Is probing without cal meaningful

Efficiency and reliability in periodontal assessment are too important today to be ignored, and I was pondering this important issue yesterday while commuting to work.

Jun 4th, 2013

by Lynne Slim, RDH, BSDH, MSDH

Efficiency and reliability in periodontal assessment are too important today to be ignored, and I was pondering this important issue yesterday while commuting to work. While driving, I was trying to peel a hard-boiled egg and a navel orange with one hand. Isn't that similar to what many of us have to endure in the hygiene operatory when we have no assistance with a periodontal exam? Sometimes I feel like I'm juggling three balls in the air while talking to a patient at the same time.

Like our ever-changing weather patterns, dental hygienists in private practice face uncertainty about this important component of their workday. Yes, many want to be complete in their periodic periodontal assessment, but they are not given adequate time to get the job done. Some hygienists I talk to are being told that adult patients are scheduled every 30 to 40 minutes without exception, and this appointment might even include a full-mouth series of radiographs. Anyone with expertise in practice management knows it's impossible to complete an adult recare patient in 30 minutes. Even with a dedicated hygiene assistant, it takes about 20 minutes just for meticulous routine scaling and polishing. Sure, you can speed up the process and get sloppy along the way, just as the oral surgeon and his team did in Oklahoma, but there are consequences.

I love to assess periodontal health on adult patients, but only if I have adequate time to do so. If I am pressed for time, I know I can't reliably assess the periodontium and communicate results to my patient. I don't always have assistance with charting, nor do I have an automated probing device, but I record and track data on a computer software program. Many times, I've found that data collected by a dental hygienist or dentist is incomplete and usually limited to probing depths.

There are many reasons why a dental hygienist or dentist only charts probing depths, and my guess is that most of the time it's the absence of an automated device or feeling rushed. In some cases, it's just habit, and as we all know, bad habits die hard.

During the month of February, I found myself studying a CE article in JADA (Michalowicz et al.) that focused on whether or not probing depth (PD) is a reliable predictor of change in clinical attachment loss.1 Most software programs will compute clinical attachment loss (CAL) if you chart recession. So let's revisit CAL, review its importance, and discuss important components of the JADA article.1

CAL is calculated from a fixed reference point (cementoenamel junction or CEJ), and it is computed by calculating the distance from the CEJ to the base of the pocket. When the gingival margin is coronal to the CEJ, you subtract (from the probing depth) the distance from the CEJ to the gingival margin. If the gingival margin is apical to the CEJ, CAL is equal to the probing depth plus the distance from the CEJ to the gingival margin.

When patients have generalized or localized gingival recession, which is the case with some patients such as aging baby boomers and others with aggressive periodontitis, probing depths underestimate CAL. When some patients have medication-induced gingival enlargement, for example, probing depths on their own overestimate CAL. Periodontal probing, by itself, is not a reliable measurement, since many variables can cause measurement error while probing.

Michalowicz et al. explored the association between change in probing depth and CAL in patients with chronic periodontitis and used data from clinical trials, all of which included mechanical debridement and at least 12 months of clinical follow-up. Authors point out that a full-mouth assessment of CAL is time consuming and technically demanding, and requires more than 300 measurements to monitor CAL at six sites on each tooth -- assuming a patient has 28 teeth. That's a lot of measurements to calculate!

Some of the discussion surrounding measured changes in probing depths (PD) and CAL are important to researchers, because some research studies have only used reduction in PD as important outcomes. This is true of recent studies assessing the efficacy of lasers, photodynamic therapy and antimicrobial agents.1 What's important to clinicians, however, are patient outcomes, because we re-evaluate patients after nonsurgical periodontal therapy at six to eight weeks. We also follow periodontal data on these patients indefinitely during periodontal maintenance.

On an individual basis (meaning an individual person and in looking at average changes), correlations between PD and CAL varied according to site location and initial PD and were highest when measuring deep pockets. The relationship between PD and CAL changes after nonsurgical treatment varied considerably according to tooth type, tooth site and initial disease severity.

According to Michalowicz et al., relatively few facial and lingual sites with progressive CAL had an increase in probing depth. When PD alone is used as an outcome, clinicians will frequently fail to detect changes in CAL, especially at initially shallow and moderate sites.

If we know that the use of PD alone as a periodontal assessment tool frequently fails to detect changes in CAL, is this a huge wake-up call for practitioners? Is that notched metal stick (a term coined by our friend, Bill Landers, fellow columnist) the be -all and end-all in periodontal assessment? I don’t think so.

Last night, I briefly read a discussion of the above referenced Michalowicz et al. article online. Suzanne Newkirk manages a LinkedIn Perioscopy blog where I post from time to time. Tom Schoen, DDS, made some excellent points about periodontal assessment and he talked specifically about the topography of the periodontium and the importance of a multifaceted and thorough assessment:

"The more real estate you have to maintain, the more time and effort you need to put into it. Topography of that real estate changes as well, increasing the difficulty of maintenance. If disease were linear, you could just go by pocket depths and extend treatment intervals out until active disease appears and back it down a bit. With large CAL and small PD you have a proven bone loser with a nonlinear disease and biofilm which becomes destructive in three months and difficult topography that takes more time to clean. I know of no patent in my practice that has CAL as their only risk factor, but even if it were the case, the risk is far greater than when there is minimal CAL. CAL is not the way to design treatment assessment any more than PD. Combined with BOP, age, med hx, location and amount of CAL, patient OH, smoking history, and other risk factors should be taken into account. It is unfortunate that there are many practitioners in this PPO driven age that monitor disease ONLY with PD. If instead they ONLY used CAL for their ill conceived STM programs, the public would be better served. Specific answer to question, SRP initial and perio-maintenance every three month forever for those with 3mm or more of circumferential CAL regardless of PD is required. I do not consider facial or lingual CAL an issue if there is a stable and adequate zone of attached keratinized gingiva. Your goal in this is to prevent further bone loss. The biofilm must be disrupted and removed with ultrasonic instrumentation. Removing calculus and stains is not enough so a prophy would not suffice."

Just as I shouldn't eat with one hand and drive with the other, periodontal assessment isn't something that can be rushed or based on only one component like probing depths. Presence or absence of inflammation, anatomical considerations, CAL and risk assessment need to be worked into the mix for improved reliability of periodontal exams. RDH


1. Michalowicz BS, Hodges JS, Pihlstrom BL. Is change in probing depth a reliable predictor of change in clinical attachment loss? JADA 2013; 144(2): 171-178.

LYNNE SLIM, RDH, BSDH, MSDH, is an award-winning writer who has published extensively in dental/dental hygiene journals. Lynne is the CEO of Perio C Dent, a dental practice management company that specializes in the incorporation of conservative periodontal therapy into the hygiene department of dental practices. Lynne is also the owner and moderator of the periotherapist yahoo group: Lynne speaks on the topic of conservative periodontal therapy and other dental hygiene-related topics. She can be reached at or

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