Situational simulation teaching effectively improves dental students' non-operational clinical competency and objective structured clinical examination performance.

BACKGROUND: Appropriate communication with dental patients enhances treatment outcomes and patient satisfaction. Implementing simulated patient interviews courses can improve patient-centered care and reduce conflict during clerkship training. Therefore, this study explored the relationship among student participation in a situational simulation course (SSC), academic performance, clerkship performance, and objective structured clinical examination (OSCE) performance. METHODS: This study was conducted with a sample of fifth-year dental students undergoing clerkship training. After implementing a situational simulation course to investigate the relationship among participation in SSC, academic performance, clerkship performance, and OSCE performance, a path analysis model was developed and tested. RESULTS: Eighty-seven fifth-year dental students were eligible for the SSC, and most (n = 70, 80.46%) volunteered to participate. The path analysis model revealed that academic performance had a direct effect on OSCE performance (ß = 0.281, P = 0.003) and clerkship performance (ß = 0.441, P < 0.001). In addition, SSC teaching had a direct effect on OSCE performance (ß = 0.356, P < 0.001). CONCLUSIONS: SSCs can enhance dental students' non-operational clinical competency and OSCE performance effectively. Simulated patient encounters with feedback, incorporated into the dental curricula, have led to improved communication. Based on our findings, we suggest implementing SSC teaching before the OSCE to improve communication and cognitive skills.

Patient perception of service quality to preanesthetic oral examination: a cross-sectional study using the SERVQUAL model.

BACKGROUND: A phase-III interdisciplinary quality improvement program, the preanesthetic oral examination (PAOE), was implemented as a new program in an academic medical center to prevent perioperative dental injuries. This study was aimed at surveying the perceived service quality and satisfaction of patients who had undergone PAOE based on the SERVQUAL model. METHODS: This cross-sectional survey was conducted at the Kaohsiung Medical University Hospital using convenience sampling. Patients referred for PAOE (PAOE group) and those who had voluntarily availed dental services (control group) were recruited. A modified SERVQUAL questionnaire was used to assess the perceived service quality and patient satisfaction with dental services. Cronbach's alpha for SERVQUAL was 0.861. RESULTS: We enrolled 286 (68.8%) and 130 (31.2%) participants in the PAOE and control groups, respectively. The path analysis revealed that the PAOE group scored lower in dimensions of reliability (ß = -0.074, P = 0.003), responsiveness (ß = -0.148, P = 0.006), and empathy (ß = -0.140, P = 0.011). Furthermore, reliability (ß = 0.655, P < 0.001) and responsiveness (ß = 0.147, P = 0.008) showed a direct effect on patient satisfaction. Overall, participants were highly satisfied with the dental services. CONCLUSIONS: The PAOE group showed lower satisfaction and perceived quality of dental services compared to the control group. Although implementing an interdisciplinary program reduces the perceived service quality, its influence is limited. Employing an interdisciplinary teamwork is a win-win strategy encouraged to improve patient safety and reduce malpractice claims. Future suggestions should focus on establishing waiting times that are considered reasonable by patients. Patient-centered education related to the risk of perioperative dental injuries should be provided, and awareness of oral conditions for patient safety should be improved. Moreover, interprofessional education in continuous and undergraduate programs is necessary to improve professional quality.

The impact of Lacticaseibacillus paracasei GMNL-143 toothpaste on gingivitis and oral microbiota in adults: a randomized, double-blind, crossover, placebo-controlled trial.

