Is Cryotherapy Beneficial After Surgical Removal of Impacted Lower Third Molars? - A Randomized Split Mouth Clinical Trial
Phase: NA
Conditions: Cold Therapy
Sponsor: Henrique Tedesco

FEDERAL UNIVERSITY OF RIO GRANDE DO SUL 
INTEGRATED RESIDENCY IN ORAL HEALTH 
ORAL AND MAXILLOFACIAL SURGERY 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
IS CRYOTHERAPY BENEFICIAL AFTER SURGICAL 
REMOVAL OF IMPACTED LOWER THIRD MOLARS? – 
A RANDOMIZED SPLIT MOUTH CLINICAL TRIAL 
 
 
 
 
 
 
 
 
 
 
Identification: NCT ID not yet assigned 
 
 
 
 
 
 
 
 
 
 
December 30th, 2025 

ABSTRACT 
 
Third molar extraction is a common oral surgical procedure often associated 
with postoperative pain, edema, and functional limitation. Effective postoperative 
management plays a key role in minimizing morbidity and promoting patient comfort. 
Strategies such as cryotherapy may contribute to improved recovery and quality of 
life after surgery. Objective: to investigate the effects of cryotherapy on postoperative 
outcomes (pain intensity, edema, trismus and quality of life) following mandibular third 
molar extraction. Materials and Methods: This study was designed as a randomized 
split-mouth clinical trial. The sample consisted of 17 patients (34 mandibular third 
molars with equivalent levels of impaction) who underwent bilateral surgical 
extraction. The surgical sites were allocated into two groups according to 
postoperative care: Group A (control side—without cryotherapy) and Group B (test 
side—with postoperative cryotherapy using ice packs). All intraoperative and 
postoperative procedures, instructions, and medications were identical for both 
groups. Patients were evaluated for pain intensity, trismus severity, presence of 
edema, and quality of life for up to seven days postoperatively (D7). The evaluator 
was aware of the postoperative intervention applied. Repeated-measures ANOVA 
was used to analyze each outcome variable, and associations between continuous 
variables were assessed using Pearson’s correlation test. Statistical significance was 
set at 5% (P < 0.05). Results: Overall, postoperative pain intensity was lower in 
patients who received cryotherapy. Group A reported significantly higher pain 
intensity on postoperative days 1 and 3. No signs of trismus were observed in Group 
B at the end of the follow-up period, whereas Group A presented restricted mouth 
opening at D7. Both groups exhibited edema on postoperative day 2 (D2); however, 
complete regression of edema by D7 was observed only in Group B. Additionally, a 
significant association between pain intensity and trismus severity was identified in 
Group A at D7. Quality-of-life assessment revealed significant differences in three 
questionnaire items favoring Group B, including greater perceived improvement, 
better mouth opening, and reduced difficulty sleeping. Conclusion: The findings 
suggest that postoperative cryotherapy is effective in reducing pain intensity and 
trismus following mandibular third molar extraction. Moreover, this physical therapy 
modality appears to enhance pain tolerance and patients’ self-perceived healing. 
 
Key-words: Third Molar; Cryotherapy; Surgery, Oral 

SUMÁRIO 
SUMMARY 
1 INTRODUCTION ...................................................................................................... 4 
2 OBJECTIVES ........................................................................................................... 5 
2.1 GENERAL OBJECTIVES ...................................................................................... 5 
2.2 SPECIFIC OBJECTIVES ....................................................................................... 5 
   3 JUSTIFICATION ....................................................................................................... 5 
4 MATERIALS AND METHODS .................................................................................. 6 
4.1 SAMPLE CALCULATION ...................................................................................... 6 
4.2 ETHICAL ASPECTS .............................................................................................. 6 
4.3 TYPE OF STUDY .................................................................................................. 6 
4.4 SAMPLE ................................................................................................................ 7 
4.5 SURGICAL TECHNIQUE ...................................................................................... 7 
4.6 POSTOPERATIVE CARE ..................................................................................... 8 
4.7 STUDY VARIABLES ............................................................................................. 9 
4.8 STATISTICAL ANALYSIS ................................................................................... 10 
5 RESULTS ............................................................................................................... 10 
5.1 POSTOPERATIVE PAIN INTENSITY ................................................................. 10 
5.2 TRISMUS ............................................................................................................ 12 
5.3 EDEMA ................................................................................................................ 13 
5.4 QUALITY OF LIFE............................................................................................... 14 
6 DISCUSSION ......................................................................................................... 14 
7 CONCLUSION ........................................................................................................ 16 
8 REFERENCES ....................................................................................................... 17 
APPENDIX ............................................................................................................. 19 

 
 
