Hydrogel tissue expanders for stomatology. Part I. Methacrylate-based polymers.

In order to create a soft tissue surplus, implantable volume expanders are often utilized in dental surgery. Implanted tissue expanders should gradually increase their volume, exerting a constant pressure on the surrounding tissue for weeks. Current tissue expanders are based predominantly on externally inflatable balloons or on osmotically active tissue expanders that use soft hydrogels wrapped in perforated plastic coatings, which limit fluid entry and swelling. We have designed and examined tissue expanders based on the controlled rate expansive hydrogels synthesized from copolymers of selected methacrylates and N-vinylpyrrolidone, cross-linked with a combination of non-degradable (glycol dimethacrylates) and hydrolytically degradable (N,O-dimethacryloylhydroxylamine) cross-linkers. These copolymers have close-to-linear volume expansion rates (up to 6-9 times their original volume) and exert an increasing swelling pressure in vitro. The anesthetic benzocaine has been incorporated into the hydrogels, and kinetic release experiments have shown that most of the drug (90%) was released within 48 h. Our proposed hydrogel expanders are homogeneous and have suitable mechanical properties, thus simplifying the surgical manipulations required. Further studies will be needed to completely evaluate their biocompatibility and tissue response to the implants.

Fractional carbon dioxide laser improves nodular basal cell carcinoma treatment with photodynamic therapy with methyl 5-aminolevulinate.

BACKGROUND: The major limitation of photodynamic therapy with 5-aminolevulinic acid (ALA-PDT) is proper photosensitizer penetration. The nodular form of BCC (nBCC) is perceived as a contraindication to ALA-PDT because the tumor layer is thicker than 2 mm. We have improved on the results of previous studies that used an ablative laser to limit tumor thickness. A fractional laser produces skin microtubules that can improve the penetration of ALA into tumors. OBJECTIVE: To evaluate the use of a fractional laser as pretreatment before ALA-PDT for nBCC treatment in an 18-month single-blind clinical trial. METHODS: Fifty-six verified nBCCs were ablated using a diode laser under ultrasound control. Half of the tumors were treated 3 weeks later using a fractional carbon dioxide laser, and the other half were treated using curettage (control). We then immediately treated with ALA-PDT. Fluorescence and photography were evaluated and compared each month, and a final histopathologic examination was performed. RESULTS: Fifty-two of 56 nBCCs in the fractional laser treatment group responded to ALA-PDT, compared with only 45 of 56 in the control group. Fluorescence was higher in 53 cases in the treatment group; 3 cases demonstrated the same fluorescence level in both groups. Healing took longer in the treatment group, and there were more side effects. CONCLUSION: Fractional laser pretreatment increases the fluorescence and clinical effectiveness of ALA-PDT for the treatment of nBCC.

Update on Focal Infection Management: A Czech Interdisciplinary Consensus.

BACKGROUND: The focal infection theory has been used to explain several chronic systemic diseases in the past. Systemic diseases were thought to be caused by focal infections, such as caries and periodontal diseases, and dentists were held responsible for these diseases due to the spread of oral infections. As knowledge of the interrelationship between oral microorganisms and the host immune response has evolved over the last few decades, the focal infection theory has been modified in various ways. The relationship between oral and systemic health appears to be more complex than that suggested by the classical theory of focal infections. Indeed, the contribution of the oral microbiota to some systemic diseases is gaining acceptance, as there are strong associations between periodontal disease and atherosclerotic vascular disease, diabetes, and hospital-associated pneumonia, amongst others. As many jurisdictions have various protocols for managing this oral-systemic axis of disease, we sought to provide a consensus on this notion with the help of a multidisciplinary team from the Czech Republic. METHODS: A multidisciplinary team comprising physicians/surgeons in the specialities of dentistry, ear-nose and throat (ENT), cardiology, orthopaedics, oncology, and diabetology were quetioned with regard to their conceptual understanding of the focal infection theory particularly in relation to the oral-systemic axis. The team also established a protocol to determine the strength of these associations and to plan the therapeutic steps needed to treat focal odontogenic infections whenever possible. RESULTS: Scoring algorithms were devised for odontogenic inflammatory diseases and systemic risks, and standardised procedures were developed for general use. CONCLUSIONS: The designed algorithm of the oral-systemic axis will be helpful for all health care workers in guiding their patient management protocol.

