Effects of extraction and nonextraction treatment on class I and class II subjects

This study aims to examine the profile as well as the dentoalveolar and skeletal effects of extraction or nonextraction treatment in a wide range of patients including Class I and Class II, division 1 cases. Results achieved with extraction and nonextraction modalities have also been compared. The study was performed on pretreatment and posttreatment lateral cephalograms of 87 orthodontic patients. There were no significant differences between the pretreatment values of extraction and nonextraction Class I groups, whereas SN-GoGn (degrees), maxillary incisor to A-Po (degrees), mandibular incisor to A-Po (mm), Co-Gn (mm), overjet (mm), and overbite (mm) measurements of extraction Class II group were significantly higher before the treatment. After treatment, these differences were eliminated in the Class II group; however, incisors were significantly protruded in both nonextraction groups. No other differences in profile or lip position were found between the extraction and nonextraction groups. The results of this study indicate that in successfully treated cases, whether by extraction or nonextraction, the same soft and hard tissue profile posttreatment end points were reached except for the incisor positioning, which is rather easier to anticipate than profile and soft tissue changes. The simple statement that extraction means a more retrusive or dished-in profile seems to be unacceptable. It seems that a more thorough assessment and investigation including pretreatment extent of crowding and factors related to anchorage, soft tissue thickness, and strain should be carried out.

Use of a tip-edge stage-1 wire to enhance vertical control during straight wire treatment: two case reports

Vertical control is one of the problems occasionally encountered in Straight wire treatment. Two cases, one with deep overbite and one with anterior open-bite, demonstrate the use of a Tip-Edge stage-1 wire to enhance vertical control in conjunction with Straight wire brackets and superelastic main arch wires.

Fracture-toughening mechanisms responsible for differences in work to fracture of hydrated and dehydrated dentine

This study investigates the nature of deformation and differences in the mechanisms of fracture and properties of dentine where there has been a loss of moisture, as may occur with removal of the pulp in the endodontic treatment of teeth. Controlled fracture toughness testing was conducted on bovine teeth to determine the influence of hydration on the work of fracture of dentine. Significant differences (p<0.01) were observed between the fracture toughness of hydrated (554+/-27.7J/m2) and dehydrated (113+/-17.8J/m2) dentine. Observations of the crack tip region during crack extension revealed extensive ligament formation occurred behind the crack tip. These ligaments provide considerable stability to the crack by significantly increasing the work of fracture, thereby acting as a fracture-toughening mechanism. Micro-cracking, reported as a fracture-toughening mechanism in bone, is also clearly seen. A zone of in-elastic deformation may occur as hydrated specimens revealed upon crack extension, a region about the tip that appeared to suck water into the structure and to exude water behind the crack tip. In dehydrated dentine, no in-elastic zone was observed. Micro-cracking is present though the cracks are smaller, straighter and with less opening than hydrated dentine. Only limited ligament formation just behind the crack tip was observed. These differences resulted in a significantly lower work of fracture with unstable brittle fracture characteristics. Based on these results, several fracture-toughening mechanisms were identified in dentine, with micro-cracking not considered the most important. These findings may be relevant for bone, a similar mineralised hydrated tissue.

Long-term follow-up of early treatment with reverse headgear

The purpose of this study was to investigate the long-term outcome of treatment with reverse headgear in young individuals with a reverse overjet and a skeletal Class III malocclusion due to maxillary deficiency. Lateral cephalograms were obtained from 21 subjects (8.4 +/- 1.5 years; 17 girls and four boys) of an original sample of 30 consecutively treated young patients who were followed for 8 years after active treatment. There was a drop-out of nine subjects; their dentofacial morphology at start of treatment did not differ from those who remained in the study. The remaining subjects were divided into a stable group and a relapse group. The results revealed that two out of three patients maintained a positive overjet 8 years after active treatment. The immediate treatment outcome in the sagittal plane was the same for the stable and relapse groups, but lower face height increased (P < 0.08) and the mandibular plane angle opened (P < 0.05) more in the relapse group. During the 8-year follow-up period, the dental compensation was similar in both groups, but the mandible outgrew the maxilla by four times in the relapse group, compared with twice that in the stable group. In young individuals diagnosed with maxillary deficiency treated with reverse headgear and who have an immediate positive treatment response, there is a potential risk that about one-third might be candidates for orthognathic surgery later in life, because of an unfavourable growth pattern.

