Three-Dimensional Surface Texture Analysis of Fluoride's Effect on Enamel Erosion

Enamel erosion has become a common clinical finding that often impairs dental esthetics and function. In the current study, we aimed to implement the three-dimensional surface texture analysis (3DST) method to explore the protective effect of fluoride on surface texture prior to erosive conditions. For each of the 50 teeth used in this study, the polished buccal enamel surface was divided into three separate areas: the first area was untouched polished enamel, the two other surfaces were immersed in 0.3% citric acid for 30 s. One was treated with high-concentration (19,000 ppm) sodium fluoride (NaF) solution prior to acid attack, and the other had no treatment prior to acid exposure. Enamel surface texture and step height measurements were obtained using a high-resolution disk scanning confocal microscope, and SEM images were also acquired. Surfaces treated with fluoride showed fewer variations in 3-D surface texture parameters than the eroded surface compared to the control group (p = 0.001). This was in accordance with the SEM descriptive images. The findings indicate that pre-fluoridated enamel areas were less affected by the acid and showed similar features to the untouched enamel. Moreover, a protective effect of the fluoride treatment against irreversible enamel damage was noted as the surface loss (step-height) was significantly reduced (p = 0.03). The study showed that 3DST analysis is a valuable methodology for detecting and quantifying subtle differences between the surfaces. When exploring the combination of all surface texture parameters, it was revealed that the pre-fluoridated eroded enamel surfaces showed considerable similarity to the untouched enamel.

Are chin and symphysis morphology facial type-dependent? A computed tomography-based study

INTRODUCTION

The chin is a major determinant of the facial profile; hence, it plays a major role in orthodontics and orthognathic surgery. It is thus essential to follow and better understand its expression in different facial types. The major objectives of the current study were to characterize morphometrically the chin and symphysis and reveal their association with different facial types.

METHODS

Computed tomography scans of the head and neck of 311 adults (163 males, 148 females; age range, 18-95 years) were classified into 3 facial types: short, average, and long. Height, width, projection, inclination, thickness, and area were measured on the chin and symphysis.

RESULTS

The majority of the population (70%) manifested an average facial type; the other 30% were almost equally distributed between short and long facial types. The long facial type was more common among females and the short facial type among males. Chin projection, area, and size were significantly greater in short-faced patients. Chin width in males was similar for all facial types, whereas, in females, chin width was the widest in the short facial type and the narrowest in the long facial type. Symphysis height was significantly greater in long-faced patients in both sexes. The mandibular incisors' inclination relative to the mandibular plane was not significantly associated with the chin or symphysis morphology.

CONCLUSIONS

Chin and symphysis morphology is facial type-dependent. Orthodontists and maxillofacial surgeons should be aware of the complex relationship between facial types and chin/symphysis size and shape when planning treatment.

Variation in Chin and Mandibular Symphysis Size and Shape in Males and Females: A CT-Based Study

The chin is a unique anatomical landmark of modern humans. Its size and shape play an important role from the esthetic perspective. However, disagreement exists in the dental and anthropological literature regarding the sex differences in chin and symphysis morphometrics. The "sexual selection" theory is presented as a possible reason for chin formation in our species; however, many other contradictory theories also exist. This study's aims were therefore to determine how chin and symphysis size and shape vary with sex, and to discuss "sexual selection" theory as a reason for its formation. Head and neck computed tomography (CT) scans of 419 adults were utilized to measure chin and symphysis sizes and shapes. The chin and symphysis measures were compared between the sexes using an independent-samples t-test, a Mann-Whitney test, and the F-statistic. The chin width was significantly greater in males than in females (p < 0.001), whereas the chin height, area, and size index were significantly greater in females (p < 0.001). Symphysis measures did not differ significantly between the sexes. Size accounted for 2-14% of the chin variance and between 24-33% of the symphysis variance. Overall, the chin was found to be a more heterogeneous anatomical structure than the symphysis, as well as more sexually dimorphic.

The prevalence of posterior crossbite, deep bite, and sleep or awake bruxism in temporomandibular disorder (TMD) patients compared to a non-TMD population: A retrospective study

Objective: To assess the prevalence of posterior crossbite and/or deep bite among patients diagnosed with temporomandibular disorders (TMD) compared to a non-TMD population.Methods: Four hundred ninety-four patients were enrolled: 345 with TMD according to the diagnostic criteria for TMD and 149 without TMD (control group). The chi-square test was used for statistical analysis.Results: A statistically significant association was found between sleep and awake bruxism and painful TMDs (p < .001 for both), but not with disc displacement. There was no association between posterior crossbite and/or deep bite with either painful TMD or disc displacement.Conclusion: Within the study limitations, sleep bruxism and awake bruxism may be related to pain in the TMD, and the severity of a deep overbite and presence of a unilateral or bilateral posterior crossbite should not be considered risk factors or as having any effect on the pain associated with TMD and/or disc displacement.

