Five years of experience using palatal mini-implants for orthodontic anchorage.

PURPOSE: The authors review 5 years of clinical experience using Straumann Orthosystem (Straumann, Basel, Switzerland) palatal mini-implants for orthodontic anchorage, describe clinical procedures, and give statistical results. MATERIALS AND METHODS: Diagnostic planning, surgical phase, and clinical procedure are described. The diagnostic planning was performed on lateral cephalogram in 13 cases; in 1 case, with an ectopically included upper canine, a computed tomography was requested. The Straumann Orthosystem kit includes a pure titanium implant with the healing cap, and a set of burs and instruments for the surgical insertion and removal. The sample comprised 14 adult patients (2 males and 12 females) requiring fixed orthodontic appliance for Class II malocclusion. Because of critical anchorage conditions they had received a palatal mini-implant as absolute anchorage during orthodontic treatment: 9 implants of 6.0 mm and 7 implants of 4.0 mm were positioned, primarily using a 2.5 mm transmucosal neck length. The orthodontic phase always started after 13 weeks of the insertion, in order to ensure osteointegration. RESULTS: In all cases, neither a perforation of the nasal cavity nor other surgical complication occurred. All implants have been successfully osteointegrated, except for 1 which has been lost for critical hygiene conditions. Two implants needed to be replaced because of tongue forces, which had been determined to interfere with the osteointegration immediately after surgery; this inconvenience was afterwards solved by the use of a resin splint. CONCLUSIONS: Palatal mini-implants revealed to be clinically easy to use and proved to be an efficient auxiliary device in orthodontics when absolute anchorage is needed.

Somatosensory evoked potentials of inferior alveolar nerve.

PURPOSE: The use of inferior alveolar nerve somatosensory evoked potentials may represent an objective means of evaluating sensory nerve function in the maxillofacial region. The aim of this work was to confirm the existence of a standard sequence of prominent events in the trigeminal somatosensory evoked potentials (TSEPs) of inferior alveolar nerve (IAN) waveform, examine those components and their normal variability by statistical analysis, and discuss TSEPs' nervous origin and some patterns of TSEPs' abnormalities due to dysfunctional nerves. MATERIALS AND METHODS: TSEPs were obtained following electrical stimulation (square wave pulses 0.2 millisecond [ms] in duration, 4 to 6.5 mA, 0.7/second repetition rate, 200 averages) of the gum at the mental foramen level via intraoral surface electrodes and recorded from the contralateral central scalp sites. RESULTS: We successfully recognized steady waveforms of sufficient quality and consistently recorded a "W"-shaped response: latency onset and peak of the initial deflection of positive polarity were approximately 12 ms and 20 ms, respectively. Negative and positive deflections followed with respective peak latencies at around 26 ms and 36 ms. One side of the lower lip can be compared with the contralateral side and patients may serve as their own control in cases of unilateral nerve injury. The anaesthetic block showed the total abolition of responses. Reproducible TSEP waveform was only obtained during nerve stimulation and not during masseter muscle stimulation. CONCLUSIONS: TSEPs, obtained with the present technique, may represent an objective, low-invasive, and reliable way of testing sensory nerve function in the maxillofacial region.