This randomized controlled pilot clinical trial evaluated the use of L-PRF membranes for increasing the width of keratinized mucosa around dental implants compared to free gingival grafts. The results showed that both treatments significantly increased the width of keratinized mucosa by 6.0 mm for L-PRF and 7.3 mm for free gingival grafts. However, patients reported significantly less postoperative pain with L-PRF, and it required less surgery time than free gingival grafts. While both treatments were effective at creating keratinized tissue, L-PRF provided advantages of lower morbidity and shorter procedure time for patients.

2. L-PRF for increasing the width
of keratinized mucosa around
implants: A split-mouth,
randomized, controlled pilot
clinical trial.
journal of periodontal research - March 2018
Authors - A. Temmerman | G. J. Cleeren | A. B.
Castro | W. Teughels | M. Quirynen
PRESENTATION BY – DR. MD ABDUL HALEEM

3. • INTRODUCTION
• MATERIAL AND METHODS
• Study design
• Inclusion criteria
• Exclusion criteria
• Participants and randomization
• Interventions
• Primary Outcomes: Width of Keratinized Mucosa and Shrinkage
• Secondary Outcomes: Postoperative Questionnaires and Surgery Time
• RESULTS
• DISCUSSION
• CONCLUSION
• REFERENCES

4. INTRODUCTION
• Clinical oral implant related research is facing many
interesting challenges.
• One of them is to create and maintain stable soft and
hard tissues around osseointegrated oral implants.
• It was suggested in a classic study that a minimum of
2 mm of keratinized mucosa (KM) around natural
teeth is necessary to maintain gingival health.*
Lang NP, Loë H. The relationship between the width of keratinized gingiva and gingival health. J Periodontol. 1972;43:623‐627.

5. INTRODUCTION
• The lack of a sufficient wide zone of KM has been
investigated as a potential contributing factor for
peri-implant disease and therefore might influence
the long-term success of oral implants.*
• However, this topic remains a matter of debate as
in some cases implant soft and hard tissue stability
can be maintained even when KM is lacking.*
Chung DM, Oh TJ, Shotwell JL, Misch C, Wang HL. Significance of keratinized mucosa in maintenance of dental implants with
different surfaces. J Periodontol. 2006;77:1410‐1420.
Brito C, Tenenbaum HC, Wong BK, Schmitt C, Nogueira-Filho G. Is keratinized mucosa indispensable to maintain peri-implant
health? A systematic review of the literature. J Biomed Mater Res B Appl Biomater. 2014;102:643‐650.

6. • Various studies have found a negative influence
of the absence of KM on plaque accumulation.
• Oral implants with a narrow zone of KM (<2 mm)
frequently exhibit significantly higher plaque
scores than those with wider zones of KM.*
• Even a subdivision can be made between KM and attached KM (AKM)*. A statistically
significant higher plaque accumulation and gingival inflammation around implants in the
groups with KM <2 mm and AKM <1 mm was observed. However, this could not be
confirmed in another study.

7. • Interestingly, the presence of an adequate band of KM adjacent to the implant
seems to reduce inflammation, hyperplasia and recession of the marginal peri-
implant soft tissues.
• Furthermore, it might facilitate restorative procedures, improve aesthetics and
enable the patient to maintain an adequate oral hygiene without irritation or
discomfort.
• Because of the controversy in the literature, the decision to augment the width of
KM around oral implants and teeth often depends on the choice of the clinician.

8. • In particular in the lower jaw, a scarce amount of KM can be regularly
encountered.
• A reduced height of the alveolar process due to crestal bone resorption result in
loss of KM due to the reduced distance between the bone crest and “genetically
defined” position of the mucogingival line.
• Notably, in the posterior segments of the lower jaw, a narrow KM might be
related to muscle pull, high frenulum attachments and a shallow vestibule.

9. • Today, the golden standard to augment KM is a
free gingival graft (FGG) harvested from the palate.
• The main problem with this technique is the
morbidity for the patient as it involves a second
surgical site.
• Reported problems following FGG procedure are pain, change in diet, paresthesia,
herpetic lesion, mucocele, arteriovenous shunt and excessive bleeding.
• To overcome this problem, different authors have proposed alternative techniques
and materials to augment keratinized tissue around teeth and oral implants.

10. • Allograft materials, such as the acellular dermal
matrix graft or a human fibroblast-derived dermal
substitute have also been used as an alternative
to the apically repositioned flap + autogenous
graft, although the results reported in terms of
increase in width of KM were significantly inferior.
• The efficacy of these techniques has been recently evaluated in a systematic review.
• From a total of 12 studies, the use of apically repositioned flap and an autogenous
graft resulted in a statistically significant weighted mean difference of 4.5 mm
compared to no treatment.

