Prevalence of diabetes among patients diagnosed with periodontitis: A retrospective cross-sectional study.

OBJECTIVE: The objective of this study was to assess the prevalence of diabetes among patients with periodontitis and to evaluate whether diabetes is related to extent and severity of periodontitis. METHOD: This is a retrospective study of data observed over a 10-year period in patients referred to a specialized clinic for periodontology in the Netherlands. Patients received at the intake appointment a full-mouth periodontal examination, and based on the clinical data, patients were classified with respect to extent and severity of periodontitis. In addition, the prevalence of diabetes was recorded, based on self-report. RESULTS: A total of 5375 periodontitis patients were included in the study sample (mean age of 50 years). The prevalence of diabetes in this patient sample was 3.7% (n=192). No relation between diabetes and extent or severity of periodontitis could be established. CONCLUSION: The prevalence of diabetes in a predominantly "controlled" diabetic population was not related to the extent and/or severity of periodontitis along with the finding that the prevalence was lower than the national diabetes prevalence in the Netherlands.

Interproximal cervical lesions caused by incorrect flossing technique.

UNLABELLED: This case report describes an interproximal cervical lesion caused by the incorrect use of dental floss. A 58-year-old man who was asymptomatic, presented with unusual notch-like cervical lesions. After clinical and radiographical examinations, it was concluded that the aetiology of these lesions was an incorrect flossing technique. The treatment plan included extraction of maxillary 3rd molars and re-education of the patient in oral hygiene technique. CONCLUSION: These lesions are irreversible and often go undiagnosed; therefore, it is important for the clinician to be familiar with the clinical presentation and aetiology.

Laser irradiation of bone: III. Long-term healing following treatment by CO2 and Nd:YAG lasers.

BACKGROUND: Relative few reports exist concerning healing of laser created osteotomies over an extended period of time. The purpose of this study was to evaluate long-term healing, from 21 to 63 days, of osteotomy defects in the rat tibia created with the Nd:YAG and CO2 in the presence of a surface cooling spray of air/water. METHODS: The experimental model consisted of 15 large Sprague-Dawley rats. Six treatment modalities were randomly distributed among 6 tibial recipient sites: 1) a negative control (no treatment); 2) a positive control (bur osteotomy); 3) CO2 laser at 5 W (860 J/cm2); 4) CO2 laser at 6 W (1,032 J/cm2); 5) Nd:YAG laser at 5 W (714 J/cm2); and 6) Nd:YAG laser at 7 W (1,000 J/cm2). All laser irradiation was delivered in the presence of a surface coolant consisting of air (15 psi) and sterile water. Five animals were sacrificed at each of 3 time intervals: 21, 35, and 63 days post-treatment. Multiple histologic sections from each treatment site were examined by light microscopy using hematoxylin and eosin Goldner's trichrome stains, and polarized light and evaluated for presence of a char layer, heat induced cracking, heat related alterations in cells or tissue matrix, and osseous regeneration. RESULTS: Healing was severely delayed in all laser treated sites compared to positive control sites. Of the laser treated sites, those irradiated by CO2 laser at 5 W (780 J/cm2) exhibited the greater amount of bone regeneration. At best, however, only a small percentage of sections from any of the laser treated specimens showed evidence of bone regeneration within the ablation defect regardless of the post-treatment time interval. CONCLUSIONS: Under the conditions of this study, the osseous healing response was severely delayed by CO2 and Nd:YAG laser irradiation of bone, even in the presence of a surface cooling spray of air/water.

Effect of sonic and mechanical toothbrushes on subgingival microbial flora: a comparative in vivo scanning electron microscopy study of 8 subjects.