Comparison of COVID-19 epidemic among Czech dentists and the Czech general population.

Dentists are one of the professional groups most at risk for COVID-19 infection. Enhanced protective measures in dentistry have been adopted worldwide; however, it is unclear to what extent they were sufficient. To assess whether the protective measures outweighed the high infection risk, we compared COVID-19-related data between Czech dentists and the general Czech population. The data was obtained through a survey study attended by 15.8% of Czech Dental Chamber members. Data of the general population were acquired from the Czech Ministry of Health database. By the end of May 2022, COVID-19 full vaccination and 1st booster dose rates among study participants were 85.8% and 70.1%, respectively, which is significantly higher (p < 0.0001) compared to the Czech general population aged over 24 years (74.9% and 49.4%, respectively). To the same date, PCR/Antigen test verified COVID-19 prevalence among participants was 41.7%, and 49.9% among the general population (p < 0.0001). Prevalence and reinfection rates among individuals who received the 1st booster were significantly lower than among individuals without the booster or full vaccination (p < 0.0001). Persons who received the booster showed a faster return to work, shorter and different types of complications. Willingness to future vaccination was positive among 79.7% of respondents. Mandatory vaccination for healthcare workers and the general population was supported by 62.0% and 49.0%, respectively. The results showed that the high risk of COVID-19 infection associated with dentistry did not lead to higher COVID-19 prevalence among respondents compared to the general population.

COVID-19 Vaccination among Czech Dentists.

This work describes and evaluates vaccination against COVID-19 among members of the Czech Dental Chamber during the pre-booster vaccination phase. A cross-sectional online survey was conducted between 23 June and 4 September 2021, among 2716 participants, representing 24.3% of all chamber members. A total of 89.5% of respondents stated that they were registered for vaccination against COVID-19, their vaccination had started or been completed, or had a medically relevant reason to avoid vaccination. A total of 79.6% of respondents stated that they were fully vaccinated, most of them with the Comirnaty (Pfizer−BioNTech) vaccine (88.3%). The vaccination rate among males was significantly higher than among females (p = 0.001, OR 1.48). The main reasons for vaccination were professional (91.5%). The share of fully vaccinated participants was significantly higher (p < 0.0001, OR = 8.17) compared to the Czech general population (30.8%). A COVID-19 vaccine breakthrough infection rate was 0.42%. The study shows that both the willingness to vaccinate and the proportion of fully vaccinated individuals among Czech dentists are high, and only about 10% of them refused vaccination based on reasons classified as not medically relevant.

Impact of COVID-19 on Czech Dentistry: A Nationwide Cross-Sectional Preliminary Study among Dentists in the Czech Republic.

This work evaluates the impact of the COVID-19 pandemic on Czech dentistry from March 2020 to March 2021. The assessment was based on questionnaires filled out by 3674 Czech dentists representing 42.6% of practicing dentists in the country. During March-May, 2020 (the first COVID-19 wave), 90.7% of dental practices remained open; however, only 22.8% of the practices continued to operate with no changes, 46.5% had fewer patients, 21.4% treated only acute cases, and 3.8% were closed. During September 2020-May 2021 (the second wave of COVID-19), 96.1% of dental practices remained open, 60.8% operated with no changes, 34.5% had fewer patients, 0.8% treated only acute cases, and 0.5% were closed. The reasons leading to the closure of Czech dental practices during the whole pandemic were a shortage of personal protective equipment (50.5%), a COVID-19 outbreak in the workplace (24.5%), fear of a possible self-infection (24.0%), and quarantine (20.5%). The time range of Czech dental practices closure during the whole pandemic was: 1-2 weeks (49.9%), 2-4 weeks (21.2%), and >1 month (0.8%). The greatest professional difficulties of Czech dentists during the pandemic were crisis operating management (55%), health safety and hygiene concerns (21%), shortage of personal protective equipment (21%), and difficulty working with the protective equipment (15%). In addition, 47.3% of dentists also observed a declining interest in preventive dental care, and 16.9% of them observed worse oral care of patients. These results show that despite the lack of protective equipment, dental care was maintained throughout the pandemic. Additionally, the pandemic negatively affected the patients' approach to dental care, indicating a deterioration in oral health as a possible delayed outcome of the COVID-19 pandemic.

