A novel method for assessment of human midpalatal sutures using CBCT-based geometric morphometrics and complexity scores.

INTRODUCTION: Management of dentofacial deficiencies requires knowledge about sutural morphology and complexity. The present study assesses midpalatal sutural morphology based on human cone-beam computed tomography (CBCT) using geometric morphometrics (GMM) and complexity scores. The study is the first to apply a sutural complexity score to human CBCT datasets and demonstrates the potential such a score has to improve objectiveness and comparability when analysing the midpalatal suture. MATERIALS AND METHODS: CBCTs of various age and sex groups were analysed retrospectively (n = 48). For the geometric morphometric analysis, landmark acquisition and generalised Procrustes superimposition were combined with principal component analysis to detect variability in sutural shape patterns. For complexity analysis, a windowed short-time Fourier transform with a power spectrum density (PSD) calculation was applied to resampled superimposed semi-landmarks. RESULTS: According to the GMM, younger patients exhibited comparable sutural patterns. With increasing age, the shape variation increased among the samples. The principal components did not sufficiently capture complexity patterns, so an additional methodology was applied to assess characteristics such as sutural interdigitation. According to the complexity analysis, the average PSD complexity score was 1.465 (standard deviation = 0.010). Suture complexity increased with patient age (p < 0.0001), but was not influenced by sex (p = 0.588). The intra-class correlation coefficient exceeded 0.9, indicating intra-rater reliability. CONCLUSION: Our study demonstrated that GMM applied to human CBCTs can reveal shape variations and allow the comparison of sutural morphologies across samples. We demonstrate that complexity scores can be applied to study human sutures captured in CBCTs and complement GMM for a comprehensive sutural analysis.

Periodontal conditions in patients with Marfan syndrome - a multicenter case control study.

BACKGROUND: Marfan syndrome (MFS) is a disorder of the connective tissues. Alterations of the elastic fibers may manifest in different tissues especially in the skeletal, cardiovascular and ocular system. Oral manifestations like orthodontic or skeletal anomalies and fragility of the temporomandibular joint have been well described by various authors. However, no data are available regarding a possible periodontal involvement of MFS. Hence, the aim of the present study was to investigate for the first time if MFS may increase the susceptibility to periodontitis. METHODS: A comprehensive periodontal examination including documentation of probing pocket depth, gingival recession, clinical attachment level, and bleeding on probing was conducted in all patients. In addition, dental conditions were assessed by determining the Index for Decayed, Missing and Filled Teeth (DMFT) and a self-administered questionnaire was filled out by patients. For statistical analysis, the unpaired t-Test was applied (level of significance: p < 0.05). Both groups were matched concerning well known periodontal risk factors like age, gender and smoking habits. RESULTS: 82 participants, 51 patients with MFS (30 female and 21 male, mean age: 40.20 ± 15.35 years) and 31 sound controls (17 female and 14 male, mean age: 40.29 ± 13.94 years), were examined. All assessed periodontal and dental parameters were not significantly different between groups. CONCLUSIONS: Based on our data, patients with MFS did not reveal a higher prevalence of periodontitis compared to the control group. However, Marfan patients showed a tendency to more inflammation signs, which can be explained by the crowded teeth. Therefore, a regular professional cleaning of the teeth is recommendable (i.e., 6 months intervals) in order to reduce the bacterial biofilm in the oral cavity and thus resulting in a decreased risk of systemic diseases, specifically endocarditis.

Prevalence of bullying in orthodontic patients and its impact on the desire for orthodontic therapy, treatment motivation, and expectations of treatment.

PURPOSE: This study aims at investigating the prevalence of bullying due to malocclusions in a sample of German orthodontic patients. Thereby, we analyzed the influence of self-reported bullying on initiation, desire and motivation, and expectations of orthodontic therapy. PATIENTS AND METHODS: Patients completed questionnaires by themselves in three orthodontic practices (n = 1020, mean age 11.8 years). The sample was divided into three groups: (1) subjects bullied due to dentofacial features, (2) subjects bullied due to physical features, and (3) non-bullied control group. The effect of bullying on initiation, desire and motivation, and expectation from orthodontic treatment was assessed and compared between these groups. RESULTS: Overall prevalence of bullying was 23.7% with male subjects revealing significantly higher values than females (p < 0.001). Subjects from the dentofacial features group (6.3%) initiated orthodontic therapy themselves significantly more often than subjects from the physical features (17.4%; p = 0.030) and control group (76.3%; p < 0.001). The dentofacial features group reported significantly more frequently that 'ugly teeth' were the major motivating factor to seek orthodontic treatment (40.4%). Within this group significantly higher mean scores for the expectation 'keep me from being bullied' were obtained compared with subjects in the physical features (p < 0.001) or control group (p < 0.001). CONCLUSION: This analysis demonstrated that bullying due to malocclusion impacts attitude towards orthodontic treatment. Victims who experienced bullying due to malocclusion initiate orthodontic treatment more often themselves and expect therapy to prevent them from experiencing further bullying.

