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Effective Scaling vs Obsessive Scaling by Larry Burnett, DDS I have to be very careful when I write about residual calculus because too many people (hygienists, periodontists, gp’s) seem to get the impression that I’m in favor of it. I’m not. And if you can remove it without doing serious damage to the hard or soft tissue, by all means remove it! My difference with some therapists is that I don’t believe a thin shell of burnished calculus is the worst thing that can happen to the patient. Excessive scaling and root planing can damage the cementum and radicular dentin - causing sensitivity for sure. By exposing tubules, it may even increase the opportunity for periodontal pathogens to penetrate to the pulp ... or vice versa. Portrait of a zealot Dr. Mike Rethman (past President of the American Academy of Periodontology) recently reminded me of Dr. A.B. Riffle, a now largely forgotten periodontist of the mid-20th-century, who authored such classic articles as “The Cementum During Curettage” and “The Dentin: It’s physical characteristics during curettage.” Dr. Riffle was so enthusiastic about removing the last scintilla of calculus and “diseased hard tissue”, he’d scale roots until he’d whittled them into strange and wonderous shapes.. His technique, known as (and I kid you not) “Riffle-izing”, allowed high-speed stripping of cementum and the underlying dentin. Mike tells me a Riffle-ized root was easily recognized on a radiograph because the shape had been visibly altered. Dr. Riffle’s papers are rarely cited today, and when they are, it’s in articles discussing hypersenstivity!1 It used to be common knowledge that the cementum could become saturated with bacterial toxins ... sort of like mildew in an old kitchen sponge. So in many practices, standard perio treatment included stripping off this outer layer of diseased hard tissue. This “common knowledge” is considerably less common today. In fact, research over the past 15 years, has pretty much debunked it. Way back in 1991, English researchers showed that simply running your ultrasonic tip over the root surface, without making any particular attempt to remove root calculus, was enough to reduce the toxins both on and within in the cementum by 99% or more. 2 However, in some practices root planing had become ritualized. By that I mean, the mere act of scraping roots with assorted sharp instruments, had become virtuous behavior ... completely independent of any objective. If science showed this deep root planing wasn’t necessary to remove contaminated cementum - well, they were doing it for some other admirable reason. Some said root planing was necessary to assure removal of all the calculus. But studies suggested that no matter how energeticly you scale, it’s virtually impossible to remove all the calculus. For example, Sherman found just 43% of meticulously scaled roots were truly calculus-free. 57% of them still contained residual calculus.3 Some said that root planing was essential to remove the burnished calculus that remained after ultrasonic or manual scaling. The theory here is that pathogens in the burnished calculus smeared on the root serves as a source of reinfection. The difference between supra and subgingival calculus Calculus is like a coral reef in a number of ways: Like a coral reef, calculus provides sanctuary to an entire ecosystem of beasts. Not just the coral polyps themselves. As Nemo discovers, life outside the reef is considerably less hospitable. And like a coral reef, only the relatively new surface is actually alive. The material deep below consists of the mineralized skeletons of prior generations. (I’m writing metaphorically here - I know that bacteria don’t have teeny skeletons.) “Ah, but even dead calculus may contain voids that hide infectious pathogens,” argues the not-a-scintilla-of-calculus crowd. And when they’re talking specifically about supragingival calculus, the research seems to suggest they’re right. In 1999 an English research team examined supragingival calculus and discovered small numbers of both anarobic and aerobic pathogens hunkered down within the lacunea and internal channels. In other words, this research supports the removal of all “infected” calculus. Recently these same researchers published the results of an expanded study in which they compared young supragingival calculus with old supragingival calculus, and this time they also included some old subgingival calculus from periodontal patients. As in the earlier study, they found that supragingival calculus (both young and mature) contained cavelike pits and channels that contained vital microorganisms. It seems quite possible that superficial scaling might open these caves allowing the dormant microbes to venture forth like monsters from some 1950’s sci-fi movie - to wreak havoc in the sewers of Los Angeles. But what about the subgingival calculus? When they examined the old subgingival calculus, they discovered it was different. In old subgingival acretions there were no channels. No internal porosities. It was a uniformly mineralized chunk.4 I’m pretty sure this isn’t what the researchers expected to find. I suspect they actually HOPED to find dormant bugs hiding in the old calculus. And in my opinion that’s what makes this study so compelling. When the findings contradict the researchers' preconceptions, there’s virtually no chance of unconscious bias. Residual root calculus can be divided into two types What I’ll call “Type 1” residual calculus are accretions that have been overlooked by the dentist or hygienist. This calculus is rough. It’s porous. And it’s generally associated with large amounts of bacterial plaque. Type 1 residual calculus is bad for the periodontal health of the patient and should be removed. I think everyone agrees with that. Type 2 residual calculus is different. It’s a thin smooth veener of inert bunished calculus left after the operator removed the Type 1 calculus. Burnished calculus is virtually impossible to feel with your hand instrument - and it doesn’t show up on a film. It wasn’t till the recent introduction of micro-video systems that many dentists recognized it’s existence. Please don’t misunderstand, it’s not that I think this burnished calculus is a really great thing. I wish it weren’t there. However, I’d rather leave patients with a little burnished calculus than subject them to severe root planing in pursuit of those glass-like root surfaces we used to admire so much.
Here are my personal conclusions. See if you agree. #1 Automatically stripping off diseased cementum cannot be justified by recent research. #2 No matter how carefully we scale, it is impossible to remove all calculus. #3 Despite the fact that calculus remains, the heavy majority of patients receiving therapy see significant improvement. #4 Therefore, periodontal health does not require calculus-free roots. #5 In the admirable but doomed attempt to totally eliminate root calculus (not just Type 1, but Type 2 as well), significant damage can be done to the patient. Everyone agrees that wicked sensitivity can be one consequence of excessive planing. But there may be other sequalae. When you strip off the protective cementum and outer layers of radicular dentin you’re opening tubules that allow communication between the pulp and the periodontal pocket. It’s been proposed that open root tubules may provide a two-lane highway for pathogens and toxins. This pocket/pulp connection may provide a source of mutual reinfection that’s very difficult to resolve. Again, let me reiterate: I’m no fan of calculus. Type 1 residual calculus should be removed because its irregular surface provides sanctuary for pathogens. If you can remove burnished Type 2 calculus without damaging the roots, do it. But just remember: no matter what you do, some calculus will remain. And extremism in pursuit of glassy roots has consequences. 1 Hafez AA, Cox CF. Definitive desensitizarion of dentin: The prevention and treatment of postoperative hypersensitivity. Research monograph - Phoenix
About Dr. Burnett ... A graduate of the Medical College of Virginia School of Dentistry, Dr. Larry Burnett has authored numerous articles and lectured extensively on conservative periodontal therapy throughout the US and Canada. A frequent speaker at the ADA annual scientific session, Chicago Midwinter and AGD meetings, he is moderator of the internet Perio Discussion Board and author of the video-based study program “Advanced Ultrasonics in General Practice.”
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