Laser Therapy to Increase Keratinized Tissue Width: Case Report and Systematic Review

Abstract

The use of laser therapy has increased in healthcare professions due to its expanding range of applications. After a case in which an increase in keratinized tissue width (KTW) was noted post laser assisted frenectomy, a systematic review of the literature was completed. Within the limitations of this review, there is growing evidence to support laser therapy to increase keratinized tissue width by up to 4.9mm with improved healing, soft tissue stability and improved aesthetics.

Keratinized tissue width (KTW) is a measure of the distance between the free gingival margin and the mucogingival junction,¹ and is important for maintaining oral health. A lack of KTW can lead to recession and inflammation,² because keratinized tissue acts as a barrier against masticatory and external trauma, as well as providing resistance to biofilm.³ According to Cortellini, 2mm of keratinized tissue and 1mm of attached gingiva is recommended to maintain periodontal health in the absence of optimal plaque control.²

The traditional method of increasing KTW is with soft tissue augmentation procedures with the most common being the free gingival graft, as more KTW can be obtained when compared with alternative approaches.⁴ There have also been case reports that have shown increased keratinized tissue following modified apically repositioned flap procedures.⁵

A laser therapy, known as laser ablation, is a widely used method for rejuvenating facial skin and enhancing its appearance. It is accomplished by removing the outer layer of skin (epidermis) and heating the deeper layer (dermis) to stimulate collagen growth, resulting in firmer skin. It also leads to a smoother and tighter new layer of skin, because neocollagenesis, neoelastogenesis and fibroblast remodelling occurs.⁶

There are currently four recognised lasers in dentistry that include: diode (wavelength: 810-980nm), CO2 (wavelength: 10600nm), erbium yttrium aluminium garnet (Er:YAG) (wavelength: 2940nm) and neodymium yttrium aluminium garnet (Nd:YAG) (wavelength: 1064nm).⁷ Lasers have varying depths of tissue penetration with diodes and Nd:YAG lasers penetrating the deeper dermal layers, whereas the Er:YAG and CO2 lasers remain at the superficial epidermis layer.⁸ The spot size for lasers is measured using cm2 and the power is quoted in Watts or Joules, which can be adjusted; wavelength is the distance in which a wave repeats and this is usually fixed.⁹ Lasers can either be a continuous wave (CW) or pulsed high energy, with the CO2 laser exhibiting the highest CW power.¹⁰ The CW emits a continuous beam of average to low power in comparison to the pulsed, short high energy beam that last less than 0.25 seconds.¹¹ From a cross sectional study in 2022, 86% of post-graduate periodontal programmes in North America use lasers; of these, 89% use diode lasers in their training.¹²
Below is a case report documenting an increase in KTW following a laser assisted frenectomy and a systematic review of the supporting literature on the subject.

Case Report

The frenectomy procedure (Fig. 1-3) was completed using ½ carpule of 4% articaine 1:200,000 with the SiroLaser Blue (Dentsply Sirona) at a wavelength of 445nm and at 2.0 W of power, on the continuous wave (CW) setting using the Siro Laser Easy tip 200. The procedure was completed using an ablation technique with the tip moving in a cross-hatched direction. The technique was completed in under 5 minutes and healing occurred by secondary intention. There were no reports of pain experienced by the patient during or after the procedure.
Although there was small evidence of carbonisation (burning/blackening) at the mesial and distal margins, that can delay healing (Fig. 4), the desired outcome was achieved by secondary intention healing. (Fig. 5) At the 4-month post-operative appointment, the healing that had occurred was pleasing to both the patient and clinician, with an increase in KTW by 2mm. (Fig. 6)

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Fig. 5

Fig. 6

Review

Laser therapy has become increasingly popular for various soft tissue procedures in dentistry, such as mucogingival surgeries, open flap debridement, proximal wedge surgeries, second stage exposure of dental implants, gingival depigmentation, and the treatment of peri-implantitis.¹³

A total of six papers met the inclusion criteria following searches in Medline, CINAHL and Dentistry and Oral Science conducted between September 12th, 2022, and October 12th, 2022. (Fig. 6)

Figure 6 is a PRISMA figure that has been adapted from the preferred reporting of systematic reviews.¹⁴

The findings from a total of 138 sites on 88 patients have been summarized in Table 1. These studies reported an increase in KTW ranged from 0.58mm to 4.90mm. Follow-up periods were from 1 week to 12 months, with the greatest KTW increase occurring within the first 3 months following treatment. At 2 months, the pilot prospective study reported an increase in KTW by 1.9mm18 and at 6 months, an increase of 1.44mm was identified by Bhardwaj¹⁷ et al. The biggest increase was reported by Uraz et. al at 3 months with an increase of 4.9mm.²⁰ The single case by Benjamin noted an increase of more than 3mm at the 12 month follow-up,16 whilst the split-mouth randomized controlled pilot study reported an increase of 0.58mm.¹⁹

Table 1: The findings from 6 papers and a total of 138 sites on 88 patients have been summarized.