Panoramic radiography: effects of head alignment on the vertical dimension of the mandibular ramus and condyle region.

The aim of this study was to assess whether it is possible to derive accurate vertical measurements of the mandibular ramus and condyle from panoramic radiographs. A human dry skull was positioned in a panoramic machine. The skull was displaced along the sagittal and transverse plane and rotated around the vertical and transverse axes. A set of 252 digital radiographs with defined positioning errors was compared with a set of 42 radiographs in the 'ideal' position. The distances between the metal markers that had been attached at the angle of the mandible at a distance of 60 mm in the condyle region to produce fixed reference points on the radiographs were measured. Statistical differences were investigated using Friedman repeated measures analysis of variance on ranks followed by the Dunnett's test for the comparison against the control group in the ideal position (α = 0.05). Vertical measurements were significantly affected when the skull was rotated around the vertical (P < 0.001) or shifted along the transverse axis (P < 0.001). Misalignment of the head affected the vertical measurement of the mandibular ramus and condyle. However, asymmetries of more than 6 per cent are probably not due to patient positioning in the panoramic machine.

A controlled evaluation of oral screen effects on intra-oral pressure curve characteristics.

The purpose of this study was to quantify the impact of oral screen (OS) application on intra-oral pressure characteristics in three malocclusion groups. Fifty-six randomly recruited participants (26 males and 30 females) who met the inclusion criteria of either an Angle Class I occlusal relationships or Angle Class II1 or II2 malocclusions, were assigned by dentition to group I (n = 31), group II1 (n = 12), or group II2 (n = 13). Two 3 minute periods of intra-oral pressure monitoring were conducted on each participant, using two different oral end fittings connected to a piezo-resistive relative pressure sensor: (1) a flexible OS and (2) a small-dimensioned air-permeable end cap (EC), which was placed laterally in the premolar region, thus recording intra-oral pressure independent of the influence of the OS. Pressure curve characteristics for both periods and between the malocclusion groups were evaluated with reference to the frequency of swallowing peaks, duration, and altitude of negative pressure plateau phases and the area under the pressure curve. Statistical analysis was undertaken using analysis of variance (ANOVA), the Wilcoxon Mann-Whitney test, and spearman correlation coefficient. A median number of two peaks (median height -20.9 mbar) and three plateau phases (median height of -2.3 mbar) may be regarded as normative for normal occlusion subjects during a 3 minute period, at rest. OS application raised the median average duration and height of intra-oral negative pressure plateau phases in the II1 subjects, exceeding those of group I, but less than the plateau duration in group II2. Median peak heights were distinctively lower in groups I and II1 during OS application. It is concluded that additional training for extension of intra-oral pressure phases may be a promising approach to pre-orthodontic Class II division 1 treatment.

Pulp vitality in teeth suffering trauma during orthodontic therapy.

OBJECTIVE: To examine pulpal vitality in teeth suffering dental trauma during orthodontic therapy with fixed appliances. MATERIALS AND METHODS: Pulpal condition was evaluated in 59 teeth that had suffered dental trauma during orthodontic treatment (TO-group), in 800 orthodontically treated teeth without previous dental trauma (O-group), and in 193 orthodontically untreated teeth with previous dental trauma (T-group). Pulpal vitality was examined clinically and with radiographs. Degree of pulp obliteration was rated as absent, partial, or total. All teeth in the TO-group showed a positive sensibility test prior to resumption of orthodontic therapy. RESULTS: Teeth in the TO-group revealed a significantly higher frequency of pulp necrosis than teeth in the O-group or teeth in the T-group (P < .001, respectively). In the TO-group, teeth with extrusive or lateral luxation (P = .031) and teeth with intrusive luxation (P = .015) injuries showed a significantly higher rate of pulp necrosis than teeth with fracture of enamel. In addition, teeth with total pulp obliteration showed a significantly higher frequency of pulp necrosis than teeth without pulp obliteration (P = .013). CONCLUSION: Teeth with severe periodontal injury during orthodontic therapy and subsequent total pulp obliteration have an increased risk of pulp necrosis during additional orthodontic treatment stages.