11. • Recently, a xenogeneic collagen matrix has also been investigated.
• Results from these randomized clinical trials demonstrated a similar increase in
the amount of KM when the xenogenic soft tissue substitute was compared with
autogenous subepithelial connective tissue grafts.
• However, biomaterials unfortunately come at a significant cost and some
biomaterials are not replaced by biological tissues.

12. • Leukocyte and platelet rich fibrin (L-PRF) is a 2nd
generation platelet concentrate, which was
introduced by Choukroun et al in 2001.
• It is obtained by a simple and inexpensive procedure
that does not require biochemical blood handling.
• Its 3-dimensional fibrin network promotes
neovascularization, accelerates wound closing and
fast cicatricle tissue remodeling.
• Platelet concentrates are considered a source of
autologous growth factors that promote cell
migration and proliferation.

13. • Given that L-PRF is produced without using any additive, the fibrin polymerization
occurs in a physiological way, resulting in a similar fibrin network as the one
formed during natural healing.
• Various medical disciplines have used L-PRF in different surgical settings, not in
the least in periodontology, implant dentistry and maxillofacial surgery.
• Moreover, the use of L-PRF in oral surgery seems to be associated with less
postoperative pain and discomfort.
• The aim of this study was to evaluate the potential of the L-PRF membranes in
increasing the width of the KM around implants and furthermore if this surgery
was associated with significantly less postoperative discomfort for the patient
compared to FGG surgery.

14. MATERIAL AND METHODS
Study design
This study was designed as a randomized controlled clinical trial with split mouth design.
Inclusion criteria
• Greater than 18 years old
• <2 mm of KM on bilateral implant sites in the lower jaw.
Exclusion criteria
• Smokers
• Patients with systemic diseases that could interfere with the healing,
• Patients undergoing bisphosphonate treatment
• Patients who previously received radiation therapy of the jaws.

15. Participants and randomization
• From May 2015 to May 2016, 8 patients were in need of bilateral soft tissue
augmentation.
• Sides were randomized as control or test site in a split mouth design, via a
randomization table.
• The treatment codes (L-PRF test/FGG control) were available in closed envelopes.
• These were sealed and opened just before the surgery by a nurse not involved in
the study.
Interventions
• All interventions were performed under local anesthesia and strict sterile
conditions.
• Both test and control sites were treated in the same surgical session.

16. The treatment at the test site was performed as follows:
1. Preparation of L-PRF: A standard venipuncture was performed (median basilica vein,
median cubital vein, median cephalic vein).
• Blood was drawn into 4× 9 mL tubes without
anticoagulant.
• L-PRF clots and membranes were prepared as
described by Choukroun et al.
• The tubes were immediately centrifuged at 2700
rpm for 12 minutes using a table centrifuge.
• After centrifugation, each L-PRF clot was removed
from the tube and separated from the red element
phase at the base with pliers.
• Four L-PRF clots were gently squeezed between a
sterile glass plate and a metal box.

17. Preparation of L-PRF according
to Choukroun et al.
(A)Tube after centrifugation clearly
showing 3 layers: acellular
plasma (top), fibrin clot
(middle), red blood cells
(bottom).
(B)L-PRF fibrin clots after being
removed from the tube using
surgical tweezers.
(C)L-PRF membranes after
compression of the L-PRF
clots.
B
C

18. 2. KM was split into two equal parts. A superficial, split-thickness flap preparation was performed
using a microblade, towards the vestibular and towards the lingual side. When necessary releasing
incisions were performed.
3. Removal of the elastic fibers to have the lamina propria firmly and directly attached to the
periosteum.
4. Vestibular flap is apically displaced and sutured to the periosteum using resorbable sutures
(Vycril 6.0).
5. Further uncovering of the implants. Removal of the cover screws and placement of healing
abutments.
6. Four L-PRF membranes are sutured together with resorbable sutures (Vycril 7.0).
7. Positioning of the L-PRF membranes and fixation using resorbable sutures (Vycril 6.0).

19. The treatment at the control site was performed following the same steps 1-
4 as that performed at the test site.
5. A tinfoil template is used to register the area of FGG needed.
6. Harvesting a 1 mm thick FGG according to the tinfoil template.
7. Further uncovering of the implants. Removal of the cover screws and placement
of healing abutments.
8. Positioning of the FGG and fixation using resorbable
sutures (Vycril 6.0).
9. Palatal wound was protected with an oxidized
regenerated cellulose layer (Surgicel original).

20. • All patients were asked to take paracetamol 1g 3 times a day and use an
antiseptic spray twice a day for 1 week (PerioAid® Spray 0.12%)
• 1 week and 6 weeks after the surgery, patients were scheduled for a
control visit.

