BB&T Contributing Editor

WASHINGTON Periodontal disease affects one in three adults in North America, generating a $6 billion treatment and services market. Gum disease is a silent, painless, chronic bacterial infection that often goes undetected or ignored until severe gum and bone destruction catches the individual's attention. It is characterized by the destruction of the tissues that surround and anchor the teeth and is the leading cause of adult tooth loss.

A growing body of research suggests that periodontal disease may play a role in a variety of systemic health problems, including heart disease, diabetes, respiratory illness and pregnancy complications. According to the American Diabetes Association (Alexandria, Virginia), diabetics are at a higher risk for gum problems and are more than twice as likely to develop gum disease.

Patients often select general dentists to treat gingivitis and early stages of periodontal disease, but periodontists perform surgical procedures on the more advanced cases of periodontal disease such as guided tissue regeneration for preserving or augmenting the bony architecture, bone grafts for replacing lost bone, soft-tissue grafts for replacing lost gum tissue, flat closure for pocket depth reduction, as well as crown lengthening for a more aesthetic smile.

The American Academy of Periodontology (AAP; Chicago) has 8,206 members, and its October annual meeting here attracted more than 6,100 participants.

Dental implants a dizzying array

A revolutionary change that has occurred in the treatment of advanced periodontal disease is the replacement of teeth with dental implants, which provides a more permanent solution than trying to save the natural tooth and also maintaining the aesthetic appeal of the original teeth.

This often entails bone grafting to assure that there is adequate supportive structural bone for anchoring an implant, and possibly a sinus lift to prevent puncturing of the sinus cavity. The placement of dental implants is the dominant procedure performed by most periodontists and has transformed the profession.

The many marketers of dental (endosseous) implants dominated the Washington Convention Center exhibit floor during the meeting with a dizzying array of devices screws, blades, abutments, cylinders, caps, crowns, etc. each endeavoring to differentiate its products by design features, strength and ease of handling for better osseointegration.

The leading dental-implant marketer, Nobel Biocare (Gothenberg, Sweden/Yorba Linda, California), introduced its NobelActive implant with a self-drilling feature for pressing through bone rather than cutting bone for use on sites that are close to vital anatomical structures.

The next-largest dental implant companies are Straumann (Basel, Switzerland/Andover, Massachusetts) and Biomet 3i (Palm Beach Gardens, Florida), a subsidiary of Biomet (Warsaw, Indiana). Straumann launched its bone level titanium implant with the SLActive chemically active implant surface for use in preserving crestal bone.

Biomet 3i displayed OsseoGuard resorbable bovine-derived collagen membrane for use in guided tissue regeneration. It replaces Ossix, a porcine-derived collagen that was supplied by ColBar Lifesciences (Herzeliya, Israel) and was acquired by Johnson & Johnson (J&J; New Brunswick, New Jersey).

BioHorizons (Birmingham, Alabama) is in the process of acquiring BioLok (Deerfield Beach, Florida), which markets a line of abutments and screws with Laser-Lok microchannels on the surface for enhanced attachment, as well as bone regeneration products. BioHorizons is the exclusive distributor of Grafton demineralized bone matrix and MinnerOss cortical and cancellous bone chips, supplied by Osteotech (Eatontown , New Jersey), and AlloDerm regenerative tissue matrix from Lifecell (Branchburg, New Jersey).

Blue Sky Bio (Grayslake, Illinois) was the first company to market dental implants on the Internet and was followed by Implant Direct (Calabasas Hills, California).

Implant placement a critical issue

Exact implant placement of endosseous implants is always critical and the need for best results is accentuated by the absence of insurance reimbursement for these procedures. Improper placement can result in poor dental occlusion, a limited use life and discomfort. Thus the utilization of image-guided navigation systems to assure precise placement is gaining wide acceptance.

The guidance systems aid in the selection of sites which have sufficient supporting bone structure to securely anchor an implant and to place the implant at the optimum angle and depth.

Nobel Biocare was the first dental implant company to offer a guidance system. Its NobelGuide uses Procera software and was introduced in July 2006. It is a model-based or computer-based (radiographic 3-D imaging with a CT scan) guidance system that employs a customized surgical template that the dentist uses when drilling a hole in the jawbone into which the implant is placed. The template can be used to produce a temporary (provisional) or final prosthesis.

