Laser Treatment for Failing Dental Implants

Keywords:laser, treatment, medical,  Time:27-11-2015

ABSTRACT

A large percentage of dental implants experience complications, most commonly, infection leading to peri-implantitis and peri-mucositis, inflammatory disease involving pathogen contamination. It presents with radiographic findings of crestal bone loss. At this time there appears to be no compelling evidence for an effective intervention. The LANAP protocol is a FDA cleared surgical protocol that produces new attachment and bone regeneration when applied to periodontally infected natural teeth. The LANAP protocol and dosimetry have been modified to treat ailing and failing implants. Twenty-one clinicians who have been trained to perform the LANAP protocol and the LAPIP™ protocol have volunteered 26 LAPIP case reports. The time from implant to intervention ranges from 3 months to 16 years. Post-LAPIP radiographs range from 2-48 months. Ten cases were excluded for technical reasons. All 16 remaining cases provide radiographic evidence of increase in crestal bone mass around the implant and, when reported, probe depth reductions. All treating clinicians report control of the infection, reversal of bone loss and rescue of the incumbent implant. Although the success/failure rate cannot be judged from these data, any successes in this area deserve reporting and further study.

INTRODUCTION

We introduce a new indication for the application of the pulsed Nd:YAG laser for the successful treatment of the infectious disease, peri-implantitis and peri-mucositis. Pilot data are presented in the form of 16 clinical case reports that provide radiographic evidence of immediate disease reversal and gradual bone regeneration following treatment with the LAPIP protocol.
 
Figure 1(a) [upper left] shows the relationship between a natural tooth (#8) in 2003 and its replacement with a dental implant in 2004. After six years the implant has developed shadows (radiolucencies) on the radiograph indicating bone loss around the coronal edge of the anchor, a primary indication for peri-implantitis. Peri-implantitis is an inflammatory disease in the bone and soft tissues that surround a dental implant. The tissues are colonized by pathogenic bacteria that gradually cause the degeneration of the alveolar bone that holds the implant in place1,2 Progression of the disease will result in loss of the implant.

Reporting of implant complication rates varies between 11% – 56% of all implants.3,4 It is estimated that annually about 1,000,000 dental implants are removed worldwide.5 The most common risk factor seems to be advanced periodontitis on prior or missing teeth.6,7 Current treatment options both surgical and non-surgical have at the most a 50-60% success rate8 and there appears to be no clear evidence to identify the most effective method of treatment nor is there a standard protocol for management of this  inflammatory process.

LANAP protocol. The LANAP protocol is a well defined step-by-step, minimally invasive, surgical procedure for treating periodontitis that requires training & proficiency certification on the 6 Watt PerioLase®MVP-7TM FR pulsed Nd:YAG laser and licensure to perform the LANAP protocol. The entire protocol is accomplished with laser, piezoultrasonic and hand instrumentation and a dental handpiece but without scalpel, sutures or graft material.9-12 LANAP therapy for periodontitis results in reattachment of natural teeth to the bone thru regeneration of the periodontal ligament and formation of new bone. The native structure of the attachment of dentition is actually regenerated

LAPIP protocol. The LANAP protocol was modified to treat peri-implantitis and peri-mucositis. The modified protocol is referred to as the LAPIP protocol). It is also a step-by-step surgery that requires training certification and licensure. The protocol follows the LANAP protocol sequence where appropriate.

We have conducted this study in preparation to running a clinical trial to establish the efficacy of the LAPIP protocol. Before/after radiographs from 26 LAPIP case reports with a successful response to treatment were submitted by 21 dentists in private practices. The time course of the response to treatment is determined from radiographic evidence. A model is developed to estimate the rate of crestal bone deposition following this laser assisted peri-implantitis procedure. Reports were also examined to identify issues for consideration in designing inclusion/exclusion criteria.