Association between posterior crossbite and/or deep bite and temporomandibular disorders among Palestinian adolescents: A sex comparison

Objective: To assess the prevalence of temporomandibular disorders (TMDs) and posterior crossbite and/or deep bite and any possible association between them. Methods: One thousand-nineteen adolescents responded to a questionnaire regarding oral habits and TMD symptoms. Afterwards, they were diagnosed according to the Axis I of the DC/TMD and underwent a dental examination. The chi-square test was used for statistical analysis. Results: A significant association  was found between posterior crossbite and some TMD diagnosis, but no association was found between deep bite and TMD, nor between occlusal diagnosis and bruxism. TMDs were more prevalent in girls. There was a significant sex difference (more among females) in the prevalence of painful TMDs. Conclusion: Posterior crossbite in the adolescent population analyzed may be related to TMDs, in contrary to deep-bite. The presence of posterior crossbite may have different impact on TMD findings between the sexes.

An interventional study for improving the manual dexterity of dentistry students

Objectives

Traditionally, the acquisition of manual skills in most dental schools worldwide is based on exercises on plastic teeth placed in a "phantom head simulator". No manual trainings are done at home. Studies revealed that preliminary training of one motoric task leads to significant improvement in performance of the required motoric task that has similar components. Performing tasks indirectly via a dental mirror are complicated for the young dental students. We hypothesized that instructed training of basic skills required in dentistry at home on a tool simulating the phantom laboratory will improve the capabilities of the students and will be reflected by their clinical grades.

Methods

We developed a portable tool PhantHome which is composed of jaws, gingival tissue, rubber cover and a compatible stand. Specific teeth produced by a 3D printer with drills in different directions were placed in both jaws. Students were requested to insert pins by using tweezers and dental mirror according to instructions initiating with easy tasks and continue to ones that are more complicated. 106 first clinical year dental students participated in the study; 65 trained only in the traditional phantom lab (control). 41 trained at home by the PhantHome tool two weeks before and 2 months during the initial stage of phantom lab. The students grades routinely provided in the phantom laboratory at different stages were compared.

Results

Students who trained with the portable tool performed better than the control group in the first direct and second indirect preparations (p<0.05). These exams were taken when the PhantHome was available to the students. Then, the tool was returned and the phantom course continued regularly. We believe that this is why no differences between the grades of the groups were observed further on.

Conclusions

Training by the PhantHome improves motor skills and consequently the clinical performances.

Parental Perceptions of Prosthetic Treatment for and Coping Abilities of Children with Ectodermal Dysplasia: A Pilot Study

Purpose: Congenital absence of teeth (oligodontia) due to ectodermal dysplasia (ED) may impact children's emotional aspects and quality of life. The purpose of this study was to investigate parents' perceptions regarding the impact of ectodermal dysplasia and oligodontia on the self-confidence, self-esteem, self-image, and social life of their children. Methods: Ten parents of ED children were interviewed via semistructured questionnaire. Results: Parents reported that their children became aware of their oligodontia at kindergarten age and received dentures before starting school. The parents also reported that most of the children like going to school and are socially active. Most parents noted that dentures improved the esthetics, self-image, and self-esteem of their children as well as mastication abilities. Conclusions: According to the parents, dentures contribute to the esthetics, self-image, self-esteem, and mastication abilities of children with ectodermal dysplasia. Their appearance generally did not affect their ability to socialize with their peers.

Agenesis of Permanent Canines in Orthodontic Patients: Prevalence, Location, Treatment Options and Outcomes

Purpose: Tooth agenesis is one of the most common anomalies of the human dentition, found most often in the maxillary anterior region and in the mandibular and maxillary premolar regions. Little information is available on the prevalence and distribution of permanent canine agenesis. The purpose of this retrospective study was to evaluate the prevalence and distribution of permanent canine agenesis in orthodontic patients and describe treatment options and outcomes. Methods: The records of 3,000 consecutively treated patients in the Department of Orthodontics, Tel Aviv University, Tel Aviv, Israel were reviewed. The pre-treatment facial and intraoral clinical photographs as well as panoramic and periapical radiographs were used to detect permanent canine agenesis in both dental arches. The data were recorded according to sex, age, number of missing canines, and their location. Results: Twenty-three patients (0.76 percent), nine males (39 percent) and 14 females (61 percent) had 38 congenitally missing canines. Of these, 22 (58 percent) were missing in the maxilla and 16 (42 percent) were missing in the mandible. Conclusions: The overall prevalence of missing permanent canines in our population was 0.76 percent. The female-to-male prevalence ratio was approximately three to two and more canines were missing in the maxilla than in the mandible.

Nonsyndromic orofacial clefts among Jews and non-Jews born in 13 hospitals in Israel during 1993-2005

OBJECTIVES

Orofacial clefts are one of the most common birth malformations and represent a significant public health economic expenditure. The purpose of this investigation was to study the epidemiology of orofacial clefts in newborns from 1993 to 2005 in Israel. In addition, a comparison of data from the National Birth Defects Registry (NBDR) and Hospital records will be made.

METHODS

A retrospective data review of reports to the Israeli NBDR on infants with orofacial clefts in comparison with records reviewed at 13 major hospitals, accounting for 60% of all births in Israel.

