October 12, 2017
by Marina Polonsky, DDS, MSc Lasers in Dentistry
Treatment of external resorption lesions, even without communication with the root canal space, has historically and continues to present challenging situations for general practitioners diagnosing these cases, as well as the specialists expected to treat them.
This case report describes a multi-disciplinary approach performed on a maxillary lateral incisor (tooth #22), using a Er,Cr:YSGG 2780nm laser and 940nm diode laser to treat both the external resorption lesion and the endodontic involvement, resulting from proximity of such periodontal pathology to the root canal space. Traditionally, the prognosis of endo-perio lesions are usually hopeless due to: 1) the inability to completely disinfect and eliminate periodontal pathology from the root surface and, 2) the inability to use conventional irrigants, such as EDTA and NaOCl, to achieve good disinfection of the root canal space, when communication exists with the PDL space.
All too often, these challenging cases are often referred to oral surgeons for extraction. Lasers of different wavelengths have been proven quite useful in improving disinfection and smear layer removal in more complicated endodontic cases, without the use of chemical irrigation. By taking advantage of lasers’ bactericidal abilities, while treating both endodontic and periodontal pathologies simultaneously, we were able to successfully treat and preserve the tooth. Conventional mechanical instrumentation was performed, followed by a dual wavelength protocol utilizing Er,Cr:YSGG 2780nm laser for smear layer removal and diode 940nm laser for deeper disinfection of the dentinal tubules. Apical flap was then raised to de-granulate and disinfect the external resorption defect, followed by MTA filling of the root surface and grafting of the existing periodontal defect. A two-year clinical and radiographic follow-up is presented as evidence of clinical success.
The process of cervical resorption, be it external or internal, has been a clinical challenge to the dental profession for decades. One of the first reported successful treatments of external resorption was published by Cvek in 1973.1 Known predisposing factors for root resorption include history of trauma, orthodontic tooth movement and “Walking bleach” treatment of endodontically treated teeth using 30% hydrogen peroxide.2 Several classifications have been suggested based on etiological factors and extent of the damage. Tronstad in 19883 suggested 3 categories of external resorption: progressive inflammatory (pulpal or sulcular infection); invasive non-inflammatory (usually cervical); and replacement non-inflammatory (ankylosis). Trope in 19984 suggested classification based on etiology which consisted of either transient or progressive resorption. Two conditions necessary for resorption to occur are: 1) Damage to the root surface (pre-dentin internally or pre-cementum externally) and, 2) Presence of inflammation adjacent to the altered root surface. A more recent classification by Fuss, et al5 is based on two etiological factors: injury and stimulation. Injury may be mechanical (trauma, surgical intervention or excessive pressure) or chemical (30% H2O2 or other agents).6 Stimulation is determined by factors affecting osteoclastic cells: infection or pressure.
The 5 categories in this classification are as follows:
– Pulpal infection root resorption (most common)
– Periodontal infection root resorption
– Orthodontic pressure root resorption
– Impacted tooth or tumor root resorption
– Ankylotic root resorption
The case described in this report is that of a periodontal infection external root resorption. This type of resorption was initiated by the injury to pre-cementum layer on the root surface, which allowed destruction by osteoclasts of cementum, dentin and ultimately near invasion of the pulp space. For successful treatment, the clinician must completely eliminate the resorptive tissue. The condition is frequently asymptomatic and detected only on routine radiographic examination. Severe defects, which present with symptoms of pulpitis, usually have a poor prognosis.7
A 53-year-old female was seen for a routine dental cleaning and check-up in May, 2015. A strange radiolucency on the mesial aspect of the root of tooth #22 was noted on a panoramic radiograph and confirmed by a close up PA X-ray (Figs. 1 & 2). Intra-oral examination was not indicative of any underlying problem, as shown in Fig. 3, and the patient was asymptomatic. The diagnosis of external root resorption in the apical 1/3 of the root nearing the endodontic involvement was made. Medical and dental histories for the patient were non-contributory; there was no history of trauma, orthodontic tooth movement or bleaching was acknowledged by the patient. Periodontal examination did not reveal any mobility, bleeding on probing, or pocket depth in maxillary anterior area. The patient was referred for both endodontic and periodontal specialist consultations and returned to the office with the recommendation for extraction of tooth #22 and replacement with an implant. Hopeless prognosis due to the extent of external resorption was conveyed to the patient. At the time of the follow-up visit in August, 2015, the patient started exhibiting symptoms of irreversible pulpitis presenting as lingering cold sensation with cold vitality test. At this time, definitive treatment was necessary and patient requested possible alternatives to extraction of the tooth #22, fully understanding that no guarantees can be offered for any such treatment.