Changes in incisor third-order inclination resulting from vertical variation in lingual bracket placement.

OBJECTIVE: To test the null hypothesis that third-order measurements are not correlated to lingual incisor features seen on radiographs. MATERIAL AND METHODS: The lateral headfilms of 38 untreated, norm-occlusion subjects without incisor abrasions or restorations were used for third-order measurements of upper and lower central incisors and assessment of the inclination of four sites suitable for lingual bracket placement with reference to the occlusal plane perpendicular. Lingual sections were determined by the tangents at the incisal fossa (S1), at the transition plateau between incisal fossa and the cingulum (S2), by a constructed line reaching from the incisal tip to the cingulum (S3), and by a tangent at the cingulum convexity (S4). Third-order angles were also assessed on corresponding dental casts using an incisor inclination gauge. Regression analysis was performed using the third-order measurements of both methods as the dependent variables and the inclination of the lingual enamel sections (S1, S2, S3, S4) as the independent variables. RESULTS: The null hypothesis was rejected. For the most common bracket application sites located on the lingual shovel (S1 and S2), third-order inclination changes of 0.4-0.7 degrees are expected for each degree of change in the inclination of the lingual surface. The impact of bracket placement errors on third-order angulation is similar between sections S1 and S2 and the cingulum convexity (S4). Section S3 proved to be least affected by interindividual variation. CONCLUSION: The third-order measurements are correlated to lingual incisor features. Accordingly, third-order changes resulting from variation in lingual bracket placement can be individually predicted from radiographic assessments.

Evaluation of tooth position, occlusion, and interproximal contacts after transplantation of immature third molars.

The aim of the present investigation was to examine position, occlusion, and interproximal contacts of 139 transplanted third molars in 136 patients (94 females, 42 males) with a mean age of 17.6 years at the time of transplantation. Ninety-two teeth were placed directly into favourable positions and left to erupt spontaneously. Forty-seven teeth were transplanted into atrophied jaw sections and underwent post-operative orthodontic adjustment. According to the post-operative treatment performed, the sample was divided into two groups: transplants with or without subsequent orthodontic treatment. The mean post-operative observation time was 4.4 years. Study models were obtained from all patients and the American Board of Orthodontics Objective Grading System was adapted for evaluation of position, occlusion, and interproximal contacts of the transplanted teeth. A Mann-Whitney U-test was used to determine significant intergroup differences with respect to the final scores and the various evaluated criteria. Absence of occlusal contacts was found in more than 30 per cent, absence of both interproximal contacts in more than 15 per cent, and inadequate position in more than 40 per cent of the transplants without subsequent orthodontic treatment. The poorest results were observed for maxillary teeth transplanted into the mandible. The results of the present study show that incorrect positioning with absence of occlusal and interproximal contacts are frequent findings in transplanted teeth. Short-term orthodontic adjustment, especially of maxillary transplants into the mandible, seems to be advisable in order to obtain correct positioning and function of these teeth.

The effect of pulp obliteration on pulpal vitality of orthodontically intruded traumatized teeth.

Limited information exists on the impact of pulp obliteration on pulpal vitality of orthodontically treated traumatized teeth. Pulpal condition was examined in 269 traumatized maxillary incisors after orthodontic intrusion (OT group) and in 193 traumatized maxillary incisors without subsequent orthodontic treatment (C group). According to the degree of initial pulp obliteration, the teeth were divided into three categories: teeth without, teeth with partial, and teeth with total pulp obliteration. Teeth in the OT group revealed a significantly higher rate of pulp necrosis than teeth in the C group (p < 0.001). In addition, teeth in the OT group with total pulp obliteration showed a significantly higher rate of pulp necrosis than teeth without (p < 0.001) or only partial pulp obliteration (p = 0.025). The results indicate that traumatized teeth with total pulp obliteration have a higher susceptibility to pulpal complications during orthodontic intrusion than traumatized teeth without or only partial pulp obliteration.

Root development of immature third molars transplanted to surgically created sockets.

