specialist clinic under local
anaesthesia or in a hospital setting. The findings of this
study will be advantageous for dental practitioners as
they endeavour to devise optimal treatment plans aimed
at minimising complications associated with the
removal of impacted mandibular third molars.
METHODOLOGY
This descriptive cross-sectional study was conducted at
the Department of Oral and Maxillofacial Surgery,
Khyber College of Dentistry, Peshawar, from January
2024 to December 2024, utilising a consecutive, non-
probability sampling technique. The study received
ethical approval from the hospital (#403-
AD/R/PG/KCD). Verbal informed consent was
obtained from all participants after they were provided
with a detailed explanation of the study. The total
sample size of 119 was determined using a frequency of
8.4% (10 cases) for the Pederson index (PI), categorised
as "very difficult", while maintaining a 95% confidence
interval and a 5% margin of error, calculated using the
WHO calculator. The study included patients
presenting to the department with impacted lower third
molars, encompassing both genders and aged between
18 and 40 years. Medically compromised patients,
recurrent pericoronitis or infection and previously
attempted third molar extractions were excluded from
this study. Pell and Gregory’s classification was
employed to ascertain the position of the impacted
mandibular third molars. Its horizontal component
indicates the amount of space available between the
ramus and the lower second molar as described below:
Class I: There is sufficient space for a third molar
eruption.
Class II: Space for third molar eruption is inadequate.
Class III: The lower third molar is partially or
completely located within the ramus.
Regarding the vertical component of this classification,
it indicates the vertical relationship of the impacted
third molar crown to the lower second molar crown:
Class A: The crown of the mandibular third molar is at
the level of the occlusal plane.
Class B: The crown of the mandibular third molar is
positioned between the cementoenamel junction (CEJ)
of the second molar and the occlusal plane.
Class C: The crown of the mandibular third molar is
positioned beneath the cementoenamel junction (CEJ)
of the second molar.
Winter’s classification is used to describe the angulation
of the impacted third molar;
Mesioangular: The tooth tilted towards the second
molar.
Distoangular: The tooth tilted away from the second
molar.
Vertical: Long axis of the tooth
Horizontal: The long axis of the third molar is
perpendicular to(900) to the second molar.
Pederson difficulty index: Pederson (1988) introduced
a difficulty index scale designed to predict the
challenges encountered during the surgical extraction of
impacted mandibular third molars. This scale considers
the angulation, depth, and relationship with the ramus
of the tooth, assessed through clinical and radiological
examination, typically utilising an orthopantomogram
(OPG). Each anatomical and radiological characteristic
of the impacted mandibular third molar is assigned a
specific score ranging from 1 to 4, with 1 indicating the
least difficulty and 4 signifying the most challenging
scenario. The difficulty index values are determined
based on the following classification:
Angulation Score: Mesioangular = 1, Horizontal = 2,
Vertical = 3, Distoangular = 4
Depth Score: Level A = 1, Level B = 2, Level C = 3
Ramus Relationship: Class I=1, Class II=2, Class III=3
The overall difficulty index value is calculated by
summing up the scores obtained from the angulation,
depth, and ramus relationship classifications. A total
score ranging from 7 to 10 indicates a "Very difficult"
scenario necessitating general anaesthesia. A total score
between 5 and 7 suggests a "Moderately difficult"
situation. A total score between 3 and 4 signifies a
"Slightly difficult" condition. SPSS 22.0 version
software was utilised for data analysis. The mean and
standard deviation (SD) were calculated for continuous
variables, such as age. Frequency and percentages were
computed for categorical variables, including gender,
classification, depth, ramus relationship, and difficulty
index. To investigate potential effect modifiers, the
difficulty index was stratified by age and gender, and
the Chi-square test was employed. A significance level
of p ≤ 0.05 was considered statistically significant.
