Two Different Clar's Sextets: Clar's Rule Does Not Necessarily Contradict the Global Pathway of Conjugated Macrocycles.

Two contradictory theories, Clar's sextet and resonance theory, explain the stability of conjugated macrocycles using localized and delocalized models, respectively. To reconcile these theories and gain better insights, PAH-containing porphyrinoids were chosen as a representative class of conjugated macrocycles. Two types of Clar's sextets were identified and proposed for the first time based on their interaction with global conjugated pathways: (i) shared sextets that integrate with and perturb the global resonance pathway, and (ii) independent sextets that are separate from the pathway and potentially stabilize or do not perturb it.

Is immediate dental implant in fibula free flap beneficial for implant survival and osteoradionecrosis in jaw reconstruction?

Objectives: This study aimed to compare the risk of osteoradionecrosis and implant survival in oral cancer patients undergoing immediate dental implants during jaw reconstruction, termed "Jaw in a Day" (JIAD), with those receiving no implants or delayed implants (non-JIAD).

Patients & Methods: Clinicopathologic data were collected from prospectively enrolled JIAD patients (n = 10, 29 implants) and retrospectively from non-JIAD patients (n = 117, 86 implants). Survival analyses were performed to assess implant survival and osteoradionecrosis-free survival.

Maxillary Bone Necrosis in Post-COVID-19 Patients: Possibility of Medication-Related Osteonecrosis of Jaws (MRONJ) Induced by Tocilizumab.

Medication-related osteonecrosis of the jaws (MRONJ) is a serious condition often linked with antiresorptive, immune modulating, and antiangiogenic drugs, initially associated with bisphosphonates but now including a broader range of medications. Tocilizumab, an interleukin-6 (IL-6) receptor-inhibiting monoclonal antibody used for conditions like rheumatoid arthritis and recently for COVID-19 to reduce IL-6 activity and alleviate symptoms, has raised concerns over its potential to induce MRONJ, particularly in post-COVID-19 patients. A case involving a 36-year-old male who developed tooth mobility and pain in the right maxillary posterior region after COVID-19 treatment with tocilizumab and dexamethasone is highlighted.

Effects of Electron-Withdrawing and Electron-Donating Groups on Aromaticity in Cyclic Conjugated Polyenes.

Determining the aromaticity of various fluorinated benzenes is challenging as easily obtained experimental aromaticity [Δδ( - )] necessitates the chemical shifts of inner and outer protons. This issue was addressed in porphyrinoids by replacing the electron-withdrawing (E.W.