The effects of activator treatment on the craniofacial structures of Class II division 1 patients

The aim of the present study was to clarify the skeletal treatment effects induced by activator treatment. Fifty actively growing patients with Class II division 1 malocclusions were treated with an activator appliance. A control group consisting of longitudinal growth data from 20 patients (untreated Class II division 1 malocclusions) was used to eliminate possible differences in growth pattern. Lateral cephalograms of each patient were taken at the start and end of treatment. Final cephalograms were taken after a mean of 16.4 (+/- 2.0) months activator treatment, compared with a mean of 14.2 (+/- 2.4) months for the control group. Each cephalogram was traced and digitized by the same individual. The mean and standard deviations for linear and angular cephalometric measurements were analysed statistically, and intra- and inter-group changes were evaluated by paired- and independent-sample t-tests. At the end of the study period, the overjet was decreased in all patients. Ramus height, corpus length, anterior and posterior face height all increased significantly (P < 0.05). In the treatment group, ANB angle decreased and the bite was opened. The activator appliance caused maxillary incisor lingual tipping and mandibular incisor labial tipping. The overjet was decreased as a result of the increased forward growth of the mandible and dentoalveolar changes. The results demonstrated that the activator appliance has a characteristic skeletal and dental effect on the developing craniofacial complex.

Dentofacial morphology of mouth breathing children

The relationship between dentofacial morphology and respiration has been debated and investigated from various approaches. The aim of this study was to verify the skeletal and dental relationship of mouth and nose breathing children. Thirty-five children, 7 to 10 years of age, were submitted to orthodontic and otorhinolaryngologic evaluations and were separated into 2 groups: 15 nose breathers and 20 mouth breathers. Each subject underwent a cephalometric radiograph analysis. Statistical analysis (Mann-Whitney U test) indicated that changed mode of breathing was associated with 1) maxillo-mandibular retrusion in relation to the cranial base in the mouth breathers; 2) the SNGoGn and NSGn angles were greater in the mouth breathing group; 3) incisor inclination in both jaws and the interincisal angle were not different between groups. There was no statistically significant difference in the maxillary and mandibular molar heights between the nose breathers and mouth breathers.

Simplified primary incisor proximal restoration

Primary anterior teeth with proximal caries lesions can be restored with resin-based composite using a simplified bonding technique. This report describes Class III restoration of primary incisors in a preschooler, using a self-etching adhesive system and a modified-bonding procedure.

Fluorosis development in seven age cohorts after an 11-month break in water fluoridation

This study used an 11-month break in water fluoridation to identify the time when developing incisors are most sensitive to fluorosis development. The study was based in Durham, NC, where an interruption to water fluoridation occurred between September, 1990, and August, 1991. A total of 1896 children was dentally examined. Fluorosis was measured by the TF index, and parents or guardians completed a questionnaire on demographics and fluoride history. Age cohorts ranged from those born 5 years before the break, to those born 1 year after the resumption of fluoridation. Fluorosis prevalence for seven age cohorts whose birth years ranged from 1985-86 to 1991-92 was 57.1, 62.3, 33.0, 32.3, 39.8, 30.2, and 36.8%, respectively. Children aged from birth to 3 years at the break, and those born 1 year after it, had less fluorosis than those aged 4-5 years at the break.

Etiology of traumatic dental injuries in 11 to 13-year-old schoolchildren

PURPOSE

To assess place, activities and human intention related to Traumatic Dental Injuries (TDI) events in 11 to 13-year-old schoolchildren in Biguaçu, Brazil. Also, to test the association between socio-economic status and TDI.

MATERIALS AND METHODS

A cross-sectional survey (n = 2,260) was carried out. A trained and calibrated dentist collected the data through clinical examinations and interviews. Clinical examination included the type of TDI, the treatment required and provided, the size of incisal overjet and the type of lip coverage.