OBJECTIVES: The purpose of this initial study was to evaluate the effects of both a sonic and a mechanical toothbrush versus the effects of no treatment on depth of subgingival penetration of epithelial and tooth-associated bacteria. METHOD AND MATERIALS: Eight adult subjects exhibiting advanced chronic periodontitis with at least 3 single-rooted teeth that were in separate sextants with facial pockets > or = 4 mm and < or = 8 mm and that required extraction constituted the experimental sample. Teeth were either subjected to 15 seconds of brushing with a mechanical toothbrush or a sonic toothbrush or left untreated. The test tooth and the associated soft tissue wall of the periodontal pocket were removed as a single unit. Samples were processed and coded for blind examination by scanning electron microscopy. Distributional and morphologic characteristics of dominant bacteria with specific emphasis on spirochetes were evaluated for both epithelial- and tooth-associated plaque. RESULTS: No differences were found in morphotypes or distributional and aggregational characteristics of epithelial-associated microbes in the 1- to 3-mm subgingival zone between the mechanical and sonic toothbrush-treated groups and the control group. Both toothbrush groups featured disruption of microbes that extended up to 1 mm subgingivally. Root surfaces on the sonic-treated samples appeared plaque-free at low magnification; however, at 4,700x, a thin layer of mixed morphotypes and intact spirochetes was found subgingivally and slightly subgingivally. In comparison, mechanical brush samples featured incompletely removed plaque, both subgingivally and subgingivally, with intact spirochetes present on subgingival root surfaces. CONCLUSION: Results suggest similar effects for both sonic and mechanical toothbrushes on epithelial- and tooth-associated bacterial plaque in periodontal pockets and adjacent root surfaces that extend up to 1 mm subgingivally. Further, the presence of intact subgingival spirochetes suggests limited exposure to acoustical or mechanical energy from the toothbrushes evaluated.

PCR monitoring for tetracycline resistance genes in subgingival plaque following site-specific periodontal therapy. A preliminary report.

BACKGROUND: The selection of antibiotic resistance genes during antibiotic therapy is a critical problem complicated by the transmission of resistance genes to previously sensitive strains via conjugative plasmids and transposons and by the transfer of resistance genes between gram-positive and gram-negative bacteria. The purpose of this investigation was to monitor the presence of selected tetracycline resistance genes in subgingival plaque during site specific tetracycline fiber therapy in 10 patients with adult periodontitis. METHOD: The polymerase chain reaction (PCR) was used in separate tests for the presence of 3 tetracycline resistance genes (tetM, tetO and tetQ) in DNA purified from subgingival plaque samples. Samples were collected at baseline, i.e., immediately prior to treatment, and at 2 weeks, and 1, 3, and 6 months post-fiber placement. The baseline and 6-month samples were also subjected to DNA hybridization tests for the presence of 8 putative periodontal pathogenic bacteria. RESULTS: PCR analysis for the tetM resistance gene showed little or no change in 5 patients and a decrease in detectability in the remaining 5 patients over the 6 months following tetracycline fiber placement. The results for tetO and tetQ were variable showing either no change in detectability from baseline through the 6-month sampling interval or a slight increase in detectability over time in 4 of the 10 patients. DNA hybridization analysis showed reductions to unmeasurable levels of the putative periodontal pathogenic bacteria in all but 2 of the 10 patients. CONCLUSIONS: These results complement earlier studies of tet resistance and demonstrate the efficacy of PCR monitoring for the appearance of specific resistance genes during and after antibiotic therapy.

Design features that may influence bacterial plaque retention: a retrospective analysis of failed implants.

OBJECTIVE: The purpose of this study was to conduct a postmortem examination of retrieved failed dental implants to identify design characteristics that may have contributed to premature loss. METHOD AND MATERIALS: Forty-five failed implants retrieved from 40 patients with no significant risk factors for implant failure (e.g., history of smoking or diabetes) were examined by scanning electron microscopy. All implants were placed by general dentists or periodontists in private practice and had functioned for an average of 4 years. RESULTS: Several design features of currently used implants present plaque-retentive areas. Plaque accumulation occurred along the implant-transmucosal abutment interfaces, transmucosal abutment-prosthesis interfaces, implant-prosthesis interfaces, and on surfaces of the abutment, the implant, and the prosthesis. The size of the microgap between the various components, the degree of surface roughness of the restorations and abutments, the exposure of plasma-sprayed coatings and threaded surfaces of implants, and overcontouring of implant restorations contributed to plaque accumulation and provided an ideal environment for bacterial colonization. CONCLUSION: These implant features may be key precipitating or exacerbating factors in the development of peri-implant inflammation, predisposing patients to implant failure.