METHODS

Laser instrumentation. The 6 Watt PerioLase®MVP-7TM FR pulsed Nd:YAG laser was designed by dentists for use by dentists. The ergonomics and output parameters are optimized for each dental application. Pulse duration can be changed in 7 increments to go from cutting to hemostasis. The ranges of other parameters are also defined in terms of tissue response. Microprocessor based controls remember and recall the parameter set for specific tasks. The procedure presets are visible and parameters can be adjusted by the clinician within the limits of biologic tolerance. The delivery handpiece and tips are adjustable for access to all pockets. Feedback informs the user of the exact energy light dose and energy density being delivered. As the LANAP and LAPIP procedures evolve, so does the laser and vice-versa. The hardware and procedure have become closely integrated.

The LAPIP protocol specifies application of laser energy around ailing and failing implants in a similar way as the LANAP protocol applies energy around natural dentition.  In both instances, device specific training and accumulated clinical judgment needs to be applied to adjust preset parameters and total dosimetry that is appropriate to the specific clinical presentation.  In LAPIP the light dose used around implants is approximately one third the energy applied around natural teeth, primarily due to less dissipation of heat in implants and the greater fragility of the tissue surrounding them.

Radiographic analysis. Pilot study to develop methods for measurements. All images were received as scanned and emailed digital reproductions of a series of at least two bitewing radiographs. One case was submitted as a CT scan of the mandible. Images were rotated, cropped and resized, if necessary, to form the sequential composites as shown in the figures. Brightness and contrast were not adjusted.

In the top row of Figure 1 the radiographs have been arranged in chronological order so that the reader can easily visualize the progression from natural tooth, to implant, to development of a lesion and the gradual diminishing of the peri-implant radiolucency following treatment.

The human eye/brain is excellent at discriminating objects from background and for identifying what has changed from one panel to the next. To capture and quantify this sequence a technician, skilled at reading dental radiographs, has identified the baseline alveolar crest (Figure 1(b) [04-28-2004, bottom]) and outlined the “areas of changes in radiolucencies” in subsequent images. A relatively easy task for the eye/brain but influenced by subjective bias. In order to be more objective we identify a criteria gray-level to define the boundary of the lesion. With these retrospective data this level is different for each case and may even vary from one visit to the next. This source of variance can be eliminated for a prospective clinical trial with controlled exposures and a computer-based algorithm. As an example, the clusters of green pixels (Figure 1(d)) represent pixels with a grey-level value that, in this case, defines the boundary criteria for the edge of the lesion. The lesion boundary is also defined by the baseline alveolar crest, the edge of the implant and for large defects the edge of the adjacent tooth. As a check for bias the aligned and outlined images were returned to investigators for their concurrence.

In some cases two processes appear evident in the radiographs (Figures 2 and 3). Dark shadows within the crestal bone are assumed to represent bone loss resulting in decreased radiodensity. Completely black areas are assumed to represent the absence of bone. Two contours are drawn; one for the black area (B) and a larger zone is outlined for the “shadow” (A).   
Once the outlines are drawn it is a simple matter to measure the cross-sectional area of the lesion using public domain software (image J). Since the exact diameter and length of the implant are known the areas can be measured in mm2 and comparisons can be made across cases. The sum of the peri-implant areas on both sides of the implant is referred to in the figures as the cross-sectional area. For calculation of the volume of the lesion the cross-sectional area is the average of the right and left areas. The rate of recovery for each lesion is calculated as the difference in area between before and after lesions divided by the follow-up period.

RESULTS

Study population. Twenty-one dentists contributed 26 LAPIP cases including before/after radiographs. Ten of the cases were excluded from analysis because: (1) The “after” radiograph was rotated relative to the “before” presenting a foreshortened or different cross-section. (2) Missing data (e.g., date of follow-up) and (3) the lesion extended beyond the image margins.  
The remaining 16 cases included 9 females and 7 males with an average age of 54 years (range: 32-79). The median time that had elapsed between the date of implant and the date of treatment was 4 years with a range of 3 months to 16 years. Follow-up data ranged from 8 to 36 months post-LAPIP.