RESULTS

The response rate was 90.6%. The prevalence of TDI was 10.7%. Boys experienced more TDI than girls, 13.6% and 7.6% respectively (P < 0.001). Fathers' and mothers' levels of education were not statistically associated with TDI (P > 0.05). Children who had an incisal overjet greater than 5 mm had more dental injuries than those whose incisal overjet was less than 5 mm (P = 0.003). There was no association between inadequate lip coverage and TDI (P > 0.05). Multiple logistic regression analysis showed that maleness and incisal overjet remained statistically associated with dental injuries, after adjusting for other risk factors. The main activities associated with TDI were physical leisure activities (28.9%), playing with other people (18.2%), collisions (9.1%), and falls (8.3%). Common places where the TDI event occurred were at home (42.6%), in the street (21.5%) and at school (9.5%). 29.2% of TDI were the result of the actions of another person.

CONCLUSION

The most common TDI events were physical leisure activities, most TDI occurred at home, and the actions of another person were an important factor in relation to the occurrence of TDI.

Immobilization of root-compromised maxillary anterior teeth: a case report with 14-year clinical follow-up

The efficacy of a modified cast-metal resin-bonded splint was evaluated after 14 years in service. The splint was used to immobilize the root-compromised maxillary central and lateral incisors of a teenage male following relapsed orthodontic treatment. The affected teeth were indirectly traumatized, before their eruption, in a bicycle accident that resulted in avulsion of their primary predecessors. The rationale for selecting this treatment modality rather than the alternatives is discussed. The clinical protocol employed during the treatment and subsequent follow-up is described.

A histochemical study of the regeneration process after injury by pulsed Nd:YAG laser irradiation of root canals

Histological changes of rat dental pulp cells were followed after injury. The regeneration process after 3, 6 and 10 days was monitored. Mandibular incisors were irradiated with a pulsed Nd:YAG laser at 2 W and 20 pulses per sec (pps) for 5 sec and the pulp was examined histologically and immunohistochemically for TGF-beta1. Eruption of the developing tooth was disturbed for a short period only. Rapid formation of osteodentin was observed. After 3 days, a zone of fibrodentin matrix as well as newly formed vessels were found. Afterwards, regenerative dentin formation was observed accompanied by the formation of a layer of odontoblast-like cells in the damaged area. Immunohistochemical staining of TGF-beta1 showed that positivity was present in small tissue areas beneath the mantle dentin, the zone of fibrodentin matrix and odontoblast-like cells. These results indicate that pulsed Nd:YAG laser irradiation of rat incisor pulp induces formation of osteodentin, and TGF-beta1 plays a role during regeneration.

The reproducibility of cephalometric measurements: a comparison of analogue and digital methods

The aim of this study was to compare the reproducibility of longitudinal cephalometric measurements between analogue and digital methods using two different resolutions. Cephalometric radiographs of 20 patients were selected at the start (T1) and end (T2) of treatment: 24 cephalometric variables were calculated at T1 and T2, and their increments (T2 - T1) were also evaluated. All measurements were performed twice by two observers. Quality of methods [analogue, digital: 300 and 600 dots per inch (DPI) resolution] was evaluated by comparing the reliability coefficients and the total error between the digital and analogue methods. The inter-observer agreement was good. The 300 DPI was comparable to the analogue method. The reproducibility for the variables was comparable, but mandibular incisor increments tended to show better results with the 300 DPI method, whereas skeletal jaw relationship increments were not reliable with either method. Maxillary incisor increments, however, were reliable with both methods. The 300 and 600 DPI resolutions were found to be comparable. Scanning of cephalometric radiographs at a resolution of 300 DPI is sufficient for clinical purposes and comparable to analogue cephalometrics. However, all methods were found to be poor in assessing skeletal jaw relationships longitudinally.

Moulding of the generate to control open bite during mandibular distraction osteogenesis