COVID-19 Prevalence among Czech Dentists.

This work evaluates the prevalence of coronavirus disease (COVID-19), a viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), among members of the Czech Dental Chamber. The assessment was based on an online questionnaire filled out by 2716 participants, representing 24.3% of all chamber members. Overall, 25.4% of the participants admitted they were diagnosed with COVID-19 by 30 June 2021, with no statistical differences between the sexes. While in the age groups under 50 the reported prevalence was around 30%, with increasing age, it gradually decreased to 15.2% in the group over 70 years. The work environment was identified as a place of contagion by 38.4% of the respondents. The total COVID-19 PCR-verified positivity was 13.9%, revealing a statistically lower prevalence (p = 0.0180) compared with the Czech general population, in which the COVID-19 PCR-verified positivity was ~15.6% (fourth highest rank in the world). The total infection-hospitalization ratio (IHR) was 2.8%, and the median age group of hospitalized individuals was 60-70 years. For respondents older than 60 years, the IHR was 8.7%, and for those under 40 years, it was 0%. Of the respondents, 37.7% admitted that another team member was diagnosed with COVID-19, of which the most frequently mentioned profession was a nurse/dental assistant (81.2%). The results indicate that although the dentist profession is associated with a high occupational risk of SARS-CoV-2 infection, well-chosen antiepidemic measures adopted by dental professionals may outweigh it.

Hydrogel Tissue Expanders for Stomatology. Part II. Poly(styrene-maleic anhydride) Hydrogels.

Self-inflating soft tissue expanders represent a valuable modality in reconstructive surgery. For this purpose, particularly synthetic hydrogels that increase their volume by swelling in aqueous environment are used. The current challenge in the field is to deliver a material with a suitable protracted swelling response, ideally with an induction period (for sutured wound healing) followed by a linear increase in volume lasting several days for required tissue reconstruction. Here, we report on synthesis, swelling, thermal, mechanical and biological properties of novel hydrogel tissue expanders based on poly(styrene-alt-maleic anhydride) copolymers covalently crosslinked with p-divinylbenzene. The hydrogels exerted hydrolysis-driven swelling response with induction period over the first two days with minimal volume change and gradual volume growth within 30 days in buffered saline solution. Their final swollen volume reached more than 14 times the dry volume with little dependence on the crosslinker content. The mechanical coherence of samples during swelling and in their fully swollen state was excellent, the compression modulus of elasticity being between 750 and 850 kPa. In vitro cell culture experiments and in vivo evaluation in mice models showed excellent biocompatibility and suitable swelling responses meeting thus the application requirements as soft tissue expanders.

Ultrasound guided ablative-laser assisted photodynamic therapy of basal cell carcinoma (US-aL-PDT).

OBJECTIVE: With proper noninvasive ultrasound measurement of tumor depth, case selection for laser pre-ablation followed by PDT is possible. This combination of methods provides a less invasive approach to the treatment of BCC. BACKGROUND DATA: Basal cell carcinoma (BCC) primarily affects the face, and, therefore, radical excision is problematic because of the possibility of poor aesthetic outcomes. Photodynamic therapy (PDT) offers an advantage in aesthetic outcomes, but topical PDT is only effective for tumors with a depth up to 2 mm. MATERIALS AND METHODS: Seventy-five histologically verified BCCs from 67 patients were selected and divided into three therapeutic groups based on the tumor depth, which was determined by 20 MHz skin ultrasound. The three groups were: A/<2 mm (PDT), B/ 2-3 mm (Er:YAG laser ablation+PDT), and C/>3 mm (diode laser ablation+PDT). The treatment consisted of laser ablation (or no ablation) followed by the application of methyl-aminolevulinate (MAL) and a 3-h treatment period using an occlusive bandage. Subsequently, illumination with 630 nm (MAL-PDT) was performed. MAL-PDT was repeated 1-3 weeks after the first treatment. A clinical evaluation was performed after 6 months. RESULTS: A 100% clearance rate (CR) in the group with the deepest tumors was observed. In addition, a 94.7% CR occurred in the group with tumors 2-3 mm in depth, and an 81.2% CR was observed in the group with superficial tumors. CONCLUSIONS: With proper ultrasound case selection and laser ablation before MAL-PDT, the depth of a BCC lesion is not a limiting factor for PDT, and aesthetic outcomes are very good. Therefore, ultrasound-guided ablative laser-assisted PDT of BCC can be the method of choice, particularly in aesthetically challenging cases.

