Improving Oral Cancer Outcomes with Imaging and Artificial Intelligence.

Early diagnosis is the most important determinant of oral and oropharyngeal squamous cell carcinoma (OPSCC) outcomes, yet most of these cancers are detected late, when outcomes are poor. Typically, nonspecialists such as dentists screen for oral cancer risk, and then they refer high-risk patients to specialists for biopsy-based diagnosis. Because the clinical appearance of oral mucosal lesions is not an adequate indicator of their diagnosis, status, or risk level, this initial triage process is inaccurate, with poor sensitivity and specificity. The objective of this study is to provide an overview of emerging optical imaging modalities and novel artificial intelligence-based approaches, as well as to evaluate their individual and combined utility and implications for improving oral cancer detection and outcomes. The principles of image-based approaches to detecting oral cancer are placed within the context of clinical needs and parameters. A brief overview of artificial intelligence approaches and algorithms is presented, and studies that use these 2 approaches singly and together are cited and evaluated. In recent years, a range of novel imaging modalities has been investigated for their applicability to improving oral cancer outcomes, yet none of them have found widespread adoption or significantly affected clinical practice or outcomes. Artificial intelligence approaches are beginning to have considerable impact in improving diagnostic accuracy in some fields of medicine, but to date, only limited studies apply to oral cancer. These studies demonstrate that artificial intelligence approaches combined with imaging can have considerable impact on oral cancer outcomes, with applications ranging from low-cost screening with smartphone-based probes to algorithm-guided detection of oral lesion heterogeneity and margins using optical coherence tomography. Combined imaging and artificial intelligence approaches can improve oral cancer outcomes through improved detection and diagnosis.

Photoacoustic Imaging for Noninvasive Periodontal Probing Depth Measurements.

The periodontal probe is the gold standard tool for periodontal examinations, including probing depth measurements, but is limited by systematic and random errors. Here, we used photoacoustic ultrasound for high-spatial resolution imaging of probing depths. Specific contrast from dental pockets was achieved with food-grade cuttlefish ink as a contrast medium. Here, 39 porcine teeth (12 teeth with artificially deeper pockets) were treated with the contrast agent, and the probing depths were measured with novel photoacoustic imaging and a Williams periodontal probe. There were statistically significant differences between the 2 measurement approaches for distal, lingual, and buccal sites but not mesial. Bland-Altman analysis revealed that all bias values were < ±0.25 mm, and the coefficients of variation for 5 replicates were <11%. The photoacoustic imaging approach also offered 0.01-mm precision and could cover the entire pocket, as opposed to the probe-based approach, which is limited to only a few sites. This report is the first to use photoacoustic imaging for probing depth measurements with potential implications to the dental field, including tools for automated dental examinations or noninvasive examinations.

Effects of a Novel Dental Gel on Plaque and Gingivitis: A Comparative Study.

OBJECTIVES: The goal of this prospective, randomized, controlled, double-blinded study was to evaluate the effects of a novel dental gel on plaque and gingival health. The dental gel was designed to (1) break up and prevent re-accumulation of microbial biofilm, and (2) inhibit metal mediated inflammation. MATERIALS AND METHODS: Twenty-five subjects with moderate gingival inflammation (Löe and Silness Gingival Index ≥2) and pocket depths <4 were randomly assigned to brush twice daily for 21 days with the test or the control dental gel. On Days 0, 7, 14 and 21, plaque levels (Quigley-Hein, Turesky Modification Plaque Index), gingival inflammation (Löe and Silness Gingival Index) and gingival bleeding (modified Sulcus Bleeding Index) were determined by one blinded, investigator using a pressure sensitive probe. RESULTS: After 3 weeks, all 3 clinical indices were significantly improved in both groups (P<0.05) and significantly lower in the test group (P<0.05). CONCLUSION: The novel dental gel formulation was provided effective plaque control and reduced gingival inflammation. CLINICAL RELEVANCE: A novel dentifrice formulation may be an effective tool for plaque removal and maintaining gingival health.

Optical diagnostics in the oral cavity: an overview.

As the emphasis shifts from damage mitigation to disease prevention or reversal of early disease in the oral cavity, the need for sensitive and accurate detection and diagnostic tools become more important. Many novel and emergent optical diagnostic modalities for the oral cavity are becoming available to clinicians with a variety of desirable attributes including: (i) non-invasiveness, (ii) absence of ionizing radiation, (iii) patient-friendliness, (iv) real-time information (v) repeatability, and (vi) high-resolution surface and subsurface images. In this article, the principles behind optical diagnostic approaches, their feasibility and applicability for imaging soft and hard tissues, and their potential usefulness as a tool in the diagnosis of oral mucosal lesions, dental pathologies, and other dental applications will be reviewed. The clinical applications of light-based imaging technologies in the oral cavity and of their derivative devices will be discussed to provide the reader with a comprehensive understanding of emergent diagnostic modalities.

