Table 2.

Data extracted from the included studies

Author, year, country	Study design	Total number of participants	Age range (years)	Terms used to refer to bullying/Type of bullying	Instrument used to assess bullying	Instrument used to assess malocclusion	Malocclusions evaluated/self-reported	Statistical analysis	Malocclusion outcomes	Association between malocclusion and bullying	Conclusions
Shaw et al, 1980 [22], UK	Cross-sectional	531	9–13	Nicknames, teasing, harassment/ verbal and physical	Interview questionnaire	Questionnaire about nicknames, teasing, harassment and physical characteristics	Not specified	Descriptive analysis and Chi-square	Not reported	66% were teased about their physical characteristics. 7% of total sample were teased about their teeth, of which 51% due to incisal prominence, 8% due to crowding. Children teased about teeth were twice likely to suffer harassment (55%) than those were not (26%) (p < 0.001)	Malocclusion was significantly related with bullying.
Helm et al, 1985 [23], Denmark	Cohort	758	First phase 13–19 Second phase 28–34	Teasing/verbal	Fifth question of an own questionnaire: “Did your schoolmates tease you about the appearance of your teeth or jaws?”	Instrument used previously by Bjork et al. 1964	Max Ovj > 6 mm, Max Ovj > 9 mm, Mand Ovj, DB > 5 mm, DB > 7 mm, AOB, CrsB, Scissor bite, Crw Max inc, Crw Mand inc, Spacing Max inc.	Chi-square and Fisher exacts test	80% (n = 606) presented malocclusion	9% of adults with malocclusion suffered teasing during adolescence, and 1.3% of adults without malocclusion suffered teasing during adolescence (p < 0.001).	Extreme maxillary overjet, extreme deep bite, and space anomaly malocclusions were significantly related with teasing.
Rwakatema et al, 2006 [24], Tanzania	Cross-sectional	298	12–15	Teased and bullying/ verbal	Ng’ang’a et al. questionnaire. Question: “Do your schoolmates tease you about the appearance of your teeth or jaws?”	Ng’ang’a et al. questionnaire. Question: “Do you generally observe that your teeth are not appropriately aligned in your mouth?”	Self-reported: teeth alignment	Chi-square	56% respondents thought their teeth were properly aligned and 69% (n = 205) related that they need orthodontic treatment.	Bullying or teasing was not significantly related to teeth alignment (p = 0.093, 0 > 0.05)	Malocclusion was not significantly related with teasing or bullying.
Badran et al., 2010 [21], Jordan	Cross-sectional	400	14–16	Teasing/ verbal	Global negative self-evaluation (GSE) scale	IOTN (AC and DHC), self-perceived AC, perceived need for orthodontic treatment	Not specified	Spearman correlation coefficient	82% (n = 338) presented little, borderline, or definite need for orthodontic treatment.	Teasing about teeth was correlated with GSE scale (0.272), with students’ high AC score (0.213) and with perceived treatment need (0.354).	Malocclusion was significantly related with teasing.
Seehra et al., 2011, [16] UK	Cross-sectional	336	10–14	Bullying/verbal and physical	Olweus Bully/Victim questionnaire	IOTN (AC and DHC)	Incisor relationship, DHC and AC component of IOTN, skeletal pattern, FMPA, LFH, increased Ovj and over bite	Chi-square and Fisher exacts test	96% (n = 324) presented little, borderline, or definite need for orthodontic treatment.	Bullying was significantly related to Class II division 1 incisor relationship (p = 0.041), increased overbite (p = 0.023), and increased overjet (> 4 mm)(p = 0.001) and high need for OT by AC component of IOTN (p = 0.0014)	Malocclusion was significantly related with bullying, principally to the AC component of IOTN.
Al-Bitar et al., 2013 [15], Jordan	Cross-sectional	920	11–12	Bullying/verbal	Self-questionnaire with component for personal experience of bullying	Self-questionnaire with component for general physical characteristics and dentofacial features	Self-reported: AOB; spacing between teeth or missing teeth; Crw of teeth; gummy smile; prominent anterior teeth; prominent Mand anterior teeth; retrognathic Mand; incompetent lip coverage; prognathic Mand.	Descriptive statements with total frequency	Not reported	73% of adolescents reported they were victims of bullying due to dentofacial features. Teeth (50%), lips (14%), and chin (9%). Space between teeth or missing teeth was the most targeted feature.	Malocclusion was related with bullying.
Agel et al., 2014, [17], East UK	Cross-sectional	728	15–16	Bullying/verbal and physical	Six items derived from the revised Olweus Bully/Victim questionnaire	WHO oral clinical exam methodology	Ovj and lip coverage	Chi-square	1.51% of the adolescents presented Ovj > 6 mm and 0.41% presented inadequate lip coverage.	Bullying was not significantly related to Ovj > 6 mm or inadequate lip coverage (p > 0.05).	Malocclusion addressed by increased overjet was not significantly related with bullying.
Chikaod et al., 2017 [25], Nigeria	Cross-sectional	835	12–17	Bullying/verbal	Self-administered questionnaire modified from Al-Bitar 2013.	Self-administered questionnaire modified from Al-Bitar 2013.	Self-reported: space incisor, prominent Ovj, incompetent lip coverage, gummy smile, diastema or missing teeth, AOB, prognathic Mand, retrognatic Mand, prominent Mand anterior teeth, Crw.	Descriptive statements with total frequency	Not reported	51.9% of adolescents reported they were victims of bullying due to dentofacial features. Teeth (24.3%), chin (15.3%), and lips (12.3%). Space between teeth or missing teeth (12.2%) was the most common dentofacial feature identified as target for bullying.	Bullies frequently target to general dentofacial appearance (malocclusion).
Julca-Ching et al. 2019 [26], Peru	Cross-sectional	147	12–18	Bullying/verbal	Self-administered questionnaire modified from Al-Bitar 2013.	DAI	Not specified	Kruskal-Wallis	87.76% of adolescents presented malocclusion	Bullying was not significantly related to malocclusion (p > 0.05).	Malocclusion was not significantly related with bullying.

IOTN Index of Orthodontic Treatment Needs, AC esthetic component, DHC dental health component, OT orthodontic treatment, Max Ovj maxillary overjet, Mand ovj mandibular overjet, DB deep bite, CrsB crossbite, AOB anterior open bite, Crw Max Inc crowded maxillary incisor, Crw Mand Inc crowded mandibular incisor, FMPA Frankfort-Mandibular Plane Angle, LFH lower facial height