PURPOSE: The aim of this study was to compare root development after transplantation of teeth into surgically created sockets or into fresh extraction sites. PATIENTS AND METHODS: The sample consisted of 62 patients with a total of 64 transplanted immature third molars. All transplants were at root development stages 3 to 4. In 22 cases, a new socket was created by means of burs. Forty-two teeth transplanted into a fresh extraction site served as controls. Postoperative root development was determined on intraoral radiographs taken immediately after transplantation and at the final follow-up. For all transplants, extraoral storage time and number of trials were recorded during transplantation. RESULTS: No significant intergroup differences were observed at root development stage 3. In contrast, at root development stage 4 transplantations to surgically created sockets showed a significantly lower final root length (P = .025) and root length increment (P = .038) than transplants in the control group. In addition, a significant correlation was determined in the prepared socket group at developmental stage 4 between root length increment and extraoral storage time (r = -0.910, r(2) = 0.828, P < .001) or number of trials in the recipient socket (r = -0.775, r(2) = 0.601, P < .001). CONCLUSIONS: Teeth at advanced developmental stages transplanted to surgically created sockets show an impaired postoperative root development. A possible explanation might be damage of Hertwig's epithelial root sheath during the transplantation procedure.

Effect of additional surgical procedures on root development of transplanted immature third molars.

The aim of this investigation was to determine the influence of additional surgical procedures on the root development of transplanted teeth. The study sample consisted of 90 immature third molars transplanted in 88 patients. All transplanted teeth were at root development stages 3 to 4. Free bone autografts were used in 23 cases (bone autograft group), mainly because of vertical atrophy of the alveolar process. A splitting osteotomy of the alveolar process was performed in 25 cases with marked horizontal atrophy (osteotomy group). Forty-two teeth transplanted into a fresh extraction site immediately after extraction of the non-retainable tooth served as controls. At root development stage 3, significant differences were determined between the osteotomy and the control groups in final root length (P<0.001) and root length increment (P=0.004). Transplants in the osteotomy group revealed a significantly lower root length increment than transplants in the bone autograft group (P=0.008). No significant intergroup differences were observed at root development stage 4. These results indicate that a splitting osteotomy of the alveolar process has a negative effect on root development of transplanted teeth at earlier developmental stages.

Influence of orthodontic intrusion on pulpal vitality of previously traumatized maxillary permanent incisors.

INTRODUCTION: Dental trauma seems to increase a patient's susceptibility to complications during orthodontic treatment. However, no previous investigation has examined the influence of orthodontic intrusion on pulpal vitality of traumatized maxillary permanent incisors. METHODS: Pulpal condition was examined clinically and radiologically after orthodontic intrusion of previously traumatized (OT group) and nontraumatized teeth (O group), and after previous dental trauma without orthodontic treatment (T group). Inclusion criteria for the OT and O groups were Class II Division 1 malocclusion with deep bite and orthodontic intrusion of the maxillary incisors, no extractions of maxillary teeth, and no additional lateral tooth movement of the maxillary incisors. All teeth in the OT group had a positive sensitivity test before orthodontic therapy. RESULTS: Teeth in the OT group, and especially those with severe periodontal injuries, showed a significantly higher frequency of pulp necrosis than teeth in the O and T groups. The occurrence of pulp necrosis was significantly higher in lateral than in central incisors. CONCLUSIONS: Traumatized maxillary incisors, and especially lateral incisors, with severe periodontal injuries have a higher susceptibility to pulp necrosis during orthodontic intrusion than nontraumatized teeth.

Influence of insertion site on the failure rates of orthodontic miniscrews.

OBJECTIVE: The aim of this study was to examine the influence of various insertion sites on the failure rates of orthodontic miniscrews. PATIENTS AND METHODS: 76 orthodontic miniscrews were inserted in 59 patients: 20 in the buccal and 18 in the palatal side of the maxilla, and 38 in the buccal side of the mandible. We attempted to insert all the screws at a minimum depth of at least 5 mm. RESULTS: The total failure rate was 18.4% on average (n = 14). Orthodontic miniscrews in the palatal side of the maxilla failed at a significantly higher rate than miniscrews in the buccal side of the mandible (p < 0.001); they also failed at a significantly higher failure rate during the first 3 months after insertion than did miniscrews in the buccal side of the maxilla (p = 0.003) or mandible (p < 0.001). We also observed a significant correlation between failure rate and screw length, with the shorter miniscrews showing significantly higher failure rates (r = -0.743; r2 = 0.552; p < 0.001). CONCLUSIONS: Insertion site seems to affect the failure rates of orthodontic miniscrews. To ensure that orthodontic miniscrews have adequate stability in the palatal side of the maxilla, the insertion depth should exceed 5 mm.