CT of the brain: a comparison of transportable and fixed-platform scanners.

OBJECTIVE: The purpose of this study was to determine whether an in-hospital transportable CT scanner can provide diagnostic brain images and to compare the quality of these images with those from a conventional fixed-platform CT scanner. SUBJECTS AND METHODS: Twenty-seven patients with known or suspected intracranial pathology underwent imaging on a transportable scanner and a fixed-platform scanner within 1 hr of each other. Images from each CT examination were evaluated independently by two neuroradiologists who were unaware of patient history. Conspicuousness of intracranial pathology and normal anatomy were rated on a 5-point scale (1 point, optimal; 5 points, poor or not visualized). Statistical comparisons were made using nonparametric tests. RESULTS: Seven CT scans were interpreted as showing normal findings and 20 scans revealed intracranial pathology on both CT scanners. Image quality was higher on the fixed scanner (average rating, 2.42 points; SE = .12) than on the transportable scanner (average rating, 3.10 points; SE = .12) (p = .001). Depiction of the cerebellum, midbrain, and supratentorial gray-white matter was better on the fixed scanner (p < .05). However, we found no significant differences in detection of intracranial pathology between scanners. Both radiologists found images from both scanners to be diagnostic in all 27 patients. CONCLUSION: Images of the brain on the transportable CT scanner were less clear than those on a fixed scanner. However, images from the transportable CT scanner were diagnostic in 27 consecutive patients. The implications of this finding are important for the provision of CT services for critically ill patients who cannot be transported to the radiology department.

Relationship between a self-reported health questionnaire and laboratory tests at initial office visits.

BACKGROUND: Dental patients routinely complete a medical questionnaire and have an oral interview during their initial visit, but may have undiagnosed systemic problems which can affect their dental treatment. METHODS: Thirty-nine consecutive patients referred for a periodontal evaluation completed a medical questionnaire and an oral interview. They were referred to a hospital laboratory for an urinalysis, complete blood count, and a standard blood chemistry panel. RESULTS: The self-reported medical history responses were compared with the laboratory data and several abnormalities were noted. Abnormal levels were found with cholesterol, (26/39 patients, 67%); triglycerides, (13/39, 33%); glucose, (6/39, 15%); eosinophils, (18/39, 46%); and monocytes, (10/39, 26%). Smokers (17/39, 44%) had a higher number of abnormal levels or percentages of cholesterol, triglycerides, basophils, lymphocytes, eosinophils, and monocytes. Gender differences were seen in elevated triglyceride levels, abnormal aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and self-reported cardiovascular disease. CONCLUSIONS: This study demonstrated that many patients are unaware of their current medical status and a significant number had undiagnosed abnormalities.

In vivo comparison of synthetic osseous graft materials. A preliminary study.

The purpose of this study was to compare the in vivo osseous healing response of 4 commercially-available synthetic bone grafting materials; hydroxylapatite (HA), calcium sulfate (CaSO4) plus autogenous bone, or a bioactive glass ceramic: with particle size of 300-360 microm (BG1) or 90 to 710 microm (BG2). 4 osteotomy sites were prepared in each tibia of 10 adult male rabbits. One unfilled osteotomy site served as negative control (NC) and another site filled with autogenous bone was the positive control (PC). All animals received BG1 in 2 sites and BG2 in 2 sites. 5 animals received HA and five CaSO4 plus autogenous bone in the remaining 2 sites. Animals were sacrificed at 28 days post-surgery, histologic sections obtained and the % surface area of new bone formation for each material was determined by computerized image analysis. All graft sites showed evidence of bone formation, i.e., (NC) 41.95%; (PC) 50.41%; (BG1) 41.82%; (BG2) 40.36%; (HA) 41.83% and (CaSO4) 58.83%. Statistical analysis using an ANOVA with repeated measures on the materials common to all animals (excluding HA and CaSO4 groups) showed significant differences between materials in surface area of bone, with positive controls better than negative controls, and BG1 and BG2 not significantly different from the negative control. These results indicate that synthetic graft materials can support new bone formation in surgically prepared defects. The utility of a rabbit model for studying physiologic osseous turnover and healing is questioned for studies of slowly resorbing synthetic graft materials.