21. (A) Immediately
postoperative. FGG (control)
site (left) and L-PRF (test)
site (right).
(B) 1 wk postoperatively
before suture removal.
(C) 6 wk postoperatively,
during the clinical
measurements.
A
C
B

22. Primary Outcomes: Width of Keratinized Mucosa and Shrinkage
• The amount of KM around the implants was
measured after Lugol staining.
• This was applied to visualize the difference
between keratinized and non-keratinized tissues.

23. • The measurements were performed using a linear evaluation (bucco-
lingual direction) of the total width of KM with a periodontal probe
(Merrit-B) at the implant site to the nearest 0.5 mm.
• Registering was done before treatment and after 6 weeks.
• To assess the shrinkage, the amount of KM vestibular to the implant
immediately after the surgery and after 6 weeks was also measured.

24. Lugol staining of a
study patient.
(A) Pre-operatively
(B) 6 wk postoperatively
A B

25. Secondary Outcomes: Postoperative Questionnaires and Surgery Time
• To assess postoperative pain between L-PRF and FGG side, the Dutch
version of the McGill Pain Questionnaire was used.*
• The reliability and the validity of the Dutch version of the McGill Pain
Questionnaire has been confirmed in various publications.*
• The questionnaire was handed out as a diary.
Melzack R. The McGill pain questionnaire: from description to measurement. Anesthesiology. 2005;103:199‐202.

26. • This questionnaire used 10 mm visual analog scores (VAS) to evaluate
the amount of pain, ranging from 0 (no pain) to 10 (worst pain
imaginable) and the amount of swelling.
• The patients were asked to fill in the VAS scales at the day of surgery
every 4 hours (h) and afterwards daily until day 7 by scoring their pain
three times; the pain they felt at the moment of questioning and the
minimum and maximum amount of pain they had felt during the past
4 or 24 hours.
• The time of surgery was measured for both treatment options.
• Timing started at the moment of first incision until the last suture was
placed.

27. RESULTS
Demographic data
• Eight patients participated in this trial.
• The mean age was 51.6 ± 7.1 years old.
• The male/female ratio was 4:4.
• None of the subjects dropped out during the 6 week follow-up.
Amount of keratinized mucosa
• There was no significant difference between both sites in the total width of KM
before surgery (test: 2.6 mm ± 0.9 vs control: 2.2 mm ± 0.4).
• The total bucco-lingual width of KM was significantly increased in both groups.
• The mean gain of KM varied from 6.0 mm ± 0.8 for the test group to 7.3 mm ± 1.2
for the control group, with 1.3 mm ± 0.9 extra gain (P < .05) for the FGG sites.

29. • After augmentation, both treatment modalities achieved the desired KM width goal of
≥2 mm vestibular of the implant.
• The mean amount of KM vestibular of the implant at the test site was 3.3 mm ± 0.9 and
3.8 mm ± 1.0 at the control site (P > .05).
• Shrinkage of the augmented sites measured by comparing the buccal width of the KM
postoperative and 6 weeks later were slightly higher at the test site (32.1%) than at the
control side (23.6%).
• However, this difference was not statistically significant (P > .05).
Postoperative pain sensation
• All the values from day 1 until day 6 were significantly higher at the control site (P < .05).
Surgical time
• Owing to the preparation of the FGG from the palate, the time needed for surgery was
less at the test site (P < .01).
• The mean surgery time was 29.1 ± 4.8 minutes in the test group vs 48.1 ± 7.7 minutes at
the control group.
• The preparation protocol of the L-PRF was not included in the timing of the surgery.

30. Graphical representation of pain scores. On the x-axis, the time in hours and days. On the y-
axis, the pain value.

31. DISCUSSION
• The present prospective, split mouth, randomized controlled clinical study
confirms that L-PRF is useful for increasing the amount of KM around
implants.
• Therefore, L-PRF might be considered an alternative treatment option.
• A general clinical impression is that the presence of a certain width of
keratinized tissue is important in maintaining periodontal health and
preventing soft tissue recession.
• However, this topic is still a matter of debate.

32. • The shrinkage of the grafted tissues after a mucogingival surgical procedure is of
outmost importance.
• In the present study, a shrinkage of 32.1% at the test site and 23.6% at the control
site was found.
• These values are comparable to the ones that found in literature.*
• According to Mörmann and co-workers, the shrinkage of a 1 mm thick FGG was
30% and primarily occurs during the first 28 days.*
• This value could be confirmed in other studies.*
• Different values were found for a collagen matrix (67.2% after 30 days) and the
subepithelial connective tissue graft (59.7% after 30 days).
• However, after 30 days no further shrinkage could be seen.*

33. • Other studies used an acellular dermal matrix allograft to achieve an increase
in KM although the contraction associated was substantial (71%).*
• From the patient’s point of view, it is important to find alternatives for the
FGG, particularly because this treatment concept is associated with higher
morbidity due to the second surgical site.
• However, an alternative needs to result in comparable treatment outcomes.
• L-PRF was able to create a sufficient amount of keratinized tissue with a
minimal invasive technique, low costs and low patient morbidity.