      
4 
 
1 INTRODUCTION 
 
Oral surgical procedures of any kind, from the extraction of a retained third 
molar to the rigid internal fixation of a mandibular fracture, may cause postoperative 
complications such as edema, trismus, and pain and interfere with the quality of life of 
patients. These aspects are important physiological responses but when observed at 
high intensity and duration, they may harm this critical period of surgical recovery. 
No consensus in the literature allows defining a gold-standard protocol as 
postoperative conduct but most surgeons try to control the complication factors with 
drug therapies, from analgesics to anti-inflammatory drugs (steroidal or not).1 Overall, 
there is an underestimating of non-pharmacological maneuvers2,3 such as an 
effective instruction on the need for absolute rest and oral cavity hygiene, as well as 
cryotherapy, which is a common approach in the health field although often used 
empirically. The topical application of ice reduces the temperature of the skin and its 
adjacent tissues by 2 to 4 cm in depth, resulting in cold-induced neuropraxia and 
decreasing the threshold of nociceptor activation and the speed of conduction of 
nerve 
pain 
signals.4 
This 
consequentially 
reduced 
blood 
flow 
through 
vasoconstriction, which may decrease the intensity of the inflammatory response of 
soft tissues to trauma.5 
The benefits of cryotherapy are not a consensus in the literature and this 
situation is often justified by the lack of a solid and effective treatment protocol, 
although the most used approach is applying ice to the region every 30 minutes in the 
first days.6 This conflict in the evidence can be seen in publications with results 
indicating that cryotherapy has no significant influence on edema and trismus7, while 
other aspects report a positive increase in pain relief and other postoperative 
symptoms. The major unknown is still the actual influence of this therapy on pain 
levels.6 
Considering the extensive use of cryotherapy in third molar surgeries and the 
lack of agreement of scientific findings on its effectiveness, the present study 
evaluated whether the use of ice has a beneficial potential capable of reducing the 
intensity and duration of pain, as well as reducing edema and trismus and improve 
the quality of life.  
 
 
 
 

 
 
      
5 
 
2 OBJECTIVES 
 
2.1 GENERAL OBJECTIVE 
 
To investigate the effects of cryotherapy on postoperative outcomes (pain 
intensity, edema, trismus and quality of life) following mandibular third molar 
extraction  
 
2.2 SPECIFIC OBJECTIVES 
 
- Measure the interincisal distance (in millimeters) on postoperative days 0, 
2, and 7. 
- Evaluate trismus by measuring the maximum interincisal opening with the 
patient seated and the tragus–ala plane parallel to the ground, using the average of 
three consecutive mouth openings. 
- Compare the levels of postoperative discomfort associated with anesthetic 
agents using a visual analog scale (VAS). 
 
 
3 JUSTIFICATION 
Cryotherapy with ice is widely used in the postoperative period as a non-
pharmacological strategy for controlling these signs and symptoms, due to its 
potential to reduce local blood flow, inflammatory response, and nerve conduction. 
However, despite its routine use in clinical practice, there is still controversy in the 
literature regarding the actual effectiveness of ice application after third molar 
extraction. Therefore, it is relevant to scientifically evaluate the effects of 
postoperative cryotherapy following this procedure in order to support evidence-
based clinical decisions and optimize postoperative recovery management. 

 
 
      
6 
 
4 MATERIALS AND METHODS 
 
The study is designed as a randomized, controlled, split-mouth clinical trial. 
Patients that don’t receive cryotherapy are defined as group A (GA), while patients 
receiving cryotherapy with ice are classified as group B (GB). 
4.1 SAMPLE CALCULATION 
The sample size was calculated based on a previously published study8, 
which adopted a significance level of 5% (p < 0.05), a statistical power of 90%, and 
a margin of error of 5%, resulting in a required sample size of 40 surgical sites. In 
the baseline study, pain perception during local anesthesia was compared between 
acupressure and cryotherapy using a split-mouth design involving 20 patients. 
Similarly, the present study employed a split-mouth design, with procedures 
performed on 20 patients, yielding a total of 40 surgical sites. 
 
4.2 ETHICAL ASPECTS 
 
The study will be conducted in accordance with the Guidelines and Regulatory 
Standards of the National Health Council (Resolution No. 466/12), which establishes 
the ethical guidelines for research involving human subjects in Brazil. 
The benefit of participating in the research is indirect, as the patient contributes 
to the discovery of scientific evidence that will serve as the foundation for safer and 
more effective treatment. 
Patient personal data, collected through direct contact with the participant during 
the study, will not be disclosed, and confidentiality will be ensured for all participants. 
This data will be stored in a Google Drive spreadsheet linked to the researchers’ 
institutional email address. 
Surgical procedures and the participant's participation in the project may 
present certain surgical and confidentiality risks inherent to participation, which are 
outlined in the Informed Consent Form (APPENDIX A). 
This study was approved by the Research Ethics Committee of the Faculty of 
Dentistry and by the CEP (CAAE: 17700019.7.0000.5347) of the Federal University 
of Rio Grande do Sul (UFRGS; Porto Alegre, RS, Brazil). 
 