An evaluation of factors affecting duration of orthodontic treatment.

One of the first questions asked by new orthodontic patients is: How long will I need to wear my braces? A multitude of factors have the potential to influence the answer to this question. The purpose of this retrospective study was to identify some of the primary factors that influence orthodontic treatment duration. Few studies have attempted to evaluate these factors. Data were gathered from 140 consecutively completed, comprehensive treatment patient records in five orthodontic offices. Thirty-one variables related to patient characteristics, diagnostic factors, modality of treatment, and patient cooperation were evaluated. Average treatment time was 28.6 months with a range of 23.4 to 33.4 months among the five offices. Nearly half (46.9%) of the variation in treatment duration was explained by a five-step multiple regression analysis. Included in the regression equation were the number of missed appointments, the number of replaced brackets and bands, the number of treatment phases, the number of negative chart entries regarding oral hygiene, and the prescription of headgear wear during treatment. An additional 6.7% of the variance was explained by variation among the five offices. Six of the 31 variables examined made a statistically significant (alpha =.01) contribution to the explanation of variation in treatment time. The quality of the finished cases and the appropriateness of the original diagnosis and treatment plan were not evaluated. Developing an objective assessment to evaluate these areas may be important for increasing our understanding of treatment time variation.

Laser irradiation of bone: II. Healing response following treatment by CO2 and Nd:YAG lasers.

BACKGROUND: Currently, the most commonly used lasers for dental procedures are the Nd:YAG and CO2. Studies comparing healing of osteotomy defects prepared with rotary burs to those created by laser irradiation have reported conflicting results. The purpose of this study was to evaluate and compare the histologic healing of bone in rat tibial osteotomy defects created either by a dental bur, CO2 laser with and without removal of the char layer, and Nd:YAG laser with char layer removed and with and without use of an air/water surface cooling spray. METHODS: Tibial osteotomy defects were created in 4 groups of 6 rats each using the following: 1) #6 round bur with simultaneous saline irrigation; 2) CO2 laser with char layer intact; 3) CO2 laser with char layer removed; 4) Nd:YAG laser with air/water surface cooling, and char layer intact; 5) Nd:YAG laser with air/water surface cooling, and char layer removed; and 6) Nd:YAG laser without air/water surface cooling, and char layer removed. Both laser types were used at energy densities typically utilized for oral soft tissue surgery. RESULTS: Progressive healing from day 0 through day 21 post-treatment was observed in all treatment groups. However, compared to controls treated by rotary dental bur, those specimens treated by laser, regardless of laser type, energy density, or other parameters, exhibited a delay in healing that appeared to be related to the presence of residual char in the osseous defect. Specimens treated with the Nd:YAG laser using an air/water surface coolant exhibited a decreased thickness and continuity of the char layer and yielded the only specimens with new bone formation at the surface of the laser ablation defect. In addition, the normal pattern of bone remodeling in the rat tibia appeared to have been altered by laser irradiation. CONCLUSIONS: In this animal model, laser-induced osteotomy defects, when compared to those prepared by rotary bur, exhibited a delayed healing response that appeared to be related to the presence of residual char in the osseous defect.

Effective laser ablation of bone based on the absorption characteristics of water and proteins.