BACKGROUND: This study examines the oral health benefits of heat-killed Lacticaseibacillus paracasei GMNL-143, particularly its potential in oral microbiota alterations and gingivitis improvement. METHODS: We assessed GMNL-143's in vitro interactions with oral pathogens and its ability to prevent pathogen adherence to gingival cells. A randomized, double-blind, crossover clinical trial was performed on gingivitis patients using GMNL-143 toothpaste or placebo for four weeks, followed by a crossover after a washout. RESULTS: GMNL-143 showed coaggregation with oral pathogens in vitro, linked to its surface layer protein. In patients, GMNL-143 toothpaste lowered the gingival index and reduced Streptococcus mutans in crevicular fluid. A positive relationship was found between Aggregatibacter actinomycetemcomitans and gingival index changes, and a negative one between Campylobacter and gingival index changes in plaque. CONCLUSION: GMNL-143 toothpaste may shift oral bacterial composition towards a healthier state, suggesting its potential in managing mild to moderate gingivitis. TRIAL REGISTRATION: ID NCT04190485 ( https://clinicaltrials.gov/ ); 09/12/2019, retrospective registration.

Acceptance and experience of digital dental technology, burnout, job satisfaction, and turnover intention for Taiwanese dental technicians.

BACKGROUND: Digital dental technology (DDT) has progressed and been introduced to Taiwan in the recent years, gradually changing the industry ecology. Many studies have demonstrated that DDT is more accurate and faster than conventional dental technology. However, there is a paucity of research exploring dental technicians' perspectives on digital dental techniques, and their burnout, job satisfaction, and turnover intention. METHODS: This cross-sectional survey with convenience sampling was conducted at the conference venue of the Taiwan Association of Dental Technology to investigate the perspectives of dental technicians. We used the snowballing method in this study; two sampling methods were adopted, a convenience sampling of dental technicians to complete a survey, followed by asking the survey participants of the convenience sample to invite their colleagues to participate in the online survey. The survey questionnaire included questions on demographics, work-related information, acceptance and experiences of dental technicians toward DDT, occupational burnout, job satisfaction, and turnover intention. Regression models were used to determine the predictors of job satisfaction and determinants of turnover intention. RESULTS: In total, 341 valid questionnaires were obtained. Overall, the participants reported long working hours (95.5%), positive score on the DDT acceptance scale, moderate job satisfaction, higher personal burnout, and work burnout, along with lower over-commitment. Among them, 32.9% and 28.2% reported the intention to leave their organization and profession, respectively. The stepwise multiple regression model revealed that higher work burnout decreased job satisfaction, while higher DDT acceptance and position as employer increased job satisfaction. The binary logistic regression models revealed that geographical area of workplace, work burnout, and job satisfaction were significant predictors of turnover intentions. CONCLUSIONS: Many Taiwanese dental technicians reported turnover intentions and higher burnout. With the trend of digitalization in the dental industry, even though most dental technicians had a positive outlook toward DDT, its influence on job satisfaction appears limited. Retaining good and professional talents required of a dental technician is crucial, especially as Taiwan's dental care becomes increasingly specialized. Strategies for improving the work environment and occupational health of dental technicians should thus be the focus of future studies.

Influence of cavity depth and restoration of non-carious cervical root lesions on strain distribution from various loading sites.

BACKGROUND: We aimed to investigate the load-induced strain variation in teeth with unrestored and resin-based composite restored non-carious cervical lesions (NCCLs). METHODS: Twelve extracted premolars were provided for measuring buccal-side root NCCLs. Strain gauges were fixed at four measuring sites of each tooth, two at the buccal surface and two at the lingual surface. NCCLs were prepared with occlusal margins at the cemento-enamel junction. A static 9-kg load was applied at seven occlusal loading points: buccal cusp tip (BC), inner inclination of the BC, lingual cusp tip (LC), inner inclination of the LC, center of the mesial marginal ridge or distal marginal ridge, and center of the central groove. The strain was detected at each site in teeth with NCCL depths of 0 (control), 0.5, 1.0, and 1.5 mm. Each NCCL was restored using an adhesive composite resin, and the strains were re-measured. RESULTS: The strains at the NCCL occlusal and gingival margins decreased with increasing defect depths, and the effect was significant when the depth of the defect was 1.5 mm. Loading on the buccal and lingual cusps induced prominent strain variation. The strains at all depth distribution recovered to nearly intact conditions when the NCCLs were restored. CONCLUSIONS: NCCLs at 1.5 mm depth are detrimental, but they can be restored using resin composites. CLINICAL SIGNIFICANCE: The existence of NCCLs should not be ignored. The depth of the NCCL may affect the progression of the lesion. Resin composite restoration is an appropriate method for preventing persistent NCCL deterioration.