RESULTS

Of 1334 newborns found to be with orofacial clefts all over Israel between 1993 and 2005, 1015 were reported to the NBDR and 319 were unreported but retrieved from hospital files. During this period, of the 976 578 live births found in the 13 participating hospitals, there were 866 newborns with orofacial clefts. Of those, 684 (79%) were nonsyndromic orofacial clefts and 182 (21%) had additional syndromes. The prevalence of nonsyndromic orofacial clefts was 7/10 000 live births, lower than reported outside Israel. Only 65% of orofacial clefts retrieved from the 13 hospitals were reported to the NBDR. A significantly higher orofacial cleft prevalence was found among non-Jews than Jews (11 and 6 of 10 000 live births, respectively), (P < .00 001). CL/P was found more frequently than isolated cleft palate (CP). More males had orofacial clefts than females, mostly unilateral with left side predominance.

CONCLUSIONS

The prevalence of nonsyndromic orofacial clefts was found to be 7/10 000 live births. The higher orofacial cleft prevalence among non-Jews may be explained by the high prevalence of consanguinity and deprived maternal nutritional status in this population.

The use of Bjork's indications of growth for evaluation of extremes of skeletal morphology

BACKROUND

Morphological indicators within the cranium for prediction of mandibular growth patterns as reported by Bjork are: (1) inclination of the condylar head (ICH), (2) curvature of mandibular canal (CMC), (3) shape of the lower border of the mandible and specifically depth of the antegonial notch (AN), (4) inclination of the symphysis (ISY), (5) interincisal angle (IIA), (6) intermolar angle (IMA), and (7) lower anterior face height (LAFH). The purpose of this study was to examine the association of these indicators as they relate to extreme skeletal patterns observed in skeletally mature subjects.

MATERIALS

The pre-treatment lateral cephalometric radiographs of 395 post-growth subjects were randomly selected from the archives of a university orthodontic department. These were divided in three groups according to their MP-SN angle [normal: 28-36degrees (G1), hypodivergent: ≤26degrees (G2), hyperdivergent: ≥38degrees (G3)].

RESULTS

It was found that only LAFH was correlated to age across all groups. However, within G1, G2, and G3, and between genders, it was found that there were statistically significant differences for all indicators in relation to age, except IMA (P > 0.05). In addition, ISY and IMA had a predictive value lower than the chance level (0.5).

CONCLUSION

Bjork's implant studies have contributed much to understanding facial-skeletal growth; however, this study suggests that their utilization as a tool in classifying extreme skeletal patterns requires careful evaluation of all the parameters involved.

Fused and Geminated Permanent Maxillary Central Incisors: Prevalence, Treatment Options, and Outcome in Orthodontic Patients

PURPOSE

Developmental disturbances during tooth formation may cause abnormalities in tooth size and shape, resulting in poor dental and facial esthetics. The purpose of this study was to evaluate the prevalence of fused/geminated teeth in the maxillary anterior region of orthodontically treated patients, and present treatment options and their outcome.

METHODS

Pre- and post-treatment facial and intraoral photographs, study models, and panoramic and periapical radiographs of 574 consecutively treated patients (mean age: 13.3 years) from the orthodontic department were examined for the presence of fusion or gemination in the maxillary anterior region.

RESULTS

There were eight patients (1.4 percent) with fused/geminated teeth in the maxillary anterior region.

CONCLUSIONS

The prevalence found is relatively high compared to previous reports. Esthetic consideration is a determining factor for various treatment alternatives. A multidisciplinary approach is imperative for the successful treatment of these dental abnormalities.

Prevalence of non-syndromic orofacial clefts among Jews and Arabs, by type, site, gender and geography: a multi-center study in Israel

BACKGROUND

Orofacial clefts are the most common craniofacial congenital malformations, with significant anatomic, ethnic, racial and gender differences.

OBJECTIVES

To investigate the prevalence, distribution and characteristic features of various types of non-syndromic clefts among Israeli Jews and Arabs.

METHODS

We conducted a retrospective multi-center survey in 13 major hospitals in Israel for the period 1993-2005. To obtain the true prevalence and detailed clinical characteristics, data on liveborn infants with non-syndromic clefts were obtained from the Ministry of Health's National Birth Defect Registry and completed by chart reviews in the 13 surveyed hospitals.

RESULTS

Of 976,578 liveborn infants, 684 presented unilateral or bilateral clefts, with a prevalence of 7.00/10,000 live births; 479 were Jews and 205 were Arabs. The prevalence was higher among Arabs compared to Jews (11.12 and 6.22 per 10,000 live births in Arabs and Jews, respectively, P 0.00001). Males had higher cleft rates than females (7.69/10,000 and 6.17/10,000 live births, respectively, P = 0.05). Males had more cleft lips (P < 0.05) and cleft lips with cleft palate (P < 0.001). There was left-side predominance. Newborns of younger mothers (age < 20 years) and of older mothers (age ≥ 45 years) had higher cleft rates than those with mothers in the 20-44 year bracket (P < 0.009). Children born at or above the 5th birth order had a higher cleft rate (P < 0.001).

