A dental attachment device, comprising: a cap for securing a dental appliance, the cap comprising: a body portion having an open end , an inner cavity forming a annular wall having an annular inner surface with a concave lip at a distal end portion thereof, and a retention head surrounded by the annular wall, the retention head comprising a substantially spherical or ball-shaped head portion and a shaft ; and a first attachment portion for securing the dental appliance; a retainer ring ; and an abutment comprising: a second attachment portion configured for attachment to a tooth or implant; an upper portion having a convex outer surface configured to mate and frictionally engage with the concave lip of the cap ; and an open end forming an internal socket configured to receive the retainer ring and engage the retention head of the cap by snap-fit engagement through the retainer ring ; and wherein the engagement of the concave lip and the convex outer surface allows a range of divergence of the cap relative to the abutment , and the engagement of the retention head and the abutment provides a retentive force between the cap and the abutment in an amount sufficient for rigid attachment of the device to the appliance and prevents, inhibits, or reduces the risk of removal of the device by a patient using the device. a cap for securing a dental appliance, the cap comprising: a body portion having an open end , an inner cavity forming a annular wall having an annular inner surface with a concave lip at a distal end portion thereof, and a retention head surrounded by the annular wall, the retention head comprising a substantially spherical or ball-shaped head portion and a shaft ; and a first attachment portion for securing the dental appliance; a body portion having an open end , an inner cavity forming a annular wall having an annular inner surface with a concave lip at a distal end portion thereof, and a retention head surrounded by the annular wall, the retention head comprising a substantially spherical or ball-shaped head portion and a shaft ; and a first attachment portion for securing the dental appliance; a retainer ring ; and an abutment comprising: a second attachment portion configured for attachment to a tooth or implant; an upper portion having a convex outer surface configured to mate and frictionally engage with the concave lip of the cap ; and an open end forming an internal socket configured to receive the retainer ring and engage the retention head of the cap by snap-fit engagement through the retainer ring ; and a second attachment portion configured for attachment to a tooth or implant; an upper portion having a convex outer surface configured to mate and frictionally engage with the concave lip of the cap ; and an open end forming an internal socket configured to receive the retainer ring and engage the retention head of the cap by snap-fit engagement through the retainer ring ; and wherein the engagement of the concave lip and the convex outer surface allows a range of divergence of the cap relative to the abutment , and the engagement of the retention head and the abutment provides a retentive force between the cap and the abutment in an amount sufficient for rigid attachment of the device to the appliance and prevents, inhibits, or reduces the risk of removal of the device by a patient using the device. <EOS>