Influence of overjet and lip coverage on the prevalence and severity of incisor trauma.

OBJECTIVE: The aim of this study was to assess the influence of overjet size and lip coverage on the prevalence and severity of incisor trauma. PATIENTS AND METHODS: Dental records made on presentation of 1,367 patients were examined for data concerning the prevalence, type and severity of incisor trauma. Original overjet was measured on the pre-treatment study models and divided into two categories: normal overjet (0-3.0 mm) and increased overjet (> 3.0 mm). Lip coverage of the upper incisors was estimated with reference to photographs showing the patient's face and was then rated as adequate or inadequate. The patients were then divided into three groups: normal original overjet and adequate lip coverage (Group 1), increased original overjet and adequate lip coverage (Group 2), and increased original overjet and inadequate lip coverage (Group 3). RESULTS: Group 1 patients revealed a significantly lower prevalence of traumatic injuries than those in Group 2 (p = 0.028) or Group 3 (p = 0.003), and the odds ratios compared to Group 1 were 1.6634 for Group 2 and 2.0336 for Group 3. Regarding the type of trauma, Group 3 patients showed a significantly higher frequency of periodontal injuries than those in Group 1 (p = 0.018) or Group 2 (p = 0.015). Furthermore, Group 3 patients had significantly more in juries to two or more teeth per person than patients in Group 1 (p < 0.001) or Group 2 (p < 0.001). CONCLUSIONS: Increased overjet and inadequate lip coverage increase the risk and severity of incisor trauma. Early orthodontic treatment might prevent dental trauma in these patients.

Temporomandibular joint dysfunction in Marfan syndrome.

OBJECTIVE: The aim of this study was to examine the prevalence of signs and symptoms of temporomandibular joint (TMJ) dysfunction in persons with Marfan syndrome. STUDY DESIGN: A questionnaire was distributed to 350 patients with Marfan syndrome. Twenty-one patients were additionally subjected to a clinical examination and magnetic resonance imaging (MRI) of the TMJ. RESULTS: The prevalence of symptoms of TMJ dysfunction was 51.6% (n=145), with 24.2 % (n=68) indicating symptoms of subluxation, and 34.9% (n=98) of the patients already undergoing medical treatment for their TMJ problems. Anterior disc displacement with and without reduction was observed in 17 of the examined patients (81.0%), with 4 of these patients additionally showing osteoarthrosis of the affected temporomandibular joints. CONCLUSION: TMJ dysfunction appears to be an important aspect in Marfan syndrome.

Results of transplanting developing third molars as part of orthodontic space management. Part 1: clinical and radiographic results.

PATIENTS AND METHOD: The aim of the present study was to contribute to a more accurate indication and better integration of developing third molar transplantation into orthodontic space management, using the results gleaned from the authors' own pool of patients. For this purpose, a clinical and radiographic examination of 61 transplanted developing molars in 57 patients was carried out after an average of 3.3 years. RESULTS: The overall success rate was 85%. Failure was due in 10% of cases to impaired periodontal healing (inflammatory root resorption, ankylosis, or increased pocket probing depths) and in 5% of cases to insufficient or arrested postoperative root development accompanied by increased transplant mobility. The incidence of postoperative cessation of further root development was significantly higher (p = 0.011) in transplants at early developmental stages, which also had a negative impact on the final root length, the crown-root ratio and the mobility values of these transplants. CONCLUSIONS: The transplantation of developing third molars should be given stronger consideration in treatment plans for orthodontic space management although it represents a real alternative to orthodontic space closure only in exceptional cases. However, unlike implantological or prosthodontic treatment, it offers an opportunity to replace a missing or non-retainable tooth with a patient's own vital and fully functional tooth, provided the appropriate transplant is selected.

Results of transplanting developing third molars as part of orthodontics space management. Part 2: results following the orthodontic treatment of transplanted developing third molars in cases of aplasia and premature loss of teeth with atrophy of the alveolar process.