Distraction osteogenesis of the craniofacial skeleton has become a widely accepted, safe, and effective means of craniofacial reconstructive surgery. Despite excellent results in general, there are still some uncertainties related to the procedure, such as development of an anterior open bite (AOB) during mandibular distraction. The aim of this study was to examine whether 'moulding of the generate', i.e. use of intermaxillary elastics during the active distraction phase is possible to close the mandibular plane angle and open bite. Three subjects, 13- and 15-year-old males and a 7-year-old female, underwent mandibular linear and angular bilateral distraction osteogenesis with moulding of the generate. Lateral cephalograms were obtained before the introduction of elastics and following distraction, once the activation was stopped and the patients were ready for the consolidation phase. Conventional cephalometric measurements were used to assess possible changes in the mandibular plane angle and incisor position. Three different anchorage systems (dental, orthopaedic, and skeletal) were used for placement of the intermaxillary elastics. Cephalometric examination showed that the mandibular plane angle was decreased during active distraction osteogenesis with the introduction of elastics and angulation of the distraction device. Depending on the type of elastic anchorage system, smaller or greater amounts of extrusion of the incisors were noted. Moulding of the generate during active distraction can be performed to reduce the mandibular plane angle and open bite. To prevent unwanted dentoalveolar changes from occurring during elastic traction, skeletal rather than dental fixation of the elastics is recommended. Intrusive mechanics may be incorporated into the orthodontic appliances to balance extrusive force by the moulding elastics.

Dental erosion in asthma: a case-control study from south east Queensland

BACKGROUND

Asthma medication places patients at risk of dental erosion by reducing salivary protection against extrinsic or intrinsic acids. But patterns of lesions in asthmatics may differ from patterns in non-asthmatics, because gastro-oesophageal reflux (GOR) is found in 60 per cent of asthmatics.

METHODS

The lesions in 44 asthma cases were compared to those of age and sex match controls with no history of asthma or medications drawn from the dental records of 423 patients referred concerning excessive tooth wear. The subjects were 70 males age range 15 to 55 years and 18 females age range 18 to 45. Anamnestic clinical data were compared between the two groups. Models of all 88 subjects were examined by light microscopy, and wear patterns were recorded on permanent central incisor, canine, premolar and first molar teeth.

RESULTS

Clinical differences were a higher incidence of tooth hypersensitivity, xerostomia, salivary gland abnormalities, gastric complaints, and self induced vomiting in the cases. No differences were found between the cases and controls on citrus fruit and acid soft drink consumption. More occlusal erosion sites were found in cases, whereas more attrition sites were found in the controls. There were no significant differences in palatal erosion on maxillary anterior teeth found between cases and controls. Lingual erosion of the mandibular incisors, found only in GOR patients, was not observed.

CONCLUSIONS

A higher incidence of erosion was found in asthmatics. Gastro-oesophageal reflux symptoms were not associated with the sign of lingual mandibular incisor erosion. The clinical significance is that asthmatics are at risk of dental erosion from extrinsic acid, but GOR does not appear to contribute in a site-specific manner.

Submentovertex cephalometric analysis of Class II subdivision malocclusions

Submentovertex cephalometric analysis was used to assess the mandibular symmetry of 20 patients with Class II subdivision malocclusion and 20 controls with Class I occlusions. Using the intercondylar line and the intercondylar axis, the relative differences were measured between mandibular landmarks in both anteroposterior and transverse dimensions. Anteroposterior and transverse differences between left and right mandibular positions and the transverse position of the dental midline showed a statistically significant difference between the groups. The position of the coronoid process also differed between the two groups. We conclude that the entire mandibular dentition is rotated in Class II subdivision malocclusions.

Submandibular gland aplasia and progressive dental caries: a case report

When severe caries occurs in mandibular permanent incisor teeth, the clinician should consider the possibility of associated submandibular gland aplasia or salivary hypofunction. Early diagnosis of submandibular gland disease is essential, as operative problems involving restoration of mandibular incisor teeth are considerable. Furthermore, progressive severe dental caries can present a dilemma for the clinician in affected individuals, despite intensive preventive and restorative therapy. A case report describing severe progressive dental caries and enamel demineralization of the permanent mandibular incisor teeth in a young girl is presented. Further investigation revealed absence of functional bilateral submandibular salivary glands contributing to the rapid breakdown of the teeth despite intensive preventive measures.