Short fish-origin DNA elements served as flanking sequences in a knockdown cloning vector enabling the generation of a functional siRNA molecule in mammalian cells and fish embryos.

Improving the quality of a siRNA-knockdown cloning vector requires simpler, shorter, and more effective flanking sequences. In this study, we designed such flanking sequences based on those found in zebrafish pre-miR3906, namely, internal element (IE) 1 and IE2. We engineered a vegf-shRNA fragment flanked by an 80-bp IE1/IE2 and then inserted into the 3' UTR of GFP reporter cDNA driven by a cytomegalovirus promoter to obtain a plasmid containing gfp-IE-vegf-shRNA-polA. Upon microinjection of this plasmid into zebrafish embryos, we found that IE flanking sequences could effectively induce the production of vegf-shRNA fragment, which was then processed into a functional siRNA to silence the target vegf121 gene. Northern blot showed that the vegf-shRNA fragment was cleaved from gfp-IE-vegf-shRNA-polA, resulting in the loss of polyA tails, subsequently degrading the remaining RNA-containing GFP. Moreover, Western blot revealed that addition of IE-based vegf-shRNA fragment could markedly decrease the expression of VEGF. Finally, to facilitate a more versatile application of the IE-based knockdown vector, we generated an inducible expression vector in which IE-vegf-shRNA was constructed downstream in a Tet-on system to generate a Tet-on-IE-vegf-shRNA construct. After doxycycline induction, the protein level of VEGF in SW620 cells harboring the Tet-on-IE-vegf-shRNA construct was decreased 77%. Interestingly, when SW620 cells harboring Tet-on-IE-vegf-shRNA cells were induced and transplanted into zebrafish embryos, we found that abnormal branch of the sub-intestinal vessels was reduced in the recipient embryos, suggesting that vegf-shRNA cleaved from Tet-on-IE-vegf-shRNA-polA was processed into a functional vegf-siRNA in embryos suppressing endogenous VEGF and reducing tumor angiogenesis. Therefore, we conclude that fish-origin IEs are flanking sequences with short, simple, and effective DNA elements. This IE-based knockdown cloning vector provides a new alternative material to facilitate the generation of functional siRNA with which to perform loss-of-function experiments, both in vitro (mammalian cells) and in vivo (zebrafish embryos).

Effect of Anchor Length on the Pullout Strength of Palatal Mini Implants.

PURPOSE: The aim of this study was to evaluate the pullout strength of 3 different orthodontic mini implants. MATERIALS AND METHODS: Twenty-seven mini implants (diameter: 2 mm, length: 7 mm) were implanted into artificial bone (Sawbones; Pacific Research Laboratories Inc.) at depths of 3, 4, and 5 mm. The insertion torque (IT), resonance frequency (RF), pullout strength (PS), and anchor length (AL) were measured. One-way analysis of variance with Tukey honest significant difference (HSD) postcomparison were used to detect intergroup differences. The null hypothesis was that IT, RF, and PS would significantly correlate in the same brand. RESULTS: In the implantation depths (ID) (5 and 4 mm), IT of Types C (16.67 and 14.33 N·cm) and Type B (14 and 13.33 N·cm) were significantly higher than Type A (10.33 and 9.33 N·cm). Type A had a largest AL and PS at the IDs (5 and 4 mm). In the IDs (3 mm), PS was no different. Type C had no correlation among the RF, IT, and PS. Therefore, null hypothesis was rejected. CONCLUSION: AL exerted crucial effects on the PS of the mini implants.