4.3 TYPE OF STUDY 
 
The study is a randomized, controlled, split-mouth clinical trial. 
 
 
 

 
 
      
7 
 
4.4 SAMPLE 
 
The sample selection consisted on patients referred to the Federal University 
of Rio Grande do Sul’s Dentistry School. The selected patients require bilateral 
extraction of lower third molars under local anesthesia in two different surgical times. 
There will be no change to the routine care for patients volunteering in the study. The 
surgical procedures will be performed by the research team responsible for this 
study. Participants of both sexes, aged 18 to 50 years, were included in the study if 
they presented an indication for bilateral surgical removal of mandibular third molars 
in similar positions according to Pell and Gregory classification.9 Additional inclusion 
criteria comprised the absence of systemic comorbidities, local conditions free of 
inflammatory or infectious processes, no history of allergy to the prescribed 
medications, and no recent or chronic use of antibiotics, anti-inflammatory drugs, 
corticosteroids, or analgesics. Participants were excluded from the study if they used 
medications other than those prescribed by the surgeon, failed to provide the 
required data, belonged to Group A (control) but used postoperative ice packs, or 
belonged to Group B (test) and did not use ice packs as instructed by the 
researchers. There were three dropouts due to noncompliance with postoperative 
recommendations and the use of non-prescribed medication, resulting in 34 
procedures performed in 17 patients. 
Postoperative consultations were conducted for follow-up, suture removal, and 
the evaluation and treatment of any potential postoperative complications. 
The selection of the control group and experimental groups were determined 
by a simple randomization in the immediate postoperative period. One surgical site 
didn’t receive cryotherapy (GA), while the other site received cryotherapy with ice 
(GB). 
 
4.5 SURGICAL TECHNIQUE 
 
All surgical procedures were performed by a team composed of two trained 
and calibrated surgeons, exclusively during the morning period. Each patient was 
treated by the same surgeon for both surgical procedures. A standardized surgical 
protocol was applied in all cases and included anamnesis, clinical examination, and 
collection of vital signs (blood pressure and heart rate). 
Patients were positioned in the dental chair and underwent antisepsis of the 
oral cavity and adjacent extraoral region using 0.12% aqueous chlorhexidine. After 
establishment of a sterile surgical field, local anesthesia was administered via inferior 

 
 
      
8 
 
alveolar, lingual, and buccal nerve blocks using 2% mepivacaine with 1:100,000 
epinephrine. A mucoperiosteal incision was made extending from the retromolar area 
to the mesial aspect of the second molar, with a relaxing incision in an open L-shaped 
design to expose the underlying bone. Under copious saline irrigation, ostectomy was 
performed in the distobuccal region using a #6 round bur, and odontosection was 
carried out when necessary using a 702 surgical bur. Following tooth removal, wound 
closure was achieved with simple interrupted sutures using 4-0 silk sutures. 
Prior to the first surgical procedure, maximum mouth opening was measured in 
millimeters using a measuring tape to determine the interincisal distance. In cases 
where maxillary or mandibular incisors were absent, the occlusal edges were used as 
reference points. This measurement was used as a baseline parameter for 
comparison between procedures.  
 
4.6 POSTOPERATIVE CARE 
 
In the immediate postoperative period following the first surgical procedure, the 
allocation of postoperative care—with or without cryotherapy—was randomized using 
a simple draw. Allocation was determined by the selection of a folded paper indicating 
Group A or Group B and was supervised by a third party to ensure allocation 
concealment. When the first surgical site of a patient was assigned to Group A 
(control), the contralateral site in the second surgical procedure was assigned to 
Group B (test), and vice versa. 
Group A (control) did not receive postoperative cryotherapy. Group B (test) 
was instructed to apply standardized ice packs (11 × 8.5 × 1 cm), provided by the 
research team, positioned diagonally to cover both the mandibular angle and the 
cheek on the operated side. Cryotherapy was initiated immediately after surgery 
under surgeon supervision and continued for the first 12 postoperative hours, 
consisting of 30-minute applications followed by 30-minute intervals (total of 12 
applications). During the intervals, patients were instructed to store the ice packs in a 
freezer until the next application. 
All participants received identical pharmacological postoperative instructions 
(APPENDIX B) for both interventions, including paracetamol1 1 g every 6 hours for 3 
days and mouth rinses with 0.12% aqueous chlorhexidine digluconate twice daily for 
7 days, starting on the day following surgery. In cases of persistent pain, trismus, or 
edema that significantly interfered with daily activities despite the use of prescribed 
analgesics, patients were instructed to use rescue medication consisting of codeine 
30 mg every 4 hours as needed. 