Author	Type of study Reported procedure	Number of patients (sites if stated as different to number of patients)	Length of study (follow-up intervals)	Type of laser	Findings (increase in KTW following laser therapy from baseline) at reported time intervals (mm)
Zeinoun et al15	Case study Apically positioned flap	19	12 months (3 months, 6 months, 12 months)	CO2 laser (2W beam diameter at focal distance; 0.3mm delivery energy density per second = 2829 J/cm2 and wavelength 10600 nm)	3 months: 3.14 6 months: 3.05 12 months: 2.70
Benjamin16	Case study Gingival augmentation	1	12 months	Diode laser (3W CW mode, wavelength 970 nm)	12 months: >3
Bhardwaj et al17	Case study Periodontal flap surgery with vestibular deepening	16 (74 sites)	6 months (clinical parameters were only measured at 6 months)	Diode laser (0.5-7W CW mode, wavelength 810 nm)	6 months: 1.44
El Hajj et al18	Pilot prospective study Gingivoplasty following a connective tissue graft	5 (20 sites): 10 sites received laser therapy, 10 sites received blade therapy	2 months (clinical and histological parameters)	Diode laser (15 W pulse mode, 9 Khz frequency wavelength 810 nm)	2 months: 1.90
Ozturan	Split-mouth randomized cont- rolled pilot study Coronally advan-ced flap adjunct with low intensity laser therapy	10: 17 sites received laser therapy, 17 received no additional treatment	1 year ( clinical parameters were recorded at baseline and 1 year)	Diode laser (120 mW CW mode, wavelength 588 nm at 4.0 J/cm2)	1 year: 0.58
Uraz et al20	Randomised prospective clinical controlled trial Frenectomy	36: 20 received laser therapy, 16 received scalpel therapy	3 months (1 week, 1 month, 3 months)	Diode laser (2.8 W CW mode, wavelength 980 nm)	1 week: 6.75 1 month: 6.15 3 months: 4.90

Zeinoun et al. and Uraz et al. noted the change in KTW was reduced over time. Zienoun et al¹⁵ noted a mean KTW increase of 3.14 mm at 3 months which was reduced to 2.7 mm at 12 months, Similarly, Uraz et al reported a reduction of 1.85mm between the immediate post-operative visit and the 3 month follow-up (6.75 to 4.90 mm). An increase in KTW was achieved in all studies, despite heterogeneity of wavelengths (588 nm-10600 nm) and the peak pulse power (0.12-14 watts).

There are significant limitations to the studies. Case reports, by their very descriptive nature, are highly biased as the implicit and unconscious biases of the researcher are likely to affect reported results.²¹ Sample sizes are generally small, limiting generalizability. In addition, there is no comparison group and results may be difficult to replicate.²² Additional limitations include lack of reporting of potential confounders that could affect the results. For example smoking is known to impair wound healing.²³ The smoking status of participants was not documented in the clinical trial by Uraz et al.²⁰ or by Benjamin.¹⁶ One study gave their patients antibiotics and analgesics following treatment,¹⁵ which could affect healing. In addition, none of the studies included a follow-up period that exceeded 12 months.

Low level laser therapy (LLLT), when used immediately following the coronally advanced flap procedure for root coverage to treat recession, improved clinical outcomes in the long-term.¹⁹ A systematic review concluded the key superior clinical outcome with LLLT, was a greater gain in KTW when compared with acellular dermal matrix allografts or emdogain as alternatives to the gold standard, autogenous soft tissue.²⁵ LLLT has been shown to be beneficial in increasing the production of ATP (adenosine triphosphate), which increases metabolism and thus increases the energy available for tissue healing.²⁴

There are certain benefits to the use of lasers which include reduced surgical time and decreased post-operative pain, redness and bleeding. As well, patients have reported a sooner return to normal function (speaking and chewing).²⁶ An increase in KTW can improve the overall health of the gingiva and reduce the risk of infection, inflammation, and other complications.

There is confirmed improved histological healing, albeit on rat models, with the use of the laser compared with the scalpel; this includes reduced wound contraction due to fewer myofibroblasts and delayed epithelial regeneration.^27,28 In human histological samples, laser gingivoplasty increased KTW compared to blade gingivoplasty as the procedure led to more pronounced parakeratinization and rete pegs (finger-like epithelial projections, formed during epithelial development or the wound healing process; they extend into connective tissue to provide better mechanical resistance and nutritional supply).¹⁸ A possible explanation is that laser therapy may provide more time for keratinocytes, which are key for healing, to migrate from the basal membrane to the surface.

The literature in this review has presented the use of CO2 and diode lasers to increase KTW. Compared to other lasers, the diode laser is smaller, more portable, the setup time is minimal, and the associated costs are lower.²⁰ Costs and limited training, especially with the CO2 laser, are the most commonly quoted barriers for the lack of laser usage, even with reported higher patient satisfaction.²⁹ Due to the low level of evidence and heterogeneity of the lasers available, the optimal frequency and wavelength cannot be suggested.

Conclusion

Within the limitations of this review, there is growing evidence to support laser therapy to increase keratinized tissue width by up to 4.9mm with improved healing.

Future research

To strengthen the level of evidence to support the use of lasers in increasing KTW, long-term (>12 months) studies and comparison of laser therapy to conventional techniques, should be conducted through high quality randomized controlled trials.

Oral Health welcomes this original article.

References

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About the Authors:

Dr. Matthew Morris is a periodontist based in Halifax and practices across Atlantic Canada. He qualified from Dalhousie University in 2023, where he continues to teach part-time. He has authored peer and non-peer reviewed articles.

Dr. Richard Bengt Price is a Prosthodontist who teaches at Dalhousie University. He is actively involved  in research and has authored more than 220 peer-reviewed articles on dental resins, curing lights, and occlusion.

Dr. Debora Matthews is Professor and Director of the Masters in Periodontics program at Dalhousie University. She has been awarded over $6M  in research funding and published over 90 peer reviewed articles. She is former Director of the NCOHR and former CDAC chair.