Arsenic Trioxide-Induced Mandibular Osteomyelitis.

Previously, arsenic was a popular devitalizing agent used to necrotize inflamed dental pulp to lower the pulp sensitivity owing to the unavailability of appropriate anesthesia. However, leakage from the apical foramen, lateral or accessory canals, or cracks in the tooth is common. This can be dangerous because of the reportedly high toxic effects of arsenic in both hard and soft tissues, leading to gingival and osseous necrosis and, consequently, osteomyelitis. Therefore, arsenic can prove fatal for both bones and teeth and is no longer used. We encountered a case involving a 50-year-old man who had developed mandibular osteomyelitis with lower lip paresthesia caused by arsenic trioxide used during endodontic treatment. The patient was treated with appropriate antibiotics, adjunctive hyperbaric oxygen therapy, and adequate surgical debridement. Hyperbaric oxygen therapy can induce neovascularization in necrosed tissues and improve bone and soft tissue healing. At a 4-year follow-up visit, bone healing was observed, with restoration of periodontal health, although the paresthesia had persisted. We describe this case, present a review of the relevant published data, and discuss the possible causes, diagnosis, treatment, and follow-up protocol of mandibular osteomyelitis caused by arsenic trioxide.

The influence of monoamine oxidase variants on the risk of betel quid-associated oral and pharyngeal cancer.

Betel quid (BQ) and areca nut (AN) (major BQ ingredient) are group I human carcinogens illustrated by International Agency for Research on Cancer and are closely associated with an elevated risk of oral potentially malignant disorders (OPMDs) and cancers of the oral cavity and pharynx. The primary alkaloid of AN, arecoline, can be metabolized via the monoamine oxidase (MAO) gene by inducing reactive oxygen species (ROS). The aim of this study was to investigate whether the variants of the susceptible candidate MAO genes are associated with OPMDs and oral and pharyngeal cancer. A significant trend of MAO-A mRNA expression was found in in vitro studies. Using paired human tissues, we confirmed the significantly decreased expression of MAO-A and MAO-B in cancerous tissues when compared with adjacent noncancerous tissues. Moreover, we determined that MAO-A single nucleotide polymorphism variants are significantly linked with oral and pharyngeal cancer patients in comparison to OPMDs patients [rs5953210 risk G-allele, odds ratio = 1.76; 95% confidence interval = 1.02-3.01]. In conclusion, we suggested that susceptible MAO family variants associated with oral and pharyngeal cancer may be implicated in the modulation of MAO gene activity associated with ROS.

Inducing cyclooxygenase-2 expression, prostaglandin E2 and prostaglandin F2α production of human dental pulp cells by activation of toll-like receptor-3, mitogen-activated protein kinase kinase/extracellular signal-regulated kinase and p38 signaling.

Background/purpose: Bacterial infection was the major etiology for pulpal/root canal infection. This study aimed to investigate the activation of toll-like receptor-3 (TLR) on cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) and PGF2α production of human dental pulp cells (HDPCs) and associated signaling. Materials and methods: HDPCs were exposed to different concentrations of Poly (I:C) (a TLR3 activator). Cell viability was determined by 3- (4,5-Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay and alkaline phosphatase (ALP) activity was evaluated by ALP staining. Activation of extracellular signal-regulated kinase (ERK) and p38 by Poly (I:C) was determined by immunofluorescent staining. The COX-2 protein expression was analyzed by Western blot. PGE2 and PGF2α production was measured by enzyme-linked immunosorbent assay. The mRNA expression was studied by real-time polymerase-chain reaction. Moreover, HDPCs were exposed to Poly(I:C) with/without U0126 or SB203580 treatment and analysis of COX-2 expression and prostanoid production were conducted. Results: Poly (I:C) showed little effect on ALP activity, but decreased viability of HDPCs. It stimulated COX-2 mRNA and protein expression. Poly (I:C) induced PGE2 and PGF2α production of HDPCs. Poly (I:C) activated p-ERK, and p-p38 protein expression. Treatment by U0126 (a mitogen-activated protein kinase kinase (MEK)/ERK inhibitor) and SB203580 (a p38 inhibitor) attenuated Poly (I:C)-induced COX-2 mRNA and protein expression as well as PGE2 and PGF2α production. Conclusion: TLR3 activation is involved in the infection and inflammatory responses of pulp tissues, via MEK/ERK, and p38 signaling to mediate COX-2 expression as well as PGE2 and PGF2α production, contributing to the pathogenesis and progression of pulpal/periapical diseases.