Tooth wear patterns in the deciduous dentition

Tooth wear is common in the deciduous dentition. A recent study suggests that tooth wear in the deciduous dentition is related to subsequent tooth wear in adults, so that early identification of factors related to tooth wear could be of long-term benefit. The purposes of this study were to describe patterns of tooth wear in the deciduous dentition and to relate tooth wear to occlusal characteristics and longitudinal dietary patterns. Data were collected as part of a longitudinal study of a cohort of children recruited at birth from Iowa hospitals. Stone casts were obtained in the deciduous dentition stage, and 355 children, 4 to 5 years old, met the selection criteria. Tooth wear was categorized for each tooth as none, mild, moderate, or severe, and related to occlusal characteristics and longitudinal data on fruit juice and soft drink consumption. All children exhibited some tooth wear on at least 1 tooth, and nearly 16% of them had at least 1 tooth with severe wear. Tooth wear was generally more severe in the maxillary arch and the anterior teeth. Severe tooth wear on the molars was significantly related to posterior crossbites, but severe tooth wear on the incisors was related to Class III canine relationships. There were no statistically significant relationships between tooth wear and soft drink or fruit juice consumption. Based on our results, we concluded that mild tooth wear is universal in the deciduous dentition, but only a few occlusal factors are related to severe tooth wear. Tooth wear was not related to any dietary patterns we investigated.

Oral care for patients with bulimia

Various conditions cause rapid and debilitating erosion of teeth. One of the most common is bulimia, or the binge-purge syndrome. Dentists frequently encounter patients who have this problem. The dentist should confirm the possibility of bulimia, refer the patient to a competent eating-disorder clinic, counsel the patient about her or his condition and restore the patient's mouth to a state of health and esthetic acceptability. Dental treatment of such patients will vary depending on the severity of the erosion.

Two-dimensional changes in soft tissue profile following surgical mandibular advancement in Japanese retrognathic adults

The purpose of this study was to evaluate changes in the hard and soft tissues and to test a preliminary method for predicting the soft tissue profile changes in 14 Japanese retrognathic patients who underwent surgical mandibular advancement. A pair of pre- and postoperative lateral cephalograms was taken for each subject. A paired t test identified significant hard and soft tissue changes following surgery. A Pearson correlation analysis was used to identify soft tissue changes for hard tissue changes in the horizontal and vertical dimensions. Multiple regression models were generated to predict postoperative variables based on preoperative variables. Significant changes in the hard and soft tissues were found in the area inferior to the point Stomion in both the horizontal and vertical dimensions. The soft tissue changes demonstrated a significant correlation not only with the corresponding hard tissue, but also with noncorresponding anatomical points. Moreover, the tendency of changes in the soft tissue was different in the lower lip area from the chin area in both the horizontal and vertical dimensions. Significant R2 and higher contribution ratio were obtained from the multiple regression analysis for the chin area compared to the lower lip area.

Stability of skeletal Class III malocclusion after combined maxillary and mandibular procedures

The aim of this study was to evaluate the skeletal stability and time course of postoperative changes after surgical correction of skeletal Class III malocclusion. Combined maxillary and mandibular procedures were performed in 40 consecutive patients. Bilateral sagittal split osteotomy stabilized with wire osteosynthesis for mandibular setback and low-level Le Fort I osteotomy stabilized with plates and screws for maxillary advancement were performed. Maxillomandibular fixation (MMF) was in place for 6 weeks. Lateral cephalograms were taken before surgery, immediately postoperatively, 8 weeks after surgery, and 1 year postoperatively. Patients were divided into 2 groups according to vertical maxillary movement at surgery: a maxilla-up group with upward movement of the posterior nasal spine of 2 mm or more (group 1, n = 22), and a minimal vertical change group with less than 2 mm of vertical repositioning (group 2, n = 18). The results indicate that surgical correction of Class III malocclusion with combined maxillary and mandibular osteotomies appears to be fairly stable. One year postsurgery, maxillary stability was excellent, with a mean horizontal relapse at point A that represented 10.7% of maxillary advancement in group 1 and 13.4% in group 2. In the vertical plane, maxillary stability was also excellent, with a mean of 0.18 mm of superior repositioning at point A for group 1 and 1.19 mm for group 2. The mandible relapsed a mean of 2.97 mm horizontally at pogonion in group 1 (62% of mandibular setback) and 3.41 mm (49.7% of setback) in group 2. Bilateral sagittal split osteotomy with wire osteosynthesis and MMF was not as stable as maxillary advancement and accounted for most of the total horizontal relapse (almost 85%) observed. A trend to relapse was observed for maxillary advancement greater than 6 mm, while the single variable accounting for mandibular relapse in group 1 was the amount of surgical setback. Clockwise rotation of the ascending ramus at surgery was not correlated with mandibular relapse in relation to the type of fixation performed and therefore does not seem to be responsible for relapse.