RESULTS
The mean age was 33.5±9.12years. In this study, the
gender distribution among 119 patients revealed that 68
(57%) were male, while 51 (43%) were female (Figure
1). Regarding age distribution, 73 (61%) patients were
between 18 and 30 years old, whereas 46 (39%)
patients fell within the 31-40 years age group. The
mean age was 33 years, with a standard deviation of
±9.12 (Table 1). The most common angulation, based
on the Pell and Gregory classification, was
Mesioangular, observed in 52 (44%) cases, followed by
horizontal/transverse in 38 (32%) cases. In terms of
The Assessment of the Difficulty Index of Impacted
56 J Gandhara Med Dent Sci
July - September 2025
vertical classification, the most frequent classification,
according to Pell & Gregory, was level A, observed in
61 (51%) cases, followed by 46 (39%) cases.
Additionally, the most common horizontal
classification based on Pell & Gregory was class 1,
noted in 59 (50%) cases, followed by class 2 in 42
(35%) cases. Regarding the difficulty index among the
119 patients, it was observed that 12 (10%) patients had
a difficulty index classified as "very difficult", 26
(22%) patients had a difficulty index classified as
"moderately difficult", and 81 (68%) patients had a
difficulty index classified as "slightly difficult" (Table
3).
Table 1: Age Distribution of Patients with Impacted Mandibular
Third Molars (n=119)
Age (years) Frequency %Age
18-30 73 61
31-40 46 39
Total 119 100
Table 2: Stratification of Difficulty Index by Age (n=119
Difficulty Index 18-30
Years
31-40
Years
Very
difficult
Yes 07 05
No 66 41
Total 73 46
Moderately
difficult
Yes 16 10
No 57 36
Total 73 46
Slightly
difficult
Yes 49 32
No 24 14
Total 73 46
Total P-Value
12 0.8212
107
119
26
0.9816 93
119
81 0.7808
38
119
Table 3: Stratification of Difficulty Index with Respect to Gender
(n=119)
Difficulty Index
Very
difficult
Yes
No
Total
Moderately
difficult
Yes
No
Total
Slightly
difficult
Yes
No
Total
Male Female Total P-Value
07 05 12
0.9299 61 46 107
68 51 119
15 11 26
0.9489 53 40 93
68 51 119
46 35 81
0.9096 22 16 38
68 51 119
DISCUSSION
Third molars in the mandible are frequently impacted
by human dentition.1 The surgical removal of impacted
mandibular third molars is a commonly conducted
minor oral surgical procedure, usually performed by
oral and maxillofacial surgeons.2An impacted tooth
does not emerge into the dental arch within the
anticipated timeframe due to factors such as
misalignment, inadequate space, or physical
obstructions blocking its path of eruption.3 According
to Elsey and Rock, the impaction of mandibular third
molars affects up to 73% of young adults in Europe.4
Normally, mandibular third molars are observed to
erupt between the ages of 17 and 24 years; however, the
eruption timing may vary among different races and
genders.5 In males, the mandibular third molar tends to
erupt approximately 3-6 months earlier than in
females.6 Moreover, there’s a higher incidence of third
molar impaction observed in females.7 In our study, the
mean age of the participants was 33 years, with a
standard deviation of ±9.12 years. Among the patients,
57% were male, and 43% were female. Furthermore,
the difficulty index analysis revealed that 10% of
patients had a difficulty index classified as "very
difficult", 22% had a difficulty index classified as
"moderately difficult", and 68% had a difficulty index
classified as "slightly difficult". Our study findings
align with those of another study conducted by Kyeong-
Lok Park et al.11 In their study, they analysed the
Pederson index (PI) values. Among 131 extractions, 95
were classified as not difficult (72.5%), 25 were
categorised as moderately difficult (19.1%), and 11
were deemed very difficult (8.4%). In a separate study
conducted by Susarla et al. (SM12), they analysed 762
extractions. Among these, 542 were identified as not
difficult (71.1%), 124 were classified as moderately
difficult (16.3%), and 96 were deemed very difficult
(12.6%). Interestingly, the distribution of difficulty
groups varied among operators (P < 0.000). In a study
conducted by Bali A et al. involving 90 surgical
extractions of impacted mandibular third molars
performed between October 2003 and April 2004, the
authors utilised univariate analysis and multiple linear
regression analysis to identify the most significant
factors.5 The relationship between these variables and
the total intervention time was used to establish a
preoperative index of difficulty. The sensitivi ty and
specificity of this new index were then compared with