Comparison of the plaque-removal efficacy of ultra-soft single-headed, triple-headed, and T-shaped toothbrushes and the subjective perceptions of users.

PURPOSE: To compare the plaque-removal efficacy of ultra-soft single-headed, triple-headed, and T-shaped toothbrushes and the subjective perceptions of users. METHODS: In this randomized, single-blind, crossover study, 30 healthy adult participants were randomly divided into three groups of 10, who tested the three types of toothbrushes in differing order, with a 1-week washout period between the tests. Dental plaque scores were recorded before and after toothbrushing, and questionnaires on subjective perceptions after toothbrushing were collected. RESULTS: The participants included 16 female participants and 14 male participants (average age: 29.4 ± 6.7 years). All three toothbrush types were effective in reducing dental plaque by 36-46%; however, the cleaning effect of the ultra-soft single-headed toothbrush was inferior to that of the triple-headed and T-shaped toothbrushes, the difference being statistically significant. The users' subjective perceptions suggested that the ultra-soft single-headed toothbrush was significantly superior to the other two toothbrush types. Plaque scores for the lower posterior tooth surfaces were higher than those for the upper posterior tooth surfaces, particularly on the left side, for both the ultra-soft single-headed and T-shaped toothbrushes. CONCLUSION: Healthcare practitioners should identify the type of toothbrush bristles used by individuals and provide appropriate oral health information.

Effects of denture maintenance on satisfaction levels of Taiwanese elderly using removable partial dentures: a pilot study.

OBJECTIVE: The aim of this study was to evaluate the correlation between patient satisfaction with removable partial dentures and denture maintenance by patients, including regular application of denture adhesives and cleansers. BACKGROUND: The success of removable partial dentures depends on patient satisfaction with dentures and their regular denture maintenance. MATERIALS AND METHODS: Demographic information, the Oral Impacts on Daily Performance (OIDP) indicator and details of denture maintenance (including the use of denture cleansers and adhesives) were collected from 193 (41.5% men and 58.5% women) participants by using questionnaires. A dentist performed oral examinations to evaluate denture function according to the OIDP items photographically and recorded the number of remaining teeth and Kennedy's classification. RESULTS: Most participants were satisfied with their removable partial dentures and tended to have higher satisfaction levels than the dentist's estimation. Further, those using denture adhesives and cleansers had higher satisfaction levels than those not using such denture maintenance. CONCLUSIONS: Appropriate education regarding denture use is important because regular denture maintenance by patients affects their degree of satisfaction with dentures, as well as the dentist's skill and the patient's oral condition. Dentists could use this information to predict the potential success of dentures.

Application of the Oral Health Impact Profile (OHIP) among Taiwanese elderly.