CONCLUSIONS

The prevalence of non-syndromic clefts was 7.00/10,000 live births. The markedly higher rate in Arabs is related to the high rate of consanguinity. Both very young and old maternal age represents a higher risk of clefts in their offspring.

Conservative orthodontic treatment for skeletal open bite associated with amelogenesis imperfecta

Amelogenesis imperfect (AI) is a hereditary dental condition that affects tooth enamel, resulting in small and discolored teeth, tooth sensitivity, poor esthetics, and anterior open bite associated with severe discrepancy in the vertical relation of the jaws. Treatment can be complex and includes an interdisciplinary approach involving orthodontics, oral surgery, and restorative therapy. The purpose of this report is to describe the case of a 12-year-old girl with AI and severe open bite who received conservative, non-surgical therapy that led to good functional occlusion and acceptable dental and facial esthetics. A three-year follow-up showed excellent post-treatment stability.

Can cone beam CT predict the hardness of interradicular cortical bone?

Objectives

Orthodontic mini implants can be inserted at the interradicular site. The bone quality at this site may affect the stability and anchorage of the implant. Bone density is clinically evaluated by Hounsfield units (HU) obtained from cone beam CT (CBCT). The objective of this study was to determine the correlations between HU, microhardness and cortical bone thickness of interradicular site at various segments (anterior/posterior) and aspects (buccal/lingual) of both jaws in a swine model.

Materials and methods

Eight mandible and maxilla swine bones were scanned by CBCT. The HU and thickness of the above-mentioned sites were determined. Then, a Knoop microhardness test was applied and the Knoop Hardness Number was obtained (KHN).

Results

The mandible parameters spread over a wider range than the maxilla. The buccal aspect of the maxilla had higher HU and KHN values than the mandible. The lingual aspect of the mandible had higher KHN values than the maxilla. Posterior segments had higher HU and KHN values. The thickness of the alveolar cortical bone was greater in the maxilla than in the mandible. Correlations were found between HU and KHN for 3 of the 4 sites (anterior or posterior, buccal or lingual) of the mandible only. No correlations were found for the maxilla. Upon pooling the HU and KHN data for the whole jaw, correlation was found for the maxilla as well.

Conclusions

Relying on HU values as a predictor of cortical bone hardness should be considered with caution.

The effects of in vitro fluoride mouth rinse on the antibacterial properties of orthodontic cements

OBJECTIVES

To investigate the ability of orthodontic cements to regain their antibacterial effect after aging for 1 month, followed by 2 weeks of fluoride 'recharging' through daily fluoride rinse.

MATERIALS AND METHODS

Four orthodontic cements were tested: composite resin-based materials (Transbond XT and Transbond Plus), a conventional glass ionomer cement (CX Plus) and dual-cured resin-reinforced glass ionomer cement (Fuji ORTHO LC) by direct contact test. After polymerization and a 30-day aging process, the samples were rinsed daily with 0.05% NaF solution for 14 days. Twenty-four hours after the last fluoride rinse, Streptococcus mutans cells (approximately 1 x 10(6) ) were placed on the surface of each sample for 1 h at 37°C to establish direct contact. Bacterial growth was monitored for 24 h by temperature-controlled spectrophotometry. Similar experiments were conducted after aging for 48 h and 72 h after the last fluoride rinse. One-way anova, two-way anova, and Tukey's multiple comparison test were applied to the data.

RESULTS

Twenty-four hours after the last fluoride rinse, the resin-modified glass ionomer and the glass ionomer showed potent antibacterial properties, whereas the composite-based material Transbond XT encouraged bacterial growth. After 72 h, only Fuji Ortho LC maintained its bacteriostatic properties while all the other tested materials showed no antibacterial activity.

CONCLUSIONS

Fourteen days daily fluoride rinse temporarily revives the antibacterial properties of the resin-modified glass ionomer cement and glass-ionomer-based cement.

An ortho-surgical approach to severe impaction using bone crestal bridge: a case report

Impaction of both mandibular canine and lateral incisor is a rare clinical finding which is often treated by way of surgical extraction. This decision is often taken because of the anatomical limitations presented by the mandible, and the horizontal position of the impacted teeth, which have occasionally transmigrated, placing them in close proximity to the roots of neighboring teeth and with a high risk for causing their resorption. In addition, this condition significantly increases the likelihood that the area involved will undergo gingival recession and loss of crestal bone if an unsophisticated ortho-surgical approach is undertaken. The present report describes a novel ortho-surgical technique which maintains the alveolar crestal bone and utilizes a lingual arch attached to the first molars with traction through tunneling with super-elastic springs. This combined approach eliminated the need for extraction of the impacted teeth, and accomplished their full alignment without any of the aforementioned side effects. Every dentist (general practitioners as well as specialists) should be aware of this procedure and refer patients to a specialist.

