**3.4 Bacterial reduction**

*Public Health in Developing Countries - Challenges and Opportunities*

pockets [16] and controlling bacteremia and gingival bleeding [16, 18]. The probing pocket depth and bleeding index scores were reduced using the pulsed Nd:YAG laser. Furthermore, clinical evaluation of soft tissue biopsies taken from human subjects using the Nd:YAG laser versus a curette presented a complete removal of the epithelium of the pocket after use of the pulsed Nd:YAG laser compared to the curette [15]. Similar effects presented in pig jaws (in vitro) after the use of a 980 nm diode laser with 2–4 W power settings and continuous wave compared to the conventional curette [37]. There are advantages in the postsurgical outcomes with the removal of pocket epithelium. A recent clinical study in India showed that the modified Widman flap with removal of the pocket epithelium was more effective in reducing mean probing depth than access flap with intrasulcular incision. It showed greater gain of clinical attachment and demonstrated less gingival recession [38]. When deep periodontal pockets are present, removal of the pocket epithelium using a fiber-optic glass laser offers benefits. With or without flap elevation and a conventional periodontal access flap procedure, the pocket epithelium will be removed from the inner and the outer part of the pocket. Depending on how the patient heals, the epithelium can later be ablated every 7–10 days from the outer part of the pocket, usually under the use of topical anesthesia, in order to control apical migration. This can result in long-term, stable connective tissue attachment, without gingival recession. The principle underlying this approach is guided tissue regeneration; it has been called "laser-assisted guided tissue regeneration" [39]. This approach should be evaluated in different prospective clinical studies involving many patients and following exactly the same protocol in order to establish that it is a technological improvement that should be incorporated routinely in daily practice. Both clinical case series and clinical research have shown the potential of this application using the CO2 laser, since the noncontact handpiece is able to ablate tissues very quickly, controlling the epithelial cell proliferation and further apical migration of a long junctional epithelium. Israel et al. [20] were able to demonstrate histologically the effects of this de-epithelialization technique in humans. The technique involves using the CO2 laser to remove (ablate) the inner part of flap after conventional periodontal flap elevation and then using the same method in the outer part of the flap to achieve epithelial retardation. Case series in patients with generalized advanced periodontal disease have shown that the laser de-epithelialization technique leads to good results without the need for multiple

The use of CO2 lasers to decontaminate root surfaces has been investigated, providing more information about the exact power settings and parameters required to avoid root damage. Barone et al. [42] showed that a defocused, pulsed CO2 laser is able to create smooth and clean root surfaces compared to a focused, continuous wave; the latter leads to melting and root surface damage. Later studies using the same parameters for CO2 lasers reported root conditioning with a better fibroblastic activity, cellular proliferation, and greater fibroblast attachment [43]. Different clinical case reports have demonstrated these advantages of CO2 laser de-epithelialization [44]. This technique has also been used in clinical studies and has shown that coronal flap advancement in conjunction with CO2 laser root conditioning leads to improvements in clinical parameters and long-term tissue stability after 15 years, compared to the modified Widman periodontal flap procedure [45]. The authors concluded that this laser technique seemed to have greater effects and should be

used in treating deep periodontal pockets (more than 7 mm deep).

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membrane therapy [40, 41].

**3.3 Laser root conditioning**

A laser application that has been especially promoted in the past is for the reduction of bacteria in pockets, due to the high absorption of specific laser wavelengths by the chromophores. Initially, the use of an Nd:YAG laser was shown to reduce the load of *Porphyromonas gingivalis* and *Prevotella intermedia* [46]. A study by Assaf et al. [47] is of special interest. Using a diode laser in conjunction with ultrasonic scaling for treatment of gingivitis, they were able to show a significantly lower incidence of bacteremia in the diode + ultrasonic group (36%) than the ultrasonic only group (68%). They suggested that diode lasers should be used to prevent bacteremia, especially in immunocompromised patients. Using a 980 nm diode laser to reduce periodonto-pathogenic bacteria in patients with aggressive periodontitis has also been investigated. Kamma et al. [48] confirmed that it was possible to reduce the total bacterial load in pockets without the use of any systemic antibiotic therapy. Clinical case series with 10 patients using in the same patient (in a randomized protocol) SRP in conjunction with 980 nm diode laser, SRP and an Nd:YAG laser, and SRP with photodynamic therapy (PDT) showed that the PDT was able to reduce significantly the bacteria in the pockets and provide a predictable clinical outcome for 3 months. In contrast to that, the use of Nd:YAG laser was not very beneficial and was similar to the control (SRP) group [49]. Due to the bacteria reduction and the reduced bleeding on probing provided by the PDT, the PDT was recommended for periodontal patients especially for the maintenance appointments.