MATERIAL AND METHODS: The aim of this study was to assess the effects of atrophy of the alveolar process and subsequent orthodontic treatment on the transplantation results of developing third molars. The material consisted of 35 teeth transplanted to an atrophied alveolar process. 19 of these teeth were treated orthodontically subsequent to transplantation. The control group consisted of 61 developing molars transplanted to a new extraction socket. The transplanted teeth were followed up clinically and radiographically for a mean period of 3.2 years. RESULTS: The success rate was 85% for transplants to new extraction sockets and 84% for transplants to atrophied jaw sections with subsequent orthodontic treatment. In contrast, transplants to atrophied jaw sections without subsequent orthodontic treatment showed a significantly (p < or = 0.001) lower success rate of only 37.5%. These poorer results were due to persistent infraocclusion and ankylosis. CONCLUSIONS: Even in cases with atrophy of the alveolar process, a transplantation with subsequent orthodontic treatment represents a promising treatment concept, whereas teeth without subsequent orthodontic treatment showed a lower success rate. Orthodontic tooth movement had no negative effect on the healing rates of transplanted developing third molars.

Torque deformation characteristics of plastic brackets: a comparative study.

AIM: The purpose of this study was to compare the torque deformation characteristics of seven commercially available plastic brackets, both amongst each other and with stainless steel brackets. MATERIAL AND METHODS: Ten brackets each of (1) pure polycarbonate, (2) ceramic reinforced polycarbonate, (3) fiberglass reinforced polycarbonate, (4) ceramic reinforced polycarbonate with metal slot, (5) fiberglass reinforced polycarbonate with metal slot, (6) polyurethane, and (7) polyurethane with metal slot were exposed to torsion in a torquemeter, following an aging process according to ISO 10477. Ten stainless steel brackets served as a control group. Torsion was applied continuously using a material testing machine (Zwick Z2.5, Zwick Materialprüfung, Ulm, Germany). RESULTS: The results showed within the group of plastic brackets that metal slot reinforced brackets were subject to the lowest degree of deformation, followed by the brackets made of pure polyurethane, pure polycarbonate and fiberglass reinforced polycarbonate. The ceramic reinforced polycarbonate brackets showed the highest deformation under torque stress. The plastic deformation of the ceramic reinforced, fiberglass reinforced and pure polycarbonate brackets started even in the recommended torque range of 10-20 Nmm. The additional ceramic and fiberglass in the plastic brackets investigated in this study did not improve the torque stability of the polycarbonate brackets. The pure polyurethane brackets showed no significant difference from the pure polycarbonate brackets at the moment of 15 Nmm which is the optimal torque for a maxillary incisor. CONCLUSION: A comparison with the stainless steel brackets illustrated that plastic brackets are suited for clinical application only if they have a metal slot.

In vitro study on the fatigue limit of single-lap joints.

Lasting adhesion between attachment and tooth is an essential prerequisite for all adhesive techniques in dentistry. However, the maximum static fatigue load is only one material-related parameter for the quality of this adhesion. Another parameter is the dynamic loading capacity of a bonded joint, which was determined in the present study for Dual adhesive resin by means of fatigue testing. This revealed a significant correlation between the recorded static and dynamic fatigue load and the gap width, which varied between 0.01 mm, 0.15 mm and 0.5 mm in the experimental setup. At 18.8 MPa, the median gap width of 0.15 mm yielded the highest static resistance, with a dynamic resistance 15% below this figure. Both the smaller and the larger gap showed significantly lower static fracture strengths (0.01 mm: 13.6 MPa; 0.5 mm: 13.7 MPa), whereas a dynamic load on the 0.01 mm bond, in contrast to the 0.5 mm bond, led to only a 5% reduction in bonding strength.

Effect of smoking on the failure rates of orthodontic miniscrews.

OBJECTIVE: The aim of this study was to investigate the effect of cigarette smoking on the failure rates of orthodontic miniscrews. PATIENTS AND METHODS: Our cohort consisted of 88 patients with a total of 110 orthodontic miniscrews. Based on their smoking habits, the patients were divided into three groups: the light smokers (< or = 10 cigarettes/day), heavy smokers (> 10 cigarettes/ day), and non-smokers. The light-smoker group consisted of 14 patients with 18 orthodontic miniscrews, and there were 15 patients with 19 miniscrews among the heavy smokers. The nonsmoker group contained 59 patients with a total of 73 miniscrews. RESULTS: The overall failure rate was 18.2% (n = 20). Heavy smokers revealed a significantly higher failure rate than light smokers (p = 0.005) or non-smokers (p < 0.001). No significant differences were observed between non-smokers and light smokers. Miniscrews in the heavy smoker group exhibited a significantly higher failure rate during the first 4 months after insertion than did the miniscrews in the light smokers (p = 0.008) or non-smokers (p < 0.001). CONCLUSION: Our results suggest that heavy smoking has a detrimental effect on the success rates of orthodontic miniscrews.