Novel bisphosphonate cyclic acetal compounds are disclosed, as well as methods of preparing the compounds, pharmaceutical compositions including the compounds, and administration of the compounds in methods of treating bone metabolism disorders, such as abnormal calcium and phosphate metabolism. Each slot 23 has a roughly rectangular backside opening 33, a roughly rectangular front-side opening 32, and a through-hole 31 that connects these two openings 33, 32. A thin membrane is disposed across a registration pin hole to close off the registration pin hole and resist dental casting material from substantially filling the registration pin hole. A deflecting mechanism is adapted for the generation of a torque on the head portion of the torque wrench to be tested. At least one elongate bead of material is fixedly applied to the second face in a desired pattern, the bead typically including a foam-in-place silicone material. In the optical fiber core assembly, plural optical fiber cores two-dimensionally are arranged in parallel with each other.