Malocclusion in early anatomically modern human: a reflection on the etiology of modern dental misalignment

Malocclusions are common in modern populations. Yet, as the study of occlusion requires an almost intact dentition in both the maxilla and mandible, searching for the ultimate cause of malocclusion is a challenge: relatively little ancient material is available for research on occlusal states. The Qafzeh 9 skull is unique, as its preserved dentition allowed us to investigate the presence and manifestations of malocclusion. The aim of this study was thus to examine the occlusal condition in the Qafzeh 9 specimen in light of modern knowledge regarding the etiology of malocclusion. We revealed a pathologic occlusion in the Qafzeh 9 skull that probably originated in the early developmental stage of the dentition, and was aggravated by forces applied by mastication. When arch continuity is interrupted due to misalignment of teeth as in this case, force transmission is not equal on both sides, causing intra-arch outcomes such as mesialization of the teeth, midline deviation, rotations and the aggravation of crowding. All are evident in the Qafzeh 9 skull: the midline deviates to the left; the incisors rotate mesio-buccally; the left segment is constricted; the left first molar is buccally positioned and the left premolars palatally tilted. The inter-arch evaluation revealed anterior cross bite with functional shift that might affect force transmission and bite force. In conclusion, the findings of the current study suggest that malocclusion of developmental origin was already present in early anatomically modern humans (AMH) (the present case being the oldest known case, dated to ca. 100,000 years); that there is no basis to the notion that early AMH had a better adjustment between teeth and jaw size; and that jaw-teeth size discrepancy could be found in prehistoric populations and is not a recent phenomenon.

Efficacy of three hygienic protocols in reducing biofilm adherence to removable thermoplastic appliance

Objectives:

To examine the ability of a removable thermoplastic appliance (RTA) to adsorb hygienic solutions and inhibit bacterial growth and to examine the efficacy of three hygiene protocols in reducing bacterial biofilm adherence to RTA.

Materials and Methods:

Solution adsorption and bacterial growth inhibition were examined in vitro using paper vs RTA discs. Subsequently, 11 patients treated with RTA (mean age, 29.1 ± 4.7 years) were assigned into a sequence of three hygiene protocols: regular RTA brushing (baseline), immersion RTAs in chlorhexidine mouthwash (CHX), and using a vibrating bath with cleaning solution (VBC). For each patient, 12 upper RTAs were examined (2 baseline RTAs, 5 CHX RTAs, and 5 VBC RTAs), for a total of 132 RTAs. All RTAs were stained with gentian violet, and biofilm presence was measured using a photodensitometer.

Results:

The RTA discs did not adsorb CHX or cleaning solution. The later agent did not show antibacterial features. Baseline RTAs showed significant biofilm adherence (P &lt; .001) on the posterior palatal side of the aligner and on the anterior incisal edge. CHX and VBC hygienic protocols significantly (P &lt; .001) reduced baseline biofilm adherence by 16% and 50%, respectively. Hygienic improvement was maintained over 140 days when CHX and VBC were used. However, VBC was three times more efficient than CHX.

Conclusions:

This study highly recommends the use of a VBC protocol. Biofilm deposits on the RTA, especially on incisal edges and attachment dimples, could lead to inadequate tooth/RTA and attachment/RTA overlap and consequently impair tooth alignment.

Mandibular second molar impaction. Part I: Genetic traits and characteristics

INTRODUCTION

Detection of mandibular second molar (MM2) impaction is imperative for orthodontic diagnosis and treatment. In this study, we examined a possible genetic trait in MM2 impaction in 2 populations and defined distinctive characteristics.

METHODS

Initial panoramic radiographs of patients of Israeli (n = 3500) and Chinese-American (n = 3000) origin, aged 11 to 15 years, were examined. Twelve distinctive characteristics were compared between the unilateral impacted and the nonimpacted sides.

RESULTS

A total of 120 subjects with MM2 impaction were found (1.8%). The Chinese-American population had a higher prevalence (n = 71, 2.3%) of MM2 impaction compared with the Israeli population (n = 49, 1.4%; P = 0.004). For the subjects with MM2 impaction, the Israelis had significantly (P = 0.039) fewer bilateral impactions (27%) than did the Chinese-Americans (45%). Mesially inclined impacted MM2s were more common (88% and 89%) in the Israeli and Chinese-American populations, respectively. The unilateral impacted side demonstrated reductions in the distance between the mandibular first molar and the ramus (P <0.001), the length of the mesial root of the MM2 (P <0.001), and the height between the MM2 and the mandibular third molar, and increases in the angulations of the MM2 (P <0.001) and the mandibular third molar (P <0.003).

CONCLUSIONS

An autosomal genetic trait is present in MM2 impaction with greater penetrance in the Chinese-American population. Within developmental impediments, the deficient mesial root length of the MM2 is the primary impaction factor.

Incremental growth of the maxillary tuberosity from 6 to 20 years-A cross-sectional study

OBJECTIVES

Although the maxillary tuberosity (MT) is a major growth site of the maxilla, its time-related growth was not fully investigated. The objectives of the study were to evaluate the MT growth from 6 to 20 years of age defining the peak growth age and to assess time-related indicators.