Er:YAG laser modification of root canal dentine: influence of pulse duration, repetitive irradiation and water spray.

The aim of this study was to determine the effects of varying parameters of Er:YAG laser irradiation with and without water spray cooling on root canal dentine in vitro. After horizontally removing tooth crowns from extracted human teeth, roots were axially sectioned into thin slices, exposing the root canal surface. An Er:YAG laser delivered 10-30 J/cm(2) into a 0.4-mm diameter laser spot on the root canal surface. Single pulses of different lengths (80-280 micro s) were applied with and without water spray cooling/irrigation, and sequences of three pulses at a repetition rate of 30 Hz were applied at selected pulse parameters. The irradiated samples were investigated using both confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). At most irradiation conditions, the root canal dentine surface was ablated. Three-dimensional images from CLSM revealed that the cavity walls were not smooth. Depths of the cavities revealed significant differences between the cavities. No debris was observed at the surface of cavities at any irradiation condition. Strong melting and recrystallisation, or unusually flat surfaces with open dentinal tubules were obtained with sequences of three pulses without water cooling. CLSM is an effective tool for investigation of laser effects on root canal dentine. By varying the irradiation conditions, the Er:YAG laser can induce different modifications of root canal surface, which may be very interesting for root canal preparation.

Treatment of dentine hypersensitivity by lasers: a review.

BACKGROUND, AIMS: Since the development of the ruby laser by Maiman in 1960, a variety of papers on potential applications for lasers in dentistry have been published. The purpose of this paper is to summarise laser applications for the treatment of dentine hypersensitivity. The effects of laser on pulp tissue and problems on laser treatment are also reviewed. This article reviews the role of lasers for the treatment of dentine hypersensitivity since 1985, summarises many research reports from the last decade, and surmises what the future may hold for lasers in this treatment. METHOD: To date, 4 kinds of lasers have been used for the treatment of dentine hypersensitivity, and the effectiveness ranged from 5.2 to 100%, which was dependent on the laser type and parameters used. The mechanism involved in laser treatment of dentine hypersensitivity are relatively unknown. RESULTS: These require clarification to result in safely effective treatment optimization. In general, the efficiency for the treatment of dentine hypersensitivity using lasers is higher than other methods, but in severe cases, it is less effective. CONCLUSION: It is necessary to consider the severity of dentine hypersensitivity before laser use.

Morphological study of the effects of CO2 laser emitted at 9.3 microm on human dentin.

OBJECTIVE: The purpose of this study was to investigate the effects of dentin ablation using a carbon dioxide (CO2) laser emitted at 9.3 microm by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). BACKGROUND DATA: There have been no reports on effects of CO2 laser irradiation emitted at 9.3 microm on dentin by SEM and CLSM. METHODS: Thirty extracted human teeth showing no clinical signs of caries were used. All teeth were horizontally sectioned to approximately 200 microm thickness and sections were irradiated using a 9.3 microm CO2 laser at different parameters as follows: 26 mJ [energy density (ED) 53.0 J/cm2] and 30 mJ (ED 61.1 J/cm2). After laser irradiation, samples were treated with sodium hypochlorite, stained using rhodamine-123, and observed with CLSM followed by SEM procedures. RESULTS: No craters or cracks were observed, but many small molten and rehardened particles were documented on the sample surface using SEM. Some small cracks were seen in the subsurface layer, and some patent dentinal tubules were detected using CLSM. CONCLUSION: These results suggest that laser irradiation at these parameters affected the sample surface only (less than 20 microm) and would be less harmful to thermal damage of dental pulp for dentin ablation.

Lasers in endodontics: a review.

Since the development of the ruby laser by Maiman in 1960 and the application of the laser for endodontics by Weichman in 1971, a variety of papers on potential applications for lasers in endodontics have been published. The purpose of this paper is to summarize laser applications in endodontics, including their use in pulp diagnosis, dentinal hypersensitivity, pulp capping and pulpotomy, sterilization of root canals, root canal shaping and obturation and apicectomy. The effects of laser on root canal walls and periodontal tissues are also reviewed. The essential question is whether a laser can provide equal or improved treatment over conventional care. Secondary issues include treatment duration and cost/benefit ratio. This article reviews the role of lasers in endodontics since the early 1970s, summarizes many research reports from the last decade, and surmises what the future may hold for lasers in endodontics. With the potential availability of many new laser wavelengths and modes, much interest is developing in this promising field.

