Dentin caries progression and the role of metalloproteinases: an update.

AIM: This review aims to summarise our understanding of the destructive role of acid environment and metalloproteinases in dentin caries progression using a review process. METHOD: The acids resulting from consumption of sugars by acidogenic and aciduric bacteria can cause demineralisation of the tooth surface, but are not able to cause caries-like lesions. The appearance of such lesions requires the activation of enzymatic proteolysis in an acidic environment for degradation of the dentin organic matrix, leading to cavity formation. Bacterial collagenases have long been considered responsible for organic matrix destruction; host cell-derived matrix metalloproteinases (MMPs) have recently been considered to be involved in the dentinal matrix destruction of carious lesions. DISCUSSION AND CONCLUSION: MMPs are initially synthesised as inactive zymogens to be activated in acid environment of dentinal fluid during the carious process, resulting in destruction of the collagenous matrix. The role of acid environment on enamel and dentin demineralisation and the role of salivary and dentinal MMPs in dentin progression of caries has encouraged general dentists to include the monitoring of oral environment not only by control of bacterial oral flora in caries treatment protocol, but mainly by inhibition of dentinal and salivary MMPs through the use of toothpaste and/or mouthwash containing specific active agents.

Upper and lower arch changes after Mixed Palatal Expansion protocol.

AIM: The aim of this study was to evaluate upper and lower dental changes after Mixed Palatal Expansion (MPE) treatment in growing patients with posterior single or bilateral crossbite and mild-to-moderate crowding, as compared to untreated growing subjects by dental cast analysis. MATERIALS AND METHODS: A group of 24 patients (18 girls, 6 boys) was treated with Hyrax-type device and compared with an untreated matched control group at T0 (8.6 yrs. ± 2) and at T1 (10 yrs. ± 2) using dental casts. The dental cast analysis was performed on four dental bilateral landmarks, on upper and lower casts; also upper and lower arch depths were measured. The groups were compared using independent sample t-test to estimate dental changes in upper and lower arches. RESULTS: The MPE group showed significant upper and lower arch changes when compared with the control group. Upper intermolar, interpremolar-2nd, interpremolar-1st (P<0.001) and intercanine widths (P<0.05) showed considerable changes in the treated group, while mandibular intermolar (P<0.001), interpremolar-1st (P<0.05) and intercanine widths (P<0.01) were slightly greater in the MPE group when compared with the control group. CONCLUSION: The changes in transverse upper and lower arch dimensions were significant, when compared with those seen in the control group.

Relationship between conductive hearing loss and maxillary constriction.

OBJECTIVE: To evaluate the relationship between conductive hearing loss and maxillary constriction. METHOD: A total of 120 people, aged from 7 to 40 years, who were referred to an audiologist when taking out health insurance or for school pre-registration check-up, were selected for this study. A total of 60 participants who had hearing threshold levels greater than 15 dB in both ears were chosen as the conductive hearing loss group. The remaining 60, with normal hearing thresholds of less than 15 dB, were used as the control group. All participants were referred to an orthodontic clinic. Participants who had a posterior crossbite and high palatal vault were considered to suffer from maxillary constriction. RESULTS: There were no significant differences between the sex ratios and mean ages of the groups. However, participants with conductive hearing loss were 3.5 times more likely than controls to suffer from maxillary constriction. CONCLUSION: Patients who suffer from conductive hearing loss are likely to show a maxillary abnormality when examined by an orthodontist.

Ankyloglossia and tongue mobility.

AIM: Ankyloglossia or tongue-tie is a congenital condition of newborns when the inferior lingual fraenulum is too short and is attached to the tip of the tongue limiting its movement. The aim of this study was to evaluate the relationship between ankyloglossia classification and tongue mobility. In addition, the prevalence of ankyloglossia among males and females was assessed. METHODS: 300 subjects (150 boys and 150 girls) with an age range of 7-12 years were randomly selected from different schools. The distance between the uppermost point of lingual fraenulum and its insertion into the oral floor was measured in the subjects. The subjects were categorised from having no ankyloglossia to severe tongue-tie based on the measurements. RESULTS AND CONCLUSION: This study showed that ankyloglossia was more common in males. It also showed that only subjects with a lingual fraenulum of <1.5 cm suffered from inadequate tongue movement.

Treatment effects of R-appliance and Fränkel-2 in Class II division 1 malocclusions.

AIM: The purpose of this study was to compare the effects of a differently designed functional appliance (the R- appliance) with Fränkel-2. STUDY DESIGN: Twenty-seven patients (16 girls and 11 boys) with a mean age of 9.8 (SD 1.6) years were treated with the R-appliance for 15.4 (SD 0.4) months and twentyseven (15 girls and 12 boys) patients with a mean age of 9.1 (SD 1.1) years were treated with a Fränkel-2 appliance for 19 (SD 5.6) months. All patients had Class II division 1 malocclusions due to mandibular deficiency and all of them had prepubertal stages of skeletal development. Lateral cephalograms obtained at the beginning (T1) and at the end (T2) of the study were analysed. RESULTS: Paired t-tests showed that SNB significantly increased in both groups. The incisor mandibular plane angle (IMPA) was reduced in the R- appliance group by 2.2 (SD 4.9) degrees (P<0.03) but increased by 2.2 (SD 2.6) degrees (P<0.001) in the Fränkel-2 group. The SNA in the R-appliance group showed an increase of 0.2 (SD 2) degrees (P<0.6), while it was decreased by 0.4 (SD 0.5) degrees (P<0.6) in the Fränkel-2 group. CONCLUSIONS: Both treatment modalities were successful in moving the mandible forward. However, with the R-appliance, this was achieved without proclination of the lower incisors.