BACKGROUND: Collateral thermal damage and residual char formation have severely limited the use of conventional lasers in the surgical preparation of bony tissue. Thermal damage from lasers can be minimized by selecting a wavelength that is strongly absorbed and by reducing the laser pulse duration. In contrast to the fixed wavelengths and microsecond pulse intervals of conventional lasers, the Vanderbilt free electron laser (FEL) can be set at wavelengths ranging from 2.1 to 9.8 microm, and the pulse duration can be reduced to a series of 1 to 2 picosecond (ps) micropulses delivered in succession over intervals of 4 microsecond macropulses. The purpose of this study was to compare the morphologic and chemical changes induced in the near-surface region of bone following exposure to the FEL at 3.0, 6.1, and 6.45 microm wavelengths. The selected wavelengths coincide with the vibrational modes of proteins and water within bone. METHODS: Under general anesthesia, laser incisions were made in the tibias of 14 skeletally mature rabbits. Laser parameters included 22.5+/-2.5 mJ/pulse delivered in individual 4 microsecond macropulses at a repetition rate of 30 Hz, focused to 200 microm and 500 microm spot sizes. Laser incisions were made using a computer-assisted surgical program, and control incisions were created with a bone saw. Rabbits were euthanized after the final incision, tibias recovered, and non-decalcified specimens processed for light microscopy. Separate samples were prepared for FTIR (Fourier transform infrared) photoacoustic spectroscopic analysis. RESULTS: The light microscopy sections of the ablation defects created at the differing wavelengths showed similar features, i.e., 2 zones of collateral damage, a zone generally < 10 mm of extensive thermal damage, and a wider zone of empty lacunae. In comparing treated and untreated surfaces, the spectral differences were limited to a relative decrease in intensity of the amide II and III absorption peaks in all laser-treated surfaces. CONCLUSIONS: Spectroscopic and histologic results indicated minimal thermal damage to bone ablated at 3.0, 6.1, and 6.45 microm wavelengths using the FEL (Fourier transform infrared) at the specified parameters. The FTIR photoacoustic spectroscopic results suggest that the char layer is limited to an area less than approximately 6 microm from the surface.

Change in temperature of subjacent bone during soft tissue laser ablation.

In tissues that closely approximate bone, sufficient heat may be transferred to the bone during laser surgery to cause damage and/or necrosis. To date, there have been few studies examining the temperatures elicited at the bone surface as a result of laser application to the overlying soft tissues. The purpose of this investigation was to determine, under in vitro conditions, temperature changes at the bone/soft tissue interface during laser ablation with CO2 and Nd:YAG lasers used with and without (w/wo) air/water coolant. Experimental specimens consisted of 5 mandibles from freshly sacrificed hogs; laser treatment sites were the buccal and lingual attached gingiva of the molars and the lingual keratinized mucosa of the incisor region. CO2 and Nd:YAG lasers were used w/wo coolant at power settings of 4 to 8 W and 5 to 9 W, respectively. Temperature changes were measured with a copper constant thermocouple contained within a 21 gauge hypodermic needle. In comparing the lasers at comparable energy densities w/wo coolant, temperature increases at the bone/soft tissue interface ranged from 8.0 to 11.1 degrees C with the Nd:YAG and 1.4 to 2.1 degrees C with the CO2. Similarly, in comparing the times required for the interface to return to baseline temperature following removal of the laser, values ranged from approximately 143 to 205 and approximately 119 to 139 seconds for the Nd:YAG and CO2, respectively. Results from this study suggest that, at energy densities equal or above those reported here, the increase in temperature at the bone surface as a result of periodontal soft tissue surgery with the Nd:YAG laser could be damaging, especially if the exposure is prolonged.

Sonic and mechanical toothbrushes. An in vitro study showing altered microbial surface structures but lack of effect on viability.