Effects on oral soft tissue produced by a diode laser in vitro.

BACKGROUND AND OBJECTIVES: This investigation determined incision characteristics and soft-tissue damage resulting from standardized incisions using a wide range of laser modes and parameters of a diode laser at 810 nm. STUDY DESIGN/MATERIALS AND METHODS: Histologic examinations were performed to verify vertical and horizontal tissue damage as well as incision depth and width. RESULTS: Incision depth and width correlated strongly with average powers, but not with laser parameters or the used tips. No laser damage was visible to the naked eye in the bone underlying the incisions in the range between 0.5-4.5 W. CONCLUSION: The remarkable cutting ability and the tolerable damage zone clearly show that the diode laser is a very effective and, because of its excellent coagulation ability, useful alternative in soft-tissue surgery of the oral cavity.

Effects of a 532 nm Q-switched nanosecond pulsed laser on dentin.

The purpose of this study was to determine whether a nanosecond-pulsed, frequency-doubled Nd:YAG laser emitting at 532 nm can be used as an alternative to mechanical methods of root canal treatment or as an adjunct to conventional endodontic preparation. Laser parameters whose thermal effects did not exceed safety thresholds for adjacent periodontal tissues were selected in a preliminary study. In 27 extracted human teeth, root canals were irradiated for 30 to 60 s at fluences of 2 to 2.2 J/cm2, and 10 Hz. Samples were observed using SEM. Laser irradiation could achieve smear layer removal after minimal manual preparation. However, results were inhomogeneous, and at higher energy densities thermal damage was observed, especially in the fully manually prepared samples. Nanosecond-pulsed irradiation at 532 nm can achieve complete smear layer removal. However, mechanisms must be developed to monitor laser effects and avoid potential damage to collateral structures.

Clinical preconditions and treatment modality: effects on pulp surgery outcome.

BACKGROUND: The purpose of this research was to evaluate the factors affecting the outcome of localized laser pulp surgery in the canine model. STUDY DESIGN/MATERIALS AND METHODS: Pulpal exposures 2 mm and 5 mm in diameter were prepared in eight healthy teeth in each of five dogs. The total of 40 teeth were left open to infection from the oral cavity for 3 hours or 72 hours; 2-3 mm of surface pulpal tissue were then removed using a fresh diamond bur or a CO2 laser emitting@9.3 microns, at 3.5 W average power in the Superpulse mode. Teeth were monitored clinically and radiographically by one blinded, pre-standardized clinician for 3 months. RESULTS: Chi-square test and Fisher's Exact test (2-tail) results associated laser treatment with significantly better clinical and radiographic outcome (P < 0.001). Using regression analysis, duration of pulpal exposure to contamination by the oral environment was identified as primary determinant for treatment outcome within the laser-treated and control groups (P = 0.0018). CONCLUSION: Clinical preconditions significantly affect the outcome of pulp surgery treatments.

Laser-induced thermal events in empty and pulp-filled dental pulp chambers.

BACKGROUND AND OBJECTIVE: The purpose of this investigation was to evaluate: 1. thermal events during laser irradiation @2.1 microns of the pulp; 2. whether these effects are adequately modeled using an empty pulp chamber/root canal. STUDY DESIGN/MATERIALS AND METHODS: In extracted human teeth, pulpal access was prepared and thermocouples placed 2, 3 mm apical to the center of the irradiation spot. Pulp-filled or empty pulp chambers were irradiated using a Ho:YAG laser: Spot Size: 1 mm; Power: 1, 2, 3.5, 4.5 W; PRR: 5, 12 Hz; DURATION: 10 sec. Thermal measurements were repeated 3x. RESULTS: Thermal trends did not differ significantly and correlated positively with power (P < 0.01), PRR (P < 0.01), irradiation duration (P < 0.05). No significant difference was determined between temperatures in empty and pulp-filled chambers at all parameters at 5 Hz and at 1-2 W at 12 Hz (P < 0.05, 2-tailed Student's t-test). At 12 Hz and > 3.5 W, pulp chamber temperatures exceeded those in pulpal tissue (P < 0.05). CONCLUSION: Pulp tissues must be present to ensure clinical relevance of thermal measurements.

The influence of laser parameter configurations at 9.3 microns on incisional and collateral effects in soft tissue.

