Muscle forces determine joint loads, but the objectives governing the mix of muscle forces involved are unknown. This study tested the hypothesis that masticatory muscle forces exerted during static biting are consistent with objectives of minimization of joint loads (MJL) or muscle effort (MME). To do this, we compared numerical model predictions with data measured from six subjects. Biting tasks which produced moments on molar and incisor teeth were modeled based on MJL or MME. The slope of predicted vs. electromyographic (EMG) data for an individual was compared with a perfect match slope of 1.00. Predictions based on MME matched best with EMG activity for molar biting (slopes, 0.89-1.16). Predictions from either or both models matched EMG results for incisor biting (best-match slopes, 0.95-1.07). Muscle forces during isometric biting appear to be consistent with objectives of MJL or MME, depending on the individual, biting location, and moment.

Objectives There is debate among otolaryngologists and other practitioners about whether upper lip tie contributes to difficulty with breastfeeding and whether upper lip tie and ankyloglossia are linked. Our objectives were to evaluate the anatomy of the upper lip (maxillary) frenulum, to determine if the visual anatomy of the upper lip has an effect on breastfeeding, and to determine whether the occurrence of lip tie and tongue tie are correlated. Methods A prospective cohort study of 100 healthy newborns was examined between day of life 3–7. Surveys were completed by the mother at the time of the initial exam and 2 weeks later. The maxillary frenulum was graded based on the Stanford and Kotlow classifications by two independent reviewers. Inter‐rater reliability and relationships between tongue tie, lip tie, and the infant breastfeeding assessment tool (IBFAT) were calculated. Results Inter‐rater reliability showed fair agreement (κ = 0.302) using the Kotlow scale and better agreement using the Stanford classification (κ = 0.458). There was no correlation between the upper lip tie classification and breastfeeding success score. Lastly, there was a modest inverse correlation in the degree of tethering for the tongue and lip. Conclusions There was no correlation between maxillary frenulum grade and comfort with breastfeeding, pain scores, or latch. There was also no relationship between tip to frenulum length (tongue tie) and visualized lip anatomy, suggesting that tongue tie and lip tie may not cluster together in infants. Level of Evidence 2 Laryngoscope, 131:E1701–E1706, 2021