The purpose of the present study was to compare the in vitro effects of a mechanical and a sonic toothbrush on the viability of Actinomyces viscosus, the rationale being that induction of irreparable microbial damage resulting from aggressive mechanical action or sonic energy, may inhibit or disrupt the process of successional colonization. Cultures of A. viscosus were grown to a standardized optical density and subdivided into 3 treatment groups of 20 specimens each. Treatment groups consisted of an untreated control and exposure to a mechanical or sonic toothbrush for 15, 30, 45, and 60 s. Subsequent to the prescribed treatment, samples were taken from each specimen dish, subcultured, and the number of CFUs determined. Additional samples were obtained for negative staining and examination by electron microscopy. The mean number of CFUs for each treatment group at each treatment interval were statistically analyzed by ANOVA and multiple pairwise comparisons. Results showed a significant main effect for toothbrushes (p<0.0001) and exposure time (p<0.01), but only marginal significance for the interaction of toothbrush with exposure time (p<0.055). Post-hoc tests showed a significantly greater number of CFUs for the sonic toothbrush compared to both the untreated control and mechanical toothbrush groups. Electron microscopic examination revealed a decrease in aggregation tendency and loss of fimbriae in the sonic toothbrush group. Based on the lack of morphologic evidence that would indicate cell damage and the increase in CFUs over that of the control group, it appeared that neither the mechanical or sonic toothbrushes affected cell viability.

In vitro evaluation of the Thermafil technique with and without gutta percha coating.

To determine the sealing ability of the Thermafil technique with and without gutta percha on the plastic carrier, 40 maxillary incisors were divided into four treatment groups: (A) Thermafil with gutta percha on the carrier; (B) Thermafil without gutta percha on the carrier; (C) lateral condensation with standardize gutta percha; and (D) a single standardized gutta percha cone. Average leakage in groups A-D were 0.64 mm, 1.32 mm, 0.53 mm, and 0.72 mm, respectively. The only significant difference was between the Thermafil without gutta percha and the other three groups (p < 0.05).

Loss of crestal bone around dental implants: a retrospective study.

The loss of crestal bone associated with dental implants is a significant clinical phenomenon. The occurrence of such bone loss will often compromise long-term prognosis and, if extensive, ultimately lead to failure. Relatively few studies have focused on the reasons for loss of crestal-supporting bone around implants, although numerous explanations for the phenomenon have been proposed. This retrospective investigation examines one potential causative factor for implant-associated crestal bone loss, which has only recently received attention, i.e., location of the implant/transmucosal abutment interface (ITAI) relative to the crestal bone. A retrospective clinical evaluation of 350 individual implants in 255 patients indicates a direct relationship between subgingival placement of the ITAI and loss of crestal supporting bone. In addition, scanning electron microscopic examination of 45 failed implants showed significant plaque accumulation at the ITAI, the transmucosal abutment/prosthesis interface (TAPI), and the interface between the implant smooth collar and subjacent plasma-spray coated surface.

Effects of tetracycline hydrochloride and chlorhexidine gluconate on Candida albicans. An in vitro study.

This study examined the effects of tetracycline hydrochloride (TCN) and chlorhexidine gluconate (CHX) on the growth and viability of Candida albicans. Subcultures of Candida albicans on Sabouraud's agar, were divided into 5 treatment groups: group 1, untreated control; group 2, 0.12% CHX; group 3, 3.0 mg/ml TCN adjusted to pH 4.5; groups 4 and 5, sodium azide free Tris buffer adjusted to pH 4.5 and pH 7.4, respectively. All groups were incubated for 10 days, and sampled and subcultured daily to determine the viability of each group. Additional samples from group 2 (day 4), group 4 (day 7) and all groups at day 10 were selected for SEM and TEM examination. Visual, SEM and TEM results showed that for groups 1, 3, 4, and 5 there was a heavy and constant uniform growth of Candida albicans throughout the period of the study. However, group 2 (CHX), showed decreasing viability and attachment from day 3 to day 10, with SEM and TEM revealing decreased blastospores and profound changes in the ultrastructural morphology, indicating inhibition of normal cell growth and replication. These results show that TCN even when used at high concentrations, in vitro, will allow uninhibited growth of Candida albicans whereas CHX inhibits cell growth and replication.

Laser irradiation of bone. I. An in vitro study concerning the effects of the CO2 laser on oral mucosa and subjacent bone.