Cephalometric characteristics of bimaxillary dentoalveolar protrusion in early mixed dentition

The children with bimaxillary dentoalveolar protrusion in early mixed dentition were compared with the normal occlusion children. The bimaxillary dentoalveolar protrusion children had significant smaller inter-incisal angle and greater convexity, A-B plane, and ANB angles than the normal children. Maxillary and mandibular growths of the bimaxillary dentoalveolar protrusion girls were greater than those of normal girls. The direction of the mandibular growth of the bimaxillary dentoalveolar protrusion boys showed a tendency of downward and backward.

Stability of maxillary advancement using rigid fixation and porous-block hydroxyapatite grafting: cleft palate versus non-cleft patients

This study was undertaken to evaluate the stability of maxillary advancement using bone plates for skeletal stabilization and porous block hydroxyapatite (PBHA) as a bone graft substitute for interpositional grafting in cleft and non-cleft patients. The records of 74 patients (41 females, 33 males) who underwent Le Fort I maxillary advancement using rigid fixation and PBHA interpositional grafting were evaluated retrospectively. All patients also underwent simultaneous sagittal split mandibular ramus osteotomies. Patients were divided into 2 groups for study purposes: group 1 consisted of 17 cleft palate patients and group 2 consisted of 57 non-cleft patients. Each group was further subdivided into 2 subgroups based on the concurrent vertical positioning of the maxillary incisors: groups 1a and 2a, where the maxilla underwent 3 mm or more of inferior repositioning, and groups 1b and 2b, where the maxilla underwent minimal vertical change (< or = 1 mm). Presurgery, immediate postsurgery, and longest follow-up lateral cephalometric tracings were superimposed and analyzed to calculate surgical change and long-term stability of results by assessing horizontal and vertical changes at point A, incisor superius, and the mesial cusp tip of maxillary first molar. The average follow-up time in group 1 was 37.9 months (range 12 to 136) and in group 2 was 28.77 months (range 17 to 88). Average maxillary advancement at point A was: group 1a, 5.4 mm; group 1b, 5.25 mm; group 2a, 5.48 mm; group 2b, 5.46 mm. Average relapse at point A was: group 1a, -0.75 mm; group 1b, -1 mm; group 2a, -0.47 mm; group 2b, -0.48 mm. Average horizontal and/or vertical relapse at the central incisors and first molars was 1 mm or less in group 1 and less than 0.5 mm in group 2. Although there was a slightly greater relapse in group 1, no statistically significant difference was observed between the groups. Maxillary advancement with Le Fort 1 osteotomies using rigid fixation and interpositional PBHA grafting during bimaxillary surgery is a stable procedure with good predictability in cleft and non-cleft patients, regardless of the direction of vertical maxillary movement.

Initial and late treatment effects of headgear-Herbst appliance with mandibular step-by-step advancement

The aim of this study was to investigate the effects of the headgear-Herbst appliance with mandibular step-by-step advancement followed by retention with the headgear activator. The sample comprised 22 consecutively treated patients (13.2 +/- 1.5 years old) and 31 matched controls (12.6 +/- 1.3 years old). Lateral cephalograms were obtained at the beginning of treatment, after 6 months (at completion of the initial phase), after 12 months of active treatment (at the end of the late phase), and after 18 months (at the end of retention). The results showed that the skeletal effects over 12 months of treatment were restrained maxillary growth, enhanced mandibular growth, and reduced increase in lower facial height. The restraint effect on the maxilla was significant in both the initial and late phases; the enhanced growth of the mandible was significant during the initial phase only; and the height of the lower face was affected during the late phase only. During retention with the headgear activator, the jaw base relationship was maintained, and the effect on the lower facial height was reinforced. A small relapse of the overjet and molar relationship was the result of dental changes only. During 18 months of active treatment and retention, the overjet correction was the result of 70% skeletal changes. The headgear-Herbst appliance is an effective orthopedic device, and the effect on the maxilla seems to increase with the length of treatment, but the pattern was reversed for the mandible.