 
 
      
9 
 
 
4.7 STUDY VARIABLES 
 
The outcome variables of this study were postoperative pain, trismus, local 
edema, and changes in quality of life following mandibular third molar extraction. 
Postoperative assessments were performed by the research team, consisting of two 
calibrated surgeons and one supervising professor, on postoperative days 0 (day of 
surgery), 2, and 7. The following evaluation protocols were applied: 
a) Pain assessment: postoperative pain was assessed using a visual analog 
scale5 (VAS– APPENDIX C) ranging from 0 to 10, in which 0 represented no pain, 1–
3 mild pain, 3.1–6 moderate pain, and 6.1–10 severe pain. Patients completed the 
scale at home daily until postoperative day 7. 
b) Trismus assessment: trismus was evaluated by measuring maximum mouth 
opening with the patient seated and the tragus–ala plane parallel to the ground. 
Patients were instructed to open their mouths three consecutive times, and the mean 
value was recorded. Measurements were obtained as the interincisal distance in 
millimeters using a measuring tape. In the absence of maxillary or mandibular 
incisors, the occlusal edges were used as reference points. Measurements were 
recorded on postoperative days 0, 2, and 7. 
c) Edema assessment: facial edema was measured using the method 
described by Gabka and Matsumura.10 Three linear facial measurements were 
obtained in millimeters with a measuring tape: tragus to pogonion, tragus to oral 
commissure, and lateral canthus to mandibular angle. The mean of these three 
measurements was calculated to quantify edema. This assessment was performed 
preoperatively and on postoperative days 2 and 7. 
d) Quality of life assessment: quality of life was evaluated using a 
questionnaire adapted from the OHIP-1411 (APPENDIX D), consisting of 14 
dichotomous (yes/no) questions addressing daily functional limitations. The 
questionnaire included items related to chewing and swallowing ability, dietary 
changes, alterations in taste, mouth opening, voice changes, speech intelligibility, 
facial appearance, sleep disturbances, and ability to perform work-related activities. 
The questionnaire was provided to participants on the day of surgery and completed 
on postoperative days 0, 2, and 7. At the conclusion of the evaluation period following 
the second intervention, participants also answered the question: “Which intervention 
did you perceive as resulting in greater postoperative improvement?”  
 

 
 
      
10 
 
4.8 
STATISTICAL ANALYSIS 
 
Data normality was assessed using the Kolmogorov–Smirnov test. Parametric 
analyses were applied to compare groups (control side vs. test side) and 
postoperative time points (from day 0 to day 7). Continuous variables, including pain 
intensity (VAS scores), maximum mouth opening (mm), and facial edema (mm), were 
expressed as means ± standard deviation (SD). 
A two-way repeated-measures analysis of variance (ANOVA), followed by 
Fisher’s least significant difference (LSD) post hoc test, was used to evaluate the 
main effects of time and treatment, as well as their interaction, for pain intensity, 
trismus, and edema. Pain reports were also qualitatively analyzed based on the 
frequency distribution of pain categories (no pain, mild pain, moderate pain, and 
severe pain) for both groups. 
Associations between pain intensity and trismus or edema were assessed 
using Pearson’s correlation coefficient. Trismus and edema were additionally 
evaluated using the formulas (Baseline − Postoperative) and (Postoperative − 
Baseline), respectively. Qualitative data related to quality of life were presented as 
percentages. 
All statistical analyses were performed using SPSS software (version 20.0; 
IBM Corp., Armonk, NY, USA). Statistical significance was set at P < 0.05. 
 
5 RESULTS 
 
 
5.1 POSTOPERATIVE PAIN INTENSITY 
 
The analysis demonstrated significant main effects of treatment (F(1,16) = 5.063, 
p = 0.039) and time (F(7,112) = 6.254, p < 0.001) on postoperative pain intensity (Table 
1). Overall, pain scores were higher in Group A than in Group B (2.0 ± 1.2 vs. 1.3 ± 
1.1; F(1,16) = 5.063, p = 0.039). 
 
 
 
 
 

 
 
      
11 
 
-1 
0 
1 
2 
3 
4 
5 
DAY 
DAY 
DAY 
DAY 
DAY 
DAY 
DAY 
DAY 
Postoperative pain 
CONTROL GROUP 
TEST GROUP 
  
   
  
  
  
  
  
  
  
  
  
  
  
  
   
  
 
 
 
 
 
 
 
Table 1: Average pain levels on every post-operative day for each group. (*) indicates statistical 
differences between control and test groups. 
In Group A, pain intensity was significantly higher on postoperative days 1 
(3.59 ± 0.59; p = 0.014) and 3 (3.24 ± 0.55; p = 0.005) compared with day 0 (1.35 ± 
0.54). No significant differences were observed between day 0 and the remaining 
postoperative time points (p > 0.05). 
On the test side (Group B), no significant differences in pain intensity were 
observed between day 0 and any postoperative evaluation (p > 0.05), suggesting that 
cryotherapy effectively prevented postoperative pain exacerbation. 
A significant interaction between treatment and time was also observed (F(7,112) 
= 2.689, p = 0.013). Pain intensity was higher on postoperative day 1 (Group A: 3.59 
± 0.59 vs. Group B: 2.12 ± 0.42; p = 0.017) and day 3 (Group A: 3.24 ± 0.55 vs. 
Group B: 1.29 ± 0.33; p = 0.007) in the control group compared with the cryotherapy 
group. 
Postoperative pain was absent in 29.4% of control cases and 44.1% of 
cryotherapy cases. Mild pain was reported by 50.0% of participants in Group A and 
47.8% in Group B, whereas moderate pain occurred in 16.9% and 7.4% of cases, 
respectively. Severe pain was reported by 3.7% of control cases and 0.7% of 
cryotherapy cases (Graphics 1 and 2).  
 