Our decision was to proceed with endodontic therapy followed by exploratory surgery to expose and clean out the resorptive lesion in the apical 1/3 of the root, using Er,Cr:YSGG 2780nm laser (Waterlase Iplus, Biolase, Irvine, CA) for endodontic decontamination and smear layer removal, as well as for soft and hard tissue surgery. 940nm diode laser (Epic 10, Biolase, Irvine, CA) was used for endodontic disinfection and post-surgical bio-stimulation.
Pre-op panoramic X-ray.
Pre-op periapical X-ray.
The reason to start with root canal treatment and not surgical curettage was made in consideration of a possible communication between the root canal space and PDL, extruded material, such as sealer and would be easily removed during the curettage of the defect. Er,Cr:YSGG 2780nm laser was chosen to aid with the procedure due to better visibility, ability to decontaminate without leaving smear layer and little to no thermal damage to the surrounding tissues associated with necrosis and pain. Diode 940nm laser was utilized for better bactericidal effect inside the root canal to target pigmented bacteria, to reduce pain and improve healing following the root canal and flap/curettage procedure.
1. Lingual access to start the root canal treatment and to access the canal.
2. Mechanical instrumentation of the canal was completed using Sybron TF adaptive reciprocating motor system up to file ML2 corresponding to ISO 35 size master file (Fig. 4). FileEze (Ultradent, South Jordan,UT, USA) was used for file lubricant and BioPure MTAD (Mixture of tetracycline isomer and citric acid by Dentsply Tulsa Dental Specialties, Tulsa, Okla.,USA) was chosen as the intra-canal irrigation.
3. Removal of the smear layer from the canal and decontamination prior to obturation (Figs. 5 & 6). Due to possible communication between PDL and root canal space, the use of conventional irrigants, such as NaOCl and EDTA had to be avoided. We did not wish to cause a very painful hypochlorite extrusion accident for the patient.
Er,Cr:YSGG laser decontamination and smear layer removal.
Diode laser disinfection.
4. The canal was filled with hydrophilic EndoRez UDMA (urethane dimethacrylate) resin based, self-priming endodontic sealer (Ultradent, South Jordan, UT, USA) to the level of CEJ (cementum-enamel junction). Soft-Core #30 (Kerr Dental) softened gutta-percha carrier was used to complete the obturation (Fig. 7).
Immediate post RCT X-ray.
5. The tooth was permanently restored with composite resin restoration (FutureBond DC bonding agent and GrandioSO nanohybrid composite resin by Voco, Germany) immediately following obturation (Fig. 8).
Immediate post RCT and restoration photo.
6. Flap semilunar incision to expose the area of external resorption between the roots of teeth #21, 22 and reflection of the flap using periosteal elevator (Fig. 9).
Laser flap incision.
7. Curettage and decontamination of the external root resorption defect (Fig. 10).
Laser curettage of external resorption lesion.
8. Filling external resorption defect on the mesial aspect of the root of tooth #22 using Pro-Root MTA (mineral trioxide aggregate, Dentsply, USA) (Fig. 11).
Completed curettage, ready for MTA filling.
9. Placement of bone graft (Accell, Citagenix) and resorbable collagen membrane (Neomem, Citagenix) in the bony defect between the roots of teeth #21, 22 (Fig. 12).
Photo following placement of MTA filling, bone graft and membrane.
10. Closing the flap with sutures and de-epithelialization (laser bandage) around the semilunar incision of the reflected flap (Fig. 13).
Photo following sutures and de-epithelialization.
Dual Wavelength Endodontic debridement, decontamination and disinfection laser protocol:
1. Debridement. 2780nm Er,Cr:YSGG laser (Biolase, IPLus, Irvine, CA), 60µs pulse (H-mode), RFT2 radial firing endolase tip 200µm diameter. Power 1.25W, Repetition rate 50Hz, Pulse energy 25mJ/pulse, 54% water, 34% air. The tip was measured 1mm short of working length and fired only on the way out of the canal. The tip was moved in a corkscrew-like motion at a speed of 1mm/s, four cycles. Total time of laser application was 50 seconds.
2. Decontamination. 2780nm Er,Cr:YSGG laser, 60µs pulse (H-mode), RFT2 radial firing endolase tip 200µm diameter. Power 0.75W, Repetition rate 20Hz, Pulse energy 37.5mJ/pulse, 0% water, 11% air. The tip was inserted into the canal 1 mm short of the apex and fired only on the way out of the canal. The tip was moved in a corkscrew-like motion at a speed of 1 mm/sec. Four cycles of laser irradiation were applied, for a total of 50 seconds.