PURPOSE: To validate the Chinese (Taiwan) version of the Oral Health Impact Profile (OHIP-49T) and develop a short form of the OHIP (OHIP-14T) for the elderly. METHODS: A total of 1402 subjects, aged 65 and above, received a personal interview and oral examination. Internal consistency, measured by Cronbach's alpha, and test-retest reliability were assessed by intra-class correlation coefficient (ICC) during a 2-week interval. The criterion-related validity of OHIP-49T was evaluated through associations between the OHIP-49 score with prosthetic need and prosthetic status. A subset (OHIP-14T) questionnaire, derived through a controlled regression procedure, was compared with the original OHIP-14 by Slade (OHIP-14S). RESULTS: The Cronbach's alpha and ICC values were 0.97 and 0.98 for OHIP-49T and 0.90 and 0.93 for OHIP-14T. Mean scores of the OHIP-49T were significantly associated with prosthetic status (P = 0.0013) and prosthetic need (P = 0.0004), which were examined by dentists. The OHIP-14T score had stronger discriminatory ability than OHIP-14S. CONCLUSIONS: The OHIP-49T showed satisfactory reliability and validity for this Taiwanese elderly population. The OHIP-14T is more effective to measure OHRQoL than OHIP-14S.

Changes in the transverse dimensions by vertical ramus osteotomy after mandibular prognathism correction.

OBJECTIVE: A harmonious face displays not only a good lateral profile but also a pleasant frontal appearance. The purpose of the current study was to evaluate the changes in the transverse dimensions by vertical ramus osteotomy (VRO) in the treatment of mandibular prognathism correction. METHODS: Twenty patients who underwent mandibular prognathism correction by VRO were included. Lateral and frontal cephalometric radiographs were obtained at the following stages: preoperative (T1), immediately after the surgery (T2), and completion of orthodontic treatment (T3). Three linear measurements (menton, intercondylion, and intergonial distances) and the ramus angle were compared from T1 to T3. RESULTS: A final mean menton setback of 12.2 mm and upward movement of 0.3 mm were noted. The intercondylion and intergonial distances significantly increased by 5.1 and 7.1 mm, respectively. Without significant difference, ramus angles decreased 1.7 degrees in the right side and 0.1 degrees in the left side. CONCLUSION: The surgical correction of mandibular prognathism using VRO led to an increase in the transverse dimensions.

Correlation between the change of gonial region and skeletal relapse after intraoral vertical ramus osteotomy for correction of mandibular prognathism.

BACKGROUND: The gonial region is coincided with harmonious face and masticatory function. The aims of the present study were to assess changes in the gonial region in patients who had mandibular setback surgery by intraoral vertical ramus osteotomy (IVRO) and to investigate the contributing factors in relation to skeletal relapse. METHODS: Twenty-one patients with mandibular prognathism were corrected by IVRO. Three cephalometric radiographs were collected from preoperative orthodontic treatment (T1), immediately after surgery (T2), and at 2-year postoperative follow-up (T3). Relapse was defined as forward movement of menton (Me) after the 2-year follow-up. Three angular (SN-Go angle, mandibular plane angle, and gonial angle) and 2 linear (horizontal-Me and vertical-Me) measurements were compared after immediate operation and at the 2-year follow-up. Spearman rank correlation and Student t tests were used for statistical analysis. RESULTS: The mean setback of the Me was 12.7 mm, and the mean relapse was 1.5 mm. The magnitude of setback was not significant for relapse. There were weak correlations between relapse and factors concerned with the gonial region (SN-Go angle, mandibular plane angle, and gonial angle). CONCLUSIONS: Surgical correction of mandibular prognathism using IVRO can lead to an increase in the angle changes of gonial region but not correlate to skeletal relapse in long-term follow-up.

Mechanical strength of orthodontic infrazygomatic mini-implants.

Orthodontic anchorages have recently been reinforced by newly developed mini-implants. The aim of the present study was to investigate the mechanical strengths of infrazygomatic mini-implants. We measured the insertion torque and pull-out strength of three brands of infrazygomatic mini-implants (AbsoAnchors, Bioray, and Lomas). All three mini-implants were 2 mm in diameter, and five of each brand were manually driven 6 mm into artificial bone. Significant differences among the brands were investigated with Kruskal-Wallis tests. We found no significant relationship between insertion torque and pull-out strength in any individual brand. Among the three brands of infrazygomatic mini-implants, we found no significant difference in mechanical strength. The design of an infrazygomatic mini-implant may be the most important factor determining its mechanical strength.