DESIGN

Panoramic radiographs from 189 patients were divided in a cross-sectional study into six age groups. A special panoramic analysis was developed including 18 parameters and 3 time-related indicators, i.e., chronological age, crown/root development stages of the maxillary second (M(2)) and third (M(3)) molars and eruption stages.

RESULTS

From 6 to 20 years, the MT vertical growth was 5.17-fold greater than the horizontal. The horizontal growth covered 36% of the maxillary growth but was inadequate to secure space for third molar eruption despite a 51% increase in MT area. MT peak growth was between 8 and 9 years and 10-11 year. During these 14 years, the maxillary length increased by pneumatisation of the maxillary sinus (86%), growth of the MT (36%) and decrease of the anterior maxillary region (-22%). Of the 18 examined parameters, 83% showed dependency to the combination chronological age with M(2), M(3) crown/root development stage and 72% to the combination chronological age with M(2), M(3) eruption stage.

CONCLUSION

MT growth peak occurs with initiation of root development of M(2) and shortly before M(2) eruption (8-9 years to 10-11 years). Dental time-related indicators adjunct with the chronological age provide an effectual system to define MT growth potential.

Duration and Anchorage Management of Canine Retraction with Bodily Versus Tipping Mechanics

Objective: To compare tipping mechanics (TM) and bodily mechanics (BM) with respect to duration, angulation, and anchorage loss during canine retraction.

Materials and Methods: TM and BM brackets were bonded to the upper right and left canines, respectively, of 14 subjects requiring maxillary first premolar extractions. The upper canines were retracted with variable nickel titanium closed coil springs (F = 0.50 or 0.75 N) attached posteriorly to a Nance anchorage appliance through the first molars. Panoramic radiographs and dental casts were taken at five time points. Canine angulation was assessed with custom metallic jigs inserted into the vertical slots of the canine brackets prior to radiographic exposure.

Results: The canine crown contacted the second premolar after 102.2 ± 106 and 99.0 ± 80.0 days, and achieved root uprighting in 72.0 ± 31.3 and 37.2 ± 42.7 additional days with the TM and BM groups, respectively. Only the uprighting stage differed significantly between the two mechanics (P &lt; .05). During retraction, tooth angulation differed significantly (P &lt; .001) between the TM (6°) and BM (−0.8°) groups. Anchorage loss, as assessed by mesial molar movement, was 1.2 ± 0.3 mm and 1.4 ± 0.5 mm for the TM and BM groups, respectively.

Conclusions: Bodily canine retraction occurred faster (38 days) than tipping due to a shorter duration of root uprighting. Anchorage loss (17%–20%) was similar for both retraction methods, ie, maximum anchorage could not be provided by the Nance appliance. Both TM and BM brackets had inadequate rotational control of the retracted canine.

Labial cervical vertical groove (LCVG) distribution and morphometric characteristics

OBJECTIVE

Labial cervical vertical groove (LCVG), a dental anomaly found at the cervical region of upper permanent incisors, can be of esthetic, periodontal and prosthetic concern. The aim of this study was to define the prevalence and characteristics of LCVG.

DESIGN

Of the 1250 examined subjects, 66 exhibited an LCVG. This group (age 19.7+/-11.4 years) was then compared with a matched No-LCVG (control) group of 49 subjects (age 17.9+/-5.7 years). Six LCVG characteristics were examined: distribution, severity and location of LCVG in central (I(1)) and lateral (I(2)) permanent maxillary incisors, Angle's classification, gender and presence of LCVG in siblings.

RESULTS

Total LCVG prevalence was 5.3% (single 3.76%; multiple 1.53%), found predominantly in I(1) (93.9%) compared with I(2) (p=0.001). The anomaly presented mostly as a single configuration (71.21%); double configuration was predominantly homological bilateral, i.e., I(1)+I(1), or I(2)+I(2) (88%). LCVG in I(2) was mainly associated with multi-configuration (75%). The severe form occurred only in I(1). A mid-crown LCVG allocation was distinctive in I(1) (62.2%, p=0.001) and mesial-crown in I(2) (66.7%, p=0.038). LCVG was found mostly in males (p=0.045). In the LCVG group 16.7% were siblings.

CONCLUSIONS

LCVG primarily involved I(1) in single configuration as the target assaulted tooth and secondarily I(2) mostly as a multi-configuration. The genetic impact on LCVG formation was primarily supported by the high prevalence in siblings and secondarily by the favourable occurrence in males, exclusive pattern of allocation within the crown and high occurrence of bilateral double-configuration LCVG.

Bracket placement in lingual vs labial systems and direct vs indirect bonding

OBJECTIVE

To examine the ultimate accuracy of bracket placement in labial vs lingual systems and in direct vs indirect bonding techniques.

MATERIALS AND METHODS

Forty pretreatment dental casts of 20 subjects were selected. For each dental cast, four types of bracket placement were compared: labial direct (LbD), labial indirect (LbI), lingual direct (LgD), and lingual indirect (LgI). Direct bonding was performed with the casts held in a mannequin head. Labial brackets were oriented with a Boone gauge, and lingual brackets were oriented with the Lingual-Bracket-Jig System. Torque error (TqE) and rotation deviation (RotD) were measured with a torque geometric triangle and a toolmaker's microscope, respectively. Both torque and rotational measurements were evaluated statistically as algebraic and absolute numeric values, using analysis of variance with repeated measures.

