Mladen M. Kuftinec

A biometric study of tooth size and dental crowding

A study was conducted for the purpose of comparing mesiodistal tooth widths between a group of patients with good tooth alignment and a group of patients with crowded dental arches. Crowded arches were defined as those with more than 4 mm. of space deficiency. The hypothesis tested was whether the arches with more than 4 mm. of crowding consistently had larger teeth than the ones with lesser or no crowding. The difference in sizes between the groups (forty males and forty females) for all teeth measured was found to be statistically significant (p less than 0.001). The multivariate data analysis indicated that the two groups were derived from two different populations and that the maxillary lateral incisors and second premolars and the mandibular canines and premolars were particularly different in these groups. It was also determined that the teeth in males were uniformly larger than in females, but not to a statistically significant level. There was less correlation, however, between the sex and the status of the tooth alignment in dental arches, so that both sexes had similar distribution of crowding versus noncrowding. On the basis of this study of eighty North American Caucasians, it is suggested that one should consider the sum of mesiodistal widths of teeth, in addition to the arch length analysis, in formulating an orthodontic treatment plan. When the cumulative tooth mass of the twenty permanent teeth is 140 mm. or more, the clinician may want to consider extraction therapy for such a case.

Hypodontia in Children with Various Types of Clefts

The prevalence of hypodontia in children with clefts, both inside and outside the cleft region, and the possible association between the side of the cleft and the side of the missing teeth were studied using radiographs of 278 patients with cleft lip, cleft palate, or both (158 boys and 120 girls), age 5 to 18 years (mean age 10.4 years). A hypodontia prevalence of 77% (excluding third molars) was found for the total cleft sample. This was significantly higher, both statistically and clinically, than the incidence of hypodontia reported for noncleft populations, and considerably higher than the prevalence reported in other studies of children with clefts. The maxillary permanent lateral incisors were the teeth most frequently missing on the cleft side (259 teeth) followed by the maxillary (47 teeth) and mandibular (23 teeth) second premolars, in both boys and girls. The teeth that were most often missing on the noncleft side were the maxillary second premolars (12 teeth), followed by the maxillary lateral incisors (10 teeth) and mandibular second premolars (6 teeth). Hypodontia of both the maxillary lateral incisors and second premolars was found more frequently on the left side, which also has a higher frequency of clefting.

Tooth transpositions — a review of the literature and treatment considerations

This paper defines tooth transposition and discusses its history, incidence and possible etiology. An interesting parallel is drawn between tooth transposition and other dental anomalies (number, size, shape and location of teeth). Treatment options are discussed in terms of the age at which the transposition is discovered, as well as in terms of severity and completeness of the anomaly. While a logical and relatively predictable treatment solution should normally be considered, in some selected cases it may be prudent to venture into more complex treatment solutions.

Congenitally missing second premolars in cleft lip and cleft palate children

Panoramic and periapical radiographs of 278 patients with cleft lip, cleft palate, or both (158 males and 120 females), age 5 to 18 years, were examined to determine the frequency of missing second premolars and the possible association between the cleft side and the side from which the premolar was absent. The prevalence (18%) of missing premolars found in this study is significantly higher than is found in the general population. A considerably higher incidence of missing second premolars was found in the maxilla compared with the mandible both for unilateral and bilateral missing teeth. The second premolar was absent more frequently on the left than on the right side, both in males and females and in both jaws. Interestingly but consistent with our previous reporting, this corresponded to the side where clefts occurred more often. The cause of the higher prevalence of left-sided clefts and missing second premolars in human beings is not known at the present time.

The distribution of clefts of the primary and secondary palates by sex, type, and location

The frequency and patterns of distribution of cleft lip, cleft lip and alveolus, cleft lip and palate, and isolated cleft palate, together with the possible association between sex, type of cleft, and affected side were studied from records of 278 individuals with clefts. These records were obtained from four cleft centers in the New York City area and constituted a racially mixed urban sample. The type of the cleft varied between sexes. Males had significantly higher rates of cleft lip and palate (p<0.0001), and females had higher rates of isolated cleft palate (p<0.0001). No sex differences were found for cleft lip or cleft lip and alveolus. Unilateral clefts of both the primary and secondary palates were found to occur over three times more frequently than bilateral clefts, and left side predominance was demonstrated.

Intrabony Migration of Impacted Teeth

Intrabony migration of impacted teeth is a rare dental anomaly, which occurs only in the permanent dentition of the lower jaw. The teeth involved in this phenomenon are the mandibular lateral incisor, canine, and second premolar. Migration of the lateral incisor is usually in a distal direction, resulting in transposition with the canine. Migration of the canine is most frequently in a mesial direction, resulting in transmigration across the mandibular symphysis to the opposite side of the dental arch. The second premolar most often migrates distally, sometimes past the gonial angle and as far as the coronoid process. Surgical and orthodontic treatment options are presented for the three intrabony migrating teeth.

