I am about to graduate from dental hygiene school. I was taught that the current standard of care is to avoid creating glassy, smooth surfaces. However, one instructor in the clinic suggested that all surfaces should be glassy and smooth. Which is correct?
In the 1960s and 1970s, dental hygienists were taught that calculus was a precipitating factor in periodontal diseases and must be eliminated. Thus, the endpoint of scaling and root planing was a glassy, smooth surface, free of calculus. This opened the door to aggressive overinstrumentation that caused problems, such as hypersensitivity and irreversible structural damage.
In the 1980s and 1990s, this approach was abandoned, as the role of the immune system and host response was better understood. This led to a new era in which the goal of scaling and root planing was preservation of root structure (cementum) at any cost, which was typically achieved via the use of low powered ultrasonic instrumentation in all instances, regardless of deposit tenaciousness, size, or location. Subsequently, this approach was found to be detrimental to periodontal health.
What we know now is that even the tiniest speck of burnished calculus will sustain an ulcerated lesion in the overlying tissue that perfectly mimics the shape of the deposit. A chronic state of inflammation continues, and until this last speck is removed, the infection will persist. The consequence of preserving the cementum at any cost is that the outermost layer of subgingival calculus becomes smooth very quickly (burnished), leading the clinician to assume the deposit has been removed. However, the deeper layers of subgingival calculus are still teeming with pathogenic biofilm, which has been substantiated through the use of the dental endoscope.
The inability of dental hygienists to administer local anesthesia in some states has played an important role in the furtherance of the "preserving cementum at all costs" approach. Local anesthesia is required to provide a thorough scaling and root planing. Unfortunately, many state practice acts still prohibit dental hygienists from providing this service.
The issue of burnished calculus being left behind remains a problem in dental hygiene. To avoid overinstrumenting and reduce the risk of burnishing deposits, a complementary approach to nonsurgical periodontal therapy is indicated. It combines definitive scaling and root planing using bladed hand instruments with ultrasonic instrumentation set at the proper power setting adequate for the task at hand. This is done in sequence to maximize both the efficiency and effectiveness of therapy. The only means of immediate evaluation during treatment is tactile and, therefore, highly subjective, but the corresponding texture should be consistently hard and smooth.
Basically, the goal of therapy is not to produce a glassy, smooth root surface, but rather to create a root surface biologically compatible with health—meaning it is free from pathogenic biofilm and local retentive factors. This is a subjective measure that can only be assessed by clinical evaluation and subsequent tissue response. In other words, we don't set out to form glassy, smooth surfaces, but in the process of creating a biocompatible root surface that can sustain health, it may feel glassy and smooth, which is not a bad thing. But don't overinstrument the root for the sake of seeking a glassy, smooth surface. If your instruments are kept sharp and your tactile sense is activated, you will immediately feel (and hear) confirmation that the root is free of hard deposits. The ultimate test is the absence of bleeding on probing at the 4-week posttreatment re-evaluation.