34. • The VAS scores of pain sensation after FGG in this trial are similar to those
reported in the literature and they were significantly higher compared to the L-
PRF site mainly due to the absence of a second surgical site.
• However, these results should be interpreted with care.
• Although split-mouth designs are popular due to the inherent advantages they
represent (eg, comparisons on a “within-patient” basis, elimination of host-
related factors and an enhanced validity), treatments at the one side of the
mouth can possibly affect the other side, inducing “carry-across effects.”
• Based on this study we can be sure that the treatments themselves do not
contain “carry across effects”.

35. • The reports on postoperative pain sensation, might have some “carry across
effects,” as the pain at the one side might possibly interfere with the total
experienced pain.
• Unfortunately, today we do not have any tools at our disposal to measure these
“carry across effects.”
• From an economical point of view the use of L-PRF in various periodontal surgical
procedures might be beneficial for the patient as the use of biomaterials will to
some degree decrease.
• In the present study, the choice of using FGG as a treatment concept has no
economic influence for the patient and the clear benefit is located in the absence
of a second surgical site.

36. • Concerning the subjects’ treatment preferences, it was significantly better for the
L-PRF side compared with the FGG side.
• The same conclusion was already provided in several studies that compared a
FGG or subepithelial connective tissue graft to an alternative procedure.
• When the morbidity is scored, the patient always preferred the alternative
technique.
• The L-PRF membranes have been also used in the management of palatal wounds
after harvesting an FGG.
• Studies have reported significant benefits in wound healing in terms of bleeding
and epithelialization.*
• The patient’s morbidity seemed to be also reduced when L-PRF was applied.

37. • The treatment time in this present study was significantly less for the L-PRF procedure.
• In addition, these results should be interpreted with care as the preparation of L-PRF
itself was not included as part of the surgical time.
• One might argue whether this time should be taken in to account.
• In the present study, it have been chosen to exclude the time needed for preparation of
the L-PRF as this might be performed by a nurse, ahead of the surgery.
• A study observed that the surgery time spent for the use of a collagen matrix was less
compared to harvesting a subepithelial connective tissue graft, with a difference of 15
minutes.*
Thoma DS, Buranawat B, Hämmerle CHF, Held U, Jung RE. Efficacy of soft tissue augmentation around dental implants and in partially
edentulous areas: a systematic review. J Clin Periodontol. 2014;41:77‐91.

38. • The present study contains a few shortcomings. First of all, this study has a rather
short follow-up time. Longer follow-up of these patients is mandatory to assess
the stability of the grafted area.
• Two recent systematic reviews on the efficacy of soft tissue augmentation around
dental implants included only studies with a follow-up of at least 3 months.*
• They assessed the gain in KM width as well as the volume gain (thickness) of the
soft tissue around implants.
• Both concluded that the use of an apically positioned flap plus an FGG resulted in
the best combination.
• For the thickening of the mucosa around implants, the use of a subepithelial
connective graft was found to have the best outcomes.

39. • The gain of soft tissue volume was not assessed in this study; however it is an
interesting topic for future research.
• A second shortcoming can be the fact that the amount of implants at either side
was not considered.
• This might be of importance as this will dictate the size of the FGG necessary to
complete the surgical procedure.
• In this way, a larger FGG might evoke higher pain scores.
• Future studies should take this into account.

40. • A third shortcoming is the limited sample size.
• In this small sample size, an FGG resulted in more augmentation and less shrinkage.
• One might speculate that these differences will be even bigger when the sample size is
increased.
• This study merely represents a proof of principle study and the results should therefore
be interpreted in this way.
• Further research with enhanced sample sizes is mandatory to draw definitive
conclusions.
• Nevertheless, this study can be of clinical importance, as for now, there is no evidence in
the literature on this topic.

41. CONCLUSION
• Within the limitations of this randomized controlled trial with a split mouth design, it can
be concluded that L-PRF can increase the width of the KM around implants.
• Furthermore, the use of L-PRF results in lower surgical time with less postoperative
discomfort and pain for the patients in comparison with the FGG.
• L-PRF is surgically easy-to- use biological patient-derived biomaterial, which can be used
in daily practice on a routine basis.
• Nevertheless, FGG still is considered as the gold standard for these types of surgical
interventions.
• Further clinical trials with bigger sample sizes are mandatory.

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