 
 
 
 
 
 
Graphic 1: Prevalence of reports of moderate to severe pain (4-10 in visual analogic scale) in the total 
number of reports of pain (1-10 in visual analogic scale) in the control group after day 2 (last day of analgesic 
medication). 
 
29.%
50.%
16.%
3.%
Proportion of pain reports in the control 
NO 
MILD 
MODERATE SEVERE 

 
 
      
12 
 
 
 
 
 
Graphic 2: Prevalence of reports of moderate to severe pain (4-10 in visual analogic scale) in the total 
number of reports of pain (1-10 in visual analogic scale) in the test group after day 2 (last day of analgesic 
medication). 
 
When moderate-to-severe pain reports were isolated and compared with the 
need for rescue medication after suspension of the standard analgesic regimen, 80% 
of participants in Group A required rescue medication, whereas no participant in 
Group B required additional analgesia. 
 
5.2 TRISMUS 
 
Cryotherapy did not significantly affect maximum mouth opening during the 
postoperative period (F(1,16) = 0.006, p = 0.93). However, a significant effect of time 
(F(2,32) = 45.410, p < 0.001) and a significant interaction between treatment and time 
(F(2,32) = 4.703, p = 0.016) were observed. 
Mouth opening decreased on postoperative day 2 compared with baseline in 
both the control group (43.8 ± 8.9 vs. 30.1 ± 12.2; p < 0.001) and the cryotherapy 
group (39.3 ± 8.8 vs. 31.4 ± 7.9; p < 0.01). In Group A, mouth opening remained 
significantly reduced on postoperative day 7 compared with baseline (43.8 ± 8.9 vs. 
37.8 ± 13.6; p = 0.005). In contrast, Group B showed recovery of mouth opening by 
day 7, with values comparable to baseline (39.3 ± 8.8 vs. 40.5 ± 8.5; p = 0.43) (Table 
2). 
 
 
 
 
 
 
 
 
 
 
Table 2: Average of maximal mouth opening values on days 0, 2 and 7 post-op. 
Correlation analysis revealed no significant association between pain intensity 
44.%
47.%
7.%
%
0.7
Proportion of pain reports in the test group 
NO 
MILD 
MODERATE 
SEVERE 
 
 
 
 
 
 
 
 
 
 
  
25 
35
35 
40 
45 
50 
DAY 
DAY 
DAY 
Mouth opening distance (mm) 
CONTROL 
TEST 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

 
 
      
13 
 
and trismus in Group B on postoperative days 2 (r = 0.15, p = 0.54) or 7 (r = 0.11, p = 
0.66). In contrast, a significant positive correlation was observed in Group A on 
postoperative day 7 (r = 0.62, p = 0.005), indicating that greater pain intensity was 
associated with increased mouth opening restriction. No correlation was found on 
postoperative day 2 in Group A (r = 0.30, p = 0.23) (Table 3). 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table 3: Correlation between pain and trismus for control group. 
 
5.3 EDEMA 
 
Time significantly affected postoperative edema (F(2,32) = 10.34, p < 0.001), 
whereas treatment (F(1,16) = 0.516, p = 0.48) and the interaction between factors 
(F(2,32) = 1.533, p = 0.23) did not. 
Both groups exhibited greater edema on postoperative day 2 compared with 
baseline (Group A: 123.0 ± 5.1 vs. 126.2 ± 7.8, p = 0.02; Group B: 123.1 ± 7.1 vs. 
126.3 ± 7.5, p = 0.005). No significant differences were observed between baseline 
and postoperative day 7 in either Group A (123.0 ± 5.1 vs. 126.1 ± 7.8; p = 0.86) or 
Group B (123.1 ± 7.1 vs. 123.5 ± 8.7; p = 0.71), indicating resolution of edema by the 
end of the evaluation period in both groups (Table 4). 
 
 
 
 
 

 
 
      
14 
 
 
 
 
 
 
 
 
Table 4: Average of edema values on days 0, 2 and 7 post-op. 
 