the Pederson index. For easy extractions, the sensitivity
and specificity of the new index were found to be 70%
and 75%, respectively, resulting in an overall accuracy
rate of 76%. In contrast, the Pederson index showed a
sensitivity and specificity of 43% and 74%,
respectively, with an accuracy rate of 49%. The positive
and negative likelihood ratios for the Pederson index
were 1.88 and 0.698, respectively. For moderately
difficult extractions, the sensitivity and specificity of
the new index were both 70%, yielding an overall
accuracy rate of 73%. In comparison, the Pederson
index demonstrated a sensitivity and specificity of 52%
and 48%, respectively, resulting in an accuracy rate of
49%. For difficult cases, the new index demonstrated
80% sensitivity and 97% specificity, resulting in a 98%
accuracy rate. In contrast, the Pederson index
demonstrated a 20% sensitivity and 89% specificity,
yielding an overall accuracy rate of 86%. The positive
and negative likelihood ratios for the Pederson index
The Assessment of the Difficulty Index of Impacted
57J Gandhara Med Dent Sci
July - September 2025
were 1.72 and 0.113, respectively. In another study
conducted by Mahdey HM et al.13, involving 1249
panoramic views, 918 (73.5%) were considered for the
study, revealing 1812 impacted third molars (fully or
partially impacted) with complete patient data. The
other studies found a significant difference between the
sexes regarding impacted third molars, with women
exhibiting a higher prevalence of impacted molars at
81.3% (n = 746) compared to men at 18.7% (n =
172).11,12 The prevalence of impacted third molars was
highest among Chinese patients at 63.4% (n = 582),
followed by Malay patients at 28.1% (n = 258) and
Indian patients at 8.5% (n = 78). The most frequent age
group affected was 20-24 years, representing 66% (n =
606) of third molar impactions, while the least frequent
impaction, at 1.5% (n = 14), was observed in the 40-44
years age group.16, 17, 18 The level of difficulty
encountered during the extraction of impacted third
molars was categorised into three categories: very
difficult, moderately difficult, and slightly difficult. The
study offers valuable insights that can aid both general
dentists and maxillofacial surgeons in devising effective
surgical plans for the removal of mandibular third
molars, enhancing patient care and outcomes. By
examining various factors associated with surgical
difficulty, the study contributes to predicting the level
of difficulty involved in removing impacted mandibular
third molars, facilitating better preparation and
management during surgeries.
LIMITATIONS
The study's limitation lies in its relatively small sample
size, which may affect the generalizability of findings
to broader populations. A larger sample size would
provide more robust and representative data. The study
relies on the Pederson scale for assessing surgical
difficulty, which may no longer be considered as
reliable as newer methodologies. This could potentially
introduce bias or inaccuracies in the difficulty
assessment process. Utilising more contemporary and
validated scales would enhance the study's reliability.
CONCLUSIONS
The study found that 69% (n = 632) of cases fell into
the very difficult category, 25% (n = 232) into the
moderately difficult category, and 6% (n = 54) into the
slightly difficult category.
CONFLICT OF INTEREST: None
FUNDING SOURCES: None
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The Assessment of the Difficulty Index of Impacted
Karamatullah - Concept & Design; Data Acquisition;
Drafting Manuscript; Final Approval
Hammad Wazir - Concept & Design; Data Acquisition ;
Drafting Manuscript; Final Approval
Muhiyuddin Malik - Concept & Design; Data Acquisition;
Data Analysis/Interpretation; Drafting Manuscript; Critical
Tahir Saeed - Concept & Design; Data Acquisition;
Data Analysis/Interpretation; Drafting Manuscript; Critical
Maidah - Concept & Design; Data Acquisition; Data
Analysis/Interpretation; Drafting Manuscript; Supervision;
Usman Ul Haq - Concept & Design; Data Acquisition; Data
Data Analysis/Interpretation; Drafting Manuscript; Supervision;
Manzoor Khan - Concept & Design; Data Acquisition; Data
Data Analysis/Interpretation; Drafting Manuscript; Final
Revision; Final Approval
Revision; Final Approval
Final Approval
Final Approval
Approval
AUTHORS CONTRIBUTION
The authors accept responsibility for all aspects of the work
and will ensure that any concerns regarding the accuracy or
integrity of any part are properly investigated and resolved.