Table 2. Selected studies.

First author	Year of publication	Type of study	Topic
Grissinger M [8]	2019	Review	Death
Abdulhamid I [9]	2016	Open-label study	Safety related to systemic condition
Huang A [10]	2015	Comparative study	Safety
Nordt SP [11]	2014	Case report	Death, safety
McCormack L [12]	2014	Nonrandomized cohort study	Safety
Kang J [13]	2012	Retrospective study	Safety related to systemic condition
Chicka MC [14]	2012	Review	Death, safety
Costa LR [15]	2012	Comparative study	Safety
Kupiec TC [16]	2011	Case report	Death
de Rezende GP [17]	2007	Case report	Safety
Martinez D [18]	2006	Prospective, pilot study	Safety
Park MK [19]	2006	Prospective randomized study	Safety
Myers GR [20]	2004	Randomized double-blind crossover study	Safety
Lee JH [21]	2002	Cross sectional study	Safety
Leelataweedwud P [22]	2001	Retrospective study	Safety
Dallman JA [23]	2001	Clinical trial	Safety
Jung JH [24]	2001	Cross sectional study	Safety
Avalos-Arenas V [25]	1998	Clinical trial	Safety
Engelhart DA [26]	1998	Case report	Death
McCann W [27]	1996	Clinical trial	Safety
Needleman HL [28]	1995	Retrospective study	Safety
Sams DR [29]	1993	Case controlled study	Safety
Wilson S [30]	1990	Clinical trial	Safety
Mueller WA [31]	1985	Data collection	Safety