5.4 QUALITY OF LIFE 
 
Among the 14 items of the OHIP-14 questionnaire, only three showed 
significant differences between groups. Regarding mouth opening, 31% of 
participants in Group A still reported difficulty opening the mouth on postoperative 
day 7, compared with 23.5% in Group B. Concerning sleep disturbances, Group A 
showed an approximate 40% reduction in complaints between postoperative days 2 
and 7, whereas Group B demonstrated a reduction of approximately 66.6%. 
When participants were asked which intervention resulted in greater 
postoperative improvement, all patients who underwent the control protocol in the first 
surgery (100%) preferred the cryotherapy intervention. Among those who received 
cryotherapy during the first procedure, 83% also indicated preference for the 
cryotherapy side. 
 
6 DISCUSSION 
 
Cryotherapy was effective in reducing both the intensity and duration of 
postoperative pain episodes, as well as shortening the period of mouth opening 
limitation. Additionally, its use in the postoperative period resulted in a reduced need 
for rescue medication and a greater patient-perceived improvement over time. These 
findings support the consolidation of a cryotherapy protocol, contributing to a more 
predictable postoperative course and improving the management of postoperative 
complications. 
As shown in Table 1, differences in mean pain scores during the first 72 
postoperative hours (from day 0 to the end of day 2) appear to be related to the lack 
of consolidation of the inflammatory response under pharmacological analgesia 
alone. Pain modulation was only stabilized after postoperative day 3 in both groups, 
as also reported by Sukegawa et al.12 However, cryotherapy demonstrated a 
110 
115 
120 
125 
130 
135 
140 
DAY 0 
DAY 2 
DAY 7 
Edema 
CONTROL 
TEST 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

 
 
      
15 
 
beneficial synergistic effect when combined with analgesic medication, resulting in 
lower pain scores during this critical period. In contrast, analgesic therapy alone was 
insufficient to adequately control pain in the control group, which exhibited two 
distinct peaks in pain intensity at 24 and 72 hours postoperatively. 
The benefit of cryotherapy for the test group was particularly evident between 
postoperative days 2 (the last day of analgesic medication) and 3 (the first day 
without medication). During this transition, pain levels increased in the control group 
and remained consistently higher than those observed in Group B, even during the 
consolidation phase of the inflammatory response. These findings suggest that the 
greater differences in pain intensity are directly associated with the absence of 
cryotherapy in the control group, despite the use of analgesics. 
Pain severity distribution over the seven postoperative days further reinforced 
these findings (Graphics 1 and 2). Proportionally, extractions performed without 
cryotherapy were associated with a significantly higher likelihood of moderate-to-
severe pain. From a clinical perspective, the absence of cryotherapy increased the 
probability of requiring rescue medication. This observation is particularly relevant for 
patients with systemic diseases who already require complex pharmacological 
regimens, increasing the risk of drug interactions, as well as for individuals 
susceptible to medication dependence, for whom minimizing drug exposure is 
essential. 
A strong association was also observed between higher pain intensity reports 
and increased requests for rescue medication in the control group. These results 
indicate that failure to use cryotherapy may increase reliance on pharmacological 
interventions to manage postoperative discomfort, which could otherwise be 
mitigated through a simple and low-cost intervention such as ice pack application for 
30 minutes over a 12-hour period. Therefore, the proposed cryotherapy protocol can 
be considered a safe and effective approach that enhances postoperative 
predictability, facilitates complication control, and promotes greater patient 
engagement in self-care. 
Trismus represents a multifactorial postoperative response influenced by 
surgical trauma, including ostectomy, extracellular fluid extravasation, tissue 
hemorrhage, and muscle fiber incision. Given the simultaneous occurrence of these 
factors, significant benefits of cryotherapy are not expected before consolidation of 
the inflammatory response, which explains the absence of intergroup differences 
during the first 72 postoperative hours. However, when comparing immediate 
postoperative measurements with those obtained on postoperative day 7, the control 

 
 
      
16 
 
group exhibited significantly greater mouth opening limitation (Table 2), indicating a 
longer duration of trismus. This finding is supported by the statistically significant 
correlation between pain intensity and trismus observed exclusively in the control 
group (Table 3), suggesting that higher pain levels are associated with prolonged 
mouth opening restriction. These results were further corroborated by the quality-of-
life questionnaire, which revealed greater difficulty in mouth opening among control 
participants.13 
Edema did not show statistically significant differences between groups (Table 
4), consistent with previous reports.14 It is hypothesized that superficial ice application 
may be insufficient to significantly reduce edema due to its limited penetration into 
deeper muscular and facial tissue planes, thereby restricting its vasoconstrictive 
effects. 
Regarding quality of life, three variables demonstrated notable percentage 
differences between groups. First, participants in the cryotherapy group reported less 
difficulty sleeping, likely reflecting the superior pain control achieved with this 
intervention. Second, when asked which procedure resulted in greater postoperative 
improvement, all 11 participants who initially underwent the control protocol reported 
greater improvement following the cryotherapy intervention.15 Participants described 
a reduction in burning or heat sensations and perceived a faster recovery trajectory 
compared with the non-cryotherapy procedure, consistent with the pain outcomes 
shown in Table 1. Third, patients treated with cryotherapy reported less difficulty 
opening their mouths, which appears to be closely related to their lower subjective 
pain perception. As demonstrated in Tables 1 and Graphic 2, the greater reduction in 
pain intensity in the test group was reflected in a lower proportion of participants 
reporting functional limitation. 
 