Biomet 3i featured its Navigator system for minimally invasive, CT-guided surgery. Although the use of a guidance system and the preparation of surgical implants entails additional processing steps, as compared to a non-guidance procedure for inserting dental implants, the actual patient's chair time is reduced from about one hour for a non-guidance procedure to only 20 minutes when a guidance-planned procedure is performed

Several companies offer software for use in guidance systems. They include SimPlant from Materialise Dental (Leuven, Belgium/Glen Burnie, Maryland), Compu-Guide from Implant Logic Systems (Cedarhurst, New York), ImplantMaster from iDent (Hod Hasharon, Israel/Fort Lauderdale, Florida), Implant Guidance from DenX (Jerusalem/Miami Beach) and Implant Location System from Tactile Technologies (Rehovot, Israel).

Also on display at the meeting were 3-D cone beam computed tomography systems used in preparing templates. They were i-Cat from Imaging Sciences International (Hatfield, Pennsylvania) and PreXion from TeraRecon (San Mateo, California).

Antibiotic and antimicrobial therapies

Bacteria and bacterial plaque play an important role in the development of periodontitis. The accumulation of sub-gingival microorganisms on the root surface leads to the formation of an adherent layer of plaque that has the characteristics of a biofilm. As periodontal infection progresses, bone and tissue are destroyed with increasing severity. The efficacy of periodontal therapy is directly related to the ability of a treatment to lower the levels and prevalence of pathogenic bacteria.

David Paquette, DMD, associate professor at the University of North Carolina School of Dentistry (Chapel Hill), and Maria E. Ryan, DDS, PhD, professor at State University of New York at Stony Brook's department of oral biology and pathology, delivered reviews of drug therapies used in the treatment of periodontal infections and after scaling and root planing. Antibiotics are widely used by general dentists and periodontists in the course of treating periodontal disease, which may entail pre-medication as well as post-surgical medication, depending on the severity of the disease and the patient's dental hygiene habits.

Commonly used antibiotics are Arestin, locally delivered injectable minocycline microspheres from OraPharma (Warminster, Pennsylvania), a subsidiary of J&J, and Periostat, systemically delivered doxycycline hyclate from CollaGenex Pharmaceuticals (Newtown, Pennsylvania), which also is now available in generic form. Doxycycline also is used as an adjunctive therapy, also known as host modulation therapy, meaning that it is delivered at a low dose for inhibiting collagenase to suppress the host response, but at a sub-potent level against bacteria. Tetracycline, amoxicillin and metronidazole also are prescribed by periodontists and other dental practitioners.

Arestin is site-specific and is injected as an individual dose that can be used only on a single tooth surface. There are six surfaces for each tooth. The company is developing Arestin for dispensing from a double-dose syringe. SunStar (Osaka, Japan/Chicago) markets minocycline gel in Korea. It is still in clinical trials.

Atridox from QLT (Vancouver, British Columbia) is a biodegradable injectable gel that contains doxycycline hyclate in a polylactide copolymer. It flows into periodontal pockets, where it is transformed into a wax-like substance that delivers its active agent over a period of seven days. Atridox has been on the market for many years and its usage has declined.

Elyzol, a metronidazole gel, is sold in Europe by Colgate-Palmolive (New York), but is not approved for sale in the U.S.

Chlorhexidine gluconate is an antimicrobial agent that is used in mouth rinses sold by several companies to dentists who prescribe it for their patients. PerioChip, distributed by MIS Implants Technologies (Fair Lawn, New Jersey), is a gelatin wafer that contains chlorhexidine gluconate. It is inserted by the dentist into a periodontal pocket and delivers the active agent for up to six days.

Dealing with inflammation

In an opening session of the conference, a panel of medical and dental professionals reviewed the role of inflammation in periodontal and systemic diseases. The damage to tissue, bone and ligaments that occurs in periodontal disease cannot be entirely explained by the action of bacterial infections. A major culprit seems to be the body's failure to turn off its inflammatory response to infection.

Ray Williams, DMD, professor and chair of the department of periodontology at the University of North Carolina, discussed the impact of gingivitis and periodontitis on systemic diseases, including cardiac disease, diabetes, osteoporosis, prenatal care, stoke and others.

He said it is "critical" for the dental professional to understand this impact and to address the inflammatory process not just as a mechanism for saving teeth but as a disease entity in its own right. It will require a major educational commitment for expanding the focus in continuing education for the practitioners as well as within dental schools, Williams said.

Another panelist, Michael McGuire, stressed that there needs to be a serious attempt to develop adjunctive therapeutics that focus on the inflammatory aspects of these diseases and that, in light of all the data, new products or therapeutic modalities will need to be added to the current therapeutic modalities. All the panel participants emphasized the need for increased communication between the medical and dental professions.

IZUN Pharmaceuticals (Jerusalem/New York) is developing the PerioPatch, a transmucosal patch that adheres to the inflamed gingiva and slowly releases a polymolecular anti-inflammatory agent over a period of weeks. It is noteworthy that there are currently no topical anti-inflammatory agents that are approved for use in periodontal disease.