RESULTS

Absolute TqE and RotD were significantly (P < .001) higher in direct than in indirect bonding techniques higher in both the labial and lingual bracket systems by twofold and threefold, respectively (LbD = 7.26 degrees , 1.06 mm; vs LbI = 3.02 degrees , 0.75 mm; LgD = 8.42 degrees , 1.13 mm; vs LgI = 3.18 degrees , 0.55 mm). No statistically significant difference was found between labial and lingual systems for the same bonding technique. Maxillary incisors demonstrated the largest RotD angle (eg, right lateral: 12.04 degrees ). A distal off-center RotD was predominant in the mandibular dentition.

CONCLUSIONS

Labial and lingual systems have the same level of inaccuracy. For both systems, indirect bonding significantly reduces absolute TqE and RotD. The TqE found can cause transverse discrepancy (scissors or crossbite) combined with disclusion with antagonist teeth. The RotD found can result in irregular interproximal contact points.

[Is there a tendency for professional saturation in orthodontics in Israel?]

OBJECTIVES

The purpose of the present study is to evaluate the demand for orthodontic treatment in Israeli society, and determine the adequacy of the profession to provide service. In addition, a database of Israeli orthodontic specialist demographics will be compiled.

METHODS

There is no statistical information available as to the orthodontic treatment needs and demands in Israel. Furthermore, no survey exists measuring response to orthodontics by the Israeli patient population (i.e. attitudes, treatment time etc). In order to gauge these parameters, a written questionnaire was distributed to all the orthodontists in Israel (specialists, post graduate students and dentists who have completed their orthodontic training but have not yet earned specialist certification). The survey contained questions regarding work hours (full or partial time), the numbers of orthodontic care facilities and the distance travelled to each office, the orthodontist's claim of "free time", and whether there is a desire to increase the time spent treating patients.

RESULTS

A total of 89 orthodontists complied with the conditions of the study. Sixty nine (77.5%) were male, and 65 (73%) of them were certified specialists. It was found that 9% of the responding orthodontists practiced general dentistry in addition to orthodontics during at least 25% of their clinic time. A majority of the orthodontists (60/89) work in more than one office and 27% work in four or more different offices. About a quarter (25.8%) of the responding orthodontists report having less work than they desire and 16.9% of the orthodontists would like to work 10 or more additional hours per week. The majority of the orthodontists (80.9%) live in the central part of Israel and they travel long distances to work. Almost half of the offices (47.6%) are located 30 km or more away from their homes.

CONCLUSIONS

The present survey indicates that the demographics within the orthodontic specialty tend towards that of professional over-supply (saturation). It was also found that the majority of the orthodontists live in the central region of Israel, therefore, travelling to satellite offices is inherently time consuming.

Posterior and anterior components of force during bite loading

Late anterior crowding of teeth has been associated with the anterior component of force (ACF) developed during biting. Possible physiologic mechanisms countering ACF, including the presence of a posterior component of force (PCF), are hypothesized. In this self-controlled study, 60 subjects aged 27.05+/-3.9 years were examined for ACF and PCF that were calculated as the change in tightness of a mandibular dental contact points from non-biting to biting state. Both ACF and PCF were found to develop simultaneously. However, the PCF was 4-7 folds smaller than the ACF (p<0.001). The ACF progressively declined by 10-20 folds (p<0.001) from the posterior to anterior dentition. The lateral incisor-canine contact point had the greatest ACF decline (63-74%). ACF effect on the anterior dentition is counteracted by a protective mechanism consisted of PCF, progressive dissipation of ACF, and canine blockage.

Assessment of open and incomplete bite correction by incisor overlap and optical density of polyvinyl siloxane bite registration

Open bite (OB) is a generalized term, which could incorporate subgroups that react differently to vertical correction. The objectives of the present study were to detect vertical treatment changes in incomplete bite (IB: inter-incisor overlap with no lower incisor contact with teeth or palate) and OB (no inter-incisor overlap) groups compared with a complete bite (CB: inter-incisor overlap with full lower incisor contact with teeth or palate) control group, to evaluate treatment response of the central and lateral incisors, and to study the vertico-sagittal interaction. Dental casts were taken at three time points, pre-treatment, post-treatment, and after one year of retention, from 54 Class II patients (22 males and 32 females with a mean age of 11 years 6 months) divided into three groups: CB (n = 21), IB (n = 18) and OB (n = 15). Measurements included incisor overlap (mm) and optical density (OD/mm2) of occlusal bite registration made of polyvinl siloxane. Both CB and IB groups demonstrated post-retention bite opening. However, bite opening in the CB group was three times greater than that in the IB group (e.g. lower lateral = -1.42 mm, 118 OD/mm2 versus -0.40 mm, 107 OD/mm2). Conversely, the OB group showed a significant (P < 0.001) bite closure (e.g. lower lateral = 1.30 mm, -377 OD/mm2). Overjet changes affected OD measurements, causing diversity in OD and millimetric measurements of the lateral incisors in the IB group. In conclusion, the OB group demonstrated a significant stable vertical correction; a post-treatment non-contact inter-incisor relationship was determined by a vertico-sagittal relapse; and full compensation of an IB was not possible.