7 CONCLUSION 
 
Postoperative cryotherapy was effective in reducing pain intensity and 
duration, decreasing the need for rescue medication, and shortening the period of 
mouth opening limitation after mandibular third molar extraction. This intervention 
also improved patients’ perception of recovery and contributed to a more predictable 
postoperative course. However, cryotherapy did not demonstrate a significant effect 
on postoperative edema. 
 
 

 
 
      
17 
 
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PUSHPASANTHY, M. et al. Effectiveness of Aculief acupressure device on 
pain perception during local anesthesia in children: A double-blinded study. Journal 
of the Indian Society of Pedodontics and Preventive Dentistry, v. 41, n. 4, p. 
309–315, 1 out. 2023. 
9. 
PELL, G. J.; GREGORY, B. T. Impacted mandibular thir molars classification 
and modified technique for removal. Dental Digest, v. 39, p. 330-338, 1933. 

 
 
      
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10. 
J GABKA; MATSUMURA, T. [Measuring techniques and clinical testing of an 
anti-inflammatory agent (tantum)]. PubMed, v. 113, n. 6, p. 198–203, 5 fev. 1971. 
11. 
SLADE, G. D. Assessing change in quality of life using the Oral Health Impact 
Profile. Community Dentistry and Oral Epidemiology, v. 26, n. 1, p. 52–61, fev. 
1998. 
12. 
SUKEGAWA, S. et al. What are the risk factors for postoperative infections of 
third molar extraction surgery: A retrospective clinical study-? Medicina Oral, 
Patología Oral y Cirugía Bucal, v. 24, n. 1, p. e123–e129, 1 jan. 2019. 
13. 
BRIGNARDELLO-PETERSEN, R. Inconsistent evidence regarding the 
benefits of cryotherapy in minimizing postoperative complications after third-molar 
extraction. The Journal of the American Dental Association, v. 150, n. 9, p. e134, 
set. 2019. 
14. 
BEECH, A. N.; HAWORTH, S.; KNEPIL, G. J. Effect of a domiciliary facial 
cooling system on generic quality of life after removal of mandibular third 
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QING, Y. C. et al. Survey and analysis of tooth extraction anxiety of dental 
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APPENDIX A – FREE AND INFORMED CONSENT FORM 
 
 
CPPG OR CAAE PROJECT NUMBER: 17700019.7.0000.5347 
 
PROJECT TITLE: "IS CRYOTHERAPY BENEFICIAL AFTER SURGICAL REMOVAL 
OF IMPACTED LOWER THIRD MOLARS? – A RANDOMIZED SPLIT MOUTH 
CLINICAL TRIAL" 
You, ____________________________, are being invited to participate in the 
research entitled “Is Cryotherapy Beneficial After Surgical Removal of Impacted 
Lower Third Molars? – A Randomized Split-Mouth Clinical Trial”, which will be 
conducted at the School of Dentistry of the Federal University of Rio Grande do Sul 
(UFRGS). 
The main objective of this study is to evaluate the real benefits of cryotherapy 
(application of ice packs) on the following postoperative outcomes: edema (swelling), 
pain, trismus (limitation of mouth opening), and quality of life. 
After the surgical removal of impacted mandibular third molars, it is common to 
experience pain, swelling, and difficulty opening the mouth due to tissue manipulation 
during the procedure. Therefore, this study aims to assess whether the application of 
ice packs to the operated area can reduce swelling, pain, and limitation of mouth 
opening. 
Your participation in this study is voluntary, and you may withdraw at any time 
without any harm or prejudice. By agreeing to participate, you consent to complete 
questionnaires related to quality of life, pain, trismus, and edema, as well as to follow 
the postoperative instructions provided by the dentists performing the surgery. You 
also agree to attend postoperative follow-up appointments on the 1st, 2nd, and 7th 
days after surgery. Transportation costs for these visits will be reimbursed. 
The benefits of participating in this study are both indirect and direct. Indirectly, 
you will contribute to the generation of scientific evidence that may support more 
effective postoperative treatments for impacted third molar removal. Directly, you will 
receive surgical treatment for your impacted teeth. 
 