Condyle-fossa modifications and muscle interactions during Herbst treatment, Part 1. New technological methods

Changes in the condyle, the glenoid fossa, and the muscles of mastication were investigated in subjects undergoing continuous orthopedic advancement of the mandible with a Herbst-block appliance. The total sample consisted of 56 subjects and included 15 nonhuman primates (in the middle mixed, early permanent, and permanent dentitions), 17 human Herbst patients in the early permanent dentition, and 24 human controls from the Burlington Growth Center. The 8 nonhuman primates in the middle mixed dentition were the focus of this study. Mandibular advancement was obtained progressively in 5 animals by adding stops to the telescopic arms of fixed functional Herbst appliances with occlusal coverage; activations of 5.0 mm, 7.0 mm, and 8.0 mm were achieved. Two primates served as controls, and the third was a sham control. Two experimental animals and the 2 controls also wore surgically implanted electromyographic electrodes in the superior and inferior heads of the lateral pterygoid muscles and in the superficial masseter and anterior digastric muscles. Changes in condylar growth direction and amount were assessed with the Björk method from measurements made on serial cephalometric tracings superimposed on metallic implants. Undecalcified sections, treated with intravenous tetracycline vital staining, were viewed with fluorescence microscopy to examine histologic changes in the condyle and the glenoid fossa. New bone formation in the fossa associated with continuous mandibular protrusion was quantified by using computerized histomorphometric analysis of decalcified histological sections and polarized light. The unique combination of permanently implanted electromyographic electrodes, tetracycline vital staining, and histomorphometry represents a significant technological advancement in methods and materials. Together, they demonstrated different muscle-bone interaction results for functional appliances than those reported in previous studies. In Part 1 of this study, we describe and discuss the techniques used in this research and give a brief overview of the findings; in Part 2 (to be published next month), we offer a more in-depth discussion of the results and the implications of our findings.

Improved clinical use of Twin-block and Herbst as a result of radiating viscoelastic tissue forces on the condyle and fossa in treatment and long-term retention: Growth relativity

Understanding mechanisms of action for orthopedic appliances is critical for orthodontists who hope to treat and retain the achieved corrections in patients with initial Class II mandibular retrognathism. That knowledge can help orthodontists produce clinically significant bone formation and avoid compression at the condyle-glenoid fossa region. It also assists us to understand the differences between short-term and long-term treatment results. It was previously thought that increased activity in the postural masticatory muscles was the key to promoting condyle-glenoid fossa growth. By analyzing results from several studies, we postulate that growth modification is associated with decreased activity, which leads to our nonmuscular hypothesis. This premise has its foundation on 3 key specific findings: significant glenoid fossa bone formation occurs during treatment that includes mandibular displacement; glenoid fossa modification is a result of the stretch forces of the retrodiskal tissues, capsule, and altered flow of viscous synovium; observations that glenoid fossa bone formation takes place a distance from the soft tissue attachment. The latter observation is explained by transduction or referral of forces. Evidence is presented, therefore, that the 3 trigger switches for glenoid fossa growth can similarly initiate short-term condylar growth modifications because the 2 structures are contiguous. These are displacement, several direct viscoelastic connections, and transduction of forces. Histologic evidence further shows that stretched retrodiskal tissues also insert directly into the condylar heads fibrocartilaginous layer. The impact of the viscoelastic tissues may be highly significant and should be considered along with the standard skeletal, dental, neuromuscular, and age factors that influence condyle-glenoid fossa growth with orthopedic advancement. These biodynamic factors are also capable of reversing effects of treatment on mandibular growth direction, size, and morphology. Relapse occurs as a result of release of the condyle and ensuing compression against the newly proliferated retrodiskal tissues together with the reactivation of muscle activity. To describe condyle-glenoid fossa growth modification, an analogy is made to a light bulb on a dimmer switch. The condyle illuminates in treatment, dims down in the retention period, to near base levels over the long-term.

Uprighting mesially impacted mandibular permanent second molars

Impaction of permanent teeth is a relatively common occurrence and can involve any tooth in the dental arch. Impacted mandibular second molars are relatively rare, but when they occur they may present a clinical problem for the orthodontist and oral surgeon. A typical case of bilaterally impacted mandibular second molars is illustrated, with orthodontic and surgical treatment options presented. Emphasis is placed on early diagnosis and initiation of corrective orthodontic therapy.

Maxillary canine-lateral incisor transposition—Orthodontic management

A case of maxillary canine-lateral incisor complete transposition is presented. Treatment options for transposed teeth, including alignment in their transposed positions, extraction of one or both transposed teeth, and orthodontic alignment to their normal positions in the arch, are discussed. The orthodontic technique and sequence used in this challenging case to align the fully transposed teeth to their normal position in the dental arch are described.