Anchorage loss--a multifactorial response

Anchorage loss (AL) is a potential side effect of orthodontic mechanotherapy. In the present study, it is defined as the amount of mesial movement of the upper first permanent molar during premolar extraction space closure. In addition, AL is described as a multifactorial response in relation to the extraction site, appliance type, age, crowding, and overjet. For this study, 87 university clinic and private practice subjects, who were defined as maximum anchorage cases and had undergone bilateral maxillary premolar extractions, were divided into four groups according to extraction site (first vs second premolars), mechanics (lingual vs labial edgewise appliances), and age (adolescents vs adults). Overjet and crowding were examined from the overall sample. Data were collected from serial lateral cephalograms and dental casts. The results showed that as the severity of dental crowding increased, AL significantly decreased (r = -0.66, P = .001). Labial edgewise appliances demonstrated a significantly greater AL than did lingual edgewise appliances (1.15 +/- 2.06 mm, P < .05). A greater, though not statistically significant, AL was found in adults than in adolescents (0.73 +/- 1.43 mm). There was a slight nonsignificant increase in AL between maxillary second compared with first premolar extractions (0.51 +/- 1.33 mm). Overjet was weakly correlated to AL. These results suggest that AL is a multifactorial response and that the five examined factors can be divided into primary (crowding, mechanics) and secondary factors (age, extraction site, overjet), in declining order of importance.

An assessment of skeletal and dental responses to the functional magnetic system (FMS)

Correction of a skeletal Class II malocclusion with functional appliances has been accepted as a viable treatment modality. However, its mechanism of action is still disputed. This retrospective study compared 20 Class II patients treated with the functional magnetic system (FMS) with Class I and Class II groups (the control groups) of 20 untreated subjects each. Dental and skeletal changes were compared using serial lateral cephalograms. The FMS group differed significantly from the control groups in 15 of 24 parameters. The great increase in articulare-gnathion distance (3.07 mm) attributed to the attractive magnetic component of the FMS dictates a prolonged propulsion of the mandible. The skeletal:dental response ratio was 1:2 for the anterior region and 1:1 for the posterior region. The dental and skeletal parameters demonstrated a synergistic response in the maxilla and a competitive response in the mandible. This means that greater maxillary molar distal movement and incisor retroclination resulted in a more significant restraint of point A. In contrast, increasing the mandibular molar mesial movement and the incisor proclination accompanied less advancement of the pogonion. Although the skeletal contribution to the resolution of the malocclusion was less than the dental contribution (anteriorly, one third), the functional correction response was found to be regulated by skeletal factors.

The etiology of palatal displacement of maxillary canines

OBJECTIVES

To test the hypothesis that palatal displacement of the maxillary canine is completely under genetic influence.

DESIGN

A randomized controlled design studied cases affected by a severe expression of lateral incisor anomaly on one side and by milder expression of the same anomaly on the other. Comparison of frequency of occurrence of unilateral palatally displaced canine measured in each. Each side acted as control for the other within the same individual.

SETTING AND SAMPLE POPULATION

The Departments of Orthodontics of the Universities of Jerusalem and Tel Aviv and in private practice. From approximately 12,000 consecutively treated patients, all those exhibiting an anterior maxilla with a missing lateral incisor on one side, a peg-shaped or reduced lateral incisor on the other, and a palatally displaced canine (n = 19).

OUTCOME MEASURE

Missing lateral incisors, peg-shaped, and reduced lateral incisors (all genetically determined characters) have been shown to be associated with palatal displacement of the canine. The canine displacement is presumed by some authorities to be similarly genetically determined. If this is so, then the impacted canine should occur with equal frequency on either side in the patient with a missing lateral incisor on one side and a peg-shaped or reduced lateral incisor on the other.

RESULTS

The canine aberration occurred far more frequently on the side of the diminutive lateral incisor.

CONCLUSION

There is an environmental factor involved in the palatal displacement of maxillary canines.

Attachment bonding to impacted teeth at the time of surgical exposure

This study examines the relative success of bonding an attachment to an impacted tooth at the time of surgical exposure, compared with placing it on a subsequent occasion. In addition, the relative merits of various attachments, the choice of bonding site and whether or not pumice prophylaxis is necessary, were tested. The results showed that bonding at the time of exposure is superior to its performance at a later date, that the use of an eyelet attachment has a lower failure rate than the use of a conventional bracket, that the palatal aspect offers the poorest bonding surface and that pumicing the exposed tooth offers no advantage over immediate etching of the exposed enamel. The results of this study refute the view that the circumstances prevalent at the time of surgical exposure are not conducive to the reliable bonding of an attachment to an impacted tooth.