 
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The surgical procedures and participation in the study may involve inherent 
surgical and confidentiality risks, including: 
Surgical risks: Possible complications include paresthesia (abnormal and 
unpleasant sensations such as burning or numbness), oral injuries, infection of facial 
spaces, hemorrhage, and mandibular fracture. If any of these complications occur, 
they will be managed appropriately by the research team, including the prescription 
of neuroregenerative agents, antibiotics, antiseptics, or immediate clinical 
intervention. Contact phone numbers of the researchers are provided for any 
postoperative complications in addition to the scheduled follow-up visits. 
Research participation risks: There is a potential risk of breach of 
confidentiality in specific situations, such as when disclosure is necessary to ensure 
the best possible care, when it is the last available resource, or when a serious 
physical condition requires intervention by other healthcare professionals. To 
minimize this risk, only information strictly necessary for clinical management will be 
disclosed, and only with your consent whenever possible. 
The use or non-use of ice packs after surgery will be determined by random 
allocation (drawing lots). If you are assigned to the cryotherapy group, ice packs will 
be provided by the researchers and should be applied immediately after surgery. The 
ice packs should be applied to the external area corresponding to the surgical site for 
30 minutes, followed by 30-minute intervals between applications, during the first 12 
hours after surgery. 
Postoperatively, you will be instructed to use pain medication (Paracetamol 
500 mg, two tablets every 6 hours for 3 days) and to perform mouth rinses with 
0.12% chlorhexidine solution. These medications will not be provided by the 
researchers and must be obtained through public health units or commercial 
pharmacies. Participants will also be responsible for the cost of a panoramic 
radiographic examination and transportation to the Teaching Dental Hospital of 
UFRGS. Transportation expenses for the day of surgery (day 0) and follow-up visits 
(days 2 and 7) will be reimbursed in cash by the researchers, based on the 
equivalent cost of two public transportation bus fares (round trip) in Porto Alegre on 
the scheduled dates. 
 
 
 
 
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All collected data will be stored for a minimum period of five years. This 
Informed Consent Form must be signed in two copies, one retained by the participant 
and the other by the researchers. 
 
 
Contacts: 
Principal Investigator: Henrique Tedesco - (51) 99960-1939 
Research Assistants: Gabriela Carvalho Massa – Phone: +55 (51) 99784-2610 
Angelo Luiz Freddo – Phone: +55 (51) 3308-5199 / +55 (51) 99257-4571 
 
UFRGS Research Ethics Committee: +55 (51) 3308-3738 
(Office hours: Monday to Friday, 8:00 a.m. to 12:00 p.m. and 2:00 p.m. to 6:00 p.m.) 
UFRGS Ethics Committee Address: Av. Paulo Gama, 110 – Room 317 
 
 
 
The participant declares that they have read and understood the information provided 
and agree to participate in this study. 
 
 
 
______________________  _______________________________ 
Signature         Phone number (landline and mobile) 
 
 
Date: 
/ 
/ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
      
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APPENDIX B – POSTOPERATIVE CARE PROTOCOL 
 
 
• 
Bite firmly on a gauze pad for 20 minutes in case of delayed bleeding. 
• 
Avoid grainy or bran-based foods until the suture is removed. 
• 
Rest, keeping your head elevated above the rest of your body. 
• 
Avoid strenuous physical activity and sun exposure for 7 days. 
• 
Brush your teeth normally 24 hours after surgery. 
• 
Gently brush the surgical site until the suture is removed. 
• 
Do not rinse your mouth for 48 hours. 
• 
Avoid spitting. 
• 
Do not smoke until discharge from surgery. 
• 
Medication: 
• 
Paracetamol 500mg, 2 tablets every 6 hours for three days. 
• 
Rinse with 10mL of 0.12% chlorhexidine digluconate aqueous solution for 1 
minute every 12 hours for seven days, starting 24 hours after surgery. 
• 
In case of persistent bleeding, severe pain, or fever (temperature greater than or 
equal to 37.8°C), contact your doctor. 

 
 
      
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APPENDIX C – VAS FOR ASSESSING POSTOPERATIVE 
 
 
 
 
 
 
 
 
 
 
A 10-cm visual analog scale is used to measure the patient's pain during the stipulated 
periods. It is used postoperatively for each operated side. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
      
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APPENDIX D – OHIP QUESTIONAIRE (ORAL HEALTH IMPACT PROFILE) 
 
 
 
 
 
 
 
 
 
 
 
Pre-op 
Second day post-op 
Seventh day post-op 
Did you have difficulty chewing? 
 
 
 
Did you have difficulty swallowing? 
 
 
 
Did you avoid certain foods? 
 
 
 
Have you lost your sense of taste in certain 
foods? 
 
 
 
Can you open your mouth normally? 
 
 
 
Are you able to taste the food normally? 
 
 
 
Have you noticed any change in your voice? 
 
 
 
Did you have any difficulty speaking? 
 
 
 
Did 
other 
people 
have 
any 
difficulty 
understanding you? 
 
 
 
Has your appearance changed? 
 
 
 
Do you look unusual? 
 
 
 
Are you having trouble sleeping? 
 
 
 
Do you wake up during the night? 
 
 
 
Are you having difficulty performing daily 
tasks?