Effects of maxillary advancement and impaction on nasal airway function.

The effects of Le Fort I osteotomy on the nasal airway are controversial. This study aimed to evaluate nasal airway changes after Le Fort I. 25 patients underwent conventional Le Fort I osteotomy and were separated into three groups depending on the type of surgery they underwent. 11 patients needed maxillary impaction, 9 underwent maxillary advancement, and 5 had both maxillary impaction and advancement. Rhinological examinations, anterior rhinomanometry and acoustic rhinometry were carried out 1 week before surgery and 3 months after that. Wilcoxon and χ(2) tests were used for data analysis. The samples included 19 females and 6 males with a mean age of 22.4 ± 3.32 years. Rhinomanometric assessment showed that total nasal airflow was increased from 406 ± 202 ml/s to 543 ± 268 ml/s in all three groups. Significant decrease in nasal airway resistance was seen in all three groups. Acoustic rhinometry revealed a significant decrease in total nasal volume but an increase in the cross-sectional areas of isthmus nasi (IN) and inferior concha. The rhinomanometric measurements showed improvements in the total nasal airflow after Le Fort I osteotomy with alar base cinch suture in cases where the impaction was not higher than 5.5mm.

A novel approach in treatment of maxillary deficiency by reverse chin cup.

The aim of this study was to evaluate the effectiveness of a newly designed small-sized extraoral appliance on Class III malocclusion and maxillary deficiency in growing patients. The case series included 10 patients (4 males, 6 females) with a mean age of 8.9 +/- 1.72 years who suffered from maxillary deficiency. All the patients were treated with an extra oral appliance which was named as reverse chin cup. This appliance consisted of a high pull cap, a chin cup with two vertical hooks, a removable appliance on the upper jaw, and two elastics which connected the hooks of the cup to the hooks of the removable appliance. The mean treatment time was 24 +/- 9 months. Mean SNA and ANB were significantly increased by 3.1 degrees +/- 1.6 degrees and 3.5 degrees +/- 1.7 degrees, respectively (p<0.001). The level of significance was set at P<0.05. The increase of SNA angle and ANS-PNS distance (p<0.001) and the decrease of nasolabial angle (P<0.004) indicated that the reverse chin cup was effective in moving the maxilla in a forward position. Moreover, the smaller size of this appliance makes it more favorable for patients.

The effect of tongue appliance on the maxilla in Class III malocclusion due to maxillary deficiency.

Various treatment approaches are applied for correction of CL III malocclusion due to maxillary deficiency. However, the benefits of a simple intraoral appliance that can move the maxilla in forward position have not been reported. 25 Cl III patients with SNA < 78 degrees, SNB < or = 80 degrees and ANB < or = 0 were selected for this study. All the patients received a tongue appliance, which originally was a habit breaker. Pre- and post-treatment cephalometric images were obtained and paired t-test revealed significant increase in SNA and significant decrease in IMPA. The tongue appliance can move the Maxilla in forward position. Therefore, this simple appliance can be an alternative method for protraction of Maxilla.

Incidence of cleft lip and palate in Tehran.

The purpose of this study was to assess the epidemiology and some of the possible risk factors causing oral cleft in Tehran. The study was a 7-year retrospective study from March 1998 to March 2005. Twenty-five live births with cleft lip and/or palate (CL+/-P) were born between 20 March 1998 and 20 March 2005 from the total of 11,651 live births in a maternity hospital in Tehran. After recognizing the child as a cleft patient, previous and following children born were recognized as a noncleft sample. Cleft and noncleft samples were compared for variables such as gender, mother's age, parity, consanguineous marriage and infant's weight, and then analyzed with Chi-square. The overall incidence was 2.14 per 1000 live births. CL+ P is more prevalent, which was 52% and the least incidence was for "only cleft lip'' patients, which was 12%. This study reveals that the incidence of oral clefts in Tehran is higher than many other countries. Consanguineous marriage and low birth weight in cleft group were significant statistically from those of noncleft group.

The effect of tongue appliance on the nasomaxillary complex in growing cleft lip and palate patients.

Midfacial deficiency is a common feature of cleft lip and palate patients due to scar tissue of the lip and palate closure procedure. The aim of this study was to evaluate the effectiveness of the physiological force of the tongue to move the maxilla in forward position. This research has been done experimentally by, before and after treatment following up in private practice. Ten patients (6 female, 4 male) with complete bilateral cleft lip and palate were selected. All of them had Cl III malocclusion with maxillary deficiency due to scar tissue of lip and palate surgery. Their age ranged from 7.6 to 9.8 years. All the patients were delivered tongue appliance to transfer the force of the tongue to maxillary complex. The mean observation time was 13+/-2 months to achieve positive overjet. Pre- and post-lateral cephalograms were compared to evaluate the skeletal changes with paired t-test. The results showed that after the application of tongue appliance, normal sagittal maxillomandibular relationship was achieved. SN-ANS angle was increased 1.9+/-1.8 - P < 0.03. This study showed that the tongue appliance could transfer considerable force during rest and swallowing period to the maxilla. This method might be considered to improve the deficient maxilla by means of growth modification and redirect concept.