The purpose of this study was twofold: first, to evaluate the histologic effects of CO2 laser irradiation on biopsies of porcine oral mucosa and underlying bone under conditions that simulate the applications of the laser during gingival surgery; and second, to evaluate the histologic effects on cortical bone following irradiation with increasing energy densities. Specimens consisting of mucosa and underlying bone were subjected to multiple passes of the laser beam in the same line of incision at energy densities ranging from 240 to 1,032 J/cm2. A second group of specimens consisting only of cortical bone was irradiated by a single pass of the laser at energy densities ranging from 40 to 2,062 J/cm2. In both groups the mean depth of ablation, width of surface damage, and widths of the zones of thermal necrosis and thermal damage were determined. Results showed a direct correlation between increasing energy density and/or number of energy beam passes and increasing depths of ablation and widths of surface damage. Further, more than three passes at 1,032 J/cm2 penetrated the mucosal layer to involve underlying bone. The mean depth of ablation for bone specimens following a single pass of the energy beam ranged from 0.02 mm at 160 J/cm2 to a maximum of 0.75 mm at 2,062 J/cm2. Using those energy densities most common to oral soft tissue surgery, the mean depth of ablation in bone specimens ranged from 0.17 mm at 240 J/cm2 to 0.28 mm at 640 J/cm2 to 0.35 mm at 1,032 J/cm2. All specimens regardless of tissue composition, energy density, or number of energy beam passes exhibited a distinct layer of residual carbonized tissue, a zone of thermal necrosis characterized by tissue coagulation, and a zone of tissue exhibiting thermal damage.

The effects of CO2, Nd:YAG and Er:YAG lasers with and without surface coolant on tooth root surfaces. An in vitro study.

The objective of this study was to compare and contrast the morphologic changes in tooth root surfaces treated in vitro by scaling and root planing followed by irradiation with the Er:YAG laser using air/water surface cooling and the CO2 and Nd:YAG lasers, both with and without surface coolant. The experimental unit consisted of 42 freshly extracted teeth which were divided equally and randomly assigned to the following 7 treatment groups: untreated control, S/RP only, CO2 laser with and without air/water surface cooling, Nd:YAG laser with and without/air water surface cooling, and Er:YAG laser with air/water surface coolant. Specimens treated with CO2 laser irradiation were subjected to energy densities ranging from 100 to 400 J/cm2; those treated with the Nd:YAG from 286 to 1857 J/cm2; and the Er:YAG was used within a range of 20 to 120 J/cm2. The degree of morphologic change following CO2 and Nd:YAG irradiation appeared directly related to energy density but unrelated to the use of surface coolant. Laser induced surface changes included cavitation, globules of melted and resolidified mineral, surface crazing, and production of a superficial char layer. In contrast, the Er:YAG laser produced root surface changes that might be expected from acid etching, i.e., removal of the smear layer and exposure of the collagen matrix. In addition, sharply defined microfractures of the mineralized structure were noted and unlike the CO2 and Nd:YAG lasers, there was no evidence of melting or surface char. Given the parameters of this study, it appears that both the CO2 and Nd:YAG lasers alter the root surface in an undesirable manner. The Er:YAG laser, however, when used at low energy densities shows sufficient potential for root surface modification to warrant further investigation.

Histologic evaluation of soft tissue attachment to CO2 laser-treated root surfaces: an in vivo study.

There is little support in the dental literature to justify the use of lasers for periodontal root therapy. To the contrary, there are several in vitro studies suggesting potentially adverse effects when lasers are applied to root surfaces. The purpose of this study was to evaluate, in vivo, soft tissue attachment to root surfaces following CO2 laser irradiation. Using a four-quadrant design with one quadrant serving as an untreated control, the remaining quadrants in each of two dogs were treated by (1) scaling and root planing, (2) laser only, and (3) laser followed by scaling and root planing. Prior to the assigned treatments, the roots of three teeth in each quadrant (including the control) were exposed by flap reflection and ostectomy. After root therapy the flaps were repositioned and allowed to heal for 28 days. Clinical attachment levels were determined prior to surgery, at 28 days, and by histologic measurement. Results indicate that specimens treated with laser only lost attachment compared to controls and other treatment groups. Furthermore, there was no histologic evidence of soft tissue attachment to a laser-treated surface that featured a residual char layer.