BOSTON — Construction has reached the halfway point for a five-story vertical addition to the existing, 10-story Tufts University School of Dental Medicine building, located at One Kneeland Street in the Chinatown neighborhood of Boston. The $64 million project will total 95,000 square feet; it will include two new clinical patient floors, an expanded simulation lab, teaching facilities, a continuing education conference center and administrative offices. It is also being constructed in anticipation of LEED certification. ARC/Architectural Resources Cambridge designed the project, and Boston-based Shawmut Design & Construction is serving as general contractor. Completion is scheduled for the end of the year.