FEM analysis of the mandibular first premolar with different post diameters.

Several reports have pointed out that endodontically treated teeth can lack strength, and that the teeth can be reinforced using posts. However, it has not been clear how to select posts that meet the needs of most clinical situations, particularly in terms of the post diameter, which has a major influence on the occurrence of root fracture. The purpose of this study was to analyze the stress distributions of posts of various diameters during masticatory loads using a finite element method. A 3-dimensional (3D) finite element model of a lower first premolar was developed. We used the image software Geomagic Studio (3D Digital 2002; Geomagic, Research Triangle Park, NC, USA) to reduce the post diameter by 6 ratios to a root diameter of 20, 30, 40, 50, 60, and 80% and then individually implemented them into the root of a tooth. A chewing static force of 100 N was applied as a 45° diagonal load on the buccal cusp tip, and the σ(von Mises) and σ(max) stresses were calculated. Analysis of the σ(von Mises) values revealed that the stresses were concentrated in the middle 1/3 of both the post and the root surface for all models, as were the σ(max) values. The results also indicated that when the diameter of the post was 50% of that of the root, the stress distributions of the post and the root surface were most favorable. In conclusion, the clinical implications of the results will need to be further studied and discussed.

Horizontal pull-out strength of orthodontic infrazygomatic mini-implant: an in vitro study.

PURPOSE: New modified mini-implants have recently come into use for reinforcing skeletal anchorage in orthodontic application. The aim of this study was to investigate the influence of the design of a mini-implant on its mechanical strength. MATERIALS AND METHODS: We measured the insertion torques and horizontal pull-out strengths of 3 brands of infrazygomatic mini-implants (AbsoAnchor, Bioray, and Lomas; 2 mm for all). Five implants of each brand were manually driven 6 mm into the artificial bone. Significant differences in various parameters among the brands were investigated with the Kruskal-Wallis test. RESULTS: There was no significant relationship between insertion torque and horizontal pull-out strength. The Bioray mini-implants had significantly greater horizontal pull-out strength than the AbsoAnchor mini-implants. CONCLUSIONS: The design of the mini-implant can influence its insertion torque and horizontal pull-out strength. In our findings, the horizontal pull-out strength of all mini-implants placed in the infrazygomatic crest was significantly greater than the orthodontic force applied.

The stability of intraoral vertical ramus osteotomy and factors related to skeletal relapse.

BACKGROUND: Intraoral vertical ramus osteotomy (IVRO) and sagittal split ramus osteotomy (SSRO) have been advocated as two major procedures for the correction of mandibular prognathism. However, only a few reports with at least a 2-year follow-up period describe the long-term stability especially of the IVRO method. This study aimed to identify factors contributing to skeletal relapse after a 2-year postoperative follow-up period. METHODS: A set of three standardized lateral cephalograms were obtained from each subject, taken preoperatively (T1), immediately postoperatively (T2), and 2 years postoperatively (T3). Relapse was defined as forward movement of the menton (Me) after a 2-year follow-up period. Two angular measurements (SNB and SN-occlusal plane angle) and five linear measurements (horizontal Me, vertical Me, overbite, anterior facial height, and mandibular length) were compared immediately after the operation and at the 2-year follow-up visit. RESULTS: The mean setback of the menton was 12.8 mm, and the mean relapse was 1.3 mm (10.2% = 1.3/12.8). The magnitude of the setback was not significantly accounted for in the relapse. There were weak correlations between the relapse and the concerned factors, namely, overbite, anterior facial height, mandibular length SNB, and SN-occlusal plane angle). CONCLUSION: The current study confirmed the stability of IVRO in the treatment of mandibular prognathism.