3. Drying. Sterile paper points were used to verify complete dryness of the canal system.
4. Disinfection. 940nm diode laser, continuous wave mode, EZ200 end-firing tip 200µm diameter. Power 1.0W. Tip was inserted 1mm short of the apex and moved at the speed of 2mm/s, while being fired on the way out of the canal. Four cycles of laser irradiation were applied for a total 25 seconds.
The patient was instructed to inform the office should any pain or discomfort persist past first two to three days, following the endodontic therapy and exploratory surgery. No antibiotic prescription was given and analgesic (400mg Ibuprofen q4h) was prescribed for an as needed basis. She returned in five days for suture removal and X-ray (Fig. 14), and in three months for a routine follow-up, when a post-op photo was taken as shown in Fig. 15. The patient reported only minor discomfort for the first two to three days, which quickly subsided, with the tooth feeling “normal” ever since. Post-op radiographs were taken at six and 12 months, and two years after the completion of laser-assisted treatment (Figs. 16-18). The tooth remains asymptomatic and functional, the patient is extremely happy with her decision to try the above described laser-assisted procedure.
X-ray at five days post-op.
Photo at three months post-op.
X-ray at six-months post-op.
X-ray at one-year post-op.
X-ray at two-year post-op.
Cases of external and internal root resorption, although rare in the past, are becoming more common, possibly due to increased popularity of elective orthodontic treatment and vital tooth bleaching procedures. There are some case reports in the literature which suggest that treatment of such lesions could be possible with conventional means,8,9 however these reports do not mention the level of pain for the patient, duration of healing time and rely on anti-biotic therapy to prevent post-operative complications and improve chances of success. This case is that of periodontal infection root resorption according to Fuss et.al classification.5 The resorption is the result of injury to pre-cementum apical to the epithelial attachment, followed by bacterial stimulation from periodontal sulcus. When there is a perforation of the root canal, associated periodontal lesions present a challenge. Bacteria can enter dentinal tubules coronal to the attachment and exit apically. Elimination of the bacterial contamination of the periodontium and the root canal, as well as regeneration of the periodontal attachment and repair of the damaged root surface, is essential for good prognosis of the treatment.
MTA (mineral trioxide aggregate) has been shown to be biocompatible and effective in repairing root canal perforations.10-12 Incorporation of lasers of various wavelengths into endodontic and periodontal treatment can offer a great advantage in situations where conventional methods of disinfection are contra-indicated, as is the case with endo-perio lesions.13-15 The effectiveness of Er,Cr:YSGG 2780nm wavelength in three-dimensional removal of organic debris and smear layer from root canals has been well documented.16-18 The ability of 940nm diode wavelength to penetrate deeper into the tubular dentin to help target pigmented bacteria, due to its high absorption in melanin and hemoglobin, also offers an advantage over conventional NaOCl irrigation.19 Laser technology can offer advantages which are not available with conventional methods, namely better visibility due to bleeding control, faster healing and less post-operative discomfort, due to the micro-invasive technique and reduced inflammation.20 A thorough understanding of laser-tissue interactions and mechanisms of action is crucial in achieving good outcomes. Both diode and Er,Cr:YSGG lasers have been shown to have higher healing potential and cell proliferation.21 Surgical advantage of the Er,Cr:YSGG laser system is due to low inflammatory response and minimal tissue damage.22 Erbium lasers have been shown to produce more pronounced revascularization, fibroblast proliferation and less inflammatory infiltrate than CO2 laser and mechanical burr.23
With evolution of laser technology, difficult clinical situations, such as treatment of external and internal root resorption of various etiology, as well as combined endodontic-periodontal lesions, should no longer automatically be doomed for extraction. As the incidence of such diagnoses becomes more common we, as a profession, owe our patients all available technologies to improve the treatment, prognosis of success, post-operative comfort and assurance of long term survival of their dentition. OH
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Disclaimer: The view and opinions of this article may not reflect the views and opinions of the Oral Health editorial advisory board.
Disclosure: Dr. Marina Polonsky has no commercial or financial interests to disclose for this article.
Dr. Marina Polonsky DDS, MSc is a Gold Medal University of Toronto ’99 graduate, she maintains private general practice in Ottawa, Ontario with focus on multi-disciplinary treatment utilizing lasers of different wavelengths. She holds a Mastership from World Clinical Laser Institute (WCLI), Affiliation with Academy of Laser Dentistry (ALD) and Master of Science in Lasers in Dentistry from RWTH University in Aachen, Germany. Dr. Polonsky is a founder of the Canadian Dental Laser Institute (CDLI).