These investigations were performed to determine histologic and incisional consequences of varying pulse duration, duty cycle, and average powers during laser incision at 9.3 microns in soft tissue. In 19 fresh pigs' jaws six standardized incisions 3 cm long were made per parameter with a template and motorized jig. Laser parameters investigated were average power: 1 to 9 W, duty cycle: 10% to 80%, and pulse duration: 1 to 200 msec. The gated Cw mode was used. Incision width and depth and collateral tissue effects were assessed statistically with general linear procedures. Multiple factors were found to influence the outcome of laser irradiation. Depth of incision correlated positively with average power. Tissue damage correlated strongly and negatively with all three variables. These results demonstrate that a wide range of surgical and collateral effects can be achieved with one specific laser device depending on the parameter configuration selected.

Investigating the range of surgical effects on soft tissue produced by a carbon dioxide laser.

The authors investigated the surgical and collateral effects on soft tissue of a carbon dioxide laser emitting at 9.3 micrometers. Specifically, incision widths and depths as well as effectiveness were studied. Three different laser modes were investigated: gated continuous wave, or Cw, Superpulse and OptiPulse (Medical Optics). Incision depths correlated positively with average power; higher powers produced deeper incisions. The gated Cw mode quickly produced wide, deep incisions; Superpulse achieved narrower, deep incisions; OptiPulse caused very narrow, shallow incisions. Collateral damage to adjacent tissues was reduced by a factor of about 2 using Superpulse, and by a factor of 10 using OptiPulse. A wide range of effects is achieved in soft tissue, depending on the laser parameter combination used.

Morphological effects of ArF excimer laser irradiation on enamel and dentin.

BACKGROUND AND OBJECTIVE: The aim of this investigation to determine the range of morphological and ablative effects that can be achieved on dental enamel and dentin using ArF excimer laser irradiation at a wavelength of 193nm. STUDY DESIGN/MATERIALS AND METHODS: Caries-free coronal enamel and dentin surfaces of 20 extracted human teeth were subjected to irradiation at 193nm using a Lamda-Physik model EMG 103 MSC and ArF fill. Morphology of cavity floors and walls were assessed by light microscopy and SEM. RESULTS: Morphological surface effects and ablation could be controlled effectively and reliably by choice of parameter combination, allowing the operator to achieve either a smooth, flat, or increasingly rough surface with differing degrees of selective ablation. No signs of thermal damage were apparent. CONCLUSION: Excimer laser irradiation at 193nm provided clinically useful cavity preparations and surface morphological effects.

Effects of nanosecond pulsed Nd: YAG laser irradiation on dentin resistance to artificial caries-like lesions.

BACKGROUND AND OBJECTIVE: Previous investigations have demonstrated improved enamel caries resistance after laser irradiation. In this study, effects of nanosecond pulsed Nd:YAG laser irradiation on crown/root dentin susceptibility to caries-like lesions were investigated. STUDY DESIGN/MATERIALS AND METHODS: Extracted human molar teeth were irradiated using a Q-switched nanosecond pulsed Nd:YAG laser. All teeth except controls were irradiated at: fluence, 1 or 5 J/cm2; spot size, 3 mm; and then subjected to demineralization. Measurements of caries lesion depth using scattering light microscopy and SEM were performed. RESULTS: Lesion depth measurements did not differ significantly between controls and irradiated samples (P < 0.01), but SEM results showed some irradiation-induced alterations on crown and root dentin surfaces. Irradiated surfaces were partially melted, with sometimes narrowed or occluded tubules. CONCLUSION: No consistent caries-protective effect of Q-switched nanosecond pulsed Nd:YAG laser irradiation on crown and root dentin was determined, but laser-induced morphological changes were observed.

CO2 laser treatment of traumatic pulpal exposures in dogs.

BACKGROUND AND OBJECTIVE: Successful non-devitalizing treatment of localized pulpal lesions in mature teeth is not ensured using conventional endodontic techniques. The objective of this study was to evaluate CO2 laser surgical treatment of pulpal exposures in canine patients. STUDY DESIGN/MATERIALS AND METHODS: 17 permanent teeth with pulpal exposures of < or = 48 h duration received localized laser pulp surgery. Laser Parameters: pulse duration: 0.01 s, pulse interval: 1.0 s, spot size: 0.004 cm2, fluence: 276 J/cm2. Exposures were dressed with CaOH and Glass ionomer. Clinical and radiographic evaluations were performed by one blinded clinician 24 and 52 weeks after treatment. RESULTS: 15/17 laser-treated teeth assessed over > or = 1 year post-treatment remained clinically and radiographically healthy. CONCLUSION: These results demonstrate the feasibility of using the CO2 laser for localized pulp surgery. Further studies must optimize laser parameters and identify the range of clinical pathologies which can be treated using this modality.