Lasers for periodontal therapy

Charles Cobb, DDS, PhD, professor emeritus of the department of periodontics at the University of Missouri at Kansas City, presented a review of 30 clinical trials that have been reported on the used of lasers for treating periodontal disease. These included Er/YAG, Nd/YAG, diode and carbon dioxide lasers.

The key message, Cobb said, is that it is difficult to draw any definite conclusions from these studies because of the many variables in the clinical study designs and in the laser parameters such as energy, wavelength, waveform (continuous or pulsed), duration and intensity.

He said the conclusions is that no single laser is effective for all periodontal procedures, which include root planing, closed flat procedures, elimination of bacteria, reduction of pocket probe depth and crown lengthening.

However, he said that there "probably" is some advantage to combining the use of lasers along with scaling and root planing.

Similar conclusions were offered in a presentation by Samuel Low, DDS, professor of periodontology at the University of Florida School of Dentistry (Gainesville). He said that "laser studies are all over the board ... there is no magic bullet" And that laser-tissue interaction "is an evolving science." Low said he is "skeptical" about the use of lasers for sterilizing a periodontal pocket, but noted that cold lasers soon will be available for photodisinfection.

It is noteworthy that OnDine Biopharma (Vancouver, British Columbia) has begun selling in Canada its PerioWave photodynamic disinfection system for killing periodontal disease. It uses laser-based activation of a photosensitive compound, tricyclic phenothiazine (related to methylene blue), that is "painted" onto infected gums. Ondine Biopharma has a Health Canada license for the treatment of chronic periodontitis in adults and a CE mark for its Periowave photodynamic disinfection system, which is being reviewed by the FDA as a medical device.

Millennium Dental Technologies (Cerritos, California) displayed its PerioLase MVP-7 multiple variable-pulsed Nd:YAG dental laser, which was designed by the company's founders specifically for use in treating periodontal disease and was the first laser to be FDA-cleared laser for this indication. It is based on the Laser-ANAP (Assisted New Attachment Procedure) protocol.

Raymond Yukna, DMD at the University of Colorado School of Dentistry (Aurora), was one of the presenters at the conference's laser session. He is the principal clinical investigator for Millennium and his studies showed evidence of root surface coating (cementum) and new connective tissue (periodontal ligament) formation on tooth roots by stimulating existing stem cells to grow following treatment with the PerioLase MVP-7 laser. His recent studies also have shown that laser energy can be used to re-grow dental tissue. PerioLase MVP-7 is Millennium's only product. About 85% of its purchasers are general practitioner dentists.

Pharos Life (Cambridge, Ontario) is developing a combination of a whole-mouth LED light source and toluidine blue for treating periodontal disease. The company has institutional review board approval to begin human trials to be conducted at the University of Toronto Faculty of Dentistry.

Biolase (Irvine, California), a leading marketer of dental lasers, featured its Waterlase MD, which uses a combination of YSGG laser energy and water in a process called HydroPhotonics to perform many traditional dental procedures with less anesthesia. It has six or seven periodontal indications, which include use for debridement of soft and hard tissues.

Oral cancer detection

According to the National Cancer Institute, about 29,000 people in the U.S. are diagnosed each year with cancer of the oral cavity (the mouth and lips) or the oropharynx (the part of the throat at the back of the mouth) with a five-year survival rate of only 50%. About 25% of oral cancers occur in people who don't smoke and have no other risk factors. Screening tests for oral cancer are being promoted to all dental professionals.

Zila (Phoenix) displayed its VizLite Plus chemiluminescent oral cancer screening test that uses a toluidine blue stain for visualization of lesions. LED Dental (White Rock, British Columbia, Canada) showed its VELscope handheld device that emits a blue light. A diagnosis is based on tissue fluorescence, which changes when abnormalities are present.

OralCDx Laboratories (Suffern, New York) markets a brush biopsy test that is performed at chairside and is examined using a computerized cell-scanning system to determine if an oral lesion is benign or malignant.

Perceptronix (Vancouver, British Columbia) is developing OralAdvance, a cytology test for the early detection of oral cancer that would be performed on a specimen of buccal mucosa to be evaluated in a clinical testing laboratory for detecting DNA abnormalities.

Researchers at the University of Texas (Austin) are developing a lab-on-a-chip test that can detect the presence of epidermal growth factor receptors (EGFRs) on the surface of cells swabbed from the lining in the mouth. EGFRs are much more common on cancerous cells than on healthy cells. The test would be performed on a sample of saliva, yielding results within 10 minutes.