Combination of Er:YAG laser and photodynamic therapy in the treatment of nodular basal cell carcinoma.

BACKGROUNDS AND OBJECTIVES: Photodynamic therapy (PDT), via topical aminolevulinic acid (ALA) is an effective treatment for basal cell carcinomas not exceeding a depth of 2 mm. This limits the treatment of basal cell carcinoma (non-melanoma skin cancer) to superficial forms and nodular therapy (only in aesthetically desired locations). This paper addresses the effectiveness of reducing tumor mass via initial Er:YAG laser ablation to depths that are therapeutically responsive to PDT with ALA. STUDY DESIGN/MATERIALS AND METHODS: This study compared three methods for the treatment of recurring nodular basal cell carcinomas (r nBCC). Method A utilized PDT with topical application of ALA methyl ester, method B with solitary Er:YAG laser ablation, and method C combined Er:YAG laser ablation reducing tumor size below 2 mm (method B) with subsequent ALA methyl ester PDT (method A). All three methods were used to treat to each patient, all subjects presenting with three or more basal cell carcinomas in order to eliminate differences in patient responsiveness to treatment. Patients were monitored and interviewed at 3, 6, and 12 month intervals to examine the progress of tumor elimination, aesthetic results as well as the patient's preference of treatment method. In all, 286 patients were treated, of whom 194 were checked at the prescribed intervals and then evaluated. RESULTS: Statistically, the combination therapy demonstrated the most effective treatment at all time intervals, with a final efficacy of 98.97% versus 94.85% (PDT only) and 91.75% (Er:YAG laser only). The combined method also provided the best aesthetic results (scale: 1--best; 4--worst) of 1.23+/-1.23, compared to 1.67+/-0.76 (PDT only) and 1.83+/-0.95 (Er:YAG laser only). CONCLUSIONS: Although 67% patients preferred solitary Er:YAG laser treatment over the PDT method (20%) and the combined treatment (13%), because of the simplicity of the treatment, the combination therapy has proven to be both clinically and aesthetically superior. Solitary Er:YAG laser ablation will remain however a fast, effective, and economical treatment alternative for simple manifestations of superficial basal cell carcinoma and has replaced PDT for uncomplicated cases at our facility. The combination of Er:YAG laser ablation and ALA-PDT aspires to be therapy of choice for BCC.

Effect of the combination of laser excision and interstitial hyperthermia in palliative therapy of head and neck tumours in the advanced stage of the disease.

BACKGROUND AND OBJECTIVES: We evaluated the potential of combining laser excision with laser interstitial hyperthermia in order to improve the quality of life of patients with 3rd or 4th stage malignant head and neck tumours. STUDY DESIGN/MATERIALS AND METHODS: To evaluate the quality of life, we used the 4th version of the University of Washington Quality of Life assessment score modified for head and neck tumours. The study group of 20 patients assessed their condition in a questionnaire, examining 12 aspects of their quality of life before the laser treatment, the second day after, and 6 weeks after the treatment. RESULTS: We observed a gain of 16.41 points, which subjectively represents a 70.32% improvement in the quality of life. CONCLUSIONS: Following this therapy the quality of life significantly improved in patients with primarily low quality of life, whereas the group of patients with less affected quality of life reported a temporary decline in the quality of life after the treatment. To obtain a proper objective indication, we suggest a mathematical modelling of possible gains for the